在980MPa级深海用低碳贝氏体高强钢MAG焊接接头上,制取5种不同形状和缺口位置的试样进行拉伸试验,原位观察了每种试样的动态断裂过程,并对其断裂机理进行了分析,确定了焊接接头的薄弱部位。结果表明：直缺口试样的断裂经历了塑性变形、裂纹起裂、裂纹扩展、裂纹尖端钝化,直至断裂的过程,并且在裂纹扩展过程中,裂纹尖端重复钝化、扩展、新裂纹产生、再钝化、再扩展;圆弧和平板试样以剪切方式断裂,经历了塑性变形、颈缩、出现微裂纹、微裂纹扩展,直至瞬间断裂的过程;所有试样的薄弱部位都为焊缝金属。
Tensile tests were applied to five kinds of specimens with different shapes and notch poisitions in the MAG welded joint of 980 MPa low-carbon bainite high strength steel used for deep-sea.The dynamic fracture process of every kind of specimens was in-situ observed to analyze the fracture mechanism,and to determine the week part of joint.The results show that the fracture of straight notch specimens suffered the process of plastic deformation,initiating,propogation,blunting and fracture of cracks.The crack tip repeatedly blunted,prapogated,new cracks initiated,re-blunted,re-propagated during crack propogation.The arc and flat specimens fractured in a shear mode and suffered the process of plastic deformation,necking,initiation,propagation and fracture of microracks.The weak part of all specimens was the weld metal.
参考文献
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