Abstract
A thermomechanical process for grain refinement in precipitation hardening aluminum alloys is reported. The process includes severe overaging, deformation, and recrystallization steps. Microstructural studies by optical and transmission electron microscopy of grain refinement in 7075 aluminum have revealed that precipitates formed during the overaging step create preferential nucleation sites for recrystallizing grains. The relationship between precipitate density following severe overaging and recrystallized grain density has been investigated; the results show that the localized deformation zones associated with particles larger than about 0.75 μ m can act at preferential nucleation sites for recrystallizing grains. The density of particles capable of producing nucleation sites for new grains is approximately ten times greater than the density of recrystallized grains. A close relationship between dislocation cell size after the deformation step and recrystallized grain density has also been established. Both quantities saturate for rolling reductions larger than approximately 85 pct. The grain size produced in 2.5 mm thick sheet by the optimum processing schedule is approximately 10 μm in longitudinal and long transverse directions and 6 μm in the short transverse direction.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
E. O. Hall:Proc. Phys. Soc. London, 1951, ser. B, vol. 64, pp. 747–53.
N. J. Petch:J. Iron Steel Inst., 1953, vol. 174, pp. 25–28.
R. W. Armstrong:Metall. Trans., 1970, vol. 1, pp. 1169–76.
R. M. Pelloux:Ultrafine-Grain Metals, J. J. Burke and V.Weiss, eds., pp. 231–43, Syracuse University Press, Syracuse, NY, 1970.
T. Kawabata and O. Izumi:J. Mater. Sci., 1978, vol. 13, pp. 945–50.
D. Lee and W. A. Backofen:Trans. TMS-AIME, 1967, vol. 239, pp. 1034–40.
N. E. Paton and C. H. Hamilton:Metall. Trans. A, 1979, vol. 10A, pp. 241–50.
B. M. Watts, M. J. Stowell, B. L. Baikie, and D. G. E. Owen:Metal Sci., 1976, vol. 10, pp. 189–97.
B. M. Watts, M. J. Stowell, B. L. Baikie, and D. G. Owen:Metal Sci., 1976, vol. 10, pp. 198–206.
E. Di Russo, M. Conserva, M. Buratti, and F. Gatto:Mater. Sci. Eng., 1974, vol. 14, pp. 23–36.
J. Waldman, H. Sulinski, and H. Markus:Metall. Trans., 1974, vol. 5, pp. 573–84.
J. Waldman, H. Sulinski, and H. Markus: U.S. Patent 3,847,681, Nov. 12, 1974.
J. Waldman, H. Sulinski, and H. Markus:Aluminum Alloys in the Aircraft Industry, pp. 105–14, Turia, Italy; 1-2 October 1976, Technicopy Ltd., Gloucestershire.
J. Zola, ASTM STP 642, H. L. Craig, Jr., T. W. Crocker and D. W. Hoeppner, eds., pp. 169-88, American Society for Testing and Materials, 1978.
B. K. Park and J. E. Vruggink:Thermomechanical Processing of Aluminum Alloys, T. G. Morris, ed., pp. 25–49, The Metallurgical Society of AIME, Warrendale, PA, 1979.
P. Cotterill and P. R. Mould:Recrystallization and Grain Growth in Metals, pp. 181–249, Surrey University Press, London, 1962.
P. Furrer and H. Warlimont:Aluminum (Düsseldorf), 1978, vol. 54, pp. 135–42.
F. J. Humphreys:Metal Sci., 1979, vol. 13, pp. 136–45.
E. Nes:Metal. Odlew., 1979, vol. 5, pp. 209–24.
F. J. Humphreys:Acta Met., 1977, vol. 15, pp. 1323–44.
N. E. Paton and C. H. Hamilton: U.S. Patent 4,092,181, May 30, 1978.
ASTM El 12-77, vol. 11, pp. 205-37, American Society for Testing and Materials, 1979.
J. R. Porter and F. J. Humphreys:Metal Sci., 1979, vol. 13; pp. 83–88.
E. Nes:Acta Met., 1976, vol. 24, pp. 391–98.
E. Nes:Scr. Met., 1976, vol. 10, pp. 1025–28.
I. L. Dillamore, P. L. Morris, C. J. E. Smith and W. B. Hutchinson:Proc. Roy. Soc. London, 1972, vol. A329, pp. 405–20.
P. R. Mould and P. Cotterill:J. Mater. Sci., 1967, vol. 2, pp. 241–55.
B. Bay and N. Hansen:Metall. Trans. A, 1979, vol. 10A, pp. 179–388.
J. T. Staley: ASTM STP 605, pp. 71-103, American Society for Testing and Materials, 1976.
W. B. Hutchinson and R. K. Ray:Phil. Mag., 1973, vol. 28, p. 953.
H. J. McQueen:Thermomechanical Processing of Aluminum Alloys, J. G. Morris, ed., pp. 1–24, The Metallurgical Society of AIME, Warrendale, PA, 1979.
M. F. Ashby and R. Ebeling:Trans. TMS-AIME, 1966, vol. 236, pp. 1369–1404.
A. H. Bowker and G. J. Lieberman:Engineering Statistics, pp. 56, Prentice-Hall, Inc., Englewood Cliffs, NJ, 1959.
G. E. Dieter, Jr.:Mechanical Metallurgy, p. 66, McGraw-Hill Book Co., New York, 1961.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Wert, J.A., Paton, N.E., Hamilton, C.H. et al. Grain refinement in 7075 aluminum by thermomechanical processing. Metall Trans A 12, 1267–1276 (1981). https://doi.org/10.1007/BF02642340
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02642340