SUPERPLASTIC BEHAVIOUR IN DYNAMICALLY RECRYSTALLISING ALUMINIUM ALLOYS
الملخص
Aluminium alloys can be thermomechanically processed to develop the grain fine microstructures required for superplasticity by either static recrystallisation prior to superplastic forming (SPF) or by dynamic recrystallisation during the early stages of deformation. The present work has examined and compared the superplastic behaviour and the microstructural evolution in Al-Li alloys (8090) sheet material processed by the second route for a wide range of temperatures and strain-rates. It was observed that the material showed a high potential for superplastic flow. Although significant superplasticity was observed at temperature of 400°C and below. The reasons for the high resistance of the material to strain localisation are discussed. It was noted that ductility enhancement could also be achieved by the control of the strain-rate path. A rapid pre-strain improved significantly the subsequent superplastic elongation to failure at optimum strain rate. Further enhancement has been obtained by pre-straining at constant velocity following by deformation to failure at lower constant velocity. The microstructure changes prior or during deformation were also examined.التنزيلات
المراجع
- Noble B., Harris S.J., Dinsdale K., J. Mat. Sci., 17 (1982), p 461.
- Dinsdale K., Harris S.J. and Noble B., Proc. 1st Int. Al-Li Conf., New York. TMS-AIME, Ed. T.H. Sanders Jr. and Sarke Jr, (1981), p.461.
- Miller W.S., Cornish A. J., Titchener A.P. and Bennet D.A., Proc. 2nd Int. Al-Li Conf., Montery, CA, TMS-AIME, Ed. T. H. Sanders Jr. and E. A. Starke, Jr, (1983), p.335.
- Papazian J.M., Bott G.C. and Show P., Mater. Sci. Eng., 94 (1987), p.219.
- Ash B.A. and Hamilton C.H., Scripta. Metall., N°22 (1988), p.277.
- Geary B., Pilling J. and Ridley N., Superplasticity in Aerospace Aluminium, Ed. R. Pearce and L. Kelly, (Cranfield, UK, SIS) (1985), p.127.
- Ghosh A.K. and Gandhi C., Pro. ICSMA-7, Ed. H. Mc Queen et al, Oxford, Pergamon Press (1986), p.2065.
- Grimes R., Superplasticity, Ed. B. Baudelet and M. Suery, Paris, CNRS (1985), p.13. 1.
- Amichi R. and Ridley N., Proc. 5th Int. Al-Li. Conf. Ed. T.H. Sanders and E.A. Starke (Birmingham, UK, MCEP (1989), p.159.
- Hales S.J. and Mc. Nelley T.R., Acta. Metall. 36, 5 (1988), p.1229.
- Avramovic G., Gara C.N., Perovic D.D. and H.J.Mc Queen, Metall. Mater. Trans., 27a (1996), p.3478.
- Gullun E.M., Humphreys F.J. and Ridley N., 16th Int. Symp. Mat. Scien., Ed. H. Hansen et al. (1995), p.309.
- Gudmundsson H., Brooks D. and Wert J.A., Acta Metall. Mater., 39, 1 (1991), p.19.
- Liu Quing, Huang Xioxu, Yao Mel and Yang Jinfeng , Acta. Metall. Mater., 40, 7 (1992), p.1753.
- Nai A. et al, J. Appli. Mech., A77 (1941), p.980.
- Nikeev N.U.E., Int. Pro. Conf. in Superpastticity in Advanced Materials, ICSAM, India, Ed. Atul. H. Chokshi. V 243-245 (1997), p.77.
- Gosh A.K. and Hamilton C.H., Metall. Trans., 10A (1979), p.699.
- Nichols F.A., Acta. Metall. 28 (1980), p.663.
- Ahmed M.I. and Langdon T.G., J. Mat. Sci., 18 (1983), p. 3535.
- Caceras C.H. and Wilkinson D.S., Acta. Metall., 32 (1984), p.415.
- Hart E.W., Acta. Metall., 15 (1980), p.663.
- Nichols F.A., Acta. Metall., 28 (1988), p.31.
- Pilling J. and Ridley N., Res. Mechan., 23 (1988), p.31.
- Piu H.P. and Huang J.C., Scripta. Metall. Mater., 28 (1993), p.1125.
- Ricks R.A. and Parson N.C., Proc. 5th Int. Al-Li. Conf. Ed. T.H. Sanders and E.A. Starke (Birmingham, UK, MCEP (1989), p.169.
- Bricknell R.H. and Edington J.W.. Metall. Trans. 10A (1979), p.1257.
- Pilling J. et Ridley N., Res. Mechan., 23 (1988), p.823.
- Matsuki, K. Minami, Kizawa M., and Mwakami Y., Met. Scien., (1977), p.156.
- Nes E., Superplasticity, Ed. B. Baudelet and M. Suery, Paris, CNRS (1985), p.7. 1.
- Mukherje A.K., Mater. Sci. Eng., 8 (1971), p.83.
- Ridley N. and Amichi R., The 4th Int. Conf. On Aluminium Alloys Atlanta, GA. Ed.2, T.H. Sanders and E.A. Starke, Jr., Vol. II (1994), p.274.
- Matsuki, K. Minami, Kizawa M., and Mwakami Y., Met. Sci. (1979), p.619.
