Modeling of weld beads for laser-GMA hybrid welding

For laser-GMA hybrid welds, the relationship between the process parameters and bead shapes was investigated by using the experimental design and the non-linear regression. The weld beads were fitted by two quadratic functions. By the statistical analysis, the primary bead was mainly affected by GMA welding parameters and the root bead was mainly by laser welding parameters. The root bead shaped deeper penetration and shallower width, as the laser power increased for the constant arc power. High laser power resulted in the martensite phase, therefore exhibiting the sudden increase of hardness as approached to the fusion line of the root bead.