Strain mapping of individual grains using diffraction contrast tomography

Lead Research Organisation: University of Manchester
Department Name: Materials

Abstract

This research project will aim to undertake a fundamental study of the early stages of plastic deformation in two types of polycrystalline alloys, low interstitial steel and commercially pure titanium (each material has a very distinct crystal structure, which has a strong impact on the deformation mechanisms), by using diffraction contrast tomography (DCT) on high-energy synchrotron x-ray radiation beam lines. Diffraction contrast tomography is a novel polycrystal grain and orientation mapping technique, which allows one to simultaneously characterize nondestructively and in 3D the grain shape and crystallographic orientation of a large number of grains in a polycrystalline material. This technique has been implemented at the European Synchrotron Radiation Facility (ESRF) beamline ID19 only very recently and substantial progress in terms of data analysis has led to the reconstruction of 1000 grains in aluminum and steel samples. To date, all diffraction contrast tomography work has been on fully recrystallised and undeformed material due to the limited contrast and diffused diffraction spots when working with material of high mosaicity. The aim of this project is to take DCT to the next level enabling the measurement the development of elastic strain between individual grains during the onset of plastic deformation. This elastic strain develops due to the crystallographic anisotropy of grains and can be used to study deformation mechanisms. Such measurements will be achieved by enhancements of the scanning procedures during DCT experiments and advances in the data analysis routine. The data recorded in this way will for the first time provide grain to grain strain/stress information, which can be used to develop and validate crystal plasticity finite element modeling.
 
Description We have improved our understanding of twinning in hcp metals. We have discovered chains of twins and twins form 3D networks. This information can be used to develop new crystal plasticity models, which will incorporate twinning.
Exploitation Route We might continue working with the ESRF to study deformation in 3D.
Sectors Aerospace, Defence and Marine,Energy,Transport

 
Description Findings will be used by the plasticity and modelling community. Our work has also been outlined in a recent (2016) ESRF highlight report. It is also considered for making the upgrade case of PETRA III to PETRA IV.
First Year Of Impact 2016
Sector Aerospace, Defence and Marine,Energy,Transport
Impact Types Societal,Economic

 
Description ESRF - DCT 
Organisation European Synchrotron Radiation Facility
Country European Union (EU) 
Sector Academic/University 
PI Contribution Research partners on topic of diffraction contrast tomography. Manchester's role was the supervision of PhD student and some mechanical tests, and microscopy.
Collaborator Contribution ESRF provided beam time, space, funding for PhD studentship, and additional on-site supervision.
Impact Publications, and please see additional narrative under other headings of the form.
Start Year 2008
 
Description Rolls-Royce plc 
Organisation Rolls Royce Group Plc
Country United Kingdom 
Sector Private 
Start Year 2007
 
Description TIMET 
Organisation Timet UK Ltd
Country United Kingdom 
Sector Private 
PI Contribution Contribution to R&D
Collaborator Contribution fund PhD students and provide material
Impact better understanding of processing of Ti alloys
Start Year 2010