Influences of pre-rolling deformation on aging precipitates and mechanical properties for a novel Al–Cu–Li alloy

Pre-rolling deformation is a preferable procedure in practice, compared to pre-stretching, to improve the performances of the rolled Al–Cu–Li plates. In the present work, the different strains of pre-rolling were applied to a rolled Al–Cu–Li alloys before aging. The influence of pre-rolling on mechanical properties and precipitates during 200 °C aging was carefully investigated through hardness test, tensile test, and microstructure characterization. It was found that the aging precipitation behavior was rather complicated for the not pre-rolled samples, various abnormal precipitates were precipitated along with the large diameter and low-density of T1 (Al2CuLi) phase after a period of aging. After pre-rolling, the nucleation of T1 phase was greatly promoted while the formation of other phases was inhibited, resulting in the precipitation behavior became dominated by the high density and tiny T1 phase. Furthermore, the precipitation kinetics of the T1 phase was continually accelerated by increasing the pre-stain, which facilitated the more rapid aging response, higher T1 phase density and continuous improvement of mechanical properties. The strain of pre-rolling could be increased to 20% to obtain the optimal properties, and the tensile strength of the 20% pre-rolled samples increased to ∼520 MPa in peak aged state, compared to ∼360 MPa of the samples only T6 tempered.