Laser engineered net shape repair of Ni-base superalloy Mar-M247

Abstract

Laser engineered net shape (LENS) technology was applied for repairing Mar-M247, and the influence of the Mar-M247 microstructure and LENS process parameters on the repair weldability was investigated. The results show that the cracking susceptibility of Mar-M247 was very high and cracking was initiated in the Mar-M247 heat-affected zone (HAZ) and then propagated into the LENS deposit. The HAZ cracking was quite sensitive to the presence of carbides in the base material, with even small quantities of carbide leading to the initiation of cracking in the deposit, which can be greatly suppressed by optimizing LENS process parameters but not eliminated. In addition, solution annealing of the as-cast base metal prior to repair significantly reduced the cracking susceptibility. Cracking was further suppressed by the aging treatment. Under the complete homogenized Mar-M247 blade, the simulated tip erosion damage was successfully repaired without cracking by optimizing LENS process parameters.