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 degrees 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 T-1 (Al2CuLi) phase after a period of aging. After pre-rolling, the nucleation of T-1 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 T-1 phase. Furthermore, the precipitation kinetics of the T-1 phase was continually accelerated by increasing the pre-stain, which facilitated the more rapid aging response, higher T-1 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 T-6 tempered. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

Pre-rolling deformation is more effective than pre-stretching in improving the performance of rolled Al-Cu-Li plates. The pre-rolling process promotes nucleation of the T-1 phase, inhibits formation of other phases, accelerates precipitation kinetics, and enhances mechanical properties. Increasing pre-strain can lead to higher T-1 phase density and improved aging response in Al-Cu-Li alloys.