某小型反应堆的异种金属环形焊接接头经由一百余道焊接后，会出现残余应力累计、变形严重等问题，影响焊接接头的抗应力腐蚀、抗疲劳破坏性能。采用X射线衍射法对该焊接接头表面残余应力测试，获得了环向、径向残余应力分布规律。结果表明：接头表面环向、径向残余应力基本呈现出拉应力状态，分布类似抛物线形状，呈现出中间高、两边低的形态；由于奥氏体不锈钢母材侧熔合线为典型的异种金属焊接区域，残余应力梯度明显偏大，焊缝有柱状晶的存在，焊缝中心处亦存在较大的应力梯度。

Following more than 100 welding process for the dissimilar metal girth welded joint, there appeared stress accumulation, large deformation and other issues in the weld joint, which should have unfavorable influence on the resistance capacities of the joint against fatigue and stress corrosion. X-ray diffraction method is employed to measure the surface residual stress, obtaining the radial and circumferential residual stress distribution rule. The results show that the radial and circumferential residual stresses are almost tensile ones, and being high in the middle and low on the both sides, like parabolic shape. Because the fusion line of austenite stainless steel base metal side is typical dissimilar metal welded zone, the residual stress gradient of the zone is larger. Additionally, there exists the columnar crystal in the weld, so larger residual stress gradient appears in the weld center.