Effect of heat treatment on fatigue crack growth performance of AlSi10Mg aluminum alloy submitted to LPBF

Aluminum alloys are used in several industries, namely in the aeronautic and aerospace industries due to its good corrosion resistance and good mechanical strength/weight ratio. The optimization of fatigue crack growth resistance in AlSi10Mg aluminum alloy is a vital issue for safety-relevant components, which are designed to work for a large number of loading cycles before periodic inspections. An unclear subject is the benefit effect of heat treatments in the fatigue crack growth of AlSi10Mg aluminum alloy submitted to LPBF. Therefore, the current work purposes to analyze the effect of a heat treatment at low temperature on fatigue crack growth of AlSi10Mg aluminum alloy submitted to LPBF. Fatigue crack growth tests in Mode I are performed in compact tension (CT) specimens at two different conditions: as-build and heat treated at low temperature. The possible befits effect is analyzed, as well as the effect of the average stress on the fatigue crack growth. The crack closure parameter is studied in order to analyze the different fatigue crack growth behaviors, as well as the microstructure, hardness, and fractography. From this work, the main achievement is the microstructural transformations associated with the standard heat treatments (T6 and stress relived at 300 °C) are unfavorable to fatigue strength in the AlSi10Mg aluminum alloy submitted to LPBF, while the non-standard stress relief heat treatment, performed at a lower temperature, cause a benefic effect in the fatigue crack growth resistance.