SKD61 alloy steel screw | Import alloy steel screw | Diameter 18mm-80mm | Hardening And tempering.vacuum hardening,Hard treatment. | HITACHI high speed steel,Datong High speed steel | HRC>55-58 | Whole smelting | 0.015mm/m | Ra0.4um | Japan HITACHI,Japan Datong | Used in Engineering Plastic with 40% defibrase |