Effect of strain path during repeated rolling on microstructure, grain refinement, and mechanical properties of Copper/Brass multilayered composites

The effect of strain path was investigated by unidirectional, reverse, and transverse movement of working rolls. This paper aims to bring more insight in the evolution of microstructure and grain refinement in Cu/Brass multilayered composites processed by a novel method of accumulative double-pass rolling (ADPR). According to microstructural images, the strain-path change could preserve the continuity of strain-hardened layers by reducing the plastic instabilities. This is due to the better strain accommodation of layers after rotating the rolling direction. However, the cross-rolling route had more contribution on increased ductility of layers than reverse-rolling route. Similar impact was observed on the size of grains. The maximum and minimum grain refinement respectively took place on cross-rolled and unidirectionally-rolled composites. Regarding the mechanical properties, changing the rolling direction could positively affect the hardness, strengths, and elongation. The highest values of these properties were seen in cross-rolled composites while the lowest values were obtained in the unidirectionally-rolled composites. The observations of fracture surfaces showed the ductile nature of fracture with delamination of interfaces although Brass surfaces in cross-rolled samples possessed deeper dimples, indicating its enhanced ductility