高速铁路新材料

以国内焊轨基地生产的钢轨闪光焊接头为样本，按照铁路标准开展了落锤与静弯试验，系统分析了接头的断口形貌及灰斑缺陷特征。结果表明：U71Mn接头的落锤与静弯试验性能均低于U75V接头，且其断口灰斑缺陷的出现概率与平均面积均显著高于U75V接头。在本研究样本集范围内，落锤试验中U71Mn与U75V接头的临界灰斑缺陷面积分别为15 mm²与10 mm²，低于该临界值时接头均能通过落锤试验，表明灰斑缺陷面积与落锤结果密切相关。静弯试验中，灰斑缺陷面积对静弯试验的影响并不明显，但缺陷位置影响显著。若灰斑在轨底边缘露头，即使面积较小，也会导致静弯承载力急剧下降，甚至引起接头断裂。对比同一批次接头的试验结果发现，落锤试验的冲击载荷更易引发接头于灰斑处开裂。

Taking the random finished rail flash butt welded joint produced in the domestic rail welding base as the sample, the drop-weight test and bending test were carried out according to the requirements of railway standards, and the fracture characteristics and flat spot defects of joints were statistically analyzed. The results show that the drop-weight test and bending test data of U71 Mn joint are lower than that of U75V joint, and the probability and average area of flat spot defects in the fracture of U71 Mn joint are significantly higher than that of U75V joint. Within the scope of the sample, the critical flat spot defect area of U71 Mn joint is 15 mm², and that of U75V joint is 10 mm². When the area of flat spot defect is lower than the critical size, the joint can pass the drop-weight test, and the area of flat spot defect in joint is strongly correlated with the drop-weight test results. The influence of the area of the flat spot defect on the bending test is not obvious, but the influence of the defect location on the static bending test is great. When small flat spot defect is exposed on the rail bottom, the bending value will be sharply reduced, even the joint will be unqualified. By comparing the drop-weight test and bending test data of the same batch of joints, it is found that the drop-weight test is easier to make the joint break from the flat spot defect than the static bending test.