| 摘要 |
PURPOSE:To determine the optimum combination of the content of C and the content of Mn by determining the equal strength curve and equal fracture transition temp. curve of a base material steel plate for the content of C and the content of Mn as variables and superposing these curves and the preliminarily determined equal fracture transition temp. curve for the toughness of a weld heat effected zone. CONSTITUTION:The equal strength curve (single-dot chain line) and equal fracture transition temp. curve (broken line) of the base material steel plate for the content of C and the content of M as the variables are determined according to the production conditions for the steel plate consisting, by weight %, of 0.01-0.25% C, 0.01-0.50% Si, 0.25-2.00% Mn, 0.005-0.100% Al, and the balance iron and unavoidable impurities. The equal fracture transition temp. curve (solid line) for the toughness of the weld heat effected zone corresponding to various weld heat input quantities is preliminarily determined. These curves are superposed and the hatched region enclosed by these curves is determined as the optimum combination of the content of C and the content of Mn to satisfy the characteristics required at the time of welding procedure. The components to satisfy the required toughness of the weld heat effected zone are thereby designed.
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