STEEL WIRE FOR SPRING

摘要

A steel wire for a spring being produced through quenching and tempering and having a tempered martensite structure, which is produced with a value of reduction of area of 40 % or more, and exhibits a shear yield stress of 1000 MPa or more after the heat treatment at 420 to 480°C for two hours or longer, wherein the steel wire preferably has a chemical composition, in mass %, that C: 0.50 to 0.75 %, Si: 1.80 to 2.70 %, Mn: 0.1 to 0.7 %, Cr: 0.70 to 1.50 %, Co: 0.02 to 1.00%, and the balance: Fe and impurities, or that C: 0.50 to 0.75 %, Si: 1.80 to 2.70 %, Mn: more than 0.7% and 1.5 % or less, Cr: 0.70 to 1.50 %, and the balance: Fe and impurities.