| 摘要 |
The invention is a process for simultaneously improving at least two mechanical properties of mill-processed ( alpha + beta ) titanium alloy, which may or may not contain silicon, which includes steps of heat treating the mill-processed titanium alloy such that the ( alpha + beta ) microstructure of said alloy is transformed into an ( alpha + alpha 2+ beta ) microstructure, preferably containing no silicides. The heat treating steps involve subjecting the mill-processed titanium alloy to a sequence of thermomechanical process steps, and the mechanical properties which are simultaneously improved include (a) tensile strength at room, cryogenic, and elevated temperatures; (b) fracture toughness; (c) creep resistance; (d) elastic stiffness; (e) thermal stability; (f) hydrogen embrittlement resistance; (g) fatigue; and (h) cryogenic temperature embrittlement resistance. As a consequence of the process, the ( alpha + alpha 2+ beta ) microstructure contains equiaxed alpha phase strengthened with alpha 2 precipitates coexisting with lamellar alpha-beta phase, where the alpha 2 precipitates are confined totally to the equiaxed primary alpha phase. The invention also encompasses a composition of matter produced by the inventive process, especially one comprising a titanium alloy having an ( alpha + alpha 2+ beta ) microstructure.
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