高钢级管道环焊缝表观断裂韧性影响因素数值模拟

Numerical simulation on influencing factors of apparent fracture toughness of girth welds on high-grade steel pipelines

为准确表征高钢级管道环焊缝与小尺寸试样表观断裂韧性的关联性,采用有限元方法,开展了含裂纹型缺陷管道环焊缝及小尺寸单边切口梁(Single Edge Notch Beam,SENB)试样的断裂数值模拟分析。通过对比全尺寸管道环焊缝与SENB试样二者之间表观断裂韧性的差异,引入表观断裂韧性转化系数,定量研究了管径、壁厚、裂纹长度及深度对全尺寸管道环焊缝表观断裂韧性的影响规律,得到不同工况下全尺寸管道与SENB试样之间的转化系数,实现了基于小尺寸试样韧性测试结果的高钢级管道环焊缝表观断裂韧性量化表征。结果表明:管径对管道环焊缝的表观断裂韧性及其转化系数的影响相对较小;表观断裂韧性转化系数随管道壁厚的增加而增大,随裂纹长度及深度的增加而减小;相较其他影响因素,裂纹深度对管道环焊缝表观断裂韧性的影响更明显。基于表观断裂韧性转化系数能够得到相对准确的高钢级管道环焊缝表观断裂韧性,可为高钢级管道环焊缝表观断裂韧性的准确表征提供理论参考。

In this study,numerical simulation analysis on fracture of girth welds on pipelines with crack defect and small Single Edge Notch Beam(SENB)was performed with the finite element method for accurately characterizing the correlation of apparent fracture toughness of the girth welds on high-grade steel pipelines and the small specimens.The conversion coefficient of apparent fracture toughness was introduced by comparing the difference of apparent fracture toughness of the girth welds on full-scale pipelines and the SENB specimens.Conversion coefficients between full-scale pipelines and SENB specimens under different working conditions were obtained by quantitatively studying the impact of pipe diameter,wall thickness,crack length and depth on the apparent fracture toughness of girth welds on full-scale pipelines,realizing quantitative characterization of the apparent fracture toughness of girth welds on high-grade steel pipelines based on the test results of small specimens.The results indicate that the pipe diameter has little effect on the apparent fracture toughness and its conversion coefficient.The conversion coefficient of fracture toughness increases with the increasing of wall thickness and decreases with the increasing of crack length and depth.The effect of crack depth on the apparent fracture toughness of pipelines is more obvious than other influencing factors.A relatively accurate apparent fracture toughness of girth welds on high-grade steel pipelines can be obtained based on the conversion coefficient,providing theoretical reference for accurately characterizing the apparent fracture toughness of girth welds on high-grade steel pipelines.