含表面裂纹非匹配焊接接头的断裂行为

Fracture behavior of mismatching welded joint with surface crack

测试了两种超高强度钢低匹配接头母材、焊缝和热影响区的表面裂纹断裂韧性,比较了母材与热影响区的断裂韧度概率分布.同时采用有限元方法分析了匹配因子和裂纹位置对裂纹尖端张开应力和应力三轴度的影响.结果表明,当裂纹位于热影响区时,由于软焊缝使其应力三轴度降低,其断裂韧性明显好于母材;而当裂纹位于焊缝一侧时,匹配因子越高,距熔合线越远,则应力三轴度越低,断裂韧性越好;当裂纹位于焊缝中心时,两种匹配的断裂韧度相当.从而解释了试验结果.

The surface crack fracture toughness of the base metal,weld seam and HAZ of undermatching welded joint of two kinds of ultra-high strength steel were tested.The fracture toughness probability distribution of base metal and HAZ was compared.At the same time,the finite element method (FEM) was used to analyze the effects of strength matching factor and the crack location on stress field of crack tip and stress triaxiality.The result shows that,while the crack locates in the HAZ,the fracture toughness of HAZ is better than that of the base metal,because the low strength seam reduces stress triaxiality of HAZ.On the other hand,while the crack locate in weld seam,the higher the strength matching factor is and the farther it is to the fusion line,the lower the stress triaxiality,so the better the fracture toughness.When the crack locate in the weld seam center,the fracture toughness of the two matching is quite.