Fatigue and corrosion fatigue performance of selective laser melted AlSi10Mg and die cast A360 aluminum alloys

The fatigue performance of selective laser melting (SLM) AlSi10Mg and die-cast A360 alloys was studied in air and 0.6 M (3.5 wt%) NaCl solution. The SLMed-AlSi10Mg exhibits lower S-N data compared to the A360 alloy in both environments, despite having higher strength and ductility. Lack of fusion defects and cyclic slip serve as fatigue initiators for SLMed-AlSi10Mg and A360 alloy in air, respectively. In the 0.6 M NaCl solution, the S-N data of both alloys significantly decrease compared to the air environment. No fatigue limit was observed as the fatigue lives sustain to increase beyond 10 ⁷ cycles. Pitting acts as the fatigue initiator at low stress levels (S _max < 100 MPa), while the failure mechanism at high stress levels (S _max > 120 MPa) remains consistent with that in air. Prior corrosion for 72 hours in the 0.6 M NaCl solution results in only a negligible decrease in fatigue performance of both alloys. Electrochemical analysis indicates that SLMed-AlSi10Mg has higher pitting sensitivity but a lower uniform corrosion rate due to its microstructure homogeneity. The combined effects of pitting sensitivity and corrosion rate result in similar corrosion fatigue sensitivity of both alloys. Additionally, the S-N data of SLMed-AlSi10Mg shows large dispersion and a small Weibull shape parameter due to variations in defect sizes and different pitting morphology.