铁路桥梁用钢冲击韧性标准研究

Research on Toughness Criterion for Bridge Steel in Railroad

研究应用裂纹尖端张开位移(CTOD)试验和冲击韧性试验结果,建立以断裂吸收功为介质的CTOD与冲击韧性的关系。指出制订防断韧性标准的控制因素为材料满足不发生脆断的最低吸收能量、试验温度与实桥温度和列车加载速率的温度移位。研究表明,达到CTOD某临界状态所需吸收功与温度无关。指出采用韧—脆破坏准则制定韧性标准更适合桥梁工程。根据我国地区温度范围,制定出不同板厚冲击韧性检验基本标准。经过比较认为该标准在国际上居中偏严。

A certain relationship between crack tip open displacement (CTOD) and impact energy is established by taking the fracture absorbing energy as medium. It points out that the major problem to determine toughness criterion is to find the base absorbing energy that would keep material from brittle fracture, the temperature moving caused by the difference between the test temperature in the laboratory and the service temperature, and the loading speed by train. The research shows that the needed absorbing energy to certain critical CTOD is independent of temperature. And the CTOD state in transition section from ductile to brittle should be the reasonable base to stipulate toughness criterion for bridge engineering. According to the region temperature in China, this paper sets down different impact toughness criterion related to steel plate thickness. Compared with the correlated criterion in other country, the suggested one is in middle level and a little strict.