Repairing casting part using laser assisted additive metal-layer deposition and its mechanical properties

Generally, it is known that a welding technology is not suitable for repairing casting parts due to metallurgical issues and high carbon contents. So, the repairing of cast iron by welding has not been satisfactorily realized yet, resulting in microstructure changes in the welding area, which greatly impacts on crack initiation and growth as well as Martensite formation in the repaired area and heat affected zone (HAZ). In this study, we evaluated how the HAZ affected the mechanical properties of gray cast iron after it was repaired by the traditional welding process (shielded metal arc welding) and by the additive metal-layer deposition (AMD) process using a laser. The results indicated that the ultimate strength of each repaired part reduced by up to 16% when compared to that of the original specimen composed of only cast iron, FC300. However, the elongations of the specimens varied according to the repair methods. In the case of repair welding, the elongation decreased by approximately 20%. However, in the case of repairing by AMD, the elongation increased dramatically to approximately 60%. Hence, the proposed repairing method based on AMD appears to be a promising method for repairing castings.