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Dissertation
Strain hardening at large strains in aluminum alloys
Doctor of Philosophy (Ph.D.), Drexel University
1988
DOI:
https://doi.org/10.17918/00010072
Abstract
The strain hardening properties of high purity Al, commercial purity Al, Al-Mn, Al-Mg and Al-Cu alloys have been investigated at large strains in the temperature range 77-473K. Torsion of short thin walled cylinders was chosen as the deformation method because large strains can be achieved without such problems as friction and redundant work. The results of the tests indicated that the stage of strain hardening known as Stage IV occurs even in pure face centered metals in torsion. The term Stage IV is derived from studies of single crystal plasticity and is the nearly constant hardening rate observed at large strains in many metals. The hardening rate in Stage IV is approximately 2.10-4 where the hardening rate has been reduced by the shear modulus and a Taylor factor in order to put it in terms of critical resolved shear stresses on a single slip system. A plot of hardening rate versus stress characteristically shows a sharp transition from steadily decreasing hardening rate in Stage III to constant Stage IV. Stage IV does not appear at high homologous temperatures. Alloying generally extends the occurrence of Stage IV to higher temperatures than in pure metals. A model has been developed that is based on the accumulation of dislocation debris such as dipoles and prismatic loops. This model is able to account for the characteristics of Stage IV, such as the sharp transition observed on a plot of hardening rate versus stress.
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Details
- Title
- Strain hardening at large strains in aluminum alloys
- Creators
- Anthony David Rollett
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xxii, 343 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Materials (Science and) Engineering (Metallurgical Engineering) [Historical]; College of Engineering (1970-2026); Drexel University
- Other Identifier
- 991021889073004721