Investigation of mechanical properties and fracture surfaces of dual-phase 60–40 brass alloy processed by warm equal-channel angular pressing

In this study, the effect of equal-channel angular pressing process on the mechanical properties of a dual-phase 60–40 brass alloy was investigated. The samples were processed up to six passes through the route C at 350 °C. Optical microscopy and tensile tests were employed for the investigation of microstructure and mechanical properties. Increasing the number of passes caused the increase in both strength and elongation. It was observed that by the sixth pass, the elongation at the room temperature was increased up to 85% and the tensile strength was obtained to be 1.5 times more than that of the annealed sample. Micro-hardness test results also showed that the hardness was increased to 100% for the specimen processed to the sixth pass. Since the process temperature was less than Tm/2, due to the low stacking-fault energy of this alloy, continuous recrystallization was expected to occur in the microstructure. However, it was observed that recrystallized grains were formed near the grain boundaries for the first pass. To determine the type of the recrystallization, primary specimens were rolled up to 95% and then annealed at different temperatures. The obtained samples microstructures confirmed that both static and dynamic recrystallizations occurring in the primary passes were the reason for the bimodal structure formation in these passes. To study the fracture surfaces, scanning electron microscope was employed. The results showed the ductile fracture in all the specimens. By increasing the passes, this type of fracture was expanded.