Improving fatigue performances of selective laser melted Al-7Si-0.6Mg alloy via defects control.

• Defects control in SLMed A357 is achieved with optimised processing parameters. • Microstructure homogenisation with Si particle modification is achieved with optimised heat treatment procedures. • Tensile ductility is significantly improved without the presence of large defects. • Fatigue property is substantially improved with defect elimination and Si particle modification. The relationship between defects and mechanical properties, especially fatigue properties, of selective laser melted (SLMed) Al-7Si-0.6Mg alloy built with different processing parameters has been investigated. With relatively high densities, although the tensile strength is not affected, ductility and fatigue properties vitally vary with different defects. Furthermore, an excellent fatigue performance with the run-out stress of 200 MPa has been achieved with optimised processing parameters, which is by far the best fatigue performance in SLMed Al-Si alloys. Microstructure and fractography are characterised by different methods, demonstrating that defects and Si particles are the main controlling factors for the fatigue properties. [ABSTRACT FROM AUTHOR]