Laser Polishing of Additive Manufactured 316L Stainless Steel Synthesized by Selective Laser Melting

Abstract

One of the established limitations of metal additive manufacturing (AM) methods, such as selective laser melting (SLM), is the resulting rough surface finish. Laser polishing is one method that can be used to achieve an improved surface finish on AM printed parts. This study is focused on the laser surface polishing of AM parts using CO2 laser beam irradiation. Despite the fact that several researchers have investigated the traditional abrasive polishing method, there is still a lack of information reporting on the laser surface polishing of metal parts. In this study, AM 316L stainless steel cylindrical samples were polished using CO2 laser beam irradiation in continuous wave (CW) working mode. Two design of experiment models were developed for the optimization of the input processing parameters by statistical analysis of their effect on the resulting roughness. The processing parameters investigated were the laser beam power, the rotational speed of the sample, the number of laser scan passes, the laser beam focal position, and the percentage overlap of the laser tracks between consecutive passes. The characterization of the measured roughness and the modified layer microstructure was carried out using 3D optical and scanning electron microscopy (SEM). A maximum reduction of the roughness from 10.4 to 2.7 µm was achieved and no significant change in the microstructure phase type and micro-hardness was observed.

Defect Prevention in Selective Laser Melting Components: Compositional and Process Effects

“…SLM of austenitic stainless steels can be performed under a wide variety of process parameters including laser power (68–400 W), scan speed (0.3–2.5 m/s), layer thickness (20–50 μm), and hatch distance; the distance between the centre of two adjacent melt pools (40–140 μm) [4,5,6,7,8,9,10,11,12,13,14,15]. Therefore, depending on the process parameters, the alloy may experience a wide variety of temperature gradients, solidification conditions, thermal stresses, and be susceptible to defects such as cracks, pores, and residual stresses.…”

Post-Processing and Surface Characterization of Additively Manufactured Stainless Steel 316L Lattice: Implications for BioMedical Use

“…Other groups have had more success with thermally based treatments. Obeidi et al [ 58 ] successfully reduced the average surface roughness of stainless steel cylinders via laser polishing. This method has the benefit of avoiding the residual debris discussed above, but again may be difficult to apply to more complex shapes.…”

In-Situ Laser Polishing Additive Manufactured AlSi10Mg: Effect of Laser Polishing Strategy on Surface Morphology, Roughness and Microhardness

“…It is the lower hatching space that can be chosen to reduce more surface roughness. Obeidi et al [ 32 ] also found that increasing the overlapping area could improve the surface quality of AM 316L.…”