Article

Design of multistep aging treatments of 2099 (C458) Al-Li alloy

Journal of Materials Engineering and Performance (Impact Factor: 0.92). 01/2005; 14(5):641-646. DOI: 10.1361/105994905X64594

ABSTRACT 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 °C (248 °F) for 12–24 h followed by a second step between 165
and 180 °C (329–356 °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.

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