Choosing between 17-4PH H1150 and 15-5PH H1025 for a 16 mm pump shaft in chlorinated water (about 250 ppm Cl-) at 40–60 C. I’m leaning 15-5PH for better toughness and weldability, but the higher strength of 17-4PH helps with bending; has anyone seen a meaningful difference in SCC or galling under these conditions?
At ‘250 ppm Cl- at 40–60 C’, I’ve had fewer SCC headaches with 17-4PH in H1150M (double-age) than with 15-5PH H1025, mostly because the overaged temper is less twitchy. It usually still covers bending on a 16 mm shaft — — what’s the mating material; if it’s stainless-on-stainless, expect galling unless you go dissimilar or coat.
I’ve had good results with 17-4PH in similar conditions — while 15-5PH is tough, I’ve seen more SCC with it in chlorinated water. Keep in mind that the H1150M temper really helps reduce issues — have you thought about testing both on a small scale first?