Split Hopkinson pressure bar tests for investigating dynamic properties of additively manufactured AlSi10Mg alloy by selective laser melting

Abstract

Dynamic properties of additively manufactured AlSi10Mg alloy by selective laser melting (AM–SLM-processed) have been investigated using the split Hopkinson pressure bar (SHPB) system. Additive manufacturing (AM) processes have attracted increased attention over the past three decades, and AlSi10Mg is an alloy commonly used in AM processes. AlSi10Mg is a widely used material, and has been a subject of extensive investigations concerning its microstructure, quasi-static properties, and post-processing. Nonetheless, dynamic mechanical properties of this alloy are yet to be explored over a wide range of strain rates. Dynamic properties of X- and Z-oriented AlSi10Mg alloy samples in the as-built and T5 heat-treated (T5-HT) states were investigated using SHPB under strain rates varying over a range of 700–7900 s−1. The investigation revealed an important dependence of dynamic properties of the said alloy on build orientation when subjected to strain rates range of the order of 1000–3000 s−1. At values of strain rate above and below this range, the observed dependency no longer existed. In addition, dependency of dynamic properties of the alloy on its thermal state (as-built versus T5-HT state) was investigated for the first time along with detection of no-strain-rate sensitivity of the AM-SLM-processed AlSi10Mg alloy. A pronounced ellipticity was observed in most samples, thereby reflecting the anisotropic nature of the alloy. Fractography and optical microscopy analyses revealed differences between fracture morphologies observed in the as-built and T5-HT samples. Cracks observed were predominantly of the radial type (with minor circumferential cracks) under the brittle fracture mode in as-built samples. In contrast, T5-HT samples mainly demonstrated the ductile mode of deformation.