Stainless Steel Grade 15-7Mo (UNS S15700)

Topics Covered

Chemical Composition
Mechanical properties
Manufacturing process


Stainless steel 15-7 Mo is a semi-austenitic and precipitation hardening stainless steel that provides good corrosion resistance, high hardness and strength and minimum distortion on heat treatment. In a heat-treated condition, this alloy offers excellent mechanical properties at temperatures up to 482°C (900°F). Its corrosion resistance is superior to that of the hardenable chromium types.

Chemical Composition

The chemical composition of Grade 15-7 Mo stainless steel is outlined in the following table.

Element Content (%)
Iron, Fe Balance
Chromium, Cr 14 -16
Nickel, Ni 6.50 - 7.75
Molybdenum, Mb 2 - 3
Silicon, Si 1
Manganese, Mn 1
Aluminum, Al 0.75 - 1.50
Carbon, C 0.09
Phosphorus, P 0.040
Sulfur, S 0.040

Mechanical properties

The mechanical properties of Grade 15-7 Mo stainless steel are displayed in the following table.

Properties Metric Imperial
Tensile Strength 650 - 880 MPa 94275 - 127633 psi
Yield Strength 350 - 550 MPa 50763 - 79771 psi
Elongation at Break 8 - 25% 10%
Young’s Modulus 200 GPa 29008 ksi

Manufacturing process

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Stainless steel 15-7 Mo can be machined in the hardened conditions. The alloy is then readily welded using common arc and resistance methods. It does not require preheating and post weld annealing. Heat treatment can be carried out at temperatures ranging from 482 to 955°C (900 to 1750°F). This alloy works well with any hot working procedures. Finally, the alloy is annealed for 1 hr at 1038°C (1900°F) and then cooled rapidly.


The following are some of the major applications of Grade 15-7 Mo stainless steel:

  • Paneling and springs
  • Diaphragms
  • Retaining rings
  • Welded and brazed honeycomb paneling
  • Aircraft components bulkheads

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