Continuous wave vs pulsed wave laser emission in selective laser melting of AlSi10Mg parts with industrial optimized process parameters: Microstructure and mechanical behaviour

Abstract

Currently, selective laser melting (SLM) is among the most widespread of the additive manufacturing (AM) technologies. Commercially available SLM systems can offer both continuous wave (CW) and pulsed wave (PW) emissions of the laser power. It has been demonstrated that relative density and geometric features can be affected by the laser emission parameters, but their effects on the material properties have not yet been investigated. In this study, specimens were produced from the same AlSi10Mg powder using two commercially available SLM machines operating with CW and PW emissions. Optimal process conditions were used, as indicated by the SLM suppliers. This choice was made to provide the most effective comparison between the material performances obtained using different industrial SLM systems. The specimen microstructures were investigated using scanning electron microscopy coupled with electron backscatter diffraction analysis. Moreover, thermal analysis, microhardness measurements, and compression tests were performed to investigate the thermal and mechanical properties. It was revealed that a slightly finer microstructure was obtained using the PW laser, while the increased thermal load during CW laser melting resulted in larger liquid pools, enhanced phase modifications, and better mechanical properties.