残余应力场下核电焊接接头应力腐蚀裂纹扩展特性研究

Stress Corrosion Crack Propagation Characteristics of Nuclear Power Welded Joint under Residual Stress Field

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(SCC)裂纹的主要应力来源。借助ABAQUS软件中的扩展有限元方法(XFEM),通过建立安全端焊接接头有限元模型,研究了残余应力场下裂纹的扩展规律,并利用子模型技术研究了裂纹尖端应力应变场分布规律。研究结果表明,随着裂纹的不断扩展,裂纹的长度增加,塑性变形的面积增加,裂纹偏移量增大。裂纹扩展初期,裂尖附近很大范围内存在较高的应力,随着裂纹的不断扩展,裂尖附近的应力不断减小。

Welding residual stress is the main stress source of stress corrosion cracking(SCC) cracks of the dissimilar metal welded joint in a nuclear power loop safety end. With the help of the extended finite element method(XFEM) in ABAQUS software, the propagation law of the crack under the residual stress field was studied by establishing the finite element model of the safety end welded joint, and the distribution laws of stress and strain field at the crack tip was studied by using the submodel technique. The research results show that with the crack extending, the length of the crack, the area of plastic deformation and crack offset increase. At the initial period of crack propagation, high stress exists in a large range near the crack tip. With the crack extending, the high stress decreases near crack tip.