Influence of Forging Temperature on the Microstructures and Mechanical Properties of a Multi-Directionally Forged Al-Cu-Li Alloy

Optimization of forging process to improve the microstructure and mechanical properties of 2195 Al-Cu-Li alloy forgings is an urgent issue. In this study, a homogenized 2195 alloy ingot was subjected to multi-directional forging (MDF), annealing, and forging at 500 degrees C, 420 degrees C, and 240 degrees C with a 50% reduction in cross-sectional area, followed by a T8 heat treatment (involving solution, quenching, cold compression, and aging). The microstructural evolution during the process and the final mechanical properties in three orthogonal directions were examined. The results showed that the grain structures of the alloy were significantly refined after MDF by dynamic recrystallization (DRX), but the structure was thermally unstable and formed coarse grains during subsequent annealing by static recrystallization (SRX). The T8-treated samples forged at 500 degrees C, 420 degrees C, and 240 degrees C obtained fine and uniform grain structures by DRX, inhomogeneous grain structures by partial SRX, and uniform, equiaxed grain structures by full SRX, respectively. The average grain size of the forging increased with decreasing forging temperature because more significant SRX occurred for the forging that was deformed at lower temperatures. The grain structures had minimal influence on precipitation behavior and strength but had a significant influence on elongation. The fine and uniform grain structures improved the elongation; whereas, the inhomogeneous grain structures, which contained extremely large grains, significantly deteriorated the elongation. The uniform, equiaxed grain structures decreased the anisotropy in three orthogonal directions and maintained fine elongation even though the average grain size of the forging was the largest. Graphic Abstract