Access Type

Open Access Dissertation

Date of Award

January 2022

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Mechanical Engineering

First Advisor

Xin X. Wu

Abstract

ABSTRACTA COMBINED ADDITIVE - DEFORMATION - MACHINING (ADM) MANUFACTURING PROCESS WITH CONTROLLED MICROSTRUCTURES by AHMED NABIL TAHER ELALEM August 2022

Advisor: Dr. Xin WuMajor: Mechanical Engineering Degree: Doctor of Philosophy

Direct metal additive manufacturing provides great flexibility in 3D shaping compared to traditional manufacturing processes of metal casting, deformation followed by machining and joining for obtaining the final production shape. On the other hand, it suffered from its dendric microstructure produced during solidification. This study reports the development of new combined metal additive and deformation processes to take advantage and reduce/eliminate the drawback of individual processes. The heating source mainly categorizes many forms of direct metal deposition processes and heat application methods used. Similarly, many deformation processes can provide a wide range of applied stress, strain, strain rate, and temperature, ultimately determining the product's final microstructure and property. One constraint for selecting the deformation process is providing local deformation to allow flexible 3D printing and forming. To demonstrate the feasibility of such concept, in this study, a common industry MIG welding process is used for metal deposition from solid wire to a solid 3D shape, and the Friction Stir Process (FSP) is used for local severe plastic deformation at controlled strains, strain rates, and temperatures within a relatively small processing volume. The processing parameters to be investigated include the MIG power rate, nozzle moving speed, wire feeding rate, friction stirring head geometry parameters, rotation speed, and moving velocity, along with the cooling rate. In addition, the grain size distribution over different additive layers is measured. A wide range of grain sizes, including submicron fine grain size, correlate with the thermomechanical conditions. Finally, the advantages and potential application of the process of MIG+FSP are discussed.

Download

Share

COinS