Investigation of Effect of Process Parameters on Multilayer Builds by Direct Metal Deposition

Abstract

Multilayer direct laser deposition (DLD) is a fabrication process through which parts are fabricated by creating a molten pool into which metal powder is injected as. During fabrication, complex thermal activity occurs in different regions of the build; for example, newly deposited layers will reheat previously deposited layers. The objective of this study was to provide insight into the thermal activity that occurs during the DLD process. This work focused on the effect of the deposition parameters of deposited layers on the microstructure and mechanical properties of the previously deposited layers. It is important to characterize these effects in order to provide information for proper parameter selection in future DLD fabrication. Varying the parameters was shown to produce different effects on the microstructure morphology and property values, presumably resulting from in-situ quench and tempering of the steels. In general, the microstructure was secondary dendrite arm spacing. Typically, both the travel speed and laser power significantly affect the microstructure and hardness. A commercial ABAQUS/CAE software was used to model this process by developing a thermo-mechanical 3D finite element model. This work presents a 3D heat transfer model that considers the continuous addition of mass in front of a moving laser beam using ABAQUS/CAE software. The model assumes the deposit geometry appropriate to each experimental condition and calculates the temperature distribution, cooling rates and re-melted layer depth, which can affect the final microstructure. Model simulations were qualitatively compared with experimental results acquired in situ using a K-type thermocouple.

Department(s)

Materials Science and Engineering

Second Department

Mechanical and Aerospace Engineering

Keywords and Phrases

Computer Simulation; Deposition; Fabrication; Finite Element Method; Mechanical Properties; Multilayers; Powder Metals; Spot Welding; Thermocouples; 3D Finite Element Model; Direct Laser Deposition; Direct Metal Deposition; Experimental Conditions; Microstructure and Mechanical Properties; Microstructure Morphologies; Secondary Dendrite arm Spacing; Stainless Steel 316L; Process Parameters; Microstructure

International Standard Serial Number (ISSN)

1359-4311

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2014 Elsevier, All rights reserved.

Publication Date

01 Dec 2014

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