The Influence of Austenite Grain Structure on Bainite and Martensite Transformations in High Strength Strip Steel
Funding amount: £17,000 per annum
Hours: Full Time
Contract Type: Contract / Temporary
Placed on: 1st December 2016
Closes: 28th February 2017
Funding: EPSRC Industrial Case, stipend of circa £17,000 per annum for four years.
Supervisors: Professor Claire Davis and Dr Martin Strangwood
Industrial sponsor: Tata Steel Europe
Start Date: October 2016
This project will investigate the influence of austenite grain size/shape, and the amount of retained strain in austenite, on the subsequent bainite and martensite transformation in commercial steel grades with different compositions and strength levels.
The outputs from the project will be used to increase the accuracy of predictions for the transformation start temperatures and transformation kinetics, which in turn will be used to improve cooling control on the run out table (ROT) during strip cooling. Regular meetings with the industrial sponsor (Tata Steel Europe) will also be held throughout this research project. See www.tatasteel.com for details of the company.
The steel strip used for yellow goods, such as crane booms and dumper trucks, can have strengths in excess of 1GPa. These high strength levels are obtained from mixed bainitic/martensitic microstructures, where the microstructure is developed by controlled cooling after hot rolling. In order to reliably produce such high strength levels in the low alloy steels, accurate control of the run out table (ROT) cooling and coiling temperature is needed. Consistent ROT cooling requires a good knowledge of the transformation behaviour of the steel (transformation start temperatures, kinetics, transformation end, heats of transformation), which is influenced by the composition, austenite grain size and shape, and retained strain.
Whilst the influences of composition and grain size for the transformation to ferrite are well known, there is less consistent information available for the effect of grain structure on the bainite and martensite transformation. For example, opposing roles of grain size have been suggested based on the bainite morphology formed, and any synergistic effects of changes in strain and grain size need to be determined.
You will conduct experimental studies, using deformation dilatometry and Gleeble thermo-mechanical simulations, to determine the influence of grain shape and retained strain on the transformation behaviour, along with microstructural characterisation and hardness testing. Industrial material with known rolling and cooling conditions will also be assessed.
Eligibility: Applicants must be UK residents and should have a 1st or 2.1 degree in a relevant science or engineering subject, such as materials, physics, mechanical engineering, or maths
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