Investigation of Laser Polishing of Four Selective Laser Melting Alloy Samples

Abstract

Selective laser melting (SLM) is a layer by layer process of melting and solidifying of metal powders. The surface quality of the previous layer directly affects the uniformity of the next layer. If the surface roughness value of the previous layer is large, there is the possibility of not being able to complete the layering process such that the entire process has to be abandoned. At least, it may result in long term durability problem and the inhomogeneity, may even make the processed structure not be able to be predicted. In the present study, the ability of a fiber laser to in-situ polish the rough surfaces of four typical additive-manufactured alloys, namely, Ti6Al4V, AlSi10Mg, 316L and IN718 was demonstrated. The results revealed that the surface roughness of the as-received alloys could be reduced to about 3 μm through the application of the laser-polishing process, and the initial surfaces had roughness values of 8.80–16.64 μm. Meanwhile, for a given energy density, a higher laser power produced a laser-polishing effect that was often more obvious, with the surface roughness decreasing with an increase in the laser power. Further, the polishing strategy will be optimized by simulation in our following study.

Surface Roughness Considerations in Design for Additive Manufacturing - A Literature Review

“…Due to the inherent nature of the LPBF to produce parts with some level of surface roughness, efficient methods of post-processing are continuing to be developed. Currently to address the surface roughness issues of AM parts, post-processing methods such as abrasive blasting (Sagbas, 2020), shot peening (AlMangour and Yang, 2016) and laser polishing (Zhang et al, 2020) are utilised. The choice of post-processing method can have an impact on the properties of the outer layer of AM parts and part geometry, therefore careful consideration of method choice must be taken (Bouland et al, 2019;Kaynak and Tascioglu, 2020;Sagbas, 2020).…”

Laser polishing of additive manufactured Ti6Al4V alloy: a review

“…3. Zhang et al 50 studied the in-situ polishing of additive manufactured Ti6Al4V with a fiber laser. There was no need to clamp the components twice after 3D printing.…”

Influence of Overlap on Surface Quality in the Laser Polishing of 3D Printed Inconel 718 under the Effect of Air and Argon

“…Recent Laser Polishing studies have shown that it is possible to achieve a reduction of roughness from 80% to 98% for additive manufactured IN718 samples [ 38 , 40 , 41 , 42 , 43 , 44 , 45 ]. However, in all of the mentioned papers, the LP of IN718 is conducted in an oxygen-free environment due to the fact that IN718 contains elements characterized by a high oxidation potential (Ni, Fe, Cr, Ti, Al) [ 39 ], which can form oxides in high temperatures both below [ 46 ] and above the melting point (1336 °C) [ 47 ].…”

“…However, in all of the mentioned papers, the LP of IN718 is conducted in an oxygen-free environment due to the fact that IN718 contains elements characterized by a high oxidation potential (Ni, Fe, Cr, Ti, Al) [ 39 ], which can form oxides in high temperatures both below [ 46 ] and above the melting point (1336 °C) [ 47 ]. In most cases, to provide an oxygen-free environment during LP, a SLM chamber filled with argon is used in order to proceed with LP directly after 3D printing [ 44 ]. However, in this case, the problem of object/laser beam manipulation limits, or even prevents, the polishing of complex parts and, therefore, the polishing can only be applied to flat horizontal surfaces.…”