Patent ID: 9593731
Date: 2017-03-14
CPC Classifications: B21D,B21F,B23K,B23P,C21D,C22C,F16F

Claim:
1. A ring spring formed to be endless by welding two ends of a raw material, the raw material being a steel material containing C: 0.10 to 0.30 mass %, Si: 0.50 to 2.10 mass %, Cr: 0.50 to 1.50 mass %, Mn: 1.0 to 2.0 mass %, P: 0.025 mass % or less, S: 0.025 mass % or less, Fe as a remainder and inevitable impurities, the steel material having carbon equivalent Ceq shown by Formula (1) below of 0.5 to 0.75 mass % and hardness of 350 HV or more as the raw material, wherein brackets indicate mass %, the ring spring comprising: a welded metal part formed at an interface of the two ends of the raw material, and a welded heat-affected zone formed at the circumference of the welded metal part and which is heated by welding, wherein tensile strength is 1000 MPa or more, and wherein the ring spring is formed without quenching and tempering,