First Application of Hybrid Laser-arc Welding to Commercial Ships

Mitsubishi Heavy Industries, Ltd. (MHI) has been working to improve the accuracy of hull-block finishing and reducing the number of assembly operations for other blocks while mounted at the dock, aiming to establish a high-accuracy building method. One of the techniques we have introduced is hybrid laser-arc welding, which requires low heat and reduces welding deformation. In the past, this method has required a large initial investment, and it has not been popular in the shipbuilding industry, except at some European shipyards that specialize in passenger ships. We have developed a procedure that requires simple equipment and can be used while following conventional shipbuilding procedures. This method, which has already been applied to general commercial ships, is described below. |1. Introduction A high-accuracy building method for general commercial ships is expected to reduce the time required to build a ship and improve the product quality. The method is expected to be an effective response to the intensifying competition from Korean and Chinese shipbuilders. To realize our goal, welding deformation needs to be reduced. We therefore considered the possibility of employing hybrid laser-arc welding in shipbuilding, which substantially reduces welding deformation. This welding method, which combines the advantages of laser welding and arc welding, was developed in the 1990s mainly by European ship builders and the Classification Society. It has been employed mainly by European shipbuilders that specialize in the construction of passenger ships and large yachts. The method makes use of low-heat welding, reducing the deformation of welded parts. However, it requires an initial investment in large-scale machinery equipment, and it has only been employed by a few shipbuilders, although they considered the possibility of introduction. We have developed a hybrid laser-arc welding method that does not require large-scale equipment and that can be used while following conventional procedures for butt welding steel plates. The welding method was approved by the Classification Society and has been applied to actual ships.