Laser beam shaping facilitates tailoring the mechanical properties of IN718 during powder bed fusion

Abstract

One of the recent technological developments in the Laser Powder Bed Fusion (LPBF) process is the use of non-Gaussian beam profiles of power density distributions. Irrespective of the strategies used to change the beam profile, spatial beam shaping enhances process flexibility since it allows manipulation of the thermal field, the melt pool shape, and the microstructure. This work showcases the impact of novel ring and conventional Gaussian beams on density, melt pool characteristics, and mechanical properties of IN718 superalloy via LPBF. A novel laser source with beam shaping capabilities provided the beam profiles, ranging from Gaussian to ring beams. The results show clear differences between the crystalline patterns obtained with Gaussian and the other ring beams attempted. This study elucidates the impact of melting modes and solidification mechanisms on the texture index, arising from the interplay between laser beam shape modes and laser speed. It also shows how the crystalline configuration associated with each case studied influences the mechanical properties and how it is possible to modify the process parameters and the beam shape mode to extend control over the mechanical properties of the components manufactured using LPBF. This leads to a broader range of mechanical properties and grain size when tailoring the power density distribution towards ring beams. Additionally, the correlation between melt pool shape geometry, texture index, and mechanical properties is discussed, and the limitations and advantages of each mode are defined.