Study on high temperature strength characteristics of material repaired by laser metal deposition method

Abstract

Overlay welding is widely applied to repair aged components in infrastructures. However, undesirable residual stress and microstructure change could be caused by the welding. This study focused on laser metal deposition (LMD) as an alternative repairing technique because of the low heat input and high deposition efficiency. In order to verify the reliability of LMD as a repairing technique, the high temperature strength of LMD layer itself and a specimen repaired by LMD was characterized by tensile tests at 873 K. As the results, it was confirmed that the yield stress of the LMD layer itself was higher than that of the bulk material with independence of the laser scanning direction. In addition, the yield stress of the specimen repaired by LMD was also higher than that of the non-repaired specimen with independence of the cutting edge angle of repaired part. The observations of the fracture surface and the cross-section of the specimen revealed that the repaired part has excellent ductility and adhesion strength. Consequently, it was demonstrated that LMD is an effective repair technique.