Exploring eutectic-forming element effects on weld cracking mechanisms in Ni-30Cr alloys

Speaker: Dr. Carolin Fink

Abstract

Cracking is a commonly encountered defect during welding, typically driven by a complex interaction of thermal, mechanical and metallurgical factors. Significant effort has been devoted to characterizing the relative crack resistance of different alloys, using a variety of weldability tests. However, the mechanisms for crack formation in the fusion zone and heat-affected zone remain ill-defined and are not well understood. Advances in computational materials science and microstructural characterization techniques have enabled further inside into metallurgical aspects of crack formation, such as phase and microstructure formation in and around the solidifying weld pool. But there remain several open questions regarding the effect of eutectic reactions, liquid distribution and grain boundary properties associated with weld cracking from the semi-solid and solid-state. This presentation will discuss the use of alternative eutectic-forming elements in Ni-30Cr alloys. Niobium is currently added to these filler metals that are used in nuclear applications for weld repair and new component fabrication. However, some weld metal compositions have been shown to suffer from ductility-dip cracking and/or solidification cracking when diluted with austenitic stainless steel. Alternative eutectic-formers may present an opportunity to mitigate cracking, but require a detailed understanding of the effect on weld microstructure evolution, the cracking mechanisms itself and the resulting weld properties. Results from computational materials modeling, weldability and property testing and advanced microstructure characterization will be presented and discussed.

Speaker Biography

Dr. Carolin Fink is an Assistant Professor in the Department of Materials Science and Engineering at the Ohio State University. She received her doctoral degree in Welding Engineering from the Otto-von-Guericke University Magdeburg, Germany in 2016, and did her postdoc in the materials joining group at Ohio State University. In recognition of her PhD research on ductility-dip cracking in nickel base alloys, she was awarded the Henry Granjon Prize, Category B: Materials Behaviour and Weldability of the International Institute of Welding. Her current research is focused on fundamentals of materials degradation and cracking phenomena in materials joining and advanced manufacturing.