MSE Colloquium: Carolin Fink, Metallurgical and Thermo-Mechanical Aspects of Materials Degradation and Cracking Phenomena in Welding of Advanced Materials

Postdoctoral Research Associate, Department of Materials Science and Engineering, Welding Engineering, The Ohio State Univer

Abstract

Weldability is a key factor for the fabrication of advanced materials for structural components in energy production, chemical processing and lightweight vehicles. Advanced materials in such applications have specifically tailored properties that are attained by complex thermo-mechanical processing and carefully controlled alloying additions. However, due to metallurgical changes and thermo-mechanical effects that occur during the welding process, weld failures and loss of properties in welded metals and alloy components are frequently experienced. This can be highly deleterious to fabrication and service-performance, and limits the implementation of some advanced alloys.

In this talk, materials degradation and weld cracking phenomena in different advanced material systems will be discussed as they are a result of metallurgical as well as thermo-mechanical aspects influenced by the material, welding process and structural design. An experimental and computational approach will be presented to determine local criteria for ductility-dip cracking, which is a solid-state type of weld cracking due to a severe ductility loss in the heat-affected zone of nickel base alloys. This work lays the foundation for predicting weld cracking of real components through stress analysis models coupled with laboratory weldability test data. Another subject will address a materials degradation phenomenon in high manganese (15-30% Mn) steels for automotive applications, which have an excellent combination of strength and ductility, such that the thickness of parts can be reduced without compromising safety. However, in dissimilar welds with zinc coated ferritic steels these fully austenitic high Mn steels experience a strong ductility loss due to liquid metal embrittlement. With the underlying mechanism being still elusive, a new testing approach was introduced to evaluate the metallurgical and ductility response in the austenitic heat-affected zone throughout the liquid zinc temperature range. These examples demonstrate that overcoming weldability issues in advanced materials can be achieved through a combination of experimental and computational techniques to obtain a detailed understanding of the material behavior during welding. Such an understanding assists in choosing suitable welding processes and design criterion, which is essential for the implementation of advanced materials.

Bio

Carolin Fink is a Postdoctoral Research Associate at the Department of Materials Science and Engineering, Welding Engineering Program at The Ohio State University (OSU). Her research interests include weld cracking and materials degradation phenomena, in particular hot cracking and liquid metal embrittlement, welding metallurgy and weldability of nickel base alloys, welding of dissimilar metals and weldability testing.

Before joining OSU in August 2015, Carolin worked as a Graduate Research Associate at the Otto-von-Guericke University Magdeburg, Germany, while pursuing her Ph.D. in Mechanical Engineering at the Institute of Materials and Joining Technology (IWF). Carolin is a certified International Welding Engineer (IWE) and earned her Diploma in Business Administration and Mechanical Engineering at the Otto-von-Guericke University Magdeburg, Germany.