Influence of ECAP as grain refinement technique on microstructure evolution,mechanical properties and corrosion behavior of pure aluminum
(1. Mechanical Design and Production Department, Faculty of Engineering, Zagazig University, Zagazig 44519, Egypt;
2. Mining and Petroleum Engineering Department, Al-Azhar University, Nasr City; Cairo 11651, Egypt)
2. Mining and Petroleum Engineering Department, Al-Azhar University, Nasr City; Cairo 11651, Egypt)
Abstract: Pure aluminum samples were processed by equal channel angular pressing (ECAP) up to 10 passes at room temperature. The effects of the ECAP number of passes on the microstructure evolution, the mechanical properties, deformation homogeneity and corrosion behavior of the processed samples were fully investigated. The imposed strain resulted in an obvious reduction in the grain size from 390 μm before ECAP down to 1.8, 0.4, and 0.3 μm after ECAP up to 2, 4 and 10 passes, respectively. The microhardness, deformation homogeneity and tensile strength were increased while the elongation decreased with the increase of ECAP number of passes. Immersion tests, open circuit potential, Tafel polarization, cyclic polarization and potentiostatic measurements in 3.5% NaCl solution revealed an obvious improvement in the corrosion resistance of ECAP processed samples compared with the as-cast sample. The increase of the number of passes can be used successfully in producing ultra-fine grained (UFG) bulk pure aluminum sample with a high misorientation angle, reasonably high mechanical properties and corrosion resistance.
Key words: equal channel angular pressing (ECAP); microstructure; mechanical properties; corrosion resistance; passive film; pitting