PH Grades Stainless Steel 15-5PH

Chemical Analysis
C Carbon
0.07 max
Mn Manganese
1.00 max
P Phosphorus
0.040 max
S Sulfur
0.015 max
Si Silicon
1.00 max
Cr Chromium
14.00 – 15.50
Ni Nickel
3.50 – 5.50
Cu Copper
Cb + Ta % Niobium

General characteristics of PH Grade Stainless Steel 15-5PH

15-5PH grade is a martensitic precipitation and age hardening stainless steel with high strength and hardness together with excellent corrosion resistance. The chemical analysis is balanced to give a minimum of delta ferrite, thus allowing superior transverse toughness and ductility, plus good forgeability.

The fabrication characteristics of 15 – 5 PH are similar to those of other precipitation hardening grades; they can be age hardened by a single step, low temperature treatment.


This grade may be used for valve parts, fittings and fasteners, forged shafts and gears, engine parts, chemical process equipment, paper mill equipment, and components for aircraft and nuclear reactors.


Stock should be uniformly heated to 2150/2200ºF (1180/1205ºC) and held for 1 hour before forging. Material should not be forged below 1850 º F (1010ºC.)

For optimum grain size and mechanical properties forged material should be air cooled to below 90ºF (32ºC) prior to further processing. Material must be solution treated before hardening.

Heat treatment

15 – 5 PH is normally supplied in the solution-treated condition, condition A. It may be hardened by heating solution-treated material to a temperature of 900ºF (480ºC) to 1150ºF (620ºC) for one to four hours, depending upon the temperature, then air cooling.

Solution Treatment

Heat at 1900ºF (1040ºC) +/- 25ºF (14ºC) for 1/2 hr., cool to below 90ºF (32ºC) so that complete transformation to martensite takes place. Sections under 3″ (76mm) can be oil quenched, sections over 3″ (76mm) should be rapidly air cooled. Material should not be used in the solution-treated condition, due to poor toughness, poor impact strength and susceptibility to stress-corrosion cracking.

Age/Precipitation Hardening

For condition H900, heat solution-treated material at 900ºF (480ºC) for 1 hour and air cool.

For H 925, H 1025, H 1075, H 1100, H 1150, heat solution-treated material at specified temperature +/- 15ºF (+/-8ºC) for 4 hours and air cool.

For H 1150M, for optimum machinability, heat solution-treated material at 1400ºF (760ºC) +/- 15ºF (+/- 8ºC) for 2 hours, air cool, and heat at 1150ºF (620ºC) +/- 8ºC) for 4 hours and air cool.


This grade is readily machined in both the solution-treated and the various age-hardened conditions. When solution treated the material machines in a similar manner to types 302 and 304 stainless. Machinability improves as the hardening temperature increases. Optimum machinability is obtained from condition 1150M.


This grade may be satisfactorily welded by the shielded fusion and resistance welding processes. Oxyacetylene welding is not recommended due to the possibility of carbon pickup. Weld joints should be designed so as to minimize stresses.

Welding in the solution-treated condition is normally satisfactory, but if high welding stresses are anticipated it may be best to weld in the H1150, overaged condition. Preheating is not normally required.


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