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

Abstract

Laser Polishing (LP) is a well-defined technology that has recently been applied to improve three-dimensional (3D) printed Inconel 718 (IN718) parts. However, the necessity to conduct the process in an argon chamber is one of its major drawbacks, which is associated with an increase in the costs of production and the limitations of the technology regarding the size of parts that can be polished. This article investigates the possibility to conduct LP of IN718 in an air atmosphere and compares the results with those from an argon chamber setup. The experiment was carried out in the context of the influence of overlap on the final surface. The improvement of surface quality was defined through the evaluation of average areal roughness parameters, material relocation, periodic surface components, and the categorization of process-induced structures. It was found that LP allows for the average roughness to be reduced by 82.8% and 87.9% for an air and argon atmosphere, respectively. The oxidation layer was characterized using Energy-Dispersive X-ray Spectroscopy (EDS) analysis. The formation of overlap with regards to Ti and Al oxides had a vital influence on surface quality.

Dense Amorphous Passivation Layer Formed on Aluminum Alloy Surfaces by Femtosecond Laser-Assisted Oxygen-Rich Doping

“…On the other hand, the reduction of line-scan spacing from D = 50 to 30 μm can lead to a significant decrease in the structural roughness for both the LPA and LPO samples. This is probably due to the fact that the higher laser spot overlapping at the smaller line-scan spacing tends to result in the nonuniform removal of the material surface and ultimately decreases the roughness of the structures …”

Laser polishing of additively manufactured metal parts: a review

“…They found that the optimal laser speed and laser power for polishing were, respectively, 0.5 m s −1 and 400 W and that surface roughness Sa decreased by 81.9% after the LP process. C'wikła et al [73] investigated the performance of LP on SLMed Inconel 718 parts under both an air atmosphere and argon atmosphere. Their results showed an increase in Sa reduction with increasing overlap in both cases and that the LP process guarantees a reduction of the roughness up to about 83% under the air atmosphere and 88% under the argon atmosphere.…”

Study of the Processing Conditions for Stainless Steel Additive Manufacturing Using Femtosecond Laser

“…Although these results highlight the extreme difficulty of accumulating heat by means of femtosecond laser pulses, relatively smooth and uniform structures were obtained by decreasing the hatch distance to values where the overlap between lines exceeded the 80 %. High overlap values were also used in other processes for both accumulating heat in the process area and achieving a good surface finish [72][73][74].…”