| DENG Yu-hua,LI Zhen-hua,YAO Bi-bo,TENG Bao-ren,LI Hao.Effect of Laser Power and Scanning Speed on Microstructure and Properties of Co-Cr Alloy by Selective Laser Melting[J],52(1):325-335 |
| Effect of Laser Power and Scanning Speed on Microstructure and Properties of Co-Cr Alloy by Selective Laser Melting |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.01.033 |
| KeyWord:CoCr alloys SLM finite element simulation by ANSYS line energy density molten pool size mechanical properties |
| Author | Institution |
| DENG Yu-hua |
School of Materials Science and Engineering, Kunming , China |
| LI Zhen-hua |
School of Materials Science and Engineering, Kunming , China |
| YAO Bi-bo |
School of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming , China |
| TENG Bao-ren |
School of Materials Science and Engineering, Kunming , China |
| LI Hao |
School of Materials Science and Engineering, Kunming , China |
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| Abstract: |
| It is an advanced manufacturing technology by direct metal laser melting. The important characteristic of the SLM technology is that it can produce parts with high geometrical dimensional accuracy, the forming parts have brilliant mechanical properties, and the relative density of the parts is close to 100%. However, the energy density cannot accurately reflect the relationship between scanning speed and molten pool size in process parameter optimization of SLM. This article studies the effect on SLM cobalt-chromium alloy of linear energy density and process parameter. Firstly, a suitable range of process parameters of linear energy density is selected, then the scanning speed is increased by fix the linear energy density for the process parameter optimization, and finally, the melt pool size is calculated by commercial finite element software ANSYS simulation under each process parameter to analyze the effect on process parameters of the molten pool size. The molten pool size obtained from the numerical simulation is analyzed to obtain the appropriate scan spacing, and the process parameters are imported into EOS M290 for specimens forming. The SLMed specimens are sandpapered and polished, and the porosity defects of the parts are observed by metalloscope, and the relative density of the parts are calculated by Imagepro software. After etch, the SLMed parts are analyzed by micrographs to determine the molten pool overlap and size under different process parameters. The variation of sub-cellular and grain size with process parameters is analyzed using FE-SEM and EBSD. The tensile strength and elongation of the SLMed specimens are tested by universal testing machine. The hardness of the SLMed specimens is tested using Rockwell hardness tester and five-point tests are collected to reduce the error. Finally, the cooling rate under different process parameters is analyzed by commercial ANSYS software again. Results showed that the molten pool size and the cooling rate decreased with the linear energy density, which result in inferior to relative density and grain sizes of the SLMed parts, and led to a decrease in the mechanical properties of the SLMed parts. At the same linear energy density of 0.242 J/mm, the densities of 98.7%, tensile strengths of 867 MPa, and elongation of 6.5% were higher for the specimens with scanning speed of 1 200 mm/s than that of scanning speed at 950 mm/s. The molten pool size and grain size of the forming parts with high scanning speed are higher than that of low scanning speed forming parts at the linear energy density of 0.242 J/mm, and the high scanning speed mechanical properties are similar to those of the specimens with 250 W+950 mm/s at a higher linear energy density of 0.263 J/mm. With the investigated the relationship between parameters and molten pool size, the linear energy density seemed to have direct effect on the molten pool size and mechanical properties of SLMed cobalt-chromium alloys, but there is no linear relationship between the molten pool size and the linear energy density. At the same linear energy density, higher scanning speed exhibited the better molten pool size, cooling rate, relative density, grain refinement, and ultimately succeeded in the mechanical properties. |
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