Investigating deformation microstructure evolution and transformation behaviour of steel using controlled thermomechanical compression

Lead Research Organisation: University of Sheffield
Department Name: Materials Science and Engineering


Over 95% of metallurgical products, both traditional and novel, undergo one or more thermomechanical processes in their production. The market place for such products is extremely competitive. Success requires the very best in quality, consistency and properties. This has led to a major challenge to develop 'designer microstructures' through predictive modelling and to process such materials to give entirely predictable properties. This can only be achieved through an integrated, multidisciplinary approach to materials development and materials processing and the effect on microstructure and texture development. To make this a reality requires elucidation and quantification of the processing variables that have a significant influence on the deformation induced microstructure and subsequent transformation and recrystallisation events that occur through the process route. Only when this has been achieved will there be sufficient scientific underpinning for the development of physically-based, through-process models to predict the ideal process route for a targeted microstructure and texture. The goal is to inform laboratory experiment and industrially based trials leading reduction cycle, improved productivity and enhanced material properties. This project aims to target some critical aspects of the modelling of microstructural evolution during thermomechanical processing by combining the expertise and world class hot working simulation facilities of the Institute for Microstructural and Mechanical Engineering: The University of Sheffield (IMMPETUS) with a six month visit to IMMPETUS by Professor Bevis Hutchinson (Head of Department of Mechanical Metallurgy, Corrosion and Metals Research Institute, Sweden). Prof Hutchinson is a renowned world expert in the fields of microstructure and texture evolution in hot and cold worked steels. His visit represents a unique opportunity for UK researchers and industrialists, particularly the many associated with the IMMPETUS programme, to gain first hand knowledge of the numerous factors that are believed to contribute to the generation of microstructure and texture in steels through the thermomechanical processing route. The main theme of Prof Hutchinson's visit will be: Further independent evidence of the proposed mechanisms for phase transformation and variant selection in steels. This area of research has received significant attention over recent years. However, there is only limited independent work investigating the many theories that have been proposed. Indeed, the theories cannot be fully validated because of the missing information, such as the starting texture in the austenite. However, a recently developed model austenitic alloy, developed by IMMPETUS, will allow, for the first time, this missing information to be derived. By using IMMPETUS' state-of-the-art thermomechanical compression simulator, we will validate or disprove the theories under controlled conditions and thereby clarify the critical process variables such that a clear modelling strategy can be developed. In addition, the visit of Prof Hutchinson will complement a wide range of work that is being done in IMMPETUS as well as introducing a number of new concepts into the IMMPETUS framework, in particular crystallographic texture evolution.


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Description During the hot working of metals, the microstructural change is well documented. What is more difficult to understand is how the complicated hot working process can influence the heterogeneities in composition and crystal orientation. This is important as it is these factors that influence properties.
Exploitation Route The understanding gained, complete with a follow on project, has been used to inform the hot working practice at Timet. They have changed their hot working schedule giving improved final properties.
Sectors Aerospace, Defence and Marine,Manufacturing, including Industrial Biotechology

Description The findings informed a follow up project looking at microstructural heterogeneities and how they change during thermomechanical processing. In addition, the understanding has been transferred to industry, most notably, Tata Steel and Timet
First Year Of Impact 2007
Sector Aerospace, Defence and Marine,Manufacturing, including Industrial Biotechology,Transport
Impact Types Economic