Influence of post-processing heat treatment on the cyclic deformation behaviour of AlSi10Mg aluminium alloy subjected to laser powder bed fusion

The effect of heat treatment on the cyclic deformation behaviour of AlSi10Mg aluminium alloy manufactured by laser powder bed fusion (LPBF) was investigated. Uniaxial fully-reversed strain-controlled fatigue tests were conducted on polished smooth specimens in the low-cycle and high-cycle fatigue regimes for three material states: no heat treatment, stress relief heat treatment and T6 heat treatment. The effect of the heat treatment on microstructure, ductility, hardness and tensile properties was also investigated. It was found that the microstructural transformation associated with the heat treatments increased the ductility, and reduced the hardness, the tensile strength, and the fatigue resistance, particularly in the low-cycle fatigue regime. Thus, these standard heat treatments used in conventional heat-treatable aluminium alloys are not recommended for LPBD aluminium alloys subjected to cyclic strain loading.