Application of equal-channel angular pressing for grain refinement of plate samples

Equal-channel angular pressing (ECAP) was applied to plate samples of pure Al and an Al-1%Mg-0.2%Sc alloy for grain refinement. The plate sample was rotated by 90° in the same sense about the plate normal between each pass, which was designated in this study route B_CZ. Samples were subjected to a total of 4 passes, equivalent to an imposed strain of ∼4. The micro structures were examined using transmission electron microscopy. It was found that the microstructure consisted of equiaxed grains and elongated grains with the former area fractions of-70-80%. The average grain sizes in the equiaxed grain area was ∼0.9 and ∼0.5 μm for pure Al and the Al-1%Mg-0.2%Sc alloy, respectively. The Vickers microhardness was measured on the three orthogonal sections and there was no significant difference throughout each section and between the sections. Tensile tests were conducted at room temperature for pure Al and at 673 K for the Al-1%Mg-0.2%Sc alloy. There was no difference in tensile behavior for the direction of the specimen gauge lengths which were taken parallel to the two orthogonal planes perpendicular to the plate normal. Superplastic ductility of more than 400% was attained in the Al-1%Mg-0.2%Sc alloy.