Laser Forging Coupled Arc Welding of Steel and the Resultant Weld Porosity and Weld Fusion Characteristics
W-L. Cai, Y-K. Zhang, Y-Q. Chi, J-H. Liu, J-F. Gou and F-T. Peng
Taking E690 marine steel as the research object, a new technology of laser forging coupled arc welding is developed. The influence of arc current and arc voltage on arc welding porosity morphology and the influence of arc current and arc voltage on arc welding fusion ratio are studied. The effect of different filament spacing, laser defocusing amount and groove width on pore morphology was studied. The arc shape and droplet characteristics of laser forging coupled arc welding are analysed. Optimal processing parameters were an arc current of 165 A, arc voltage of 28 V and welding speed of 550 mm/min. With these the weld bead shape of arc welding is good, the splash is less and the weld bead is sound. Also, the fusion ratio is the highest at 38.891% and the fusion area is also high at 19.028 mm2. at the same time, stress concentration and porosity defects are caused. When laser impact forging is added, the fusion ratio of the weld seam at the position of 6 to 8 mm is the highest, which is 39.247 and 39.168%, respectively. The fusion area is the largest, with the fusion area of 20.340 and 19.373 mm2, respectively. With the increase of arc current and arc voltage the arc profile gradually increases, the arc stability decreases, the heat is dissipated and the temperature difference is large. With laser forging coupled arc welding, the heat is relatively concentrated, and the arc profile decreases with the increase of distance between laser and arc. The laser impact forging can gather the arc energy, attract the arc and improve the forming quality of the weld.
Keywords: Nd:YAG laser, E690 marine steel, laser forging, arc welding, pore, morphology, microstructure, fusion rate, arc shape