Papers by Keyword: AZ31 Alloy

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Authors: Hung Hsiou Hsu, Yeong-Maw Hwang
Abstract: Friction stir processes (FSP) are important for enhancing mechanical properties of metal sheets, such as the tensile strength, the elongation, etc. The stress distribution of the tool pin is affected by the thermo-mechanical characteristics of the workpiece in FSP. Recently, magnesium alloy AZ31 is widely used in machine industries due to the light-weight material property. In this paper, a thermo-mechanical model for FSP using three dimensional FEM analyses is proposed for exploring temperature distributions, strain distributions and stress distributions of the workpiece. The heat generated from the plastic deformation and the friction between the head tool and workpiece is considered as the heat source in the simulation of the FSP process. A commercial finite element code – DEFORM 3D is used to carry out the simulation of the plastic deformation of AZ31 sheets during the FSP. The analytical results of temperature, strain and stress distributions of the workpiece and head tool can provide useful knowledge for tool pin design in FSP
Authors: F. Kaiser, Dietmar Letzig, Jan Bohlen, A. Styczynski, Ch. Hartig, Karl Ulrich Kainer
Authors: Tian Mo Liu, Pan Xiao, Fu Sheng Pan, Qing Liu
Abstract: The cold-compressed AZ31 magnesium alloys with different (2.5%, 5%, 7.5%, 10%, 12.5% and 15%) were annealed at different temperatures (573, 623 and 673K) for different time. With aid of the optical microscopy, and microhardness tester, the microstructural evolution during annealing at different temperature of the compressed AZ31 has been investigated. The microstructural characterized results were further related to the hardness test results and the calculated activation energy. The results showed that for the compressed AZ31, the recrystallization can occur on the samples with the strain just above 10% and the deformation twinning plays an important role on the nucleation and grain growth of the recrystallization. It was found that the twinning boundary was the location of the recrystallization nuclei and a lot of recrystallized grains with equiaxed shape were found along the twinning boundaries. The relationships among the nuclei orientations and the crystallographic orientations on both sides of the twining boundary have been statistically investigated. The effects of the compressed strain and the annealing temperature on annealing behavior were also discussed based on the experimental results.
Authors: Y.G. Jeong, Woo Jin Kim, Seo Gou Choi, Ha Guk Jeong
Abstract: For the Magnesium alloy AZ31, hot rolling is usually carried out in the temperature range between 250 and 400°C but the processed sheets usually exhibit high anisotropy in mechanical properties. In the current study, DSR process was found to be effective in improving anisotropy of mechanical properties and ductility at room temperature. Full recrystallization takes place from 200°C and above. A large drop of UTS occurs above 200°C where full recrystallization starts. Tensile elongation increases with annealing temperature but anisotropy degrades from 200°C onwards. Texture change during recrystallization is believed to be responsible for this result.
Authors: T. Kobayashi, Junichi Koike, Toshiji Mukai, Mayumi Suzuki, H. Watanabe, Kouichi Maruyama, Kenji Higashi
Authors: Jong Kwan Hwang, Keun Yong Sohn, Kyung Hyun Kim, Dae Min Kang
Authors: Jia Tong Song, Gao Feng Quan, Zhao Ming Liu, Ying Bo Zhang, Jia Le Sun
Abstract: Compression properties, microstructure evolution and deformation behaviors of cast and extruded AZ31 alloys are investigated. The results show that compressive yield stress, ultimate strength and ultimate compression ratio between extruded and cast AZ31 alloy are quite different. The yielding pattern of as-cast AZ31 alloy is continuous, and the yield pattern of extruded AZ31 alloy demonstrate an obvious yielding plateau mode. The angle between the fractures and specimens axis of as-cast and extruded AZ31 alloy is about 45°. A mass of reliefs and damage can be found on the specimen surface of as-cast AZ31 alloy and the twinning is main deformation sign in as-cast AZ31 alloy as seen a rough surface. The slip activity might be a predominant deformation mechanism in extruded AZ31 alloy judged by smooth surface after fracture.
Authors: Ying Hong Peng, Ying Bing Luo, Da Yong Li, Ji Long Yin
Abstract: To examine the formability of a magnesium-based alloy AZ31 sheet, a temperature and strain rate related constitutive model for AZ31 sheet was developed based on tensile experiments. The relative parameters were obtained by fitting the equation to the experimental data. The comparison between the fitted and the experimental data proved the effectiveness of the model. Based on this model, the deep drawing process has been simulated with the finite element method and the limit drawing ratio (LDR) of AZ31 sheet was numerically studied. The study result was helpful to the application of the stamping technology for the magnesium alloy sheet.
Authors: Tatiana V. Ivleva, Jürgen Göken, Igor S. Golovin, Zuzana Zuberova, Manuel Maikranz-Valentin, Kurt Steinhoff
Abstract: Study of anelasticity in AZ31 magnesium-based alloy in initial (hot-rolled at 370 оС) condition and after one and four passes of equal channel angular pressing is carried out. An internal friction peak was found at 170 °C at a frequency f of about 1 Hz. Two possible mechanisms of this peak are discussed: it is suggested that the peak origin is the grain boundary relaxation.
Authors: J. Göken, J. Swiostek, Dietmar Letzig, Karl Ulrich Kainer
Abstract: Magnesium cast parts as well as indirectly and hydrostatically extruded profiles were used in order to investigate the influence of different microstructures on the damping behaviour of magnesium AZ-alloys. Especially, hydrostatic extrusion leads to a significant grain refinement in the extruded profile compared to indirect extrusion. Strain dependent damping measurements were carried out at room temperature using alloys AZ31, AZ61 and AZ80. Damping was determined as the logarithmic decrement of free bending beam vibrations. The results of these measurements after indirect and hydrostatic extrusion are shown and discussed.
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