MANUFACTURE OF HOT WORKING TOOL STEEL WITH SUPERIOR HEAT CHECK RESISTANCE

摘要

PURPOSE:To provide superior heat check resistance to a hot working tool steel having a specified composition by specifying the heat treatment of the tool steel. CONSTITUTION:A hot working tool steel contg., by weight, 0.2-0.45% C, 0.3- 1.2% Si, 0.2-0.8% Mn, 4-6% Cr, 0.3-1.5% Mo and 0.3-1.5% V is hot rolled at =800 deg.C finishing temp., and it is slowly cooled from 800 deg.C to 650 deg.C in =180min. Hardening is carried out by heating from =650 deg.C to 900-1,000 deg.C and cooling to =200 deg.C. The hardened steel is held at 750-850 deg.C for =120min to make carbides fine, and it is cooled. The surface layer of the steel is hardened by heating to 900-1,100 deg.C and cooling to =200 deg.C. Tempering is then carried out by heating to 575-680 deg.C.