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PROCCESS FOR PRODUCING THICK HIGH-STRENGTH STEEL PLATE EXCELLENT IN BRITTLE FRACTURE ARRESTABILITY AND TOUGHNESS OF ZONE AFFECTED BY HEAT IN LARGE-HEAT-INPUT WELDING AND THICK HIGH-STRENGTH STEEL PLATE EXCELLENT IN BRITTLE FRACTURE ARRESTABILITY AND TOUGHNESS OF ZONE AFFECTED BY HEAT IN LARGE-HEAT-INPUT WELDING
PROCCESS FOR PRODUCING THICK HIGH-STRENGTH STEEL PLATE EXCELLENT IN BRITTLE FRACTURE ARRESTABILITY AND TOUGHNESS OF ZONE AFFECTED BY HEAT IN LARGE-HEAT-INPUT WELDING AND THICK HIGH-STRENGTH STEEL PLATE EXCELLENT IN BRITTLE FRACTURE ARRESTABILITY AND TOUGHNESS OF ZONE AFFECTED BY HEAT IN LARGE-HEAT-INPUT WELDING
Method for producing a thick high-strength steel sheet is, by mass%, C: 0.05 to 0.12%, Si: 0.3% or less, Mn: 1 to 2%, P: 0.015% or less, S: 0.005% or less, B: 0.0003 to 0.003 %, V: 0.01 to 0.15%, Al: 0.001 to 0.1%, Ti: 0.005 to 0.02%, N: 0.002 to 0.01%, and O: containing less than 0.004%, and contains iron and inevitable impurities as the remainder the continuously cast slab which was cooled to not higher than Ar 3 -200 ℃, and reheated to 950 to 1100 ℃, continuously subjected to rough rolling of 30% or greater reduction in the amount of accumulated over 900 ℃ to the continuously cast slab, still 700 ℃ finish rolling the cumulative amount of 50% or greater reduction from the above, the rolling termination temperature of finish rolling starting and finishing temperatures, all of them at a temperature less than indicated by the food {-0.5 × [slab heating temperature (℃)] 1325} + (℃) conditions and by performing rolling disc in, continue to B amounts to employ in the rolling discs by applying accelerated cooling to a cooling to the steel sheet to below 500 ℃, and the continuously cast slab, transformation before the austenite possession {effective B amount : Bef (%)} calculated value is 0% or less of, and the carbon equivalent Ceq is 0.32 to satisfies the relationship of 0.42%. ; Slabs, austenitic, roughing, steel, rolled metal disc
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