Extra strengthening and superplasticity of ultrafine-grained A2024 alloy produced by high-pressure sliding

Abstract

In this study, the method of high-pressure sliding (HPS) was applied for grain refinement of an A2024 alloy. Sheet samples with 10-15 mm width and 100 mm length with 1 mm thickness were processed by HPS under pressures of 2-3 GPa. Microstructural observations revealed that the grain size was refined to ∼200 nm. Tensile tests showed that the ultimate tensile strength reached 886 MPa with a total elongation of 7.1% and the anisotropy of samples was less developed in the HPS-processed samples. Extra strengthening was attained by aging at 423 K after HPS processing, leading to an ultimate tensile strength of 967 MPa at the peak aged condition. Superplastic elongation of more than 400% appeared when the A2024 alloy processed by HPS for 20 mm was deformed in tension at a testing temperature of 623 K with an initial strain rate of 1.0×10-3 s-1.