Porosity Reduction and Characterization of Aluminium Components Produced by Additive Manufacturing
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Selective laser melting (SLM) is a relatively novel method used to produce metallicparts directly from computer models by selectively fusing metallic powder. The productionis fundamentally different from traditional production methods as it adds materialin a layer by layer manner to make up a part, instead of subtracting the material toachieve the wanted geometry. Due to the high thermal gradients the material is subjectedto under production a unique macro- and microstrcture is produced in SLM processedparts. This unique structure results in superior mechanical properties found in the parts,however there are challenges in regards to porosity, specially in systems with low laserpower. In this work two aluminium alloys are investigated: a AlSi10Mg casting alloy anda AA6061 wrought alloy. Both materials are build from a powder state to solid components.The goal of the build was to produce parts with minimal amounts of porositywith the equipment available. The completed specimens were investigated by light- andelectron microscopy, and the mechanical properties of both alloys were tested. The results show that the porosity of the components can be reduced by employingproper process parameters and post treatment, however the quality of the feedstock powderused is equally important. The two alloys are dominated by two kinds of differentpores, cracks are largely present in the AA6061 alloy while so called keyhole pores makeup most of the porosity found in the AlSi10Mg alloy. The unique micro- and macrostructurecould be identied in both alloys by employing appropriate specimen preparation.The AlSi10Mg alloy was found to be mechanicaly superior than the AA6061 alloy, thisis partly attributed to the much ner microstructure of the cast alloy and partly to thecracks found in the AA6061 alloy.