| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel for soft-nitriding having machinability as hot-forged or as normalized after that, and suitable as the stock for a component requiring the reduction of noise. SOLUTION: The steel for soft-nitriding has a composition comprising 0.04 to 0.12% C, 0.02 to 0.50% Si, 0.2 to 1.5% Mn, 0.51 to 1.5% Cr, 0.3 to 1.3% Mo, 0.03 to 0.20% V, (48/14)×N to 0.05% Ti, 0.005 to 0.05% S, 0.01 to 0.06% Al, 0.0003 to 0.003% B and 0 to 0.05% Nb, and the balance Fe with impurities; in the impurities, N≤0.012%, O≤0.003% and P≤0.03% are satisfied, and in which the value of (Mo/16)+(V/4.2) satisfies 0.05 to 0.09, the value of C-(Mo/16)-(V/4.2) satisfies≥-0.020, and the value of 8.54×C<SP>1/2</SP>×(1+0.681×Si)×(1+3.066×Mn+0.329×Mn<SP>2</SP>)×(1+2.007×Cr)×(1+3.14×Mo)×(1+1.73×V)×1.4 satisfies 40 to 160; wherein, the atomic symbols in the equations denote the contents (%) of each element in the steel, and, in the case of O≤0.0015%, the content of S may be 0.005 to 0.08%. COPYRIGHT: (C)2006,JPO&NCIPI
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