UBC Theses and Dissertations
Analysis of the steady state hot deformation of aluminum Barclay, George Allan
It has been suggested by others that hot working is an extension of high temperature creep because of the similar observed dependencies of stress, strain rate, temperature and the similar activation energies of the two types of deformation. This suggestion has been evaluated for commercial purity aluminum by obtaining stress, strain rate and temperature data in the strain rate range 10⁻⁴ to 10¹/second. Published hot compression, hot torsion, and high temperature creep work of others is used to provide supplementary data. A combination of the published work of others with the present experimental work provides data in the strain rate range 10⁻⁷ to 10⁺²/second. From the present analysis, contradictions arise against the theory that hot working is an extension of high temperature creep. First, the method of evaluation of the material constant α in the hyperbolic stress-strain rate relation, [formula omitted], must change in going from creep to hot working. Secondly, the activation energy varies. Those that have suggested that hot working is an extension of high temperature creep found that α and the activation energy were independent of strain rate. Their work is compared to the present analysis and many discrepancies were found. The work in the literature left a data gap in the strain rate range 10⁻³ to 10⁰/second. Hot tensile tests and hot rolling tests were used to provide data in this gap.
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