Microstructural and Mechanical Characterization after Thermomechanical Treatments in 6063 Aluminum Alloy
- 1
- 2
- 3
- 4
Abstract
The aim of this work is the mechanical and microstructural characterization by optical and electron microscopy as well as microhardness of Al 6063 alloy after mechanical and thermal treatment. Al-Mg based alloys have special attention due to the lightness of the material and certain mechanical properties and recyclability. Such alloys produce good mechanical properties in moderate mechanical efforts (up to 700 MPa) and good resistance to the corrosion. Cold rolling steps (30%, 60% and 90% in area reduction) in Al 6063 alloy were employed for the recrystallization studies, followed by thermal treatment using four isothermal heating (423K, 523K, 623K and 723K) during 1800, 3600, 5400 and 7200s. The direct observation and chemical microanalysis were made in a JEOL200C and JEOL2010 transmission electron microscopes combined with mechanical characterization utilizing Vickers microhardness measurements. Normally classified as non-heat-treatable these alloys obtain higher strength either by strain-hardening or by solid solution. The nucleation of new grains is a non stability of the deformed microstructure, depending on subgrain size heterogeneities present as potential embryos in the deformed state adjacent to high local misorientation. The results indicate a significant effect of second-phase particles on recrystallization and how to control the resulting microstructure and texture by the use of particles. It may be a preferential growth in the early stage due to their local environment or a selection of certain orientations from among those produced by particles stimulated nucleation or a preferential nucleation at particles in favored sites such as grain boundaries.
- G. J. Marshall, “Microstructural Control during Processing of Aluminium Canning Alloys,” Journal of Materials Science, 1996, pp. 217-222.
- Metals Handbook, ASM, Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (a), Vol. 2, ed. 9, 1979.
- E. A. Simielli, “The Physical Metallurgy of Aluminum Alloy 6063, VIII Seminar of Non-Ferrous Metals,” S?o Paulo, 1993 (in Portuguese).
- L. P. Troeger and E. A. Starke, “Microstructural and Mechanical Characterization of a Superplastic 6xxx Aluminum Alloy,” Materials Science and Engineering: A, Vol. 277, No. 1, 31 January 2000, Elsevier Science Ltd, pp. 102-113.
- F. J. Humphreys and M. Hatherly, “Recrystallization and Related Annealing Phenomena,” Ed., Elsevier Science Ltd, 1996.
- B. N. Arzamasov, Material Science, chapter 12, Mir Publish Moscow, 1989.
- L. E. Murr, “Interfacial Phenomena in Metals and Alloys,” Addison-Wesley, 1975.
- G. Petzow and V. Carle, “Metallographic Etching,” Ed., American Society for Metals 1978, pp. 41.
- Aluminum Standard and Data—The Aluminum Association, Inc., 9th Edition, July 1988.
- I. M. Esposito, “Characterization and Kinetics of Recrystallization of the 6063 Aluminum Alloy after Ther- momechanical Treatments,” MSc dissertation, 2006, IPEN-USP (S?o Paulo/Brazil (in Portuguese).
- R. D. Doherty and J. A. Szpunar, “Kinetics of Subgrain Coalescence—A Reconsideration of the Theory,” Acta Metallurgica, Vol. 32, 1984, pp. 1789-1798. doi:10.1016/0001-6160(84)90235-9
- A. R. Jones, B. Ralph and N. Hansen, “Subgrain Coalescence and the Nucleation of Recrystallization at Grain Boundaries in Aluminum,” Proceedings of the Royal Society of London, Vol. 368A, 1976, pp. 345-357.
- A. R. Jones, B. Ralph and N. Hansen, “Nucleation of Recrystallization in Aluminium Containing Dispersion of Alumina,” Metal Science, Vol. 13, 1979, pp. 149-154.
- D. A. Hughes and N. Hansen, “High Angle Boundaries and Orientation Distributions at Large Strains,” Scripta Metallurgica et Materialia, Vol. 33, No. 2, 1995. doi:10.1016/0956-716X(95)00143-J
- K. Uttarask, S. Ngernbamrung and N. Sirikulrat, “Microstructures and Mechanical Properties of Heat Treated Aluminium Alloy 6063,” 33nd Congress on Science and Technology of Thailand, 18-20 October, 2007.