A three-dimensional analytical calculation model of GMAW heat transfer was established, and the weld temperature field of JG590 with different welding parameters was analyzed by numerical simulation. The phase transformation in CGHAZ of JG590 steel was studied by physical simulation. SH-CCT diagrams, the effects of weld thermal cycle on microstructure, impact toughness and hardness were obtained. The results show that the critical cooling time of bainite, ferrite and pearlite appeared are respectively 8s, 110s and 150s. The critical cooling time that martensite takes to finish transferring is 35s. When t8/5 is below 10s, CGHAZ has a better toughness and when t8/5 is beyond 15s, there is a wide range decrease on the toughness. In this paper prediction of CGHAZ microstructure and property of JG590 steel was realized based on the analytical calculation model of GMAW heat transfer and physical simulated results mentioned above
