| 摘要 |
<p>Disclosed is a steel plate for cold forging which comprises a hot-rolled steel plate, the hot-rolled steel plate containing, in terms of mass%, 0.13-0.20% C, 0.01-0.8% Si, 0.1-2.5% Mn,0.003-0.030% P, 0.0001-0.008% S, 0.01-0.07% Al, 0.0001-0.02% N, and 0.0001-0.0030% O, with the remainder comprising Fe and incidental impurities, and having a value A shown by equation (1) of 0.0080 or less and a thickness of 2-25 mm. In a cross-section parallel to the rolling direction of the hot-rolled steel plate, the amount in areal percentage of pearlite bands having a length of 1 mm or longer which are present in the area ranging from (4/10)t to (6/10)t, where t is the thickness of the plate, is not more than the value K shown by equation (2). Value A = O%+S%+0.033Al% (1) Value K = 25.5×C%+4.5×Mn%-6 (2)</p> |
