Cold forming spring having high fatigue strength and high corrosion fatigue strength, and method for producing spring steel wire

摘要

PPROBLEM TO BE SOLVED: To provide a cold-formed spring combined with both corrosion resistance and durability, and a steel for the spring. PSOLUTION: A wire rod comprises, by weight ratio, 0.45-0.52% C, 1.80-2.00% Si, 0.30-0.80% Ni, 0.15-0.35% Cr, and 0.15-0.30% V with the balance being substantially Fe. The wire rod with the composition is induction-heated at 920-1,040C for 5-20 seconds, and after the quenching, tempered at 450-550C for 5-20 seconds so as to obtain a hardness of 50.5-53.5 HRC. Subsequently, the material is subjected to shot-peening to generate a residual stress of -600 MPa or more at the position of 0.2 mm below the surface. PCOPYRIGHT: (C)2008,JPO&INPIT