On determining the internal stress using Hall-Petch data

Accurate evaluation of σ μ , the internal stress, is essential for determining σ ∗ , the effective stress, because experimental yield stress data yield only the sum of σ ∗ and σ μ . In the past, the most popular method of determining σ μ has been the back extrapolation technique which assumes that σ...

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Bibliographic Details
Published in:Scripta materialia 1997-06, Vol.36 (12), p.1361-1366
Main Authors: Reed-Hill, R.E., Iswaran, C.V., Kaufman, M.J.
Format: Article
Language:English
Subjects:
Applied sciences
Cross-disciplinary physics: materials science
rheology
Elasticity and anelasticity
Elasticity and anelasticity, stress-strain relations
Exact sciences and technology
Materials science
Metals. Metallurgy
Physics
Treatment of materials and its effects on microstructure and properties
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Summary:Accurate evaluation of σ μ , the internal stress, is essential for determining σ ∗ , the effective stress, because experimental yield stress data yield only the sum of σ ∗ and σ μ . In the past, the most popular method of determining σ μ has been the back extrapolation technique which assumes that σ ∗ = 0 at the flow stress plateau of a constant strain rate σ vs. T plot, so that in this region σ = σ μ . Back extrapolating this σ μ to absolute zero while giving it the temperature dependence of the shear modulus was then assumed to determine σ μ at temperatures below the plateau. This technique has been shown to seriously overestimate σ μ and underestimate σ ∗ and it has been shown that σ μ may be measured more accurately [1,2,3] using strain rate sensitivity data. However, strain rate sensitivity data at sub-ambient temperatures are very difficult to obtain accurately. This paper discusses another possible method for measuring σ μ based on Hall-Petch data, which appears to be much easier to use and of still greater accuracy.
ISSN:1359-6462
1872-8456
DOI:10.1016/S1359-6462(97)00050-X