Research Articles (Mechanical and Mechatronic Engineering)
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Browsing Research Articles (Mechanical and Mechatronic Engineering) by Subject "Additives -- Manufacturing"
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- ItemSelective laser melting produced Ti-6Al-4V : post-process heat treatments to achieve superior tensile properties(MDPI, 2018) Ter Haar, Gerrit M.; Becker, Thorsten H.ENGLISH ABSTRACT: Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α’/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.
- ItemStandard method for microCT-based additive manufacturing quality control 3 : surface roughness(Elsevier, 2018) Du Plessis, Anton; Sperling, Philip; Beerlink, Andre; Kruger, Oelof; Tshabalala, Lerato; Hoosain, Shaik; Le Roux, Stephan G.ENGLISH ABSTRACT: The use of microCT of 10 mm coupon samples produced by AM has the potential to provide useful information of mean density and detailed porosity information of the interior of the samples. In addition, the same scan data can be used to provide surface roughness analysis of the as-built surfaces of the same coupon samples. This can be used to compare process parameters or new materials. While surface roughness is traditionally done using tactile probes or with non-contact interferometric techniques, the complex surfaces in AM are sometimes difficult to access and may be very rough, with undercuts and may be difficult to accurately measure using traditional techniques which are meant for smoother surfaces. This standard workflow demonstrates on a coupon sample how to acquire surface roughness results, and compares the results from roughly the same area of the same sample with tactile probe results. The same principle can be applied to more complex parts, keeping in mind the resolution limit vs sample size of microCT.