HIGH HARDNESS PREHARDENED STEEL FOR COLD WORKING HAVING EXCELLENT MACHINABILITY, DIE FOR COLD WORKING USING THE STEEL AND WORKING METHOD FOR THE STEEL

摘要

PROBLEM TO BE SOLVED: To provide a high hardness prehardened steel which has excellent machinability, a die for cold working using the steel, and a working method for the steel.;SOLUTION: The prehardened steel for cold working has a composition containing, by mass, 0.3 to 0.5% C, 0.7 to 2.0% Si and 0.08 to 0.25% S, and is refined to a hardness of 50HRC. Preferably, the prehardened steel concretely has a composition containing 0.3 to 0.5% C, 0.7 to 2.0% Si, 0.1 to 2.0% Mn, 0.08 to 0.25% S, 0.5 to 15.0% Cr, one or two kinds selected from W and Mo by ≤3.5% in terms of (Mo+1/2 W), ≤4.0% V and ≤0.15% N, and the balance Fe with inevitable impurities. Then, the die for cold working is obtained subjecting the prehardened steel to cutting, e.g. at a cutting speed of ≥50 m/min. Further, in the working of the steel having a hardness of ≥50HRC at a cutting speed of ≥50 m/min, the steel contains 0.3 to 0.5% C, 0.7 to 2.0% Si and 0.08 to 0.25% S.;COPYRIGHT: (C)2002,JPO