HPM38,S136,SUS440,9cr18mov,etc import stainless steel | Stainless screw | Diameter 18mm-80mm | vacuum hardening,CNC Circular grinding one-time processing control | HITACHI high speed steel,Datong High speed steel | HRC50-55 | Whole smelting | 0.015mm/m | Ra0.4um | Japan HITACHI,Japan Datong | Used in optical glasses,LGF,transparent. |