ASTM International is actually a nonprofit Firm that delivers alongside one another professionals from several industries to produce and manage an unlimited selection of voluntary consensus expectations. “PH”: Means Precipitation Hardening, indicating a steel that may be hardened by a special heat treatment process. Grades like 17-4PH slide into this https://madanijayateknik.com/service/detail/round-bar-plate-sheet-pipe-tube-stainless-steel-321-uns-s32100-din-x6crniti18-10-aisi-321-dan-321h-uns-s32109-din-x8crniti18-10-aisi-321h