The Effect of Laser Scanning Design on Crack Susceptible Superalloys: Defect Minimization and Microstructural Modification

Laser scanning behaviour in Selectively Laser Melting (SLM) process can drastically influence the solidification behaviour and solid-state thermal cycle, affecting microcracking and grain structure that determine can have determining impact on the mechanical properties of especially superalloys. Available research so far hints that the cracking is mainly related to high temperature phenomena such as solidification cracking and thermal stress. In this research, we are reporting our funding on how and why different laser scanning parameters and scanning strategies can have large influence on the microcracking and microstructure. Several gamma prime bearing (Ni₃Al/Ti) Ni-based superalloys were test printed with different laser scanning settings and the process were also simulated by multiphysics SLM modelling. This presentation emphasizes on explaining specifically on the solidification factors such as constitutional supercooling and epitaxial grain growth directions that are important to determine the microcracking susceptibility and the solidified grain structure. Practical advice on the better design of laser scanning methods will also be discussed based on the above finding. This presentation aims facilitate the adaptation of SLM on high strength superalloy printing via better laser scanning design.