Effect of asymmetric rolling and subsequent ageing on the microstructure, texture and mechanical properties of the Al-Cu-Li alloy

Abstract

Abstract The influence of asymmetric cold rolling (ASR) and subsequent ageing on microstructures and mechanical properties of the Al–Cu–Li alloy was investigated systematically in this work. Both the hardness and yield strength increased with the asymmetric cold rolling degree. The peak hardness, yield strength and ultimate tensile strength of aged samples increased from 138 HV, 380 MPa, 430 MPa of the conventional hot rolled sheet (CHR) to 162 HV, 420 MPa and 480 MPa of 90% ASR sheet (ACR90), respectively, while the elongation keeps near 10%. The grain size decreased and the recrystallization degree increased with the asymmetric rolling degree. Textures of four rolled sheets, such as solid solute of conventional hot rolled sheet (CHR), conventional cold rolling with reduction of 50% (CCR50), asymmetric cold rolling with reduction of 50% and 90% (ACR50 and ACR90) were mainly Copper, S, and Brass types along the β fiber. In particular, volume fractions of textures were different, and CCR50, ACR50, ACR90 samples had similar average Taylor factors (M), which was lower than the CHR sample. The number density and the average diameter of T1 precipitates in matrix increased with the ASR degree. The CHR sample with higher average M value in the tensile direction at room temperature can sufficiently compensates for the loss of strengthening due to less precipitates as compared with the CCR50 sample. The strength of two ASR samples is higher than the CHR sample due to the coupling effect of textures and precipitation strengthening.