Severe Deformation of a Carbon Steel within the Ferritic Region
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Published:2008-06
Issue:
Volume:584-586
Page:667-672
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ISSN:1662-9752
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Container-title:Materials Science Forum
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language:
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Short-container-title:MSF
Affiliation:
1. Sahand University of Technology
Abstract
The influence of severe warm deformation on the microstructural evolution and flow behavior of a
plain carbon steel has been investigated through torsion testing. The specimens were severe
deformed within the ferritic region up to strain of 70 with constant strain rate of 0.1 s 1 − .
Microstructural evolutions have been investigated using high resolution electron backscatter
diffraction (EBSD). True stress-true strain curves exhibit a single and smooth maximum, followed
by a slow but significant softening stage. A steady state is observed at very large strains. This
finding suggests that the relative balance between comparable work hardening and dynamic work
softening results in the occurrence of warm ductility during large deformation. The initial grain
structure was equiaxed, but at low strains the grains become elongated in the torsion direction.
However, at large strains the grain aspect ratio decreases and finally, further straining leads to the
formation of new fine grains with high-angle boundaries, which become more equiaxed than the
previous fragmented structure. The flow stress, as well as all the average microstructural
parameters, then remains independent of strain. The mechanisms operating during such warm flow
behavior and structure changes are discussed in detail.
Publisher
Trans Tech Publications, Ltd.
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science