HIGH-TOUGHNESS SPRING STEEL

摘要

A high-toughness spring steel having sufficient drawing and impact energy value at a high strength, particularly at a tensile strength of as high as 1,500 MPa or above, and having a composition comprising, in terms of mass %, 0.35 to 0.85 % of C, 0.9 to 2.5 % of Si, 0.1 to 1.2 % of Mn, 0.1 to 2.0 % of Cr, 0.005 to 0.07 % of Ti and 0.001 to 0.007 % of N, wherein Ti mass % > 4 x N mass %, P < 0.020 % and S < 0.020 % and the balance consists of Fe and inevitable impurities. The composition may selectively contain B, V, Nb, Ni, Mo and Cu.