The manner which produces the spring with production manner and its steel wire material of the steel wire material and that steel wire material for the spring of the high intensity high tenacity which is superior in cold processability

摘要

Provided is a steel wire rod for a high strength and high toughness spring having excellent COLD workability and the steel wire rod having a composition comprising: in weight %, C: 0.4 to 0.7%, Si: 1.5 to 3.5%, Mn: 0.3 to 1.0%, Cr: 0.01 to 1.5%, Ni: 0.01 to 1.0%, Cu: 0.01 to 1.0%, B: 0.005 to 0.02%, Al: 0.1% or less and O: 0.0020% or less and P: 0.02% or less and S: 0.02% or less and N: 0.02% or less, remainder Fe, and other unavoidable impurities, having a microstructure formed of ferrite and pearlite and in which a prior (before cooling) austenite grain size is 8 m or less.