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
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摘要: 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.Abstract: 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 stress-strain 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.
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