View
217
Download
0
Category
Tags:
Preview:
Citation preview
Lab IV: Phase Transformations Sample Data
Brass 360 Aluminum 2024 Steel 4340 Steel 1018
Quench
Soft
58 HRB
Soft off-scale low HRB
no precipitates, saturated alloy solution
Hardest 43 HRCMartensite
Hardest 38 HRCmartensite or bainite
Quench + Anneal
Hardest 70 HRBOptimum large number and
small size of precipitates
Hard 40 HRCtempered martensite
Hard 32 HRCtempered martentsite or
tempered bainite
Slow CoolSoft off-scale low
HRBOveraged
Soft 94 HRBpearlite
Soft 90 HRBpearlite
Slow Cool + Anneal
Soft off-scale low HRB
Even more overaged
Soft 88 HRBtempered pearlite
Soft 74 HRB tempered pearlite
*All hardness values are from a previous quarter and should not be expected to match your data exactly, but your numbers should be in the same relative order (hardest to softest) for each material – example: for the Quenched 4340 sample, you shouldn’t expect to get exactly 43 HRC, but that sample should be the hardest of the rest of your 4340 samples
Medium Grains
Brass 360
30 % Zn
All alpha phase
550° C
Medium Grain size
70% Cu30% Zn
Quench Soft58 HRB
Quench and Anneal
Soft58 HRB
Slow Cool Soft58 HRB
Slow Cool and Anneal
Soft 58 HRB
Ha
rdn
ess m
ay slig
htin
g in
crea
se
with
lon
ge
r time
at h
igh
tem
p.
Sm
all in
crea
se in
gra
in size
Note: With no heat treatment Brass 360 is hard [74 HRB]. Heat treatment brings as received samples through recrystalization and grain growth. Must mean that samples were received cold worked
Callister sections 7.10-7.13
Callister p402
Aluminum 2024
4.4% Cu
Quench Soft off-scale lowFew, if any precipitates form. Supersaturated alloy solution
Quench and Anneal
Hardest 70 HRBOptimum large number and small size of precipitates
Slow Cool Soft off-scale lowFewer number and larger precipitates -OVERAGED
Slow Cool and Anneal
Soft off-scale low Even Fewer number and larger precipitates – even more OVERAGED
4.4% Cu1.5% Mg0.6% Mn
Age at 260*C for 20 min Precipitates and lattice strain
impedes dislocation motion
Steel 4340 Quench Hardest 43HRC Martensite
Quench and Anneal
Hard 40 HRC Tempered Martensite
Slow Cool Soft 94 HRB pearlite and proeutectoid ferrite
Slow Cool and Anneal
Soft 88 HRB tempered pearlite and proeutectoid ferrite
0.40% Cand Cr, Mo, Mn
heat to 900*C Austentize
0.40% C
Higher Carbon content in 4340 produces more lattice distortion in martentsite phase
Quench produces martensite
Steel 1018 0.18% Cand Mn
Quench Hardest 38 HRC
Martensite
Quench and Anneal
Hard 32 HRC Tempered Martensite
Slow Cool Soft 90 HRB pearlite and proeutectoid ferrite
Slow Cool and Anneal
Soft 74 HRB tempered pearlite and proeutectoid ferrite
0.18% C
Quench produces martensite
Included in back of lab handout – use 1019 to approximate 1018 TTT behavior
Recommended