Laser metal deposition repair applications for Inconel 718 alloy

Abstract

Laser metal deposition (LMD) is a layer manufacturing technique, which is used in freeform fabrication and repair applications of critical aerospace engine components. This paper focuses on deposition of Inconel 718 material for refurbishment of existing Inconel 718 components. The benefits of LMD process are good metallurgical bonding with less heat-affected zone when compared to traditional metal joining processes. To achieve best bonding between layers of deposited Inconel 718 it is important to optimize laser metal deposition parameters. In order to study the process parameter techniques and their effects on the deposited part from the point of mechanical and metallurgical strengths specific to aerospace applications, Taguchi’s L9 orthogonal array technique has been used. The optimal process parameters have been found from the experimental trails to achieve the fine microstructure, maximum hardness and reduced porosity, which finally lead to good bonding strength of the deposit. Using analysis of variance (ANOVA), effect of process parameters on the deposit were identified and verification tests were conducted to determine performance of the optimal process parameters. X-ray diffraction analysis revealed increased hardness and presence of high intensities of Ni3Al intermetallic elements in the optimized test specimens. The optimized results revealed improved properties in repairing of aero engine components using Inconel 718 powder.