Abstract
The plastic instability and necking behavior of AA8079 aluminum alloy sheet has been investigated in temper-annealed and fully annealed conditions. The approach taken was largely phenomenological; the description of the instability was based on macroscopic material properties, such as total elongation, strain-hardening, and strain-rate hardening exponents. A decrease in ductility resulting from strain localization was observed for the materials in the temper-annealed conditions. For the high-temperature annealed materials, however, necking occurred after significant plastic deformation. The relationship between post-uniform deformation, as a measure of diffuse necking, and material formability indexes (m and n) was established.
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Abbreviations
- F/Fmax :
-
Rate of loss of load-carrying ability
- H:
-
Homogenized conditions
- K:
-
Strain-hardening coefficient
- m:
-
Strain-rate sensitivity index
- n:
-
Strain-hardening exponent
- PUE:
-
Post-uniform elongation
- U:
-
Unhomogenized conditions
- Δɛ*:
-
Quasistable flow increment
- ɛ:
-
True strain
- ɛLI :
-
Load instability strain
- ɛLN :
-
Localized necking strain
- ɛPIC :
-
Pressure instability strain
- ɛt :
-
True thickness strain at pressure instability in bulge test
- ɛo :
-
Strain rate
- σ:
-
True stress
- σt :
-
True stress at pressure instability
- dσ/dɛ:
-
Strain-hardening rate
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M. Aghaie-Khafri earned his M.Sc. in materials engineering at Tehran University in 1996. He is currently a Ph.D. student at that university.
R. Mahmudi earned his Ph.D. in metallurgy and materials engineering at the University of Birmingham in 1987. He is currently an associate professor at Tehran University.
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Aghaie-Khafri, M., Mahmudi, R. Flow localization and plastic instability during the tensile deformation of al alloy sheet. JOM 50, 50–52 (1998). https://doi.org/10.1007/s11837-998-0287-5
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DOI: https://doi.org/10.1007/s11837-998-0287-5