| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a steel plate for simultaneously achieving low temperature toughness of a high heat input weld zone and stable low temperature toughness as a thick high strength steel plate.SOLUTION: A method of manufacturing a steel plate for high heat input welding includes the processes of: heating a steel raw material having a component composition containing, by mass%, a fixed quantity of C, Si, Mn, P and S, further Al: 0.005 to 0.1%, Nb: 0.003 to 0.04%, Ti: 0.003 to 0.04%, N: 0.003 to 0.01%, B: 0.0003 to 0.003% and the balance Fe with inevitable impurities and containing Ceq of 0.33 to 0.45 at 1000°C or higher; conducting first acceleratively cooling to an austenitic non-recrystallization temperature range after rolling in an austenitic recrystallization temperature range; and conducting second acceleratively cooling to a temperature range of 600°C or less after rolling with cumulative rolling reduction of 40% or more in the austenitic non-recrystallization temperature range. |
