Official Answer
Answer
17-7PH Stainless Steel (Condition CH900) is a semi-austenitic precipitation-hardening alloy that offers significantly higher strength and better fatigue resistance than Type 302. After cold-working to Condition C, it is aged at $900^\circ F$ to reach Condition CH900, resulting in a typical tensile strength of $240$-$265$ ksi. Type 302 depends solely on cold reduction for its $160$-$190$ ksi strength. In medical applications where miniature wave springs are subject to repeated sterilization (autoclaving), 17-7PH is preferred because its higher elastic limit prevents permanent deformation during high-strain cycles. Furthermore, 17-7PH exhibits superior dimensional stability during heat treatment compared to 300-series steels which may warp.
