High temperature behavior of severely deformed AA 5083 through equal channel lateral extrusion

Abstract

Describing the high temperature behavior of a fine-grained AA 5083 aluminum alloy using an improved constitutive model is the focus of this paper. Dual Equal Channel Lateral Extrusion (DECLE) was utilized to create fine-grain microstructure in AA 5083 aluminum alloy. EBSD confirmed the formation of fine-grain microstructure after 5 passes of DECLE. The hot deformation behavior of the DECLEd alloy was assessed by hot compression tests at temperatures of 200–275 °C and strain rates of 10−4-10−1 s−1. The material constants, A, n and Q, in the hyperbolic-sine constitutive equation were calculated at peak stresses. The results suggested that the grain size affects the values of α and n, while the activation energy (Q) is more or less independent of the grain size. The values of α and n for the fine-grain material were obtained as 0.004357 (MPa−1) and 9.97, respectively. These calculated values (α and n) are respectively lower and higher than those reported for a coarse-grain one in the literature. This result was related to the high flow stress of the refined microstructure. The value of Q showed that the dislocation-dispersoid interactions are the rate-controlling mechanism during hot deformation. By iterating the calculation of constants at various strains, a strain-compensated constitutive equation was proposed for the prediction of flow stress over a wide range of strain. Finally, the processing maps were developed for the AA 5083 alloy at various strains.