General Description

17-7PH stainless steel (UNS S17700/SUS 631), is a precipitation-hardening stainless steel featured with high strength, high hardness, excellent fatigue properties, good corrosion resistance and good formability.

17-7PH stainless steel is the best choice for making springs. It has strong corrosion resistance and high tensile strength. It can reach 2000MPA or higher after aging treatment. The most important thing is that the strength is not weaken during long-term usage. This fatigue resistance is due to the addition of AL as a precipitation hardening effect, making the 17-7ph stainless steel a semi-austenitic and semi-martensitic stainless steel.

Chemical Composition

Grade Fe% Ni% Cr% C% Mn% Si% P% S% Al%
17-7PH Bal. 6.50-7.75 16.00-18.00 Max 0.09 Max 1.0 Max 1.0 Max 0.035 Max 0.03 0.75-1.50


UNS S17700

Werkstoff Nr. 1.4564

AISI 631


17-7PH Wire: AMS 5678

17-7PH Bar: AMS 5644

17-7PH Sheet/Strip/Plate: AMS 5528

Physical Properties






A 7810 0.800
TH1050 7650 0.825
RH950 7650 0.830
CH900 7670 0.838

Mechanical Property




0.2% YS


Elongation % Hardness
A 893 274 35 B85
TH1050 1370 1280 9 C43
C 1517 1310 5 C43
RH950 1620 1510 6 C48
CH900 1820 1890 2 C49


Wire available from 0.1mm, in coil or precision ground cut lengths

Strip thickness from 0.03mm

Bar and sheet are also available


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