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.
The article presents the results of a comparative analysis of the metal substructure for dental prosthesis made from a Co-Cr-Mo-W alloy by
two techniques, i.e. precision investment casting and selective laser melting (SLM). It was found that the roughness of the raw surface of
the SLM sinter is higher than the roughness of the cast surface, which is compensated by the process of blast cleaning during metal
preparation for the application of a layer of porcelain. Castings have a dendritic structure, while SLM sinters are characterized by a
compact, fine-grain microstructure of the hardness higher by about 100 HV units. High performance and high costs of implementation the
SLM technology are the cause to use it for the purpose of many dental manufacturers under outsourcing rules. The result is a reduction in
manufacturing costs of the product associated with dental work time necessary to scan, designing and treatment of sinter compared with
the time needed to develop a substructure in wax, absorption in the refractory mass, casting, sand blasting and finishing. As a result of
market competition and low cost of materials, sinter costs decrease which brings the total costs related to the construction unit making
using the traditional method of casting, at far less commitment of time and greater predictability and consistent sinter quality.
The densification behavior of H13 tool steel powder by dual speed laser scanning strategy have been characterized for selective laser melting process, one of powder bed fusion based metal 3d printing. Under limited given laser power, the laser re-melting increases the relative density and hardness of H13 tool steel with closing pores. The single melt-pool analysis shows that the pores are located on top area of melt pool when the scanning speed is over 400 mm/s while the low scanning speed of 200 mm/s generates pores beneath the melt pool in the form of keyhole mode with the high energy input from the laser. With the second laser scanning, the pores on top area of melt pools are efficiently closed with proper dual combination of scan speed. However pores located beneath the melt pools could not be removed by second laser scanning. When each layer of 3d printing are re-melted, the relative density and hardness are improved for most dual combination of scanning. Among the scan speed combination, the 600 mm/s by 400 mm/s leads to the highest relative density, 99.94 % with hardness of 53.5 HRC. This densification characterization with H13 tool steel laser re-melting can be efficiently applied for tool steel component manufacturing via metal 3d printing.
The aim of the paper is the residual stress analysis of AlSi10Mg material fabricated by selective laser melting (SLM). The SLM technique allows to product of complex geometries based on three-dimensional model, in which stiffness and porosity can be precisely designed for specific uses. As the studied material, there were chosen solid samples built in two different directions: parallel (P-L) and perpendicular (P-R) to the tested surface and cellular lattice built in perpendicular direction, as well. In the paper, for the complex characterization of obtained materials, the phase analysis, residual stress and texture studies were performed. The classical non-destructive sin2ψ method was used to measure the residual stress measurements.
The final products, both solid sample and cellular lattice, have a homogeneous phase composition and consist of solid solution Al(Si) (Fm-3m) type, Si (Fd-3m) and Mg2Si (Pnma). The obtained values of the crystallite size are in a range of 1000 Å for Al(Si), 130-180 Å for Si phase. For Mg2Si phase, the crystallite sizes depend on sintering process, they are 800 Å for solid samples and 107 Å for cellular lattice. The residual stress results have the compressive character and they are in a range from –5 to –15 MPa.
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.