温度对焊接热模拟X80管线钢断裂韧性的影响

Effect of temperature on fracture toughness in weld thermal simulated X80 pipeline steels

通过试验和3D有限元模拟相结合的方法分析了焊接热模拟X80管线钢在不同温度(-90,-60,-30和0℃)下的断裂韧度.文中选取标准三点弯曲试样在不同温度下进行断裂韧度测试,同时对测试件进行三维有限元实体建模与分析计算.结果表明,X80管线钢的断裂韧性随温度减低显著减小,并使其倾向于脆性断裂.材料在不同温度下的真实应力—应变曲线行为从光滑拉伸到断裂力学试样具有良好的可传递性,温度对材料的硬化行为没有明显影响,有限元计算的结果表明,应用该方法可以准确地计算X80钢焊接热影响区不同温度下的CTOD值.

The aim of this paper is to study the effect of temperature on cleavage fracture toughness of weld thermal simulated X80 pipeline steels in ductile-to-brittle transition( DBT)regime. A large number of fracture toughness( as denoted by crack tip opening displacement-CTOD) tests together with finite element analyses are carried out by using deep-cracked single edge notched bending( SENB with a/W = 0. 5) specimens at various temperatures(-90℃,-60℃,-30℃ and 0℃). 3D finite element models of tested specimens have been used for the numerical simulation in this study. Coarse-grained heat-affected zone( CGHAZ) is considered as the material microstructure in preparation of weld thermal simulated fracture mechanics specimens. It has been found that the transferability of the true stressstrain curves obtained from weld thermal simulated round tensile bar to the fracture mechanics specimens works very well. Temperature shows only a slight effect on the material hardening behavior. As compared with experimental results,the 3D model can precisely predict the fracture toughness( CTOD-values) at different temperatures considered in this study.