| 摘要 |
PURPOSE:To obtain the titled steel material superior in toughness, by adding V, Nb, Ti, etc. to Mn-Cr-Mo steel, hot rolling it at a specified temp. range, then quenching and tempering said plate. CONSTITUTION:Steel contg. 0.05-0.20wt% C, <=0.80% Si, 0.2-1.5% Mn, <=5.0% Cr, 0.4-1.5% Mo, <=0.35% V, 0.01-0.12% total of >=one kind of Nb, Ti, 0.01-0.1% sol Al, further 0.0003-0.002% B, while restricting N to <=0.005% is melted. Steel ingot or slab of the compsn. is heated to 1,100-1,280 deg.C, then hot rolled at 800-1,050 deg.C by >=1.2 draft, to refine crystal grains up to center part in thickness of ultrathick steel plate. Next, the plate is immediately quenched directly from >=800 deg.C, temperated to obtain the titled steel material having superior toughness.
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