Structure and Anisotropy of the Mechanical Properties of Hot- and Cold-Rolled Semi-Finished Products from Aluminium-Lithium Alloys

Research of structure and anisotropy of the mechanical properties of hot-and cold-rolled semi-finished products from Al-Mg-Li (1420 and 1424) and Al-Cu-Li (V-1461) alloys was conducted. Semi-finished products were made in industrial conditions by standard technologies. During the tension test ultimate strength, yield stress, elongation and coefficients of lateral strain in three directions (at 0°, 45° and 90° angles to the rolling direction) were determined in order to study the planar anisotropy. It was established that the main characteristic inherent to both the first generation of aluminium-lithium alloys (1420) and the subsequent ones (1424, V-1461) is a pronounced anisotropy of the mechanical properties including the characteristics of plastic strain. At the same time, as for most aluminium alloys, aluminium-lithium alloys are characterized by low values of the lateral strain coefficients. It leads to a number of negative consequences in the subsequent forming: distortion and dimensions alteration of parts, limitation of formability, metal losses due to overestimation of thickness and dimensions of blanks, weight increase of the construction.