OD1422 mm X80管道环焊接头拉伸应变行为研究

Study on deformation behavior of girth welded joint of OD1422 mm X80 pipe

基于非线性有限元方法,结合数字化图像相关技术(DIC)、硬度云图以及断裂韧性测试等手段,进行了含缺陷天然气管道环焊接头的变形能力评估。该方法考虑了管道、焊缝以及缺陷尺寸形状特征,利用钢管母材、焊缝、热影响区的实际性能构建分析模型,对比了不同缺陷尺寸下的断裂驱动力与裂纹扩展阻力,获得环焊接头拉伸应变能力,并利用宽板拉伸试验对分析结果进行了验证。结果表明:当拉伸应变为0.5%时,裂纹扩展阻力始终高于断裂驱动力,裂纹不会发生扩展;当拉伸应变为1.3%、裂纹深度为8.2 mm时,裂纹扩展阻力与断裂驱动力相等,裂纹处于临界失稳状态;当拉伸应变为4.3%时,裂纹深度高于5.2 mm,裂纹会发生扩展;宽板拉伸结果中,当裂纹深度低于5 mm时,失效模式均为母材颈缩;裂纹深度为9 mm时,失效模式为裂纹扩展,模型分析与宽板拉伸试验结果一致性较好。

Based on nonlinear finite element method and in combination with digital-image correlation(DIC)technology,hardness cloud map and fracture toughness test,an evaluation method of deformation capacity for the pipe with defects in girth weld was set up.This method considers the shape of the pipe,weld shape feature and defect size.The properties of pipe metal,weld and heat affected zone were used to build the analysis model.The driving force of crack with different sizes of defects was compared with the crack propagation resistance,the tensile strain capacity of the girth weld was obtained,and the analysis results were verified by curved wide plate tensile tests(CWP).The results show that when the tensile strain is 0.5%,the crack propagation resistance is always higher than the crack driving force,and the crack does not propagate.When the tensile strain is 1.3%and the crack depth is 8.2 mm,the crack propagation resistance is equal to the crack driving force,and the crack is in a critical instability state.When the tensile strain is 4.3%and the crack depth is higher than 5.2 mm,crack propagation will occur.Based on the result of CWP,when the crack depth is less than 5 mm,the failure mode is the necking of pipe metal.When the crack depth is 9 mm,the failure mode is crack propagation,and the finite element evaluation results are in good agreement with the test results.