高張力鋼溶接ボンド部の靱性に関する研究(第 1 報) : 高張力鋼溶接ボンド部の靱性におよぼす要因について

概要

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The impact properties at the bond of weld joints for 80kg/(mm)^2 class high tensile strength steels were investigated in relation to the austenite grain size, ferrite lath size and shape of carbide. Fracture mode at 0℃ with increasing heat input changed cleavage type from dimple partten and fracture continuation was found to pass through a region of the relative rough ferrite lath, which was situated at about 50-250μm from fusion line. With increasing heat input, the region of the relative rough ferrite lath was widly, austenite grain size at near by bond also grew up and the transition temperature raised. The toughness at near by bond depended on austenite grain size in only rapid cooling rate, but in lower cooling rate and in size of 60-200μm austenite grain, its toughness did not show clearly to depend on austenite grain size. Therefore, based on the observation of fracture surface and microstructure by two-stage replica method, the unit facet and ferrite lath size were defined. The unit facet and ferrite lath size showed a good correlation to the transition temperature. These results suggested that the bond brittelness depend on the morpology of structure, namely, the ferrite lath size and/or the distance of individual carbide precipitated lath boundary and in lath.
社団法人溶接学会の論文
1974-10-05