In-situ characterization of the role of nano-precipitation and strain distribution on the conditioning of austenite during themo-mechanical processing of high strength structural steels
Prof S Seetharaman
Dr v Janik
Applications accepted all year round
Funded PhD Project (European/UK Students Only)
This project is with leading researchers in WMG’s Steels Processing Group at the University of Warwick.
This is an exceptional opportunity to utilize novel in-situ materials characterization tools during development of a modern advanced high strength structural steels. You will gain a unique set of material characterization skills, together with close involvement with leading researchers and scientists at WMG, University of Warwick, and at Tata Steel R&D.
The objective of the project is to study the effect of varying densities and morphologies of nano-precipitates, and of varying strains during hot deformation of austenite, on the formation of ferrite during controlled cooling. The chief aim is to design a metallurgical processing route allowing us to maximise the strength and impact tongues of modern construction steel grades such as Celsius 420.
Experimental facilities including Elevated Temperature Deformation Stage in Confocal Laser Scanning Microscopy (ETDS-CLSM), and Elevated Temperature Stage in Electron Back Scattered Diffraction (ETS-EBSD) will be applied extensively, together with thermo-mechanical testing at a Gleeble 3800 testing machine.
Additionally, High Resolution Transmission Electron Microscopy with analytical spectroscopy will focus on describing the nano-precipitates in detail.
Deformation of austenite to a different strain level will cause strain heterogeneity of the austenitic grain. Additionally, pre-existing and strain induced nano-precipitates will further influence the morphology of austenite and its growth. In-situ characterization using ETDS-CLSM and EBSD will allow us for the first time to characterize this heterogeneous nature of austenite with sufficient detail. The transformation to ferrite will occur in-situ during controlled cooling inside the ETDS-CLSM or EBSD chamber, allowing analysis of the
ferritic grain transforming at varying cooling rates and/or different isothermal temperatures from differently conditioned austenitic grains. The level of nano-precipitation will be quantified by FIB lift-out method from selected austenitic grains.
To obtain both high strength and high toughness of the final material, transformation from austenite to ferrite has to occur under maximum nucleation rate of ferrite. Austenite therefore has to be conditioned by strain and controlled by nano-precipitation in a way to give raise to a maximum amount of effective nucleation sites of ferrite. Our aim is to find the optimum austenite conditioning by studying in situ the transformation of conditioned austenite to ferrite and by conducting site specific TEM to analyse the role of
SCOPE OF WORK
- Experimental studies capturing the interaction between strain, softening processes and precipitation during conditioning of austenite
- Recommendations on alloy and process for optimised precipitation hardening
- Model capturing influence of austenite conditioning on final mechanical properties
- Publications in scientific journals and conference proceedings
- Monthly reporting and interaction with researchers at WMG and TATA
This position provides an annual stipend of £14,296, with an additional industry top up of £3,000 per annum from the industrial sponsor (Tata Steel), for 3.5 years. To qualify for this funding you must me the EPSRC criteria for UK/EU nationals.
Tuition fees will be paid UK/EU nationals for up to 3.5 years.