On the Relevance of Volumetric Energy Density in the Investigation of Inconel 718 Laser Powder Bed Fusion.

Fabrizia Caiazzo,Giuseppe Casalino,Vittorio Alfieri

doi:10.3390/ma13030538

Fabrizia Caiazzo, Giuseppe Casalino + Show 1 more

Open Access

https://doi.org/10.3390/ma13030538

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Journal: Materials	Publication Date: Jan 23, 2020
Citations: 69	License type: CC BY 4.0

Affiliation: University of Salerno, Polytechnic University of Bari

Abstract

Laser powder bed fusion (LPBF) can fabricate products with tailored mechanical and surface properties. In fact, surface texture, roughness, pore size, the resulting fractional density, and microhardness highly depend on the processing conditions, which are very difficult to deal with. Therefore, this paper aims at investigating the relevance of the volumetric energy density (VED) that is a concise index of some governing factors with a potential operational use. This paper proves the fact that the observed experimental variation in the surface roughness, number and size of pores, the fractional density, and Vickers hardness can be explained in terms of VED that can help the investigator in dealing with several process parameters at once.

Highlights

New methods of manufacturing are receiving special interest to pursue specific advantages in comparison with conventional technologies
No densification occurred with the lowest level of volumetric energy density (VED) of the plan; the powder was sintered but not fully melted, resulting in the highest roughness
As regarding the other conditions, effective densification was obtained; interestingly, for each given condition, any dependence of the mean roughness on the direction of probe can be discarded and ascribed to the experimental error; one may assume that the surface pattern is uniform and the lay resulting from manufacturing is negligible over a surface parallel to the building plate

Summary

Introduction

New methods of manufacturing are receiving special interest to pursue specific advantages in comparison with conventional technologies. One may expect any outcome in LPBF to depend on the leading factors such as laser power, scanning speed, layer thickness and hatch distance [7], the exposure strategies, as well as the build orientations of the parts [8] and the required supports [9]. Other factors, such as the inert gas selection [10], are deemed to have minor impact, these have been addressed only recently in the literature. It has been shown that the porosity, in terms of both amount [11] and size [12] of pores, is crucial for any process involving the laser beam [13], since an effect is played on the ultimate tensile strength and the overall hardness [7,8]; interestingly, a proper selection

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