Mechanical properties of the solution treated and quenched Al–Cu–Li alloy (AA2195) sheet during high strain rate deformation at room temperature

Abstract

In this paper, mechanical properties of the solution treated and quenched Al–Cu–Li alloy (AA2195) sheet were obtained by means of quasi-static tensile tests and split Hopkinson bars tests at room temperature. The mechanical properties results showed that the break elongations were 32.3%, 43.2%, 59.4% corresponding to the strain rates of 2000 s−1, 3500 s−1 and 4500 s−1, which was 18.6% at the strain rate of 0.001 s−1. With the increase of strain rate, the yield strength increased gradually and reached 302 MPa at the strain rate of 4500 s−1, which was 150 MPa at the strain rate of 0.001 s−1. The tensile strength were 341 MPa, 360 MPa, 369 MPa corresponding to the strain rates of 2000 s−1, 3500 s−1 and 4500 s−1, which was 359 MPa at the strain rate of 0.001 s−1. Significant thermal softening behaviors were observed with the softening ratio increased from 1.4% to 23.3% when the strain rate ranged from 0.001 s−1 to 4500 s−1, resulting in an increasing break elongation and a little change in ultimate tensile strength. Microstructure characteristics, including the crystallographic orientation distribution of grains and the average Schmid factor, were observed by electron backscattering diffraction (EBSD) under the condition of the same elongation with different strain rates, revealing the reasons of the plastic improvements during high strain rate deformation. The crystallographic orientation distribution of grains showed that an evident <001>-orientation was observed at the strain rate of 0.001 s−1, which was not changed obviously at the strain rate of 2000 s−1 under the same elongation. The average Schmid factor was 0.436 at the strain rate of 0.001 s−1, which was 0.462 at the strain rate of 2000 s−1 under the same elongation.