HARD DRAWN SPRING HAVING EXCELLENT FATIGUE STRENGTH

摘要

PROBLEM TO BE SOLVED: To provide a hard drawn spring which exhibits fatigue strength equal to or greater than that of a spring obtained by using an oil tempered steel wire. SOLUTION: The hard drawn spring has a composition containing 0.5 to 0.7% C, 1.0 to 2.0% Si, 0.5 to 1.5% Mn and 0.5 to 1.5% Cr, and the balance Fe with inevitable impurities. The difference between the surface residual stress at the inside of the spring (R+) and the surface residual stress at the outside of the spring (R-), i.e., [(R+)-(R-)], is≤500 MPa. COPYRIGHT: (C)2004,JPO