| 摘要 |
PROBLEM TO BE SOLVED: To provide steel for a spring which requires no working of whole grinder grinding after hot rolling. SOLUTION: The steel for a spring is consisting of a hot rolling stock of a steel kind having a composition containing, by weight, 0.3 to 0.6% C, 1.0 to 2.0% Si, 0.1 to 0.5% Mn, 0.4 to 1.5% Cr, 0.1 to 0.3% V, 0.2 to 1.2% Ni, 0.1 to 0.3% Cu, <=0.030% S, <=0.0020% O, <=0.015% P, 0.0005 to 0.0035% B and 0.01 to 0.05% Nb, and the balance Fe with inevitable impurities. The maximum depth of ferrite decarburization in the surface upon the end of a cooling stage is <=0.02 mm.
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