Fatigue assessment of additively manufactured aluminium alloys processed by laser powder bed fusion

Abstract

This thesis examines the fatigue behavior of the aluminum silicon alloy processed with Laser Powder Bed Fusion, along with hardness distribution and microstructure characterisation with optical microscopy, scanning electron microscopy and transmission electron microscopy. The fatigue life data has produced the S-N curve with the slope m = 22, a clear decrease in fatigue life with the increase in stress amplitude, and scatter is also accommodated as the experimental error. Hardness of the material is obtained as significantly higher than casting process, with the higher average value of 140.4 HV. Optical microscopy, scanning and transmission electron microscopy have produced microstructure results establishing the melt pool structure due to LPBF, cellular patterns layer by layer, and concentration of silicon precipitate at the grain boundaries. Overall, the study of aluminum silicon-based alloy has shown good fatigue results as compared to other processes of additive manufacturing and other aluminum alloys.