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焊接残余应力是引发核电一回路安全端异种金属焊接接头应力腐蚀开裂的主要原因。借助ABAQUS软件中的扩展有限元方法(XFEM),利用预定义温度场加载法建立了残余应力场下异种金属焊接接头模型,基于最大主应力判定准则实现了材料的裂纹扩展模拟,初步探究了残余应力场下不同初始长度、不同位置裂纹的扩展规律。结果表明,在残余应力场下,裂纹扩展过程中扩展路径总是偏向于材料屈服极限较小的一侧,初始裂纹长度越短,其扩展能力越强;裂纹处材料区屈服极限越小,裂纹扩展能力越强,且材料交界处裂纹的扩展能力总是大于两侧材料区内部裂纹的扩展能力。
Welding residual stress is the main cause of stress corrosion cracking in dissimilar metal welded joint of nuclear safety circuit. Based on the extended finite element method (XFEM) in ABAQUS software, a model of dissimilar metal welded joint under residual stress field was established by using the pre-defined temperature field loading method. Based on the criterion of maximum principal stress, the crack propagation simulation was carried out and the residual Propagation law of crack with different initial length and different position under stress field. The results show that in the residual stress field, the propagation path always deviates from the smaller yield side of the material during the crack propagation. The shorter the initial crack length, the stronger its expanding ability. The smaller the yield point of the material area, The stronger the scalability is, the more the crack propagation capacity at the interface of the material is always larger than the scalability of the cracks in the material areas on both sides.