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A synchrotron X-ray diffraction study of non-proportional strain-path effects

DOI: 10.1016/j.actamat.2016.11.011 DOI Help

Authors: D. M. Collins (University of Oxford) , T. Erinosho (Department of Mechanical Engineering, University of Bristol) , F. P. E. Dunne (Department of Materials, Imperial College London) , R. I. Todd (University of Oxford) , T. Connolley (Diamond Light Source) , M. Mostafavi (Department of Mechanical Engineering, University of Bristol) , H. Kupfer (BMW Group) , A. J. Wilkinson (University of Oxford)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Acta Materialia , VOL 124 , PAGES 290 - 304

State: Published (Approved)
Published: November 2016
Diamond Proposal Number(s): 9333

Open Access Open Access

Abstract: Common alloys used in sheet form can display a significant ductility benefit when they are subjected to certain multiaxial strain paths. This effect has been studied here for a polycrystalline ferritic steel using a combination of Nakajima bulge testing, X-ray diffraction during biaxial testing of cruciform samples and crystal plasticity finite element (CPFE) modelling. Greatest gains in strain to failure were found when subjecting sheets to uniaxial loading followed by balanced biaxial deformation, resulting in a total deformation close to plane-strain. A combined strain of approximately double that of proportional loading was achieved. The evolution of macrostrain, microstrain and texture during non-proportional loading were evaluated by in-situ high energy synchrotron diffraction. The results have demonstrated that the inhomogeneous strain accumulation from non-proportional deformation is strongly dependent on texture and the applied strain-ratio of the first deformation pass. Experimental diffraction evidence is supported by results produced by a novel method of CPFE-derived diffraction simulation. Using constitutive laws selected on the basis of good agreement with measured lattice strain development, the CPFE model demonstrated the capability to replicate ductility gains measured experimentally. © 2016 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY license

Journal Keywords: Synchrotron radiation; X-ray diffraction (XRD); Lattice strain; Texture; Crystal plasticity

Subject Areas: Materials, Engineering

Instruments: I12-JEEP: Joint Engineering, Environmental and Processing


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