SLM-fabricated A357 aluminium alloy: Dry sliding behaviour

This work investigates how the microstructure resulting from Selective Laser Melting (SLM) influences the friction and wear behaviour of the as-built A357 (AlSi7Mg0.6) alloy, considering sand-cast A357 (hot isostatically pressed and heat teated in the T6 condition) as the benchmark. Two sets of parameters were taken into account for SLM processing: maximum productivity (P) or optimised microstructure (M). Tribological tests were carried out in dry sliding conditions, by using a block-on-ring tribometer. The bearing steel EN 100Cr6 (62 HRC) was used as counterfacing material. Normal load ranged from 20 to 60 N, whilst sliding speed was set at 0.3 ms-1. The results showed that microstructural refinement induced by SLM processing in optimised conditions (M) decreases the wear rate of A357 by comparison to the corresponding cast alloy, already in the as-built condition. Conversely, the coefficient of friction was not significantly affected by the manufacturing process.