Date of Award

Fall 2019

Document Type

Open Access Thesis

Department

Mechanical Engineering

First Advisor

Anthony P. Reynolds

Abstract

This thesis discusses WAAM (wire arc additive manufacturing) technology using TIG (Tungsten Inert Gas) welding method with aluminum 2219 as the substrate and aluminum 2319 as the filler material. The most important characteristic of this method of manufacturing is very little wastage of material as it does not follow the conventional method of manufacturing where material is removed from a bigger block to finally achieve the desired shape. This method uses a layer by layer approach to build the part. Generally, in additive manufacturing, the production time may vary depending on the type of method used. The material deposition rate in WAAM is one of the highest among all the processes.

A DOE (design of experiment) was performed with three independent variables namely (i) welding speed, (ii) wire feed rate and (iii) current. The resultant extent of the actual material deposition with respect to the desired bead shape was studied using this DOE. The topics discussed here are the equipment, process parameters involved in this method and their optimization to achieve the desired shape with suitable mechanical properties. Full factorial designs using Minitab were created with the aforementioned factors with three levels of input values for each parameter. The output was studied from the main effects plots and the interaction plots of the variables. These efforts intend to discuss the effects of the heat input on the bead shape with a combination of the wire feed and welding speed.

In addition to the weld bead geometry, the hardness of the deposited material was tested by a Vicker’s hardness tester by creating a contour plot on the weld beads and

thereafter the heat affected zone was also studied. In order to verify the change in the mechanical properties of the specimens, a heat treatment was conducted to achieve a T6 conditioning according to the ASM Handbook, Volume 4 [1] and a hardness test was conducted on the same samples. Another important aspect studied in this research was the porosity in the weld beads. The percentage of holes per unit area of the weld beads was studied by the point counting method [2].

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