奥氏体不锈钢管窄间隙焊接残余应力分布及径厚比影响研究

Investigation on Residual Stress Distribution in An Austenitic Stainless Steel Pipe Narrow-gap Girth Weld and Effect of Radius-to-wall Thicknesss Ratio

采用轮廓法试验测试和有限元数值模拟研究φ273 mm×28 mm的316L奥氏体不锈钢管窄间隙多道焊接残余应力的分布特征,并基于数值模拟研究了不同径厚比对管环焊缝残余应力的影响规律。结果表明:计算得到的环向应力和轮廓法测试结果在焊缝内部的分布趋势相近;焊缝区环向应力和轴向应力沿厚度方向呈现“弯曲型”分布特征,即内壁附近的焊缝及邻近区域为压缩应力,外壁区域为拉伸应力。厚度不变的情况下,随着径厚比R/t增大,焊缝区域的环向拉伸应力区略增大,压缩应力区减小;而内壁附近的轴向压应力值减小,外壁附近的轴向拉应力值也减小,沿厚度方向的轴向应力向“自平衡”应力状态转变。

The residual stress distribution in narrow gap multipass girth weld of an austenitic stainless steel pipe of φ273 mm×28 mm was investigated with the experiment by contour method and finite element numerical simulation method.The effect of radius-to-wall thickness ratio(R/t)on the residual stress distribution in the girth weld was also investigated using the finite element method.The results show that the distributions of hoop stress in the girth weld obtained by the contour method and finite element method are similar.The hoop and axial stresses in the weld zone demonstrate a bending-type distribution,which means that the stress of the inner surface in the weld and its adjacent region is compressive and that of the outer surface is tensile.Under the same wall thickness,the region of hoop tensile stress increases a litle with the value of R/t increasing,while the region of hoop compressive stress decreases.With the value of R/t increasing,the axial compressive stress value of the inner surface and its adjacent region decreases,and that of the outer surface and its adjacent region decreases too,and the axial stress in thickness direction changes to self-equilibrating stress type.