Constitutive equations for the superplastic behaviour of titanium and aluminium aerospace alloys have been presented and computational procedures developed for the determination of the material parameters arising in the equations. The behaviour of the titanium alloy Ti-6Al-4V and the aluminium alloys Al-Zn-Mg and Al-Mg, has been modelled to validate the constitutive equations. Excellent agreement between experimental data and computed results has been achieved. A semi-analytical method for the determination of strain rate sensitivity has been presented. The model correctly represents the dependence of the strain rate sensitivity on strain, strain rate, and grain growth and therefore provides useful information for process design and optimization, in particular, because of the strong dependence of ductility on strain rate sensitivity. The model has been validated by comparisons of predictions with experimental data. Two standard experimental testing methods for the determination of strain rate sensitivity have been appraised using the models. It has been shown that errors in strain rate can lead to considerable errors in the determination of strain rate sensitivity in using the strain rate jump test. The problem arises because in the jump test, the errors in strain rate can be of the same order as the strain rate jump. In these circumstances, constant strain rate tests are likely to provide better estimates of strain rate sensitivity.
Determination of superplastic constitutive equations and strain rate sensitivities for aerospace alloys
Bestimmung der superplastischen Materialgleichungen und Dehnungsgeschwindigkeits-Empfindlichkeiten für Luft- und Raumfahrt-Legierungen
1997
14 Seiten, 12 Bilder, 1 Tabelle, 20 Quellen
Article (Journal)
English
SAGE Publications | 1997
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