Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Materials Science

Committee Chair

Judy Schneider

Committee Member

Sherri Messimer

Committee Member

Luke Brewer

Committee Member

Michael Banish

Committee Member

Seyed Sadeghi

Research Advisor

Judy Schneider


Additive manufacturing, Gas tungsten arc welding, Carbon steel--Microstructure, Metals--Heat treatment


Additively manufactured (AM) parts are subjected to rapid and repeated localized melting, solidification, and reheating, which produces a heterogeneous microstructure. To homogenize the resulting heterogeneous microstructure that results from this non-equilibrium thermal cycling, ex-situ heat treatments can be used. However, this is intended to provide homogenous properties to the printed part, thereby not realizing one of the potential benefits of AM in providing site-specific properties such as fatigue resistance, wear resistance or high strength. This study explores the use of in-situ heat treatments to spatially control microstructure evolution, thereby controlling the location of specific mechanical properties. To guide the processing parameters, numerical models were used to predict the thermal histories and the corresponding desired microstructures and properties. To achieve this goal, a Gas Tungsten Arc Welding (GTAW) based AM process has been designed and built for spatial control of microstructures in a carbon steel. The GTAW process is selected due to the ability to separate the heat flux from the material deposition, providing the ability for in-situ heat treatments.



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