| dc.description.abstract | The purpose of this study has been to investigate if 316L powder for Selective Laser Melting (SLM) can be made from scrap material by the process of Vacuum Induction Gas Atomizing (VIGA). Unused parts from storage represented 90% of the input material used by the VIGA process to produce suitable powder for SLM and the average sized particle of the powder ended up being 34.30 µm. Then by the use of the so-called “green” powder, the SLM process managed to produce suitable and almost dense (porosity<99.5%) specimens for testing. Further, the characterization of the mechanical properties and microstructure was carried out by performing tensile testing, impact testing, Vickers hardness measurements and light optical microscopy were the porosity also was examined. By investigation of the microstructure, it was found that the microstructure exhibited similar characteristics found in other studies studying SLM manufactured 316L specimens. These similarities include observations of overlapping melt pools due to partially remelting, what is believed to be epitaxial grain growth as well as grains growing in no preferred direction. Thus, indicating that the laser scanning pattern has successfully manage to create isotropic like conditions in the microstructure. Overall, the microstructure seems to correspond well with the achieved mechanical properties and as can be normally observed with regards to SLM produced specimens, exhibited the z-oriented tensile specimens lower yield and tensile strength. However, the mechanical properties generated by tensile testing where all within the requirements of the relevant standard, though they exhibited slightly lower properties than the specimens produced by regular powder. Which is most likely due to the chemistry being slightly different in the finished specimens of this study compared to the ones produced by the regular powder. The tensile specimens in x-, y- and z-direction of this study exhibited tensile strength of 619.1 (x), 631.1 (y) and 554.2 ± 6.35 (z) and yield strength of 519.3 (x), 541.9 (y) and 455.8 ± 2.45 (z) respectively. Therefore, it can be concluded that it is feasible to produce 316L powder, suitable for Selective Laser Melting (SLM) by the use of scrap material as the main input material when producing powder by Vacuum Induction Gas Atomizing (VIGA). | |
