Grain refinement in hot working of 2219 aluminium alloy: On the effect of deformation mode and loading path

Abstract

To study the effect of deformation mode together with loading path on the microstructure evolution of 2219 aluminium alloy at elevated temperature, plane strain compression (PSC) and uniaxial compression (UC) along different loading paths (rolling direction (RD), transverse direction (TD) and normal direction (ND)) as well as equal-channel angular pressing (ECAP) along RD were performed on the cubic and cylindrical samples cut from thick plate. Detailed microstructure evolution was characterized by optical microscope and electron backscattered diffraction (EBSD). The results indicate that the PSC deformation shows a higher stress level than UC and an increasing discrepancy in flow softening occurs with the increasing strain during PSC along different loading paths. The volume fraction of dynamic recrystallization (DRX) after RD-UC is higher than that of RD-PSC, while the grain refinement level is the lowest in the one pass ECAP. DRX is the main grain refinement mechanism for RD-UC, while deformation bands (DBs) are dominant in RD-PSC and ECAP. Due to the grain morphology anisotropy, a significant microstructural difference was exhibited in the PSCed samples along different loading paths. The grain refinement in hot working of 2219 aluminium alloy plate is greatly related to the deformation modes and loading paths in view of the brick-like grains.