EVALUATION METHOD OF STEEL PLATE EXCELLENT IN WELDING HEAT AFFECTED PART TOUGHNESS

摘要

PROBLEM TO BE SOLVED: To provide an evaluation method of a steel plate for evaluating welded part toughness without performing a synthetic weld thermal cycle test.SOLUTION: According to the evaluation method for a steel plate, 0.01 mass % or less of Al, 0.5 to 2.0 mass % of Mn, 0.0005 to 0.0100 mass % of O, 0.0005 to 0.0100 mass % of S, 0.0010 to 0.0100 mass % of REM are contained, and content of O, content of Mn, and content of REM satisfy equation (1); content of S and content of Mn satisfy equation (2); a composition and the number of depositions per unit area of a steel plate where a remaining part has composition comprising Fe and unavoidable impurity are measured to perform evaluation by using REM content and Mn content of the deposition and proportion of the number of depositions to be oxysulphide among the deposition: (1) [Mn]×[O]×0.2[REM][Mn]×[O]×1.2; (2) [S]0.00294/[Mn].