Simulation of Laser-assisted Directed Energy Deposition of Aluminum Powder: Prediction of Geometry and Temperature Evolution.

Fabrizia Caiazzo,Vittorio Alfieri

doi:10.3390/ma12132100

Abstract

One of the main current challenges in the field of additive manufacturing and directed energy deposition of metals, is the need for simulation tools to prevent or reduce the need to adopt a trial-and-error approach to find the optimum processing conditions. A valuable help is offered by numerical simulation, although setting-up and validating a reliable model is challenging, due to many issues related to the laser source, the interaction with the feeding metal, the evolution of the material properties and the boundary conditions. Indeed, many attempts have been reported in the literature, although some issues are usually simplified or neglected. Therefore, this paper is aimed at building a comprehensive numerical model for the process of laser-assisted deposition. Namely: the geometry of the deposited metal is investigated in advance and the most effective reference shape is found to feed the simulation as a function of the governing factors for single- and multi-track, multi-layer deposition; then, a non-stationary thermal model is proposed and the underlying hypotheses to simulate the addition of metal are discussed step-by-step. Validation is eventually conducted, based on experimental evidence. Aluminum alloy 2024 is chosen as feeding metal and substrate.

Highlights

In the frame of additive manufacturing, the process of directed energy deposition (DED) is effective and minimally invasive; it is receiving increasing interest in industry to prevent replacement of price-sensitive metal products [1,2]
A valuable help is offered by numerical simulation, setting-up and validating a reliable model is challenging, due to many issues related to the laser source, the interaction with the feeding metal, the evolution of the material properties and the boundary conditions
Namely: the geometry of the deposited metal is investigated in advance and the most effective reference shape is found to feed the simulation as a function of the governing factors for singleand multi-track, multi-layer deposition; a non-stationary thermal model is proposed and the underlying hypotheses to simulate the addition of metal are discussed step-by-step

Summary

Introduction

In the frame of additive manufacturing, the process of directed energy deposition (DED) is effective and minimally invasive; it is receiving increasing interest in industry to prevent replacement of price-sensitive metal products [1,2]. Additional metal can be applied over worn-out surfaces, restoring the nominal dimensions and preventing part disposal; with this aim, the technology has been investigated over flat surfaces [3] and even in challenging deposition conditions such as damaged edges [4]. The same process has been studied to the purpose of freeform fabrication, aiming to control the crystal orientation in metals and eliminating residual pores for superalloys [5]; DED is expected to have high potential in large-scale aerospace and automotive production [6]. Wide research activity has been devoted to simulation tools based on finite elements methods, and even to simplified 2-dimension approaches [11]. Pros and cons of the models available for DED have been addressed in depth and are comprehensively discussed in the literature [12]: Materials 2019, 12, 2100; doi:10.3390/ma12132100 www.mdpi.com/journal/materials

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Conclusion