MSE Colloquium: Boian Alexandrov, New Developments in Weldability Evaluation of Advanced Alloys

Research Scientist, Welding Engineering, The Department of Materials Science and Engineering, The Ohio State University

Abstract

 

The global demand for energy resources and energy efficiency has led to the development and deployment of variety of advanced metallic alloys in the power generation, oil and gas, petrochemical, transportation, and defense sectors. The improved service properties of these alloys are achieved through complex alloying and sophisticated thermo-mechanical processing. However, weld failures and loss of properties are frequently experienced during manufacturing and service of welded structures in advanced alloys. Poor weldability has often been reported as the root cause of catastrophic failures, costly repairs, and expensive shut-downs of critical installations, and as the limiting factor for implementation of some advanced alloys. The conventional methods for weldability testing are not always applicable for evaluation of the response to welding in advanced alloys.

 

This talk will address unique methods and tools for weldability evaluation and phase transformation analysis that have been invented, developed, and/or improved at OSU. These tools, complemented with advanced metallurgical characterization and computational modeling, have been implemented to address major weldability problems experienced in the industry. Metallurgical phenomena leading to loss of properties and failures in dissimilar high strength steel / Ni-base alloy welds for sub-sea service, in weld overlays of Ni-base filler metals in nuclear power repair, and in creep resistant steel welds in ultra-super critical power plants will be discussed.

An approach for computational modeling of weldability tests aiming at quantification of material-specific properties related to weldability will be introduced. Such properties, i.e. critical strain for solidification cracking, can be utilized in computational models for prediction of crack-free process conditions and prevention of loss of properties and weld failures during manufacturing and service.

Bio

Dr. Boian Alexandrov is a Research Scientist in Welding Engineering at the Department of Materials Science and Engineering of the Ohio State University. He received a MS degree in Materials Engineering and a PhD degree in Welding Engineering from the Technical University of Sofia in Bulgaria, where he later worked as an Associate Professor. Dr. Alexandrov had a scholarship at Cambridge University in UK, a DAAD fellowship at Otto von Guericke University in Magdeburg, Germany, and completed a NATO-NSF postdoctoral fellowship in Welding Engineering at the Ohio State University.

The research interests of Dr. Boian Alexandrov are primarily focused on the physical metallurgy, specifically on non-equilibrium metallurgical phenomena related to weldability, of advanced alloys. He has developed innovative methods for weldability evaluation and phase transformation analysis that are complemented with advanced characterization and computational modeling and enable quantification of non-equilibrium phenomena occurring during processing in metallic alloys. His research has contributed towards resolution of major technology-restricting problems related to weldability.