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HARDENABILITY
Hardenability
bull The ability of an alloy to be hardened by the formation of martensite as a results of a given heat treatment It is a qualitative measure of the rate at which hardness drops off with distance into the interior of a specimen as a result of diminished martensite content Steels with high hardenabilityform martensite even on slow cooling It can be tested experimentally bythe Jominy End-Quench
3
Heat Treatment of Steels Hardenability
bull Hardenability is the capability of an alloy steel to form martensite as a result of a given heat treatment
bull NOTE hardness hardenabiltybull High hardenability in a steel means that the steel
forms martensite not only at surface but to a large degree throughout the interior
bull Hardenability more related to depth of hardness of a steel upon heat treat
bull The depth of hardening in a plain carbon steel may be 2-3 mm vs 50 mm in an alloy steel
4
Heat Treatment of Steels Hardenability
bull How is the hardenability of steels assessed
ndash Jominy End-Quench Test
ndash Test bar is heated to form 100 austenite It is then quenched directly at one end with a stream of water
Jominy Test
Generally the faster steel cools the harder it will be The Jominy bar measures the hardenbility of a steel
Softest
Hardest
6
bull Ability to form martensitebull Jominy end quench test to measure hardenability
bull Hardness versus distance from the quenched end
24degC water
specimen (heated to phase field)
flat ground
4rdquo
1rdquo
Hard
ness
H
RC
Distance from quenched end
Fig 145
Hardenability of Steels
Jominy Test for Hardenability
bull Hardenability not the same as hardness
8
Heat Treatment of Steels HardenabilityThe cooling rate thus varies throughout the length of the bar the rate being highest at the lower end which is in direct contact with waterThe hardness along the length of the bar is then measured at various distances from the quenched end and plotted in a graphThe greater the depth to which the hardness penetrates the greater the hardenability of the alloy
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Hardenability
bull The ability of an alloy to be hardened by the formation of martensite as a results of a given heat treatment It is a qualitative measure of the rate at which hardness drops off with distance into the interior of a specimen as a result of diminished martensite content Steels with high hardenabilityform martensite even on slow cooling It can be tested experimentally bythe Jominy End-Quench
3
Heat Treatment of Steels Hardenability
bull Hardenability is the capability of an alloy steel to form martensite as a result of a given heat treatment
bull NOTE hardness hardenabiltybull High hardenability in a steel means that the steel
forms martensite not only at surface but to a large degree throughout the interior
bull Hardenability more related to depth of hardness of a steel upon heat treat
bull The depth of hardening in a plain carbon steel may be 2-3 mm vs 50 mm in an alloy steel
4
Heat Treatment of Steels Hardenability
bull How is the hardenability of steels assessed
ndash Jominy End-Quench Test
ndash Test bar is heated to form 100 austenite It is then quenched directly at one end with a stream of water
Jominy Test
Generally the faster steel cools the harder it will be The Jominy bar measures the hardenbility of a steel
Softest
Hardest
6
bull Ability to form martensitebull Jominy end quench test to measure hardenability
bull Hardness versus distance from the quenched end
24degC water
specimen (heated to phase field)
flat ground
4rdquo
1rdquo
Hard
ness
H
RC
Distance from quenched end
Fig 145
Hardenability of Steels
Jominy Test for Hardenability
bull Hardenability not the same as hardness
8
Heat Treatment of Steels HardenabilityThe cooling rate thus varies throughout the length of the bar the rate being highest at the lower end which is in direct contact with waterThe hardness along the length of the bar is then measured at various distances from the quenched end and plotted in a graphThe greater the depth to which the hardness penetrates the greater the hardenability of the alloy
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
3
Heat Treatment of Steels Hardenability
bull Hardenability is the capability of an alloy steel to form martensite as a result of a given heat treatment
bull NOTE hardness hardenabiltybull High hardenability in a steel means that the steel
forms martensite not only at surface but to a large degree throughout the interior
bull Hardenability more related to depth of hardness of a steel upon heat treat
bull The depth of hardening in a plain carbon steel may be 2-3 mm vs 50 mm in an alloy steel
4
Heat Treatment of Steels Hardenability
bull How is the hardenability of steels assessed
ndash Jominy End-Quench Test
ndash Test bar is heated to form 100 austenite It is then quenched directly at one end with a stream of water
Jominy Test
Generally the faster steel cools the harder it will be The Jominy bar measures the hardenbility of a steel
Softest
Hardest
6
bull Ability to form martensitebull Jominy end quench test to measure hardenability
bull Hardness versus distance from the quenched end
24degC water
specimen (heated to phase field)
flat ground
4rdquo
1rdquo
Hard
ness
H
RC
Distance from quenched end
Fig 145
Hardenability of Steels
Jominy Test for Hardenability
bull Hardenability not the same as hardness
8
Heat Treatment of Steels HardenabilityThe cooling rate thus varies throughout the length of the bar the rate being highest at the lower end which is in direct contact with waterThe hardness along the length of the bar is then measured at various distances from the quenched end and plotted in a graphThe greater the depth to which the hardness penetrates the greater the hardenability of the alloy
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
4
Heat Treatment of Steels Hardenability
bull How is the hardenability of steels assessed
ndash Jominy End-Quench Test
ndash Test bar is heated to form 100 austenite It is then quenched directly at one end with a stream of water
Jominy Test
Generally the faster steel cools the harder it will be The Jominy bar measures the hardenbility of a steel
Softest
Hardest
6
bull Ability to form martensitebull Jominy end quench test to measure hardenability
bull Hardness versus distance from the quenched end
24degC water
specimen (heated to phase field)
flat ground
4rdquo
1rdquo
Hard
ness
H
RC
Distance from quenched end
Fig 145
Hardenability of Steels
Jominy Test for Hardenability
bull Hardenability not the same as hardness
8
Heat Treatment of Steels HardenabilityThe cooling rate thus varies throughout the length of the bar the rate being highest at the lower end which is in direct contact with waterThe hardness along the length of the bar is then measured at various distances from the quenched end and plotted in a graphThe greater the depth to which the hardness penetrates the greater the hardenability of the alloy
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Jominy Test
Generally the faster steel cools the harder it will be The Jominy bar measures the hardenbility of a steel
Softest
Hardest
6
bull Ability to form martensitebull Jominy end quench test to measure hardenability
bull Hardness versus distance from the quenched end
24degC water
specimen (heated to phase field)
flat ground
4rdquo
1rdquo
Hard
ness
H
RC
Distance from quenched end
Fig 145
Hardenability of Steels
Jominy Test for Hardenability
bull Hardenability not the same as hardness
8
Heat Treatment of Steels HardenabilityThe cooling rate thus varies throughout the length of the bar the rate being highest at the lower end which is in direct contact with waterThe hardness along the length of the bar is then measured at various distances from the quenched end and plotted in a graphThe greater the depth to which the hardness penetrates the greater the hardenability of the alloy
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
6
bull Ability to form martensitebull Jominy end quench test to measure hardenability
bull Hardness versus distance from the quenched end
24degC water
specimen (heated to phase field)
flat ground
4rdquo
1rdquo
Hard
ness
H
RC
Distance from quenched end
Fig 145
Hardenability of Steels
Jominy Test for Hardenability
bull Hardenability not the same as hardness
8
Heat Treatment of Steels HardenabilityThe cooling rate thus varies throughout the length of the bar the rate being highest at the lower end which is in direct contact with waterThe hardness along the length of the bar is then measured at various distances from the quenched end and plotted in a graphThe greater the depth to which the hardness penetrates the greater the hardenability of the alloy
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Jominy Test for Hardenability
bull Hardenability not the same as hardness
8
Heat Treatment of Steels HardenabilityThe cooling rate thus varies throughout the length of the bar the rate being highest at the lower end which is in direct contact with waterThe hardness along the length of the bar is then measured at various distances from the quenched end and plotted in a graphThe greater the depth to which the hardness penetrates the greater the hardenability of the alloy
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
8
Heat Treatment of Steels HardenabilityThe cooling rate thus varies throughout the length of the bar the rate being highest at the lower end which is in direct contact with waterThe hardness along the length of the bar is then measured at various distances from the quenched end and plotted in a graphThe greater the depth to which the hardness penetrates the greater the hardenability of the alloy
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
9
Heat Treatment of Steels Hardenabilitybull A correlation may be drawn
between position along the Jominy specimen and continuous cooling transformations
bull For eg figure shows a continuous cooling transformation diagram for a eutectoid iron-carbon alloy onto which is superimposed the cooling curves at four different Jominy positions and corresponding microstructure that result from each
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
10
Factors that influence hardenability
bull Carbon content The hardness at any Jominy position increases with the concentration of C
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Alloying and Hardenability
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Carbon and Hardenability
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Hardness and HardenabilityPredict the center hardness in a water quenched 3rdquo bar of 8640
Water Quenched Oil Quenched
Jominy Distance =17mm
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Hardenability bull Hardenability
Relative ability of a steel to be hardened in depth by quenching ndash Depends on 1 Alloy composition Cr Ni V Mo rarr increase hardenability2 Austenite grain size
Cr Mo W Ni
tem
per
atu
re
time
bull Hardenability of a steel increases with an addition of alloying elements such as Cr Mo Ni W C curve move to the right direction in the TTT diagram
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Alloying and Hardenability
Hardness at Center of a3 inch bar is about 42 HRC
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
16
Heat Treatment of Steels Hardenability
During the industrial production of steel there is always a slight unavoidable variation in composition and average grain size from one batch to another This variation results in some scatter in measured hardenability data which frequently are plotted as a band representing the max and min values
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Cooling rate and Jominy distance do not change with alloying elements as the rate of heat transfer is nearly independent of composition
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Jominy test and CCT diagrams
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Effects of alloying elements on the hardenability of alloy steels
bull Example Next slide all alloys have 04wt C but with different alloying elements(1)At the quenched end all alloys have thesame hardness which is a function of carbon content only(2)The hardenability of the 1040 is low because the hardness of the alloy drops rapidly with Jominy distance The drop of hardness with Jominy distance for the other alloys is more gradual(3)The alloying elements delay the austenite1048774pearlite andor bainite reactions which permits more martensite to form for a particular cooling rate yielding a greater hardness
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Effects of alloying elements on the hardenability of alloy steels
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Effects of carbon content on the hardenability of alloy steels
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Effects of composition variation and grain size change on the hardenability of alloy steels
bull The industrial products of steels may change composition and average grain size from batch to batch there fore the measured hardenability of a given type of steel should be presented as a band rather than a single line as demonstrated by the Figure at right
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Effects of composition variation and grain size change on the hardenability of alloy steels
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Dr Ken Lewis ISAT 430 27Spring 2001
Quenching Media
bull The fluid used for quenching the heated alloy effects the hardenabilityndash Each fluid has its own thermal properties
bull Thermal conductivitybull Specific heatbull Heat of vaporization
ndash These cause rate of cooling differences
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Dr Ken Lewis ISAT 430 28Spring 2001
Quenching Media2
bull Cooling capacities of typical quench media are
ndash Agitated brine 5ndash Still water 1ndash Still oil 03ndash Cold gas 01ndash Still air 002
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Dr Ken Lewis ISAT 430 29Spring 2001
Other quenching concerns
bull Fluid agitationndash Renews the fluid presented to the part
bull Surface area to volume ratiobull Vapor blankets
ndash insulationbull Environmental concerns
ndash Fumesndash Part corrosion
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Influence of quench medium and sample size on the cooling rates at different locations
bull Severity of quench Water gt Oil gt Air eg for a 50 mm diameter bar the cooling rate at center is about 27degCs in water but 135 degCs in oil
bull For a particular medium the cooling rate at center is lower when the diameter is larger For example 75mm vs 50mm
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Influence of quench medium and sample size on the cooling rates at different locations
Quenched in water Quenched in oil
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Radial hardness profile of cylindrical steel samples of different diameter and composition
04C+10Cr+02Mo
Quench in water
04C only
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Depth of Hardening
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Example ProblemDetermine the radial hardness profile for a 50mm (2 in) diameter cylindrical specimen of 1040 steel that has been quenched in moderately agitated water
Thanks
Thanks
