MONDAY PM
2:00 PM 3-Dimensional Microstructure of Al-Al3Ti Alloy Severely Deformed by ECAP: Hisashi Sato1; Takahisa Hishikawa1; Yuuki Makino1; Takahiro Kunimine1; Yoshimi Watanabe1; 1Nagoya Institute of Technology Microstructure of Al-Al3Ti alloy deformed by Equal-Channel-Angular Pressing (ECAP) is 3-dimensionally investigated. Especially, distribution of Al3Ti particles is focused in this study. The Al-Al3Ti alloy has coarse Al3Ti platelet particles in Al matrix. When the Al-Al3Ti alloy is deformed by ECAP under route A, fine Al3Ti platelet particles are observed. These Al3Ti particles are aligned on a shear plane. In addition, the plane normal of the Al3Ti particles is parallel to that of the shear plane. On the other hand, Al-Al3Ti alloy ECAPed under route Bc has groups consisted of fine Al3Ti platelet particles. Moreover, longitudinal sizes of the Al3Ti particle groups are close to those of initial particles in the four-pass-ECAPed specimen. These distribution behaviors of the Al3Ti particle can be explained by plastic flow of Al matrix. Finally, it is concluded that distribution of Al3Ti particle in ECAPed Al-Al3Ti alloy is controlled by plastic deformation of Al matrix.
Technical Program
2:20 PM Abnormal Recrystallization Behavior of High Purity Aluminum Foil: Guangjie Huang1; Jing Zhang1; Yunlei Wang1; Qing Liu1; 1Chongqing University The influence of heating rates on recrystallization behavior of high purity aluminum foils was systematically studied in present paper. The result showed that the average grain size of the recrystallized sample is smaller when experiencing a low heating speed (280°C/h, holding at 180°C for one hour then heating to 500°C) than experiencing a high heating speed (put the sample into the furnace at 500°C), which conflicts with recrystallization behavior of typical metals. It is demonstrated that the variation of heating speeds induces transition of recrystallization types from continuous recrystallization at low heating rate to a discontinuous recrystallization at high heating speed. The recovery before recrystallization and the distribution of impurities are suspected to be closely related with the abnormal recrystallization behavior.The study strongly suggests that the heating speed maybe an effective way to modify the grain size in high purity of aluminum foils. And more detailed research will be done soon.
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2:40 PM Effect of Annealing Condition on Earing and Texture Formation in Cold Rolled AA5182 Aluminum Alloy: Minemitsu Okada1; Seiichi Hirano1; 1Sumitomo Light Metal Industries, LTD The effect of annealing condition on earing and recrystallization texture formation in cold rolled AA5182 aluminum alloy was investigated. The earing of AA5182 aluminum alloy depends strongly on the heating rate. At low heating rate (0.01-1K/s) the ears on drawn cup situated at 45 deg. to the sheet rolling direction. At high heating rate (10K/s) the ears were little. The earing behavior was characterized by the texture components. As the heating rate increases, the intensity of cube component increases where as the intensities of Brass and R components decrease. The transformation kinetics of recrystallization during isothermal annealing was quantified by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. The results show that the JMAK exponent for recrystallization was determined to be 2.4 at 553K and around 4 at 573K and 593K. The apparent activation energy for recrystallization was estimated to be 203kJ/mol. 3:00 PM Break 3:20 PM Effect of Quenching Wait Time on Microstructure and Mechanical Properties of As-extruded AA6063 Alloy: Yuna Wu1; Hengcheng Liao1; Jian Yang1; 1Southeast University Effect of quenching wait time after hot extrusion on microstructure and mechanical properties of AA6063 alloy was investigated by optical microscopy observation, tensile and Brinell hardness tests. Results
show that the quenching wait time has an important influence on the microstructure and mechanical properties of AA6063 alloy. During hot extrusion, dynamic recrystallization occurs only in local areas suffered much larger strains, however, only within 10s’ wait time after extrusion, the static recrystallized grains have maturely developed. After subsequent T6 heat treatment, the recrystallized grains of the prompt-quenched sample are more uniform than that of the wait-quenched sample, and mechanical properties of the former are also better than that of the latter. 3:40 PM Hot Deformation Behavior and Microstructural Evolution of Homogenized 7150 Aluminum Alloys Micro-Alloyed with Zr and V: Cangji Shi1; X. Grant Chen1; 1Université du Québec à Chicoutimi Hot deformation behavior of homogenized 7150 aluminum alloys micro-alloyed with 0.12% Zr and 0.11% V was studied by compression tests conducted at various temperatures and strain rates. The microstructural evolution was investigated using an optical microscope and the electron backscattered diffraction technique. The results showed that the peak flow stress of alloy 7150 increased due to the addition of Zr or V. The hot deformation activation energy of the base alloy was determined to be 209.0 kJ/mol, which increased to 244.7 kJ/mol and 248.7 kJ/mol when alloyed with 0.12% Zr and 0.11% V respectively. The softening mechanism of the base alloy was dynamic recovery during hot deformation at low temperatures (300 °C - 400 °C), which transformed to dynamic recrystallization at a high temperature (450 °C) and a low strain rate (0.001 s-1). Adding Zr or V generally displayed a retardation of the dynamic recovery and inhibition of the dynamic recrystallization, and hence resulted in the increase of flow stresses. 4:00 PM Modeling of Texture Evolution during Thermomechanical Processing in AA6xxx: Christian Bollmann1; Günter Gottstein1; 1Institute for Metallurgy and Metal Physics The formability of aluminum sheet is strongly depended on the terminal recrystallization texture. Since all processing steps influence the final recrystallization texture, a Through-Process Modeling (TPM) concept was applied to predict texture changes during thermomechanical processing routes. While the texture evolution during deformation was modeled with the Grain Interaction model, the process of recrystallization was simulated with the Statistical Recrystallization Texture model. The major advantage of TPM is to predict terminal recrystallization textures depending on various material and processing parameters. Moreover, the formation of recrystallization textures can be analyzed with regard to their physical mechanisms. The present study was designed to improve the prediction of texture evolution during thermomechanical processing of 6xxx alloys. For this, the models were evaluated for different material and processing conditions. Furthermore, through-thickness texture gradients were considered to address the recrystallization behavior for inhomogeneous deformation conditions and its effect on the terminal anisotropy of rolled sheet. 4:20 PM Orientation Effects in the Particle Stimulated Nucleation of 1 Recrystallization: Lawrence Ko1; Joao Fonseca1; University of Manchester Second phase particles present in commercial alloys have strong influence on the recrystallization kinetics, microstructure and texture. By varying the alloying composition and material processing, distribution of second phase particles can be controlled so as the grain size and texture, if these mechanism is completely understood. It is known that there is lattice rotation around the particles after deformation, in a so-called particle deformation zone (PDZ), which is important to give randomized texture after recrystallization. Here presents a study of the relationship of orientation of the deformed grains and the orientation present in the