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Superplastic Forming Characteristics and Microstructural Development of an Aluminium Lithium Alloy (8090)

Published online by Cambridge University Press:  16 February 2011

G. J. Mahon ,
R. Keyte ,
N. C. Parson  and
R. A. Ricks
G. J. Mahon
Affiliation:
Alcan International Ltd., Southam Road, Banbury, Oxon OX16 7SP, England.
R. Keyte
Affiliation:
Alcan International Ltd., Southam Road, Banbury, Oxon OX16 7SP, England.
N. C. Parson
Affiliation:
Alcan International Ltd., Southam Road, Banbury, Oxon OX16 7SP, England.
R. A. Ricks
Affiliation:
Alcan International Ltd., Southam Road, Banbury, Oxon OX16 7SP, England.
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Abstract

Superplastic testing of the aluminium-lithium alloy 8090 has been performed in the temperature range 485°C to 550°C. Up to 530°C, raising the test temperature has the effect of increasing the m-value and decreasing the flow stress. Changes in superplastic forming characteristics and microstructure have been followed during straining using a variety of techniques. Jump-strain rate testing reveals that in the optimum temperature range (515°C to 525°C).there is a steady decrease in m-value. Cavitation also occurs, but can be suppressed effectively by applying a hydrostatic pressure during testing. Raising the test temperature above this optimum range to 550°C produces a significant decrease in the m-value and a more rapid fall-off with strain. These observations are explained in terms of recrystallisation and grain growth, and the effectiveness of precipitates in pinning grain boundaries at the various temperatures.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 196: Symposium T – Superplasticity in Metals, Ceramics, and Intermetallics , 1990 , 155
Copyright
Copyright © Materials Research Society 1990

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References

REFERENCES

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