| LIU Qi,YUAN Meixia,KOU Tingyu,LIU Xiaoke,JIANG Linlin.Research on Edge Slagging and Center Depression of Thin Walled Titanium Alloy Structures Formed by SLM[J],53(13):187-197 |
| Research on Edge Slagging and Center Depression of Thin Walled Titanium Alloy Structures Formed by SLM |
| Received:July 01, 2023 Revised:September 23, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.13.018 |
| KeyWord:selective laser melting titanium alloy Ti-6Al-4V thin-walled structure edge slagging central depression laser power scanning speed |
| Author | Institution |
| LIU Qi |
School of Mechanical-Electronic and Vehicle Engineering,Beijing , China |
| YUAN Meixia |
School of Mechanical-Electronic and Vehicle Engineering,Beijing , China ;Beijing Key Laboratory of Performance Guarantee on Urban Rail Transit Vehicles, Beijing University of Civil Engineering and Architecture, Beijing , China |
| KOU Tingyu |
School of Mechanical-Electronic and Vehicle Engineering,Beijing , China |
| LIU Xiaoke |
School of Mechanical-Electronic and Vehicle Engineering,Beijing , China |
| JIANG Linlin |
School of Mechanical-Electronic and Vehicle Engineering,Beijing , China |
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| Abstract: |
| To investigate the accuracy of thin-walled specimens formed by Selective Laser Melting (SLM), the effects of laser power and scanning speed on the edge dross dropout and dimensional accuracy of thin-walled structures formed by SLM of titanium alloy Ti-6Al-4V were investigated, and the main factors causing the concave phenomenon in the center of thin walls were discussed. By adjusting the laser power and scanning speed, a total of nine specimens were prepared in a two-factor, three-level full-factor test to observe and compare the slagging phenomena and thin-wall dimensions on the microscopic surfaces of thin walls formed under different process parameters. In this process, the influence mechanism of different process parameters on the thin-wall forming accuracy was proposed, and the optimal forming process parameters for the forming of thin-wall structures were obtained. It was found that the slag hanging phenomenon on the side surface of the thin wall was the main reason affecting its accuracy, and the laser power was the main factor causing large area slag dropping. Low laser power and low scanning speed were beneficial to reduce the slag hanging thickness, but too high scanning speed was likely to cause surface defects. Compared with the scanning speed caused by the hanging slag and sticky powder phenomenon, the laser power had a greater impact. Under the same process parameters, with the increase of thin-wall thickness, the slagging area became smaller and smaller. The wall width of SLM thin wall had a three-dimensional nonlinear relationship with laser energy density, and the wall width of SLM thin wall increased with the increase of energy degree. When having the same laser energy density at different process parameters, the specimens still exhibited large differences. The problem of diffusion of residual energy would lead to serious dimensional error problems for thin-walled structures with small thickness. Low energy density corresponding to low laser power could obtain a thin-walled structure with less error, while a reasonable scanning speed should be selected to avoid excessive defects on the upper surface of the thin wall. In this study, experimental data were compared, and the specimens all exhibited large dimensional errors when the laser power was 300 W. When the energy density is 44.44 J/mm3, the minimum wall width value obtained is 529.37 mm, the final test yields the minimum process parameters for forming thin-walled structures with errors of P=200 W, v=900 mm/s, and h=50 mm. The degree of concavity on the surface of thin walls of different thicknesses in SLM forming varies. With the increase of thin wall thickness, the height difference between the edge of thin wall and the center also increases. Especially at the thin wall edge, the height of the thin wall shape decreases sharply. The sharp decrease in the height of the thin wall edge caused by the edge scanning strategy, and the edge warping and thermal shrinkage caused by residual stresses combined to cause the concave phenomenon in the center of the thin wall. |
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