RESUMO
Casting of aluminum with different concentration of alloying elements such as Mg, Mn (similar to that in AA5083) with additional percentages of 0.1, 0.2 and 0.3% Ti, are carried out using graphite crucible. The as-cast microstructure is modified by hot rolling to a thickness of ~ 2 mm. Mechanical and metallurgical and characterization of heat-treated thin sheets are carried out using tensile testing, hardness measurement, metallography, image analysis and optical microscope. By increasing the Ti content, the results show grain refinement and increase in the formation of Al3Ti which reflected positively on the mechanical properties. Specifically, Ultimate tensile strength is increased from 260 MPa (0 wt% Ti) to 345 MPa (0.3 wt% Ti) when using water quenching, 32.6% improvement for air cooling, and 23.3% for furnace cooling. Electrochemical corrosion behavior of heat-treated water quenched, air cooled and furnace cooled samples were tested in 3.5% NaCl solution. The results show that the heat-treated alloys have very good resistance against corrosion, while by increasing the Ti content, the corrosion rate increases due to the grain refinement phenomena.
RESUMO
In the present study, the stress corrosion cracking (SCC) behavior of ECAP Al5083 alloy was investigated in air as well as in 3.5 % NaCl solution using the slow strain rate tensile test (SSRT). The characteristics of grain boundary precipitates (GBPs), specifically the microchemistry of the SCC behavior of Al5083 alloys, both in "as-received" condition and when deformed by the ECAP process, were examined. The correlations between the SCC resistance and GBP microchemistry were examined. A microstructural evaluation was performed using an optical microscope. SCC tests were carried out using a universal tensile testing machine and the fracture surfaces were studied using scanning electron microscopy (SEM). A strain rate of 1×10-6 s-1 was applied for the SSRT. As the passes increased, the SCC susceptibility of the fine-grained ECAP Al5083 alloy also increased. Moreover, higher ultimate tensile strength and greater elongation were observed. This was due to grain refinement, high-density separations, and the expanded extent of high-density dislocations instigated by severe plastic deformation. Due to the high strength and elongation, the failure analysis showed a ductile mode of fracture. Electron backscattering diffraction (EBSD) analysis was performed to determine more clearly the nature of cracking. EBSD analysis showed that the crack propagation occurred in both transgranular and intergranular modes.
