Texture evolution during dynamic recrystallization in a magnesium alloy at 450 °C

During thermomechanical processing of wrought magnesium alloys, the microstructure and texture continue to evolve as dynamic recrystallization (DRX) proceeds. New grains generated by DRX with a low dislocation density also participate in the texture evolution as the strain increases. However, the controlling mechanisms that drive the evolution are not yet understood. In this work, we studied texture evolution in an extruded Mg-Al-Mn alloy (AM30) during uniaxial compression at 450 degrees C and under various strain rates (epsilon < 1.0 s(-1)). The tests were performed along the extrusion direction (ED) and the radial direction (RaD), respectively. Texture evolution was examined by electron backscatter diffraction and X-ray diffraction at different strains. At epsilon <0.1 s(-1), the effect of twinning was negligible. At epsilon = 0.5 s(-1), a high volume fraction of twins were activated but the twins were consumed by DRX as the strain increased. At epsilon = 0.8 s(-1), twins were not completely consumed by DRX, and the remaining twins had highly incoherent twin boundaries and contributed to the texture. In compression along the ED and with strain rates of <= 0.5 s(-1), prismatic slip dominated the texture evolution, and the final orientations clustered around 10 (1) over bar0 parallel to ED and 2 (1) over bar(1) over bar0 parallel to ED, resulting in two stable orientations with a 30 degrees misorientation. At 0.8 s(-1), basal and pyramidal slip began to dominate the texture evolution at larger strain. In compression along the RaD, basal and pyramidal slip dominated the texture evolution, creating a texture located near 1 0 (1) over bar 2 - 1 0 (1) over bar5 - 2 (1) over bar(1) over bar9 - 2 (1) over bar(1) over bar 5 and 1 0 (1) over bar 0 - 2 (1) over bar (1) over bar0 in the inverse pole figure. Texture simulations based on the Sachs and the viscoplastic self-consistent models show a satisfactory correlation between texture evolution and deformation modes. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.