The Influence of Work Hardening, Internal Stresses, and Stress Relaxation on Ductility of Ultrafine Grained Materials Prepared by Severe Plastic Deformation

Abstract:

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Ultrafine grained materials prepared by methods of severe plastic deformation appear to show good ductility for their high strength. To a large extent this ductility enhancement, for the given strength, is shown to correspond to the fracture ductility and not the uniform ductility at maximum stress. The improved fracture ductility is often due to the refinement or removal of the coarse defects that act as sites for failure nucleation. The low work hardening rate inherent to the very fine microstructures produced by severe plastic deformation essentially condemns such materials to very low uniform ductility. Stress relaxation occurring during unloading after processing, and changes of internal stresses during reloading for mechanical testing, appear to play a significant role in determining deformation behaviour near the onset of plastic flow, and this can affect the measured uniform strain.

Info:

Periodical:

Materials Science Forum (Volumes 633-634)

Edited by:

Yonghao Zhao and Xiaozhou Liao

Pages:

263-272

DOI:

10.4028/www.scientific.net/MSF.633-634.263

Citation:

D. G. Morris et al., "The Influence of Work Hardening, Internal Stresses, and Stress Relaxation on Ductility of Ultrafine Grained Materials Prepared by Severe Plastic Deformation", Materials Science Forum, Vols. 633-634, pp. 263-272, 2010

Online since:

November 2009

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$35.00

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