In-situ characterisation of the role of nano-precipitation and strain distribution on the conditioning of austenite during thermo-mechanical processing of high strength structural steels
Funding amount: £14,296
Hours: Full Time
Contract Type: Contract / Temporary
Placed on: 3rd August 2016
Closes: 30th November 2016
Prof Sridhar Seetharaman
Dr Vit Janik
The stipend will be in the region of £14,296 per annum with an additional £3,000 pa top up from the industrial sponsor.
This project offers an exceptional opportunity to utilize novel in-situ materials characterization tools during development of a modern advanced high strength structural steels. The PhD student will gain 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. Experimental facility 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 Gleeble 3800 testing machine. Additionally, High Resolution Transmission Electron Microscopy with analytical spectroscopy will focus on describing the nano-precipitates in detail.
Objective of this work 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. Chief aim of this project is to design a metallurgical processing route allowing to maximise the strength and impact tongues of modern construction steel grades such as Celsius 420.
Scientific hypothesis: 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 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. 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 nano-precipitates.
Detailed 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
Funding Source: EPSRC and Tata Steel
Funding Duration: 3.5 years
Funding Eligibility: UK or EU if satisfy EPSRC criteria
Sponsor Company (if applicable): Tata Steel
Applicants should have or expect a first class honours or good upper second class degree (or an equivalent) in Metallurgy, Materials Engineering and/or Mechanical Engineering. Experience with advanced Materials Characterisation methods such as Electron Microscopy and Electron Back Scattered Diffraction is a plus.
Full details of the duties and selection criteria for this role are found in the vacancy advert on the University of Warwick jobs page. You will be routed to this when you click on the Apply button below