热影响区软化的X70管线环焊缝应变容量分析

针对一种拉伸试验断裂于热影响区附近的X70管线环焊接头，通过数值仿真和韧性试验分别获得断裂驱动力和断裂阻力曲线. 在此基础上使用切线法预测该环焊接头具有较高的拉伸应变容量，与宽板拉伸试验结果一致. 结果表明，与现行标准中要求焊接接头强匹配，并且拉伸试验不应断于“近缝区”的准则相比，使用延性撕裂行为进行热影响区软化环焊接头的定量分析，可以避免对材料性能的过度要求，并且能科学有效的预测环焊接头拉伸应变容量.

Investigation on tensile strain capacity of circumferential weld of X70 pipeline steel with softened heat affected zone

The circumferential welding joints of strain-based design X70 pipeline always fractured at heat affected zone in the tensile test. The crack driving force and fracture resistance curve of the circumferential welding joint defects were obtained by numerical simulation and impact toughness test separately. On the above basis, the considerable high strain capacity has been demonstrated by the tangent method and verified by wide plate tensile test. The results proved that the pipeline had considerable fracture resistance which may lead to high strain capacity and the crack driving force approach was more reasonable than current standard which required that the weld joint should not be fractured in the vicinity of the weld zone, and remitted the over-demand from material properties.