Selected Metals - 5: 15 & 17 Stainless
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S1xxxx (AISI/ASE 15 and 17) series are martensitic steels that provide good corrosion resistance. They are similar to 400 series in most ways. However they do not use same method of heat treating that is usually used with carbon steels or 400 series stainless steels. They are heat treated using the Precipitation Hardening (PH) method. Also, this steel - like 400 series - is magnetic
Precipitation Hardening was first used on Aluminum in 1909 by Alfred Wilm. However the application of these principles were not used on stainless steels with any significance until after WWII when the aerospace industry began to demand steel with the characteristics PH ultimately provided. These unique heat treating process can be used with both austenitic and martensitic steels which means high corrosion resistance as well as hardenability are available with a single stainless steel.

Following are two of these PH stainless steels familiar to most machinists:

S15500 (AISI/SAE 15-5 or 15-5PH)

  • Carbon no data
  • Chromium no data
  • Nickel no data
  • Other alloys no data
  • Machinability machinable in most conditions
  • Hadenability precipitation method
  • Weldability resistance methods or shielded fusion
  • Applications aircraft parts, valves, fasteners
  • Comments martensitic, precipitation hardening, chromium-nickel-copper stainless steel, corrosion resistance comparable to 304 stainless.

S17400 (AISI/SAE 17-4 or 17-4PH)

  • Carbon no data
  • Chromium no data
  • Nickel no data
  • Other alloys no data
  • Machinability gummy chips, stringy chips, use chip breaker
  • Hadenability precipitation method
  • Weldability resistance methods or shielded fusion
  • Applications jet turbines, chemical plants
  • Comments the most widely used precipitation hardening stainless, good corrosion resistance, high harness, toughness and strength.
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