Laser-arc hybrid welding of thick high tensile strength steel plates

Abstract

In this study, a high power disk laser-GMA hybrid welding system was established to weld 11 mm and 24 mm thick plates of high strength steel HT780 without welding grooves. The effects of welding conditions such as laser power, root gap and shielding gas on the weld bead geometry and welding stability were studied. The welding phenomena were observed by a high-speed video camera. The results showed that the sound welded joints (11 mm) could be obtained by one pass hybrid welding using either MAG (80%Ar-20%CO2) or 100% CO2 shielding gas. The range of laser powers for the production of sound welds was wider in using CO2 gas, although more spatters occurred. However, the optimization of the arc parameters could reduce spattering significantly by forming a buried arc transfer mode. The tensile test results showed that the tensile strengths of the joints hybrid-welded in either MAG or CO2 gas were much higher than those of the base material. The Charpy V-notch test results revealed that the values of hybrid weld joints in MAG were higher than those in CO2 gas. The sound welded joints (24 mm) could be obtained by either double-sided or one-sided two passes welding procedures in CO2 gas.In this study, a high power disk laser-GMA hybrid welding system was established to weld 11 mm and 24 mm thick plates of high strength steel HT780 without welding grooves. The effects of welding conditions such as laser power, root gap and shielding gas on the weld bead geometry and welding stability were studied. The welding phenomena were observed by a high-speed video camera. The results showed that the sound welded joints (11 mm) could be obtained by one pass hybrid welding using either MAG (80%Ar-20%CO2) or 100% CO2 shielding gas. The range of laser powers for the production of sound welds was wider in using CO2 gas, although more spatters occurred. However, the optimization of the arc parameters could reduce spattering significantly by forming a buried arc transfer mode. The tensile test results showed that the tensile strengths of the joints hybrid-welded in either MAG or CO2 gas were much higher than those of the base material. The Charpy V-notch test results revealed that the values of hybrid wel...