Microstructure and texture control of Al-Mg alloy sheets by differential speed rolling

Large shear deformation was successfully introduced in 5182 aluminum alloy sheets by 2-pass differential speed warm rolling under a high friction condition. The roll speed ratio was varied from 1.0 to 2.0. When the roll speed ratio was smaller than 1.4, shear strain increased near the surface, but the strain decreased to zero at the mid-thickness. At a roll speed ratio larger than 1.4, shear strain was introduced even at the mid-thickness, and it increased near the surface. Thus the shear strain increased with the roll speed ratio. After 2-pass differential speed rolling, a large shear strain prevailed throughout the thickness. The rolling direction of the second pass was so selected that the direction of shear deformation introduced in the second pass was similar to (unidirectional shear rolling) or opposite (reverse shear rolling) that in the first pass. A shear texture with main components of {111)< 110 >, 1112)< 110 > and {001)< 110 > prevailed throughout the thickness, and conventional rolling textures such as {112} < 111 > or {123}< 634 > orientation were not detected in any part of thickness. The rolling direction of the second pass had little effect on the deformation texture. After recrystallization annealing, the shear texture components were retained. The intensity of the shear texture components after recrystallization was almost similar to the deformation texture. The r-value of the annealed sheet was slightly increased and the planar anisotropy of the r-value was decreased by differential speed rolling. Differential speed rolling, by which shear deformation can be introduced throughout the thickness, was thus shown to be a promising process for improving the physical and mechanical properties of rolled and annealed aluminum alloy sheets by texture control.