Multistep artificial aging treatments coupled with various natural aging times for aluminum lithium 2099 alloy (previously called C458) are discussed to obtain mechanical tensile properties in the T6 condition that match those in the T861 condition, having a yield strength in the range of 414-490 MPa (60-71 ksi), an ultimate strength in the range of 496-538 MPa (72-78 ksi), and 10-13% elongation. Yield and ultimate tensile strengths from 90-100% of the strength of the as-received material (in the T861 condition) were obtained. The highest tensile strengths were consistently obtained with two-step, low-to-high temperature artificial aging treatments consisting of a first step at 120 degrees C (248 degrees F) for 12-24 h followed by a second step between 165 and 180 degrees C (329-356 degrees F) for 48-100 h. These T6-type heat treatments produced average yield and ultimate strengths in the longitudinal direction in the range of 428-472 MPa (62.1-68.5 ksi) and 487-523 MPa (70.6-75.9 ksi), respectively, as well as lower yield strength anisotropy when compared with the as-received material in the T861 condition.
Copyright 2005 ASM International. This paper was published in Journal of Materials Engineering and Performance, Volume 14, Issue 5, pp. 641-646 and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial pruposes, or modification of the content of this paper are prohibited. Available on publisher's site at http://www.springerlink.com/content/6j033262043x8124/.
Romios, M., Tiraschi, R., Parrish, C., Babel, H.W., Ogren, J.R., and Es-Said, O.S., 2005, "Design of Multistep Aging Treatments of 2099 (C458) Al-Li Alloy," Journal of Materials Engineering and Performance, 14(5), pp. 641-646.