Steel wire material for spring and its producing method

摘要

The present invention relates to a steel wire material for a spring comprising; C: 0.38 - 0.47%, Si: 1.9 - 2.5%, Mn: 0.6 - 1.3%, Ti: 0.05 - 0.15%, Al: 0.003 - 0.1 %, and the balance composed of iron with inevitable impurities, wherein; the depth of ferrite decarburized layer is 0.01 mm or less, Ceq1 as exhibited in the equation (1) below is 0.580 or more, Ceq2 as exhibited in the equation (2) below is 0.49 or less, and Ceq3 as exhibited in the equation (3) below is 0.570 or less. Ceq �¢ 1 = C + 0.11 Si - 0.07 Mn - 0.05 Ni + 0.02 Cr Ceq �¢ 2 = C + 0.30 Cr - 0.15 Ni - 0.70 Cu Ceq �¢ 3 = C - 0.04 Si + 0.24 Mn + 0.10 Ni + 0.20 Cr - 0.89 Ti - 1.92 Nb
(In the above equation, [ ] shows the content (mass %) of each element in steel.)