Influence of standoff distance and laser defocusing distance on direct laser metal deposition of a nickel-based superalloy

Marco Mazzarisi,Sabina Luisa Campanelli,Vito Errico,Andrea Angelastro

doi:10.1007/s00170-022-08945-3

Marco Mazzarisi, Sabina Luisa Campanelli + Show 2 more

Open Access

https://doi.org/10.1007/s00170-022-08945-3

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Abstract

The direct laser metal deposition (DLMD) is an additive manufacturing technology, based on laser cladding, which focuses mainly on 3D manufacturing applications. DLMD allows the production of thin-walled components by overlaying single-track depositions. Several issues can affect the deposition process and compromise the flatness of the surface on which subsequent tracks will be deposited. This work focused on deposition troubles simulated by means of a designed variation of the standoff distance and the laser defocusing distance. The effects of these two important process parameters on the deposition process were investigated. The experimental tests were performed by depositing a nickel-based superalloy powder on AISI 304 stainless steel plates through a coaxial nozzle. The work was carried out using an ytterbium fiber laser source and a deposition head equipped with an advanced and innovative motorized optics system. This allows the decoupled variation of the laser defocusing distance and consequently the laser spot size on the substrate surface with respect to the standoff distance. Results showed an influence of standoff distance and laser defocusing distance on the geometrical characteristics of the clad, such as clad width, clad height, penetration depth, and dilution. An experimental setup consisting of a light coaxial to the powder flow and a laterally positioned camera was designed to investigate the spatial powder distribution. Moreover, an analytical model for the powder distribution and clad width were proposed and validated. The analysis of variance (ANOVA) with a general linear model was also employed to describe the results.

Highlights

The direct laser metal deposition (DLMD) is an additive manufacturing (AM) technology based on a combination of laser cladding and 3D printing principles [1]
The results proposed by Ermurat et al [31] show that a clad of minimum size was obtained by using the highest values of the standoff distance combined with the value of the laser focal distance that generates the lowest laser spot size on the substrate
In laser cladding and 3D manufacturing applications of DLMD technology, an important process variable is the clad width, which mainly is dependent to the melt pool size [47, 48]

Summary

Introduction

The direct laser metal deposition (DLMD) is an additive manufacturing (AM) technology based on a combination of laser cladding and 3D printing principles [1] This is usually used to repair and reconfigure worn or damaged components through the application of wear and corrosion-resistant coatings. The laser deposition of metal powders is suitable to produce metal components with complex geometry or employing innovative materials, extremely difficult to work utilizing traditional techniques. This explains the growing interest of the industry for the DLMD process, mainly in highly specialized manufacturing sectors [2,3,4,5,6,7]. Other research groups focused on improving the deposition efficiency to make the

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