A357 aluminium alloy produced by LPBF: Tribological behaviour in dry sliding conditions

Abstract

Laser Powder Bed Fusion (LPBF) is increasingly used in packaging, automotive and aerospace sectors for manufacturing Al alloy components where fatigue and wear damage can readily occur. Therefore, this work aims to assess the tribological behaviour of A357 alloy (AlSi7Mg0.6) produced by LPBF as a function of both printing parameters and heat treatment conditions, applying a novel T6 based on rapid solution followed by artificial aging, which improves the strength-ductility balance. Dry sliding tests (block-on-ring) were performed using A357 samples as stationary blocks against rotating quenched and tempered AISI 52100 (100Cr6) steel. LPBF samples were compared with A357 obtained by sand casting, subjected to Hot Isostatic Pressing (HIP) and conventional T6 heat treatment. Microstructural refinement induced by LPBF carried out in optimised conditions, even without post-processing treatments, reduced the wear rate in comparison to conventional sand-cast, HIP-ed and T6 heat-treated A357, while maintaining comparable coefficient of friction. The rapid solution T6 did not worsen the tribological behaviour of as-built LPBF A357 components, even though it induced a slight hardness decrease.