Study on temperature- microstructure- stress fields of thick-walled plate welded by hybrid laser arc welding

The 25mm DH36 steel was welded by hybrid laser arc welding (HLAW), and a sequence coupled thermal-metallurgical-mechanical (TMM) model was developed based on SYSWELD. The temperature-microstructure-stress fields are predicted by simulation verified by experiment. The ratio between the arc and laser energy showed a significant effect on weld profile. The laser provided the main power and ensured deep penetration, and the arc power showed a dominant effect on the bead width of the hybrid weld during HLAW. For the hybrid welding of a thick-walled plate, the microstructure and thermal cycles varied along with the thickness. The weld profile and microstructure were experimentally characterized. The 3-pass welding procedure produced larger welding residual stress than the 9-pass welding procedure, and the process stability is poorer than the 3-pass welding process. Overall, numerical results matched well with experimental results.