贯穿件J形坡口焊接残余应力分析

核电站反应堆压力容器（RPV）顶盖控制棒驱动机构（CRDM）管座J形坡口焊缝在一回路高温高压水环境下存在应力腐蚀开裂（SCC）的风险，而焊接残余应力是SCC的主要驱动力。使用二维轴对称模型有限元方法对CRDM中心管座J形坡口进行焊接残余应力分析。为了探索一种简单、高效和保守的方法，研究了热源简化、焊缝形状简化、屈服强度、相变和强化行为对焊接残余应力的影响。结果表明:双椭球热源与均匀热源得到的残余应力结果基本一致；焊缝形状由鱼鳞状简化为方块模型对焊接残余应力结果影响不大，但是与合并焊道的结果相差较大；采用低屈服强度得到的残余应力结果并不保守；在ANSYS软件中，固液相变对残余应力结果影响不大；等向强化模型的结果比随动强化模型的结果保守；在工程上，建议采用均匀热源、方块焊道模型和等向强化模型进行焊接模拟。 

Analysis of Weld Residual Stress of J-Groove Weld in Penetrate Part

In nuclear power plants, the stress corrosion cracking(SCC) is the main reason to cause the cracks in the control rod drive mechanism(CRDM) nozzle with the J-groove attachment weld to the reactor pressure vessel(RPV) head. However, SCC is mainly driven by welding residual stresses. Thus 2 D axisymmetric model is used to study the weld residual stress distribution in J-shaped groove. In order to obtain a simple, efficient and conservative method, the effect of simplification of heat source, simplification of weld geometry, weld material yield strength, phase transformation, and material hardening behavior on the welding residual stress is investigated. The research result shows that the double ellipsoid heat source and uniform heat source lead to the same weld residual stress distribution;the simplification of scale weld model to block weld model has little influence on the result, but the simplification to dumped weld model could produce relatively great variation on weld residual stress distribution;low yield strength could not obtain the conservative result;in ANSYS, the phase transformation has no effect on the stress result;the result by the isotropic hardening behavior is higher about two times than that by kinematic hardening behavior;for the welding simulation in engineering, the uniform heat source, block weld model, and isotropic hardening behavior are suggested.