Influence of Different Process Gases on Alsi10mg Parts Processed by LPBF - Microstructure and Mechanical Properties

This studyⁱ presents investigations on the influence of various process gases on the Laser-based Powder Bed Fusion (LPBF) of AlSi10Mg. In particular, argon (Ar), nitrogen (N2) and various argon-helium (Ar-He) mixtures were used for the build jobs. The focus was placed on the use of the Ar-He mixtures. The scientific hypothesis investigated was that the thermal properties of He lead to different thermal conditions in the process and result in differences in the microstructure and in the mechanical properties of the built part. To systematically study the occurring effects, two Ar-He mixtures (30 % and 50 % He) were applied. Finally, microstructure examinations and investigations on the mechanical properties were conducted to quantitatively compare the influences of the different atmospheres. The results showed no differences between the gases in the porosity and the hardness of the built parts. Differences were found in the microstructure and in the mechanical properties of the built parts. The use of Ar-He gas mixtures led to a higher tensile strength and a higher elongation at break of the built parts. These findings may be attributed to a faster cooling of the melt pool when using Ar-He gas mixtures.