Effect of Multidirectional Forging and Subsequent Annealing to the Microstructure of Al-Mg-Mn Type Alloy

Abstract

The grain refinement is important to improve both service properties at room temperature and superplasticity at elevated temperatures. This study focuses on the effect of multidirectional forging in isothermal conditions on the microstructure of Al-Mg-Mn-type alloy. The evolution of dislocation and grain structure, and precipitates of Mn-rich phase during multidirectional forging in a temperature range of 200 to 500 °C was studied. Multidirectional forging at temperatures of 200 and 300 °C leads to the formation of shear bands in the deformed grains. The multidirectional forging at 400 and 500 °C leads to the formation of a bimodal grain structure with fine- and coarse-grained areas. Subsequent recrystallization annealing at 500 °C increases the grain size and decreases the fine grains fraction in the samples pre-deformed at 400-500°C, and, on the contrary, annealing leads to formation homogeneous and fine grain structure with size up to 6.5 μm in samples pre-deformed at 200 and 300 °C.