STRUCTURAL STEEL EXCELLENT IN COLD FORGEABILITY AND SEPARATION WORKABILITY BY BREAKING, AND PRODUCTION OF FORGED MEMBER USING ITS STEEL

摘要

PROBLEM TO BE SOLVED: To provide a structural steel excellent in cold forgeability and separation workability by breaking and a method of production of a forged member using the steel. ;SOLUTION: This steel for machine structure use, excellent in cold forgeability and separation workability by breaking, has a composition, at to the contents of alloying elements, consisting of, by weight, 0.05-0.15% C, 0.05-0.45% Si, 0.20-0.45% Mn, 1.00-2.00% Cu, 0.0010-0.0080% B, 0.015-0.050% Ti, further one or more kinds selected from 0.005-0.080% S, 0.005-0.300% Pb, 0.005-0.200% Bi, 0.003-0.020% The, and 0.005-0.0050% Ca, Ni and N limited to ≤0.50% and ≤0.010%, respectively, and the balance essentially Fe. The forged number for machine structural use is produced by subjecting the above steel to cold forging, to machining, further to heat treatment consisting of holding at 450-550°C for 30-120 min, and then to separation working by breaking.;COPYRIGHT: (C)1999,JPO