WE Seminars: Colleen Hilla and Dean Sage

Understanding cuboidal microstructure in additive manufacturing builds

Colleen Hilla
Advised by Drs. Wei Zhang & Michael Mills

Abstract

One of the biggest challenges for the application of additive manufacturing is understanding the process-microstructure-properties relationship. This study aims to understand the effect of various processing on the microstructure of gamma prime strengthened nickel-based super alloys. Specifically, understanding what parameters lead to the development of a cuboidal microstructure and how this can be exploited to improve material properties. Three samples were printed using laser powder bed fusion using various printing parameters. The grain structure was analyzed using EBSD and compared to various other material systems to gain an understanding into this grain growth phenomena.

Bio

Colleen is a second year PhD student in Welding Engineering. She received her bachelor's degree from the University of Pittsburgh in Material Science and Engineering on 2017 where she was heavily involved in research and formula SAE. Colleen’s main research interest reside in additive manufacturing and microstructural analysis/microscopy. Outside of work she is an aerialist and enjoys spending her time in the air.

Liquid Metal Embrittlement in Advanced High Strength Steels

Dean Sage
Advised by Dr. Carolin Fink

Abstract

With recent environmental concerns, the automotive industry is striving towards lighter and stronger materials. The most recent generation of advanced high strength steels (AHSS) use increasingly complicated microstructures to achieve their mechanical properties, but with new solutions came new problems. One such issue is liquid metal embrittlement (LME). The zinc coating used to prevent corrosion of these materials can melt and penetrate the steel, significantly embrittling it. Factors influencing the embrittlement as well as the effects of grain boundary engineering will be discussed.

Bio

Dean Sage is a third year PhD student in the Welding Engineering program at The Ohio State University. His undergraduate career consists of B.S. degrees in Biological Engineering and Materials Engineering from the University of Florida. Dean’s main research interests are failure analysis and characterization, particularly in regards to weldability. Outside of the lab Dean enjoys hiking, camping, and scuba diving.