ラインパイプ用高張力熱延鋼板のオーステナイト粒度と材質におよぼすホットストリップミル圧延条件の影響

概要

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Effects of processing variables on the properties of high-strength, high-toughness hot rolled coils for high-test linepipe have been studied. Through laboratory and trial production tests using low C-high Mn-Nb-V and low C-high Mn-Nb-Mo steels, it has been confirmed that by the combination of lowering the slab reheating temperature to 1140∿1170℃ at which some amount of Nb-carbonitrides is undisolved, and rough rolling of more than 85% reduction, an austenite grain size after rough rolling is refined to the ASTM 8. These conditions are essential to obtain final products with fine grained ferrite structure free from bainite and accordingly low ductile to brittle transition temperature, especially when the total reduction during finish rolling is limited to less than 50% due to a heavy thickness of the products. By controlling coiling temperature below 600℃, the yield strength is increased without impairing the transition temperature.
社団法人日本鉄鋼協会の論文
1977-06-01