17-7PH®, or Type 631 (UNS S17700), is a chromium-nickel-aluminum Precipitation Hardening Stainless Steel used in spring applications for numerous industries. The alloy offers corrosion resistance comparable to 302, but it can achieve higher strength after precipitation hardening due to aluminum additions.
CWI is the leading producer of aerospace and commercial quality 17-7PH® spring wire in the U.S. and U.K.
CWI has decades of metallurgical experience with processing of 17-7PH® wire for spring applications. This research and process development optimizes the microstructural characteristics of our 17-7PH® spring wire to be fully compliant with AMS 5678G. CWI has established tight controls on several wire-drawing parameters and laboratory microstructure evaluations to ensure that the product is fully compliant to AMS 5678G.
Commercial use of the alloy is governed by industry standards such as: ASTM A313, EN 10270-3, ISO 6931. These standards define nominal as-shipped (Condition C) tensile, CH900 tensile, and ductility evaluations through wrap and coiling tests.
Aerospace use is supplied via AMS 5678G which further controls the material with additional qualification tests on the final drawn wire’s microstructure.