Early Career Researcher: Student (poster and 2-minute poster pitch) at Digital Twin Symposium 2019, presented by Panneer selvam Ponnusamy
Selective Laser Melting (SLM) is a layer-by-layer metal additive manufacturing process. Parts processed by SLM can be subjected to severe dynamic loadings and high temperature in service, in applications such as defence, aerospace, automotive and high-speed machining. Very few studies have reported on the behaviour of additively manufactured metal parts subjected to high strain rate loading conditions. The present work is focused on studying the mechanical behaviour of SLM-processed and heat treated AlSi12 aluminium alloy parts under quasi-static and dynamic compression. The quasi-static low strain rate tests were carried out at 4 × 10-3 s-1 , whereas dynamic high strain rate tests were carried out in the range of 1 × 103 – 2 × 103 s-1 using the split Hopkinson pressure bar (SHPB) apparatus. A significant reduction in both quasi-static and dynamic yield strength and ultimate compressive strength was observed when the as-built AlSi12 samples were tested at elevated temperatures. This reduction in flow stress was attributed to the softening of the samples due to the agglomeration and growth of Si-rich precipitates at the test temperatures (200°C and 400°C). Finally, the test data was used to evaluate the parameters of the Cowper-Symonds equation that could be applied to predict the dynamic flow stress values up to a strain rate of 3 × 103 s-l for both as-built and heat treated AlSi12 samples, subjected to room temperature.