Single-pass Hybrid Laser Welding of 25 mm Thick Steel

The manufacturing of large steel structures involves welding thick-section steels. Using hybrid laser welding, it is possible to reduce production costs significantly. However, avoiding solidification cracks in the weld is difficult when welding thick-section steels. In this study, a number of experiments were performed on the hybrid laser welding of 25 mm steel. Different techniques of full penetration and partial penetration welding were discussed. Crack-free welds were obtained using single-pass or two-pass welding techniques. The results of the experiments showed that the joint preparation method and the penetration mode are very important factors in obtaining crack-free welds in welding thick section steels. With the same process parameters applied to hybrid laser welding, partial penetration welds were more susceptible to cracking than full penetration welds. This was partly attributed to a change in the melt flow and, consequently, a different solidification mode that occurred during the full penetration mode welding.