07MnNiVDR再热裂纹敏感性及试验

Analyses of reheat cracking sensitivity and test methods for 07MnNiVDR steel

采用热模拟后缓慢拉伸试验、夏比摆锤冲击试验、插销试验以及小铁研试验等方法,研究了调质高强钢07MnNiVDR的再热裂纹敏感性.热模拟研究表明,采用小热输入焊接时,该钢对再热裂纹不敏感;大热输入情况下,敏感温度在600℃左右.插销试验表明,该钢具有一定的再热裂纹敏感性,敏感温度在600℃左右.热模拟试验和插销试验的结果一致,小铁研试验不适合试验材料的再热裂纹敏感性研究.热模拟后缓慢拉伸是判断材料再热裂纹敏感性的有效方法,插销临界断裂初应力对生产有指导意义.尽管未在小铁研试验中发现明显再热裂纹,对该钢实施焊后热处理还应慎重.

Reheat cracking sensitivity of the quenched and tempered high strength 07MnNiVDR steel was investigated with methods,such as low strain rate tensile test at high temperature after thermal simulation,Charpy pendulum impact test, implant test and small Tekken test. The thermal simulation results show that the steel was insensitive to reheat cracking with low welding heat input,but sensitive with high welding heat input and the sensitive temperature was around 600 ℃. Implant test also indicates that the steel had risk of reheat cracking to some extent,with sensitive temperature of about 600 ℃. The results of thermal simulation test and implant test were consistent with each other,while small Tekken test was not suitable for testing reheat cracking sensitivity. Low stain rate tensile test after thermal simulation was a practical and effective method for reheat cracking sensitivity assessment. The critical stress of implant test was important for engineering practice. Post-weld heat treatment of this steel joint should be prudent,although no apparent reheat cracking was found in small Tekken test.