Influence of laser processing parameters on microstructure and defect formation in PBF-LB printed Al-Si-Mg alloys

¹ Centre for Nano-engineering and Advanced Materials, School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, South Africa
² University West, Department of Mechanical Engineering Science, Division of Welding Technology (KAMPT), Sweden

Abstract

The performance and reliability of additively manufactured Al-Si-Mg parts are strongly influenced by processing parameters, which affects microstructure and defect formation. This study examines five scanning speeds using powder bed fusion – laser beam (PBF-LB) and analyses porosity, grain morphology, and crystallographic texture via SEM and X-ray diffraction. Higher scanning speeds led to increased porosity and incomplete fusion, while lower scanning speeds produced refined columnar grains and continuous eutectic silicon networks due to prolonged thermal exposure. Phase analysis confirmed α-Al as the dominant matrix phase, with presence of intermetallics and oxides reflecting thermal history and potential contamination. Crystallographic texture analysis showed that reduced scanning speeds enhanced grain orientation and residual stress. Intermediate scanning conditions minimized defects while preserving desirable microstructural characteristics. This study gives insights into process-structure relationships, supporting parameter optimization for high performance application of Al-Si-Mg alloys in aerospace and automotive sectors.