NON-HEAT TREATED STEEL FOR HOT FORGING, MANUFACTURE OF HOT FORGED NON-HEAT TREATED ARTICLE, AND HOT FORGED NON-HEAT TREATED ARTICLE

摘要

PROBLEM TO BE SOLVED: To provide a non-heat treated steel stock for hot forging, having high strength and high toughness in a hot-forged state as it is and capable of induction hardening, a method for manufacture of a hot forged non-heat treated article using the same, and a hot forged non-heat treated article. ;SOLUTION: This process is constituted of the non-heat treated steel for hot forging, having a composition consisting of, by weight, 0.30-0.60% C, 0.02-0.20% Si, 1.65-3.00% Mn, 0.02-2.00% Cr, 0.0080-0.0200% N, either or both of 0.005-0.050% Al and 0.005-0.050% Ti, either or both of 0.01-0.30% V and 0.01-0.30% Nb, and the balance Fe with inevitable impurities; the method of manufacturing a hot forged non-heat treated article by subjecting the steel to working at 1,270 K and to air cooling; and a hot forged non-heat treated article which has the same composition and in which bainitic structure comprises 80% of the volume of steel structure.;COPYRIGHT: (C)1999,JPO