STEEL CASTING OF COLD-WORKING TOOL STEEL EXCELLENT IN MACHINABILITY, AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To improve toughness and machinability by incorporating C, Si, Mn, Cr, Mo, W, S, Ca, and the balance essentially Fe in the specific composition. ;SOLUTION: This steel casting has a composition consisting of, by weight, 0.5-1.2% C, ≤3.0% Si, ≤3.0% Mn, Sh3.0% Cr, 0.1-8.0% of (2Mo+W), 0.05-0.4% S, 0.0002-0.02% Ca, and the balance essentially Fe. Further, by adding either or both of ≤3.0% Ni and 0.05-2.0% V, hardenability can be improved. Further, by adding either or both of 0.02-2.0% Nb and 0.02-2.0% Ta, deterioration in toughness caused by coarsening of crystalline grains when flame hardening is applied to the surface of the steel casting, can be suppressed. Moreover, at the time of manufacture of tools such as dies, it is desirable to apply soaking treatment in the gamma single phase region after forging. By this method, coarse primary carbides formed at the time of casting can be decreased or removed and toughness can be improved.;COPYRIGHT: (C)2000,JPO