The deformation behaviours and microstructure transformations during the cold rolling process of Al-1.4Fe-0.2Mn alloy sheets prepared from 99.7% pure aluminium were investigated by means of hardness-testing, transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS). The phenomena of work hardening and work softening were observed. The hardness of Al-1.4Fe-0.2Mn alloy sheets increased with the increasing of cold rolling reduction firstly, and reached to a peak at 80% cold rolling reduction, meaning work hardening. However, with further increasing of cold rolling reduction, the hardness decreased, which indicates work softening. During the initial deformation stage, the dislocation density and the number of sub-grain structures increased gradually, and many dislocations formed tangles, resulting in work hardening. When the cold rolling reduction exceeded 80%, the dislocation density decreased and sub-grain structures polygonized, leading to work softening. The forming of Mn, Fe and Si bearing compounds is an important reason for the work softening due to lowering solid solution content.
The effect of boronizing treatment on the conductivity of a high-conductivity and heat-resistant Al-Zr alloy conductor material was studied. The results showed that the conductivity of industrial pure Al containing transition element (Ti, V, Cr, Mn)>0.01 wt % (mass fraction, the same below) was improved to a certain extent by using boronizing treatment to remove transition metal elements through the formation of borides. Using the boronizing treatment, B can react with transition elements to form blocky (Ti, V, Fe)B2 and flocculent (Ti, V, Fe, Zr)B2. The boronizing treatment makes Ti and V out of the solid solution state, form borides and finally deposit to the bottom of the furnace, thus significantly improving the conductivity of the ingot. In addition, Cr and Mn were not found in the borides at the bottom of the furnace. However, for the high-conductivity and heat-resisting Al-Zr alloy conductor material, B will have poison effects on Zr during boronizing treatment, thus reducing the heat-resistance of the alloy. Therefore, in the preparation process of high-conductivity and heat-resistant Al-Zr alloy conductor material, the converter process should be added after boronizing treatment to ensure that the Al-Zr alloy conductor material has good heat-resistance and conductivity at the same time.
5083 aluminum alloy, due to moderate strength, good thermal conductivity and formability, is an ideal structural material for car production. Influence of cold rolling process on microstructures and mechanical properties of 5083 aluminum alloys is significant and research hotspots. In this paper, cold deformation and annealing processes on grains, tensile properties and anisotropies of 5083 alloy sheets were studied. Results showed that incomplete recrystallization occured on 5083 alloy sheets when annealing temperature was at 300°C. The degree of recrystallization increased slightly with the cold deformation raised from 30% to 50% and varied slightly with prolonged annealing time from 2h to 4h. Furthermore, fully recrystallization occurred on 5083 alloy sheets at the annealing temperature above 320°C. Tensile strength of 5083 alloy sheets reduced significantly when the annealing temperature was raised from 300°C to 320°C, while it varied slightly when the annealing temperature continued to rise to 380°C.
By means of Vickers hardness tester, optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and high resolution transmitted electron microscope (HRTEM), the bake softening and precipitation behaviors of AA5182 H19 sheet for can end stock at 205°C and 249°C were investigated. All specimens at both temperatures showed recovery and bake softening phenomenon, which meaning the dislocation density and HV decreased. However, the specimens baked at 205°C showed higher recovery impediment, because the bake softening curve departed from the dynamic laws when it had less amount of recovery than the specimens baked at 249°C. The hardness was higher for the specimen baked at 205°C compared with the specimen baked at 249°C, even both specimens had the same dislocation density measured by XRD. Further observations revealed that the precipitated particles in the specimens baked at 205°C distributed along the shear bands. The precipitates were needle shape with the length of 5-15 nm and the width of 5-10 atom layers, which occurred mostly in the area with higher dislocation density. These precipitates were guessed to be Al-Mg binary phases, which could contribute to the higher hardness of the specimens baked at 205°C.
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