| 摘要 |
PURPOSE:To produce high tensile steel of small anisotropy and good weldability by subjecting a steel slab of the specific compsn. contg. a specific amt. of N to heating, rolling, hardening and tempering under specific temp. conditions. CONSTITUTION:A steek slab contg., by weight %, 0.03-0.20% C, 0.03-0.75% Si, 0.50-1.80% Mn, 0.01-0.10% V, <=0.0040% N, 0.10-0.100% SolAl, and further contg. 1 or >=2 kinds of 0.05-0.50% Cu, 0.15-2.50% Ni, 0.10-2.50% Cr, 0.03- 1.50% Mo, 0.00015-0.0025% B, and consisting of the balance Fe and impurities is heated to 1,000-1,230 deg.C. Thence, it is rolled at finish temp. above 850 deg.C, and immediately after this, it is hardened from the temp. above the Ar3 transformation point. Following to this, it is tempered to the temp. above the Ac1 transformation point. |
