| 摘要 |
PROBLEM TO BE SOLVED: To produce a non-heat treated high tensile strength steel plate small in the reduction of Bauschinger effect without requiring the addition of a large amt. of Cr, and to provide a method for producing the same. SOLUTION: A steel slab having a compsn. contg., by weight, 0.03 to 0.12% C, 0.05 to 0.30% Si, 0.30 to 2.00% Mn, 0.005 to 0.06% Nb, 0.01 to 0.10% Al and <=0.007% N, moreover contg. one or >= two kinds selected from 0.05 to 1.30% Cu, 0.10 to 10.0% Ni, 0.05 to 1.50% Cr, 0.03 to 0.50% Mo, 0.01 to 0.15% V, <=.070% Ti, 0.0005 to 0.0040% Ca and 0.001 to 0.020% rare earth metals, and the balance Fe with inevitable impurities is subjected to hot rolling so as to control the rolling finishing temp. to >=(Ar3-50 deg.C), and, after the completion of the rolling, it is subjected to forced cooling to the temp. range of 400 to 700 deg.C.
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