Official Answer
Answer
17-7PH is a precipitation-hardening stainless steel that provides significantly higher tensile strength and better relaxation resistance than 302 or 316. In the CH900 condition (cold reduced and then aged at $900^\circ F$), it can withstand operating temperatures up to $343^\circ C$ ($650^\circ F$) with minimal load loss. Standard 302 stainless relies purely on work hardening, which begins to recover (anneal) at much lower temperatures, leading to a rapid loss of spring force (stress relaxation). For aerospace fuel injectors, 17-7PH is the baseline for maintaining constant pressure across the flight envelope.
