Abstract
Process parameters of the Laser-Arc hybrid welding of HSLA-590 steel have been studied using 2.4 kW CO2 laser machine and a MAG welding machine. The effects of power ratio, laser power, arc power and leading process have been investigated in this study. The results shows that the power ratio between laser power and arc power is higher, the bead shape is better. And the effects of root gap and bevel angle in butt joint were investigated. From the experiments, the maximum gap tolerance and suitable bevel angle are found, that are 1 mm and 45°, respectively. The effects of shielding gases, helium or argon, are also investigated for finding the effects on penetration, bead width and bead appearance. The microstructures of welds are studied by laser scanning microscope and Scanning Electron Microscope (SEM). The Dendrite Arm Spacing is measured in laser, MAG and hybrid welds. The maximum hardness is not appeared in the HAZ, but in the weld metal. And there is a soften zone on the fusion line.
