A Comparative Study of Arc Welding and Laser Welding for the Fabrication and Repair of Multi-Layer Hydro Plant Bellows

The development of clean energy resources, including hydro power, plays an important role in protecting the global environment. Multi-layer bellows are key components and are widely used in hydro power plants. Due to the special multi-layer structures, conventional arc welding is prone to the defects of pores and insufficient fusion when fabricating or repairing such bellows. Precise laser welding with a high energy density and a low heat input has the potential to join multi-layer bellows in a high-quality manner. In this study, a comparative investigation was conducted on the arc welding and laser welding of multi-layer 316L stainless steel sheets and B610CF high-strength steel plates regarding the weld quality, microstructure and tensile properties. The results show that laser-welded joints produced a narrower heat-affected zone and a full weld without visible defects. Compared with arc welding, laser welding had more equiaxed grain regions in the fusion zone and a homogeneous elemental distribution in the heat-affected zone. This led to a more reliable welded joint using laser welding.