基于裂纹扩展的管道钢阻力曲线测试评估

Measurement and Assessment of Resistance Curve Based on Crack Propagation for Pipeline Steel

高级别新型管线钢的不断涌现,其管材韧性和强度都得到了大大提高。然而,现有断裂韧性测试方法要求采用高约束的标准试样,管线钢很难满足试样尺寸条件,管道钢断裂韧性和裂纹扩展阻力的测试需要经过大量的实验和数值模拟评估。本文利用三点弯试样,测试了X65管线钢的断裂韧度和阻力曲线,对现有断裂韧度测试标准进行了评估,利用损伤模型评估了X65管材阻力曲线的厚度约束效应。结果显示:标准BS7448比ASTM-E1820计算得到的CTOD值更大,并且随着裂纹扩展长度增加,两种方法得到的CTOD比值增大。

The toughness and strength have greatly improved in the emerging new high-grade pipeline steels. However, the standard samples are required for high constraint in the existing measurement methods, in which the pipeline steels are difficult to meet the thickness condition. The testing of fracture toughness and resistance curve requires a large number of experimental and numerical assessment. The R curve of X65 pipe steel was measured using the three point bending specimens, the test of X65 pipeline steel fracture toughness and resistance curve, and the results were assessed by two testing standards. Thickness constraint effects of R curve are analyzed by finite element model with damage criteria. The results showed that： the CTOD values calculated by standard of BS7448 are more than the ASTM E1820＇ s, and the ratio of CTOD in the two methods increases with the crack propagation length increasing.