The experimental study on plastic flow and anisotropic properties of the new generation Aluminum Lithium alloy sheet

This study is to investigate the formability of a new generation Al-Li-Cu-Mg alloy sheet through uniaxial tensile tests. The yield strength, tensile strength, elongation rate of seven different orientations of the sheet material were obtained. The tension curves of different orientations were plotted and compared to work out the anisotropic index. The constitutive equation of this new Al-Li-Cu-Mg alloy was established on the basis of the tensile test data. The characteristic parameters in Hill48 and Barlat89 yield criteria were calculated through the experiment curves and the yield locus of this Al-Li-Cu-Mg alloy was also obtained. Then, the characteristics of the anisotropic behavior of this alloy during the forming process were analyzed on the basis of the First Strength Theory and the Third Strength Theory. In the end, the cross section of fractured specimens were observed using Scanning Electron Microscopy (SEM) and the results indicated that, if the elongation rate increases, the population of dimples increases correspondingly, in the contrary, if the elongation rate decreases, more fracture belt were observed. The different features of the fracture along different orientations confirm the significant anisotropy of the material.