Study of nickel-based super-alloys Inconel 718 and Inconel 625 in high-deposition-rate laser metal deposition

Nickel-based super-alloys Inconel 718 (IN718) and Inconel 625 (IN625) have comparable chemical composition and similar physical constants such as density and melting range; however, in high-deposition-rate laser metal deposition (HDR-LMD), processes with IN625 are not transferable to that with IN718. In order to compare HDRLMD process with IN718 and IN625, the current study has been conducted. Initially, parallel experiments have been performed, and the metallurgical analysis for macro- and microstructures have been carried out. Then, the strengthening effects of HDR-LMD for both alloys have been compared. Finally, in order to understand and explain the obtained results, both processes have been characterized by using a high-speed camera. According to the study, the following conclusions have been drawn: in comparison to IN718, there seems to have a stronger convection in the melt pool of IN625; this convection could be the reason for the faster solidification of IN625 since it may accelerate the dissipation of heat; As a further consequence of the stronger convection, the degassing during the solidification can be enhanced.