高AI冷轧双相钢点焊热影响区研究

HAZ of spot welded joint for high aluminum cold-rolled dual phase steel

通过热模拟试验以及点焊试验对高Al冷轧双相钢WHT600DP的点焊热影响区微观组织进行了研究。研究结果表明,在设定的热循环条件下,随着峰值温度升高,WHT600DP的模拟热影响区中出现了明显的晶粒粗大的现象,且马氏体等淬硬组织的比例显著增加,模拟焊接热影响区的最高硬度可达250 HV0.2左右。WHT600DP实际点焊热影响区微观组织的变化趋势与模拟热影响区的结果一致,但实际点焊热影响区的硬度值高于模拟热影响区,最高可达280 HV0.2。热循环过程中冷却速度的差异是模拟热影响区和实际热影响区微观组织差异的根本原因。

Based on the thermal simulation and spot welding experiment,the HAZ of spot welded high.Al cold rolled dual phase steel WHT600DP was studied.The results show that under the thermal cycles designed in the thermal simulation experiments.with the increase of peak temperature,there is an obvious phenomenon of coarse grains in the heat affected zone,and the proportion of hardened phases such as mar.tensite increases significantly with the highest hardness of HV0.2250 or so.In the actual spot welding experiments,the trend of microstructure variation in the heat affected zone is consistent with the simulation.However,the hardness is higher than that in the simulated heat affected zone,up to HV0.2280.The difference of microstructure between the simulated and actual heat affected zone can be caused by various cooling rate during the process.