厚板 80kg/(mm)^2 高張力鋼溶接部の脆性破壊発生特性(第 1 報) : 角変形付広幅溶接引張継手のひずみおよび破壊挙動

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80kg/(mm)^2 high strength thick plate steels come into extensive use. In many application, welded structures are used under such a stress condition that tension and bending are superimposed, and danger of brittle fracture initiation at weld fusion line becomes greater all the more. So, the brittle fracture intiation characteristics of the welded joints, both manual arc welded and submerged arc welded made of 80kg/(mm)^2 high strength steel with a plate thickness of 50mm were investigated using the wide plate tension test specimens with an angular distortion. The main results are summarized as follows : (1) The joints welded with a heat input of 45-50kJ/cm does not cause low stress fracture in the temperature range above 0℃ if it is free from weld defects, even under such a stress field condition that bending stress is almost twice as much as tension stress. The fracture stress is almost equal with ultimate tensile strength of round bar uniaxial tension specimens. (2) In the manual arc welded joints annealed for stress relief, crack initiates at a weld toe and propagates to the weld fusion line and developes to low stress fracture at -15℃ under the same stress condition. An annealing for stress relief for welded joints of the 80kg/(mm)^2 high strength steel cannot be recommended. (3) The submerged arc welded joints offer higher elongation than the manual arc welded joints, and even if it is of a cross welded type shows ductile fracture. In mannual arc welded joints, elongation of specimens as welded is higher than that of annealed specimens for stress relief and becomes lower in cross welded specimens. (4) Even in a specimen as welded the repair weld zone enhances the risk of low stress fracture. The quantitative investigation into this problem is to be made sometimes in the future. (5) The strain behavior of a specimen with angular distortion varies depending on the amount of angular distortion and the end restraint condition. Therefore comparison of its test result with those of actual structures in terms of the amount of angular distortion only is not advisable. Prediction of fracture for actual structures is possible, by comparing the stress condition of the structures with taking into account bending moment working on the weld zone estimated from the measured values of strain.
社団法人溶接学会の論文
1975-08-05

厚板 80kg/(mm)^2 高張力鋼溶接部の脆性破壊発生特性(第 1 報) : 角変形付広幅溶接引張継手のひずみおよび破壊挙動

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