Aerospace Structural Metals Handbook

June 1970 Aerospace Structural Metals Handbook Ferrous Alloys FeAHPH15-7Mo

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Author C. F. Hickey, Jr.

1999 by Purdue Research Foundation, West Lafayette, Indiana 47907. All Rights Reserved.U.S. Government License. This material may be used, duplicated or disclosed by United StatesGovernment agencies without the payment of any royalty.

Fe15.0 Cr7.0 Ni2.5 Mo

1 GENERAL

This alloy is a semi-austenite precipitation-hardeningstainless steel. It is a modified 17-7PH alloy in which2 to 3 percent molybdenum is substituted for anequivalent percentage of chromium, thus higherstrengths can be obtained both at room andelevated temperatures in the various heat treatedconditions (16). The alloy can be considered forutilization at temperatures up to 1000 F. PH15-7Mois essentially austenitic at room temperature in theannealed or solution-treated condition, but can betransformed to martensite by a series of thermaltreatments or by cold working. The alloy can thenby further hardened by thermal treatment tostrengths in excess of 200 ksi at room temperature(9). The alloy is available in sheet, strip, plate, barand wire form. It can be formed readily in theannealed condition and is easily welded by variousmethods. Its heat treatment is identical with that of17-7PH and much of the information available forthe latter alloy also applied to PH15-7Mo (9).

1.01 Commercial Designation

PH15-7Mo

1.02 Alternate Designation

AISI No. 632.

1.03 Specifications

1.03 [Table]

1.04 Composition

1.041 [Table] Specified composition.

1.042 [Table] Typical producer composition.

1.05 Heat Treatment

1.051 Solution treat to Condition A.

1.0511 Sheet and strip. 1925 to 1975 F, 3 minutesper 0.1 inch thickness, air cool (1, 9).

1.0512 Bar and forging. 1925 to m1975 F, waterquench (2, 5, 7); 1975 to 1925 F, waterquench (6).

1.052 Age Condition A to Condition TH 1050. 1375 to1425 F, 11/2 hour (austenite conditioning), air coolto 50 to 60 F within 1 hour, hold at 50 to 60 F1/2 hour (Condition T) + 1040 to 1060 F, 11/2 hour,air cool (1, 2, 5, 6, 7).

1.053 Age Condition A to Condition RH 950. 1735 to1765 F, 10 minutes (austenite conditioning), air cool(Condition A 1750) + -90 to -110 F, 8 hour(Condition R-100) + 940 to 960 F, 1 hour, air cool(2, 5, 6, 7).

1.054 Age Condition C of sheet (coldrolled) or wire (cold drawn) toCondition CH 900. 890 to 910F, 1 hour, air cool(7, 9).

1.055 TH and RH conditions are alsoused with different final agehardening temperatures, e. g.,TH 1150, RH 1050, etc. Effect ofaging temperature on tensile properties of sheet invarious RH conditions, Figures 1.055 and 1.0551.

1.06 Hardness

1.061 [Table] Typical hardness of sheet for variousconditions.

1.062 Effect of aging tempering on hardness in ConditionRH 950 (see Section 3.0214).

1.063 [Table] Effect of cold work in Condition A onhardness in Condition TH 1050.

1.0631 Effect of modified TH 1050 heat treatmenton cold worked properties (see SpecialConsiderations, Section 1.095).

1.064 [Figure] Relationship between hardness andstrength for heat-treated conditions.

1.07 Forms and Conditions Available

1.071 Alloy is available in the full commercial range ofsizes for sheet, strip, plate, bar, wire and weldedtubing (12).

1.072 Alloy is available in the Condition A for the fullrange of products. Strip up to 0.050-inch thick andwire up to 0.050-inch diameter are also available inCondition C (13).

1.08 Melting and Casting Practice

Conventional stainless steel melting and castingpractices are used. Induction and consumableelectrode vacuum melts are also available.

1.09 Special Considerations

1.091 Alloy is available in numerous forms (see Section1.071), but the primary usage is in the sheet andstrip form (13).

1.092 In common with the general class of precipitationhardening stainless steels, this alloy is unstableduring exposure to temperatures exceeding about500 F. This instability is reflected in an increase inthe yield strength and a decrease in fracturetoughness. The transverse direction has lowertoughness than the longitudinal direction.

1.093 Dimensional changes during heat treating toConditions TH 1050 to RH 950 need considerationand special provisions must be made for machiningand tooling.

FeAH Ferrous Alloys Aerospace Structural Metals Handbook June 1970PH15-7Mo

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1.094 Thorough cleaning prior to thermal treatments isrecommended in order to avoid carburization andto minimize difficulties when descaling.

1.095 A modified TH 1050 heat treatment has beendeveloped to compensate for cold working inCondition A when TH 1050 properties are desired(9, p. 70). The treatment is as follows:

Austenite Condition: 1550 F 25 F 90 minutes. AirCool Refrigerate: 0 F 10 F 4 hours. PrecipitationHarden: 1050 F 10 F 90 minutes.

2 PHYSICAL AND CHEMICAL PROPERTIES

2.01 Thermal Properties

2.011 Melting range. 2580 to 2640 F.

2.012 Phase changes. Similar to those in 17-7PH.

2.0121 Time-temperature-transformationdiagrams.

2.013 [Figure] Thermal conductivity.

2.014 [Figure] Thermal expansion.

2.015 Specific heat. 0.11 Btu per lb F.

2.016 Thermal diffusivity.

2.017 [Figure] Dilatometer curve indicating dimensionalchanges during heat treatment from Condition A toCondition RH 950.

2.02 Other Physical Properties

2.021 [Table] Density.

2.022 [Table] Electrical resistivity.

2.023 [Table] Magnetic properties. Permeability.

2.024 [Figure] Emittance.

2.025 Damping capacity.

2.03 Chemical Properties

2.031 Corrosion resistance (see also 17-7PH).

2.0311 General corrosion resistance of PH15-7Moin Condition TH 1050 and RH 950 issuperior to standard hardenable types ofstainless steels such as Types 410, 420 and431, but is not quite as good as Type 304 (9).

2.0312 [Table] Corrosion rate in several corrosivemedia.

2.0313 [Table] Stress corrosion cracking. Results ofstress-cracking exposure test on sheet invarious conditions at Kure Beach.

2.03131 Salt coated specimens of this alloyin Condition 1050 exhibitexcellent resistance to stresscorrosion cracking at 550 F for

exposure times to 10,000 hours;however, it does showsusceptibility to pitting (15).

2.0314 Intergranular corrosion may occur duringacid pickling, except in Conditions A andCH 900.

2.0315 Hydrogen embrittlement may occur duringplating and recommended procedures forpreventing it must be followed (12).

2.032 Oxidation resistance (see 17-7PH).

2.04 Nuclear Properties

3 MECHANICAL PROPERTIES

3.01 Specified Mechanical Properties

3.011 [Table] AMS and MIL specified mechanical propertiesfor sheet, strip and plate.

3.012 [Table] AMS and ASTM specified mechanicalproperties for bar.

3.013 [Table] Producers guaranteed mechanical propertiesfor sheet, strip and plate.

3.02 Mechanical Properties at Room Temperature

3.021 Tension (see also Section 1.055).

3.0211 Stress-strain diagrams.

3.0212 [Table] Typical tensile properties for variousconditions of sheet, strip and plate.

3.0213 [Figure] Effect of solution temperature ontensile properties in Conditions A, TH 1050and RH 950.

3.0214 [Figure] Effect of aging temperature ontensile properties and hardness in ConditionRH 950.

3.0215 [Figure] Effect of exposure to elevatedtemperatures on tensile properties of sheetin Conditions RH 950 and TH 1050.

3.0216 [Figure] Effect of exposure time to elevatedtemperatures on strength properties inCondition RH 1075.

3.0217 [Table] Effect of exposure time, elevatedtemperature and load on tensile propertiesof sheet in Condition RH 950.

3.0218 [Figure] Effect of thickness on tensileproperties of sheet.

3.0219 [Figure] Effect of reduction by shearforming on tensile properties of sheet.

3.02111 [Table] Effect of reduction by cold workingin Condition A on tensile properties inCondition TH 1050.


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3.02112 [Figure] Effect of percent cold reduction andcold reduction temperature on yieldstrength.

3.022 Compression.

3.0221 Stress-strain diagrams (see Figure 3.0321).

3.023 Impact.

3.024 Bending.

3.025 Torsion and shear.

3.0251 [Figure] Effect of reduction by shearforming on shear strength of sheet.

3.026 Bearing.

3.0261 [Table] Bearing properties of sheet inConditions TH 1050 and RH 950.

3.027 Stress concentration.

3.0271 Notch properties.

3.02711 [Figure] Effect of agingtemperature on sharp notchstrength of sheet in variousRH conditions.

3.02712 [Figure] The effect of crack lengthon percent of tensile strength ofsheet.

3.0272 Fracture toughness. KQ (plain strain) ofCondition TH 1050 is 63 ksi vin; RH 950 is52 ksi vin.

Valid plain strain fracture toughness, KIc,data that have been derived from tests thatconform in all aspects to the ASTMRecommended Practice appears to belacking for this material (22). However,data reported by Steigerwald can bepresented as KQ and used as a qualitativemeasure of fracture toughness (23). Forexample, the above data indicates a strongdependence on heat treat condition (thisalso applies to 17-7PH) (23). Due to therelatively low fracture toughness that existsfor PH15-7Mo and 17-7PH in Condition RH950, the PH14-8Mo alloy should be usedwhen a combination of high strength andhigh fracture toughness is required(9, p. 14).

3.028 Combined properties.

3.03 Mechanical Properties at VariousTemperatures

3.031 Tension.

3.0311 Stress-strain diagrams.

3.03111 [Figure] Stress-strain curves forsheet in Conditions TH 1050 andRH 950 at elevated temperatures.

3.03112 [Figure] Stress-strain curves atroom and low temperature forsheet in Conditions RH 950.

3.03113 [Figure] Stress-strain curves intension for sheet in ConditionsTH 1050 at elevated temperaturesand for various exposure times.

3.03114 [Figure] Stress-strain curves intension for sheet in Condition RH950 for various exposure times atelevated temperatures.

3.0312 Tension properties for Condition TH.

3.03121 [Figure] Effect of test temperatureon tensile properties of sheet inConditions TH 1050 and RH 950.

3.03122 [Figure] Effect of exposure andtest temperature on tensileproperties of sheet in ConditionsTH 1050.

3.0313 Tension properties for Condition RH.

3.03131 Effect of test temperature ontensile properties of sheet inConditions RH 950(see Section 3.03121).

3.03132 [Figure] Effect of test temperatureon tensile properties of exposedand unexposed sheet inCondition RH 1050.

3.03133 [Figure] Effect of testtemperatures on tensileproperties of exposed andunexposed sheet in ConditionRH 1100.

3.03134 [Figure] Effect of low testtemperature on tensile propertiesof sheet in Condition RH 950.

3.0314 Tension properties for Condition CH.

3.03141 [Figure] Effect of test temperatureon tensile properties of exposedand unexposed sheet inCondition CH 900.

3.03142 [Figure] Effect of test temperatureon tensile properties of sheet inCondition CH 900.

3.0315 Tension properties for various conditions.

3.03151 [Figure] Effect of exposuretemperature on tensile propertiesof sheet in Conditions TH 1050and RH 950.


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3.03152 [Figure] Effect of low testtemperature up to 200 F ontensile properties of sheet inConditions RH 950 and CH 1100.

3.03153 [Figure] Effect of test temperatureon tensile properties of plate inCondition TH 1050.

3.03154 [Figure] Effect of test temperatureon tensile properties of plate inCondition RH 950.

3.032 Compression.

3.0321 [Figure] Stress-strain curves in compressionat elevated temperatures for sheet inConditions TH 1050 and RH 950.

3.0322 [Figure] Effect of test temperature oncompressive yield strength of sheet inConditions TH 1050, RH 950 and CH 900.

3.0323 [Figure] Effect of exposure time and testtemperature on compressive yield strengthof sheet in Condition TH 1050.

3.033 Impact.

3.0331 [Figure] Effect of low test temperature onimpact strength of alloy in Condition TH1050 and RH 950.

3.034 Bending.

3.035 Torsion and shear.

3.0351 [Figure] Effect of test temperature on shearstrength of sheet in Condition TH 1050 andRH 950.

3.0352 [Figure] Effect of exposure time and testtemperature on shear strength of sheet inCondition TH 1050.

3.036 Bearing.

3.0361 [Figure] Effect of exposure time and testtemperature on bearing properties of sheetin Condition TH 1050.

3.0362 [Figure] Effect of exposure time and testtemperature on bearing properties of sheetin Condition TH 1050.

3.037 Stress concentration.

3.0371 Notch properties.

3.03711 [Figure] Effect of test temperatureon notch and crack strength ofsheet in Condition CH 900.

3.03712 [Figure] Effect of test temperatureon notch and crack strength ofsheet in Condition RH 1050.

3.03713 [Figure] Effect of test temperatureon the sharp notch strength ratioand crack strength ratio for sheetin RH 1050 Condition.

3.03714 [Figure] Effect of test temperatureon notch and crack strength ofsheet in Condition RH 1100.

3.03715 [Figure] Effect of exposure timeand test temperature on notchstrength of sheet on ConditionTH 1050.

3.03716 [Figure] Effect of low testtemperature on notch strengthof sheet in Condition RH 950.

3.03717 [Figure] Effect of stressconcentration factor on notchstrength ratio at roomtemperature and -320 Ffor sheet in Conditions CH 900and RH 1100.

3.0372 Fracture toughness.

3.038 Combined properties.

3.04 Creep and Creep Rupture Properties

3.041 [Table] Creep properties for sheet, strip and plate inCondition RH 950 at 600 to 900 F.

3.042 [Table] Creep rupture properties for sheet incondition TH 1050 and RH 950 at varioustemperatures.

3.043 [Figure] Isochronous stress-strain curves for sheet inCondition RH 950 at 600 to 900 F.

3.044 [Figure] Creep and creep rupture curves for alloy inCondition RH 950.

3.045 [Figure] Creep rupture curves for alloy at 1000 F inCondition RH 950.

3.05 Fatigue Properties

3.051 [Figure] S-N curve for sheet in Condition RH 950.

3.052 [Figure] S-N curve for notched sheet in ConditionRH 950.

3.053 [Figure] S-N curves for notched and smooth sheet asa function of temperature in Condition TH 1050.

3.054 [Figure] S-N curves for notched and unnotchedsheet as a function of temperature in ConditionTH 1050.

3.055 [Figure] S-N curves for notched and unnotchedsheet as a function of temperature in ConditionTH 1050.

3.056 [Figure] Fatigue crack propagation rate for two testtemperatures for sheet in condition TH 1050.

3.057 [Figure] Fatigue crack propagation curves as afunction of initial net section stress for sheet inCondition TH 1050.

3.058 [Figure] Fatigue crack propagation curves as afunction of initial net section stress for sheet inCondition TH 1050 at R= -1.


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3.06 Elastic Properties

3.061 Poissons ratio. Condition RH 950, 0.28.

3.062 Modulus of elasticity.

3.0621 [Figure] Modulus of elasticity at room andelevated temperatures.

3.0622 [Figure] Modulus of elasticity incompression at room and elevatedtemperatures.

3.0623 [Figure] Effect of exposure time and testtemperature on modulus of elasticity incompression of sheet in Condition TH 1050.

3.063 Modulus of rigidity.

3.0631 [Figure] Modulus of rigidity at room andelevated temperatures.

3.064 Tangent modulus.

3.0641 [Figure] Tangent modulus curves incompression for sheet in Condition TH 1050at elevated temperatures and for variousexposure times.

3.0642 [Figure] Secant modulus curves incompression at elevated temperatures forsheet in Conditions TH 1050 and RH 950.

4 FABRICATION

4.01 Formability (see also 17-7PH)

4.011 Hydroforming and marforming operations canreadily be performed on this alloy and 17-7PH inCondition A. Parts including formers, flanges, hatsections and frames that have been processed bythese methods are used by aircraft manufacturers(9).

4.012 Spinning characteristics of this alloy are similar to17-7PH and Type 301. The strength developedduring cold working is primarily dependent uponthe amount of cold working and the temperature atwhich it is done (see Sections 3.0219, 3.02112 and3.0251) (9).

4.02 Machining and Grinding (see also 17-7PH)

4.021 Grinding. Material appears to offer no majorproblems in grinding; however, Conditions TH 1050and RH 950 are easier to grind than Condition Amaterial (9). Conventional grinding wheels atconventional speeds and feeds appear satisfactory.Grinding characteristics of 17-7PH are comparableto those of this alloy (9).

4.03 Welding

(See also 17-7PH)

4.031 Inert gas tungsten arc fusion welding of annealedand subsequently heat-treated metal yields a weldefficiency of 80 to 100 percent.

4.032 Most welding is performed with the inert gastungsten arc process or the resistance spot and seamwelding processes. Resistance flash butt-welding isnot recommended for joints to be placed in highstrength conditions (11, p. 65).

4.033 The molybdenum addition in this alloy causes largeramounts of delta ferrite or free ferrite to form inweld deposits upon solidification. The amounts offerrite require some control in order to maintaingood ductility in the highest strength conditions.The control is effected with filler metal ofappropriate chemical composition or through heattreatment (11, p. 65).

4.034 [Table] To avoid problems with weld metal crackingor lowered ductility a specific composition ofhardenable weld wire, designated as W PH15-7Mo,is recommended for use as electrode or filler rod.

4.035 [Table] Strength of spot weld joints.

4.04 Heat Treatment

(See 17-7PH)

4.05 Surface Treatment

(See 17-7PH)


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REFERENCES

1. AMS 5520A (November 1, 1958).

2. AMS 5657 (June 30, 1960).

3. AMS 5812B (January 15, 1963).

4. AMS 5813A (January 15, 1963).

5. ASTM A461 (August 31, 1965).

6. ASTM A564 (September 7, 1966).

7. MIL-S-8955 (ASG) (October 25, 1965).

8. Complication of Tensile and Creep Rupture Data ofSeveral Al, Mg, Ti and Steel Alloys and Ni SuperAlloys, AFML-TR-67-259 (April 1968).

9. Armco Steel Corporation, Armco 17-7PH and PH15-7Mo (July 1968).

10. Espey, G. B., Jones, M. H. and Brown, W. F., Jr., TheSharp Edge Notch Tensile Strength of Several HighStrength Steel Sheet Alloys, American Society of TestMaterials, Proceedings Volume 59 (1959).

11. AISI, High Temperature High Strength Alloys,(February 1963).

12. Armco Steel Corporation, Armco PrecipitationHardening Stainless Steel Technical Manual,(March 1, 1958).

13. Private Communication with R. I. Psyck, Metallurgist,Armco Steel Corporation, Baltimore, MD.

14. Ludgigson, D. C., Semi-Austenitic PrecipitationHardening Stainless Steels, DMIC Report 164(December 6, 1961).

15. Braski, D. N., The Susceptibility of Six Stainless Steelsto Stress Corrosion at Ambient and ElevatedTemperatures, NASA TN D-2499 (December 1964).

16. Favor, R. J., Deel, O. C. and Achbach, W. P., DesignInformation on PH15-7Mo Stainless Steel for Aircraftand Missiles, DMIC Report 135 (August 22, 1960).

17. Fracture Micromechanics in High Strength Steelsand Titanium, ML-TDR-64-182 (July 1964).

18. Chance Vought Corporation, Mechanical Propertiesof Some Engineering Materials - Unpublished Datafrom Company Sponsored Programs(March 15, 1962).

19. Jacobs, F., Mechanical Properties of Materials byShear Forming, ASD TDR-62-830 (February 1963).

20. Roy, A., Chave, C. and Weiss, V., Materials Evalua-tion for a Mach III Transport Plane, Quarterly ReportNo. 4A, Syracuse University (April 1963).

21. Spalding, L. P., The Use of Precipitation HardeningStainless Steels in Supersonic Aircraft, MaterialsScience and Technology for Advanced Science, PrenticeHall, Inc. (1962).

22. Recommended Practice for Plane-Strain FractureToughness Testing of High Strength Metallic MaterialsUsing a Fatigue Cracked Bend Specimen, ASTM Bookof Standards, Part 31 (1968).

23. Steigerwald, E. A., Plane Strain Fracture Toughnessfor Handbook Presentation, AFML-TR-67-187(July 1967).

24. Rice, L. P., Campbell, J. E. and Simmons, W. F.,The Evaluation of the Effects of Very Low Tempera-tures on the Properties of Aircraft and Missile Metals,WADD TR 60-254 (February 1960).

25. Lemcoe, M. M., Trevino, A., Jr., Determination of theEffect of Elevated Temperature Materials Properties ofSeveral High Temperature Alloys, ASD TDR-61-529(June 1962).

26. Armco (February 1959).

27. Baneerjee, B. R. and Hauser, J. J., Research andApplication Engineering to Determine the Effect ofProcessing Variables on Crack Propagation of High-Strength Steels and Titanium, ASD-TDR-62-1034,Part 1 (April 1963).

28. Espey, G. B., Bubsey, R. T. and Brown, W. F., Jr.,A Preliminary Report on the NASA Sheet AlloyScreening Program for Mach III Transport Skins,American Society of Test Materials, ProceedingsVolume 62 (1962).

29. Denke, P. H., Materials for the Supersonic Transport,Materials Science and Technology of AdvancedApplication, Prentice Hall, Inc. (1962).

30. Titanium Metal Corporation of America, FatigueProperties of High Strength Titanium and StainlessSteel Sheet Alloys, TMCA (January 1960).

31. Illg, W. and Castle, C. B., Axial Load FatigueProperties of PH15-7Mo Stainless Steel in conditionTH 1050 at Ambient Temperature and 500 F, LangleyResearch Center, NASA TN D-2358 (July 1964).

32. Hudson, C. M., Fatigue-Crack Propagation in SeveralTitanium and Stainless Steel Alloys and One Super-Alloy, Langley Research Center, NASA TN D-2331(October 1964).

33. Hudson, C. M., Fatigue Crack Propagation andResidual Static Strength of PH15-7Mo (TH 1050)Stainless Steel, Langley Research Center, NASA TND-3151 (December 1965).

34. Northrop Corporation, General Materials Information- Phase I Progress Report No. 2 (September 30, 1961).

Alloy GroupsSimilar AlloysTextGeneralCommercial DesignationAlternate DesignationSpecificationsCompositionHeat TreatmentHardnessForms and Conditions AvailableMelting & Casting PracticeSpecial Considerations

Physical and Chemical PropertiesThermal PropertiesOther Physical PropertiesChemical PropertiesNuclear Properties

Mechanical PropertiesSpecified Mechanical PropertiesMechanical Properties at Room TemperatureMechanical Properties at Various TemperaturesCreep and Creep Rupture PropertiesFatigue PropertiesElastic Properties

FabricationFormabilityMachining and GrindingWeldingHeat TreatmentSurface Treatment

References

Documents

Aerospace Structural Metals Handbook