Effect of annealing treatment on microstructure and mechanical behaviour of additively manufactured AlSi10Mg alloy

Additive Manufacturing (AM), a game-changer technology, allows the manufacturing of complex geometries with high specific strength while maintaining low weight. AlSi10Mg alloy, produced through selective laser melting (SLM), is widely utilized in aerospace and various other industries because of its unique properties such as lightweight, good corrosion resistant, better hardness, good thermal conductivity, superior mechanical properties etc. and these characteristics can further improve by applying annealing treatment. Therefore, exploring the impact of annealing treatment on the microstructure and mechanical characteristics is highly important. In this work, the AlSi10Mg alloy samples were printed using a selective laser melting process and subsequently subjected to annealing treatment at 280 °C, 300 °C and 320 °C for durations of 2, 3 and 4 h with a heat input rate of 5 °C/min, 10 °C/min and 15 °C/min respectively. The microstructural properties of the samples were analysed using both scanning electron microscopy (SEM) and optical microscopy. To evaluate the impact of annealing treatment on the microstructures and mechanical properties, tensile tests and nano-indentation were conducted. The experimental results reveal that the higher annealing temperature (320 °C) results in reduced tensile strength, yield strength and hardness, while increasing elongation. The highest ultimate tensile strength and yield strength of 442 MPa and 233 MPa observed at 300 °C for 2 h and heating rate of 15 °C/min.