塑性变形对落锤撕裂试验异常断口的影响

摘要

This paper describes the effect of plastic deformation on occurrence of abnormal fracture during DWTT using various steels with different microstructures. Each DWTT was carried out at the same test temperature using 20 mm plates with approximately the same tensile strength. This paper describes the deformation during DWTT, which consists of deformation caused by hammer impact, bending compression, and bending tension. The deformation due to the impact of the hammer during DWTT on a 20 mm plate was limited, and the location affected by the hammer impact did not correspond to that where abnormal fracture occurred. Moreover, the equivalent plastic strain from bending deformation was dominant as compared with that of hammer impact regardless of the microstructure. This suggests that abnormal fracture occurred by exceeding the critical equivalent plastic strain due to the bending deformation.%介绍了塑性变形对不同组织管线钢DWTT出现异常断口的影响，试样抗拉强度基本相同，采用20 mm厚相同规格，在同一温度下进行试验。研究结果表明， DWTT中的变形主要包括3部分，分别为落锤冲击、弯曲压缩和弯曲拉伸产生的变形；落锤冲击对20 mm厚试样产生的变形有限，且影响区域与异常断口出现的位置不相对应；与落锤冲击相比，弯曲变形产生的塑性应变当量占主导地位，与显微组织无关。这说明异常断口是弯曲变形超过了材料临界塑性应变当量而产生的。