The influence of processing parameters on aluminium alloy A357 manufactured by Selective Laser Melting

• Published in: Materials & design 2016-11, Vol.109, p.334-346
• Main Authors: Rao, Heng, Giet, Stephanie, Yang, Kun, Wu, Xinhua, Davies, Chris H.J.
• Format: Article
• Language: English
• Subjects: Aluminum; Aluminum base alloys; Al–Si alloys; Laser beam melting; Mechanical properties; Microstructure; Porosity; Process parameters; Selective Laser Melting; Silicon substrates; Tensile properties
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2016.07.009

The aim of this work is to investigate the effects of Selective Laser Melting (SLM) on the microstructure and mechanical properties of A357 aluminium alloys. The SLM processing parameters were optimised to achieve maximum density, corresponding to an extremely fine microstructure with very few pores. This translates to differences in mechanical properties compared to conventional cast alloy. Porosity in SLMed A357 Al samples was analysed based on relative density versus laser parameter and energy input curves. Substrate temperatures and the combination of laser parameters influence the mechanical properties via changes in melt pool morphology and eutectic Si cell characteristics. The anisotropy of SLMed Al samples is explained in relation to the directionality of the microstructure based on differences in the deformation response of horizontal and vertical tensile samples. Fractographic studies have been performed to understand tensile properties by comparing fracture surfaces of tensile samples with microstructural features in different planes. This has led to an explanation of why the tensile properties are better for the horizontal test samples than for the vertical ones in an as-SLMed material.