Investigation into the Formation of Texture, Microstructure, and Anisotropy of Properties during Rolling Sheets of the Aluminum–Lithium 1420 Alloy

Abstract

Results of investigations into the formation of the crystallographic orientation of the structure and anisotropy of properties during rolling sheets of the aluminum–lithium 1420 alloy of the Al–Mg–Li system are given. Hot-rolled billets of the 1420 alloy were cold-rolled with intermediate quenching according to the following schedule: 7.3 mm → 4.8 mm → 3.0 mm → 1.8 mm. The samples were selected after each passage to perform mechanical testing and analyze the structure using optical microscopy and diffractometry. A deformed fibrous structure and considerable anisotropy of mechanical properties is characteristic of sheets of all considered states. Herewith, the maximal plasticity is observed at an angle of 45° to the rolling direction. The character of anisotropy of properties formed at the hot-rolling stage is not varied during cold rolling. Sheets of the 1420 alloy have a sharp deformation texture at all rolling stages due to the conservation of the unrecrystallized structure. For example, when analyzing pole figures and preferential orientations, an increase in volume fractions of rolling texture is revealed (the slow one of the brass type and more rapid of the S type) with the rise of summary deformations of cold rolling. The recrystallization texture (of the R type) is present in small amounts only after hot rolling. The volume fraction of the texture-free component decreases with an increase in summary deformations. It is concluded based on these results that, in order to decrease the fraction of the deformation texture and lower anisotropy of properties in sheets of the 1420 alloy, it is first and foremost necessary to provide the running of recrystallization at the hot-rolling stage in order to fabricate the recrystallized hot-rolled billet for subsequent cold rolling.