Pores formation in laser-MAG welding of 42CrMo steel

Effects of welding parameters on the pores formation of laser-metal active gas (MAG) hybrid welding of quenched and tempered 42CrMo steel were investigated. The flow of the molten pool and the dynamic behavior of the keyhole were observed with a high speed video camera. The information on the variations in the weld temperature was collected using an infrared (IR) thermal imaging system. The pore morphology and pore types were analyzed via scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The flow of the molten pool, the keyhole stability, the weld cooling rate and the pore escaping rate as a result of different parameters could all affect pores formation. The majority of the pores were invasive pores.