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The presentstudy investigated the mechanical properties and microstructure of ultrafinegrained (UFG) brass processed by four passes of equal channel angular pressing(ECAP) and annealed at elevated temperatures. The mechanical properties of allsamples were assessed using tensile and micro-hardness tests. Microstructureanalysis was performed using optical microscopy (OM) and scanning electronmicroscopy (SEM). Ultimate tensile strengths (UTS) and yield strengths (YS) of878 and 804 MPa, respectively, ductility of 15%, and hardness of 248 HV wereobtained for samples processed by four passes of ECAP with equivalent truestrain of 4.20. Annealing at 300°C caused UTS and YS to decrease significantly,to 510 and 408 MPa, respectively, ductility to increase to 28%, and hardness todecrease to 165 HV. Fractography analysis of un-annealed samples after fourECAP passes showed small brittle fractures with shallow dimpling. Ductilefailures were found on annealed samples. After four ECAP passes, themicrostructure of un-annealed samples was UFG and dominated by lamellar grainwith shear band. In contrast, after annealing, the microstructure changed dueto recrystallization, showing nucleation and grain growth. |
