Evolution of microstructure and crystallographic texture in α-β Brass during equal channel angular pressing

Two-phase alpha-beta Brass was severe plastically deformed by equal channel angular pressing using route A up to four passes at 330 degrees C. The microstructure and crystallographic texture evolution were investigated for the alpha-FCC and beta-Ordered B2 phase individually to understand their underlying deformation mechanism. Microstructural analysis reveals a decrease in the average grain size in both alpha- and beta- phases from similar to 7 mu m to similar to 1.5 mu m where most of the grain refinement took place up to 2nd pass. In alpha-phase, {111}(11 (2) over bar) type twins evolve during deformation that reduces the strain in the alpha-grains with successive passes. This also leads to the formation of Sigma 3 coincident site lattice boundaries. In beta-phase, dislocation slip occurred, and grains get elongated along the shear direction. beta-grains come together to develop small bands about similar to 15 degrees to the extrusion direction (ED). These small beta-bands are interconnected to form larger beta-bands parallel to ED. In alpha-phase, weak texture components evolve at positions deviated from the ideal end orientations due to the presence of secondary beta-phase and twinning due to the low stacking fault energy of the alpha-phase. In beta-phase, characteristic ECAP texture components evolve and strengthen with consecutive passes. This is attributed to the formation of the beta-banded structure.