METHOD FOR STRENGTHENING ALLOY STEEL FOR HOT-WORKING DIE, AND ALLOY STEEL OF HOT-WORKING DIE FOR RESTRAINING GENERATION OF HEAT-FATIGUE CRACK WITH THIS METHOD

摘要

PROBLEM TO BE SOLVED: To provide a method for strengthening an alloy steel for hot-working die, preventing the generation of a heat-fatigue crack.;SOLUTION: The alloy steel for hot-working die (e.g. SKD61 steel) using a steel containing 0.32-0.42% C, 0.80-1.20% Si, ≤0.50% Mn, ≤0.030% P, ≤0.020% S, 4.50-5.50% Cr, 1.00-1.50% Mo, 0.30-1.15% V and the balance Fe with inevitable impurities and having 450-520 HV is used to a material to be heated and on this material to be treated, grinding powders having 550-1100 HV, are spouted together with compressed air and thus, a nano-crystallizing structure accompanied with non-lamellar formed structure, is generated on the surface layer near the surface of the material to be treated. Successively, if necessary, nitrogen is diffused on the lower part of the surface layer with a plasma-nitriding.;COPYRIGHT: (C)2008,JPO&INPIT