Prediction of Cross-Sectional Shape, Microstructure and Mechanical Properties of Full Penetration Laser-GMAW Welded Butt Joints

Finite element simulation and thermal dynamic simulation were employed to investigate the formation feature dimensions, microstructure and mechanical properties of full penetration laser-GMAW welded joints. An ellipsoidal-conical hybrid heat source was established, and the thermal processes of hybrid welding for butt joint on a steel plate with 5, 10 and 14 mm thickness were predicted. The effects of arc power, laser power, and welding speed on the characteristic size at the cross section were investigated. It is found that the arc power only affects the size of upside, the laser power mostly determines the size of backside and the minimum width, and less effect on the width of upside, while the welding speed affects all the characteristic size of cross section. A relationship among phase composition, mechanical properties and cooling rate was established by thermal dynamic simulation. Combining the simulation of welding thermal cycle, the microstructure and mechanical properties of the joints can be predicted. This research is interesting and important for the design of process parameters during welding.