This study was carried out to evaluate the aspect of microstructure and mechanical property development on additive manufactured pure Ti at elevated heat-input. For this work, pure Ti powder (commercial purity, grade 1) was selected, and selective laser melting was conducted from 0.5 to 1.4 J/mm. As a result, increase in heat-input led to the significant grain growth form 4 μm to 12 μm, accompanying with the change of grain shape, correctly widmanstätten structured grains. In addition, Vickers microhardness was notably increased from 228 Hv to 358 Hv in accordance with elevated heat-input, which was attributed to the increased concentration of oxygen and nitrogen mainly occurred during selected laser melting process.
Industries that rely on additive manufacturing of metallic parts, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect the properties of manufactured elements, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with specimen deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on the material strength. Specimens manufactured with 20% lower energy density had almost half the elongation, which was directly connected with the porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to specimens manufactured using different levels of energy density.
Microstructure and wear property of AlSi10Mg alloy manufactured by selective laser melting (SLM) were investigated. Also, the effect of post heat treatment on the mechanical and wear properties was examined. Two kinds of heat treatments (direct aging (DA) and T6) were separately conducted to SLM AlSi10Mg alloy. As-built alloy had a cellular structure formed inside the molten pool. Eutectic Si was also observed at the cellular boundary in as-built alloy. After DA heat treatment, the cellular structure still remained, and a large amount of nano-size Si particles were newly formed inside the cell structure. Both molten pool and cellular structure disappeared, and the size of Si increased in T6 alloy. The values of Vickers hardness measured as 139.4 HV (DA alloy), 128.0 HV (As-built alloy) and 85.1 HV (T6 alloy), respectively. However, concerning to wear property, T6 alloy showed better wear resistance than other alloys. The correlation between microstructure and wear mechanism of SLM AlSi10Mg alloy was also discussed.
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