Effect of Rolling Temperature and Subsequence Ageing on the Mechanical Properties and Microstructure Evolution of an Al-Cu-Li Alloy

Lin Wang,Alexander Pesin,Charlie Kong,Puneet Tandon,Denis Pustovoytov,Hailiang Yu

doi:10.3390/met11060853

Abstract

The mechanical properties and microstructure evolution of an Al-Cu-Li alloy sheet processed via hot rolling (HR) (at 400 °C and 500 °C) or cryorolling (CR) (at −100 °C and −190 °C) and subsequence aging at 160 °C for 10 h were investigated. Before aging, the highest ultimate tensile strength of 502 MPa was achieved when the sheets were cryorolled at −190 °C, while the better ultimate tensile strength of 476 MPa and the best elongation rate of 11.1% was achieved simultaneously when the sheets were cryorolled at −100 °C. The refined grains and numerous uniform deformation-induced dislocations microstructures were responsible for the improved strength and enhanced ductility of the cryorolled sheets compared to that of the alloy processed by hot rolling with a low dislocation density zone (LDDZ) and high dislocation density zone (HDDZ). After aging at 160 °C for 10 h, the ultimate tensile strength further improved resulted from the greater precipitation strengthening, and the increased precipitates provided greater resistance to dislocations movement resulting in the increased ductility although the dislocation density decreased. The uniform dislocation microstructures in the cryorolled sheets provide numerous nucleation sites for the precipitates, leading to higher strength after aging.

Highlights

Aluminum-copper-lithium (Al-Cu-Li) alloys have been widely used as structural materials for aerospace and aircraft vehicles [1,2,3]
The highest ultimate tensile strength of 549 MPa and the elongation rate of 13.9% was achieved simultaneously when the sheets were processed by CR at −190 ◦ C and subsequence aging for Ultimate tensile stress and elongation vs rolling temperature; (c) Ultimate tensile stress vs rolling temperature after 10 h aging at 160 °C; (d) Engineering strain vs rolling temperature after aging at 160 °C for 10 h
The mechanical properties and microstructure evolution of an Al-Cu-Li alloy processed by CR and hot rolling (HR) were investigated

Summary

Introduction

Aluminum-copper-lithium (Al-Cu-Li) alloys have been widely used as structural materials for aerospace and aircraft vehicles [1,2,3]. A comprehensive review about the development of the third generation Al-Li alloy was reported by Rioja et al [4] and quantitative calculations of the Al-Cu-Li alloy during the deformation process were operated [5]. The alloy is a typical precipitation strengthening alloy resulting from the T1 (Al2 CuLi) or θ0. (Al2 Cu) phases [6]. With the increase of the Cu element, proper heat treatment can further improve the strength via increasing precipitation strengthening [8,9,10]. In the past 30 years, people have developed several severe plastic deformation (SPD)

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Results

Conclusion