对比了两种热循环(实际焊接与模拟单道次焊接)对Q690 TMCP钢粗晶区组织性能的影响。结果表明:模拟焊接热循环条件下,随热输入增大粗晶区组织分别经历了板条马氏体、回火马氏体、上贝氏体及粒状贝氏体转变,粗晶区冲击功随热输入能量的增大先增大后减小,峰值对应热输入20 kJ·cm-1;相同热输入能量的实际焊接试样粗晶区的冲击功变化趋势与模拟焊接试样相似,但数值均低。分析得出,实际焊接试样粗晶区中新生M-A组元导致了其冲击功相对更低。 The effects of two thermal cycles (actual welding and single pass welding) on ​​the microstructure and properties of Q690 TMCP steel were compared. The results show that under the conditions of simulated welding thermal cycle, the coarse grain zone structure undergoes the transformation of lath martensite, tempered martensite, upper bainite and granular bainite with the increase of heat input respectively. The impact energy The heat input energy increases first and then decreases with the peak value corresponding to heat input of 20 kJ · cm-1. The variation tendency of the impact energy in the coarse grain region of the actual welding sample with the same heat input energy is similar to that of the simulated welding sample The values ​​are low. The analysis shows that the newly formed M-A component in the coarse grain region of the actual welding specimen results in a relatively lower impact energy.