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

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.