The cryogenic mechanical properties of Vintage III 2090 T81

This paper reports on the cryogenic mechanical properties of a 12.7 mm (0.5 in) Vintage III 2090-T81 (Al-3.05Cu-2.16Li-0.11Zr by weight) plate material were studied. The results indicate that both the through-thickness anisotropy and in-plane anisotropy in the yield strength of Vintage I 2090-T81 is reduced in the Vintage III material by utilizing a partial recrystallization step during the thermal mechanical processing, but at some cost to the elongation and cryogenic fracture toughness. Sharp discontinuities in the microstructure which result from this thermal-mechanical treatment give rise to distinct differences in the variation of the work hardening behavior with temperature between those regions which undergo recrystallization and those which do not. The lower elongations are a result of an overall decrease in slip homogeneity and subsequent work hardening ability while the reduced cyrogenic toughness may be due in part by the disruption of the monolithic unrecrystallized grain structure previously observed in Vintage I 2090-T81. The dependence between the various microstructures and the corresponding mechanical behavior suggest that a fully unrecrystallized structure is required for good cryogenic toughness