The purpose of this research is to investigate the creation of a bimodal microstructure in brass alloy (Cu-10%Zn), in order to achieve optimal conditions in terms of strength and flexibility, by the accumulative bond rolling process and subsequent annealing, as well as the effect of changing the strain path in the mentioned process, on bimodal microstructure, mechanical properties and texture. In the bimodal microstructure, which is caused by the abnormal growth of the grains, the strength and flexibility are simultaneously in optimal conditions. For this purpose, after accumulative roll bonding, the brass samples were subjected to annealing at 400, 450, 500, 550, 600 and 650 degrees Celsius and for 1 hour. Then the microstructure was eva‎luated by light microscopy. According to the investigation, the annealing time was changed to improve the microstructure. In order to check the mechanical properties, uniaxial tensile test and microhardness test were used. Microstructural studies showed that by changing the annealing time at different temperatures, the bimodal microstructure is improved, and the samples annealed at 450 and 500 degrees Celsius and for a duration of 2 hours have a bimodal microstructure and the highest toughness. According to the obtained conditions, the samples produced by the accumulative roll bonding process with different strain paths (A, Ba, Bc and C) were subjected to annealing. The different strain gradients caused by the change of the strain path in the accumulative roll bonding process, and as a result, the different stored energy in the microstructure, lead to the creation of different bimodal microstructures under the same annealing conditions. It was found that the sample with Ba strain path and annealed at 450 degrees Celsius and 2 hours has the highest toughness. It was also found that in all four strain paths, the toughness changes are reversed according to the annealing temperature, so that the order of toughness reduction at 450 degrees Celsius is Ba, A, C and Bc, while this order at 500 degrees Celsius, it changes into Bc, C, A and Ba. By eva‎luation the texture of the samples, it is clear that changing the strain path, changes the annealing texture of the samples, so that new components are developed in the texture. Meanwhile, the Brass component and the A component are sensitive to 90 degree rotation and the Rotated Goss component is sensitive to 180 degree rotation, and with the increase in the number of these rotations, the intensity of the corresponding components also increases.

محمدرضا طرقي نژاد

احمد رضائيان، احمدرضا كرمانپور