Lifei Wang

Influence of strain rate on microstructure and formability of AZ31B magnesium alloy sheets

Abstract The effects of strain rate on microstructure and formability of AZ31B magnesium alloy sheets were investigated through uniaxial tensile tests and hemispherical punch tests with strain rates of 10−4, 10−3, 10−2, 10−1 s−1 at 200 °C. The results show that the volume fraction of dynamic recrystallization grains increases and the original grains are gradually replaced by recrystallization grains with the strain rate decreasing. A larger elongation and a smaller r-value are obtained at a lower strain rate, moreover the erichsen values become larger with the strain rate reducing, so the formability improves. This problem arises in part from the enhanced softening and the coordination of recrystallization grains during deformation.

Effects of grain size on shift of neutral layer of AZ31 magnesium alloy under warm condition

Abstract: The effects of grain size on the shift of neutral layer of AZ31 magnesium alloy sheets with different grain sizes ranging from 12.1 to 34.7 μm were investigated by the 90° V-bending tests at 150 °C. The results show that the neutral layer tends to shift to outer region of the sheets and the coefficient of neutral layer value ( k -value) increases with the increasing grain size. This phenomenon is mainly owing to the enhanced asymmetry between the outer tension region and inner compression region with the increase of grain size. Twinning dominates the deformation in inner region while slips dominate the deformation in outer region. Key words: AZ31 magnesium alloy; grain size; V-bending; neutral layer; asymmetry 1 Introduction Due to the high specific strength, high stiffness and low density, magnesium alloy has been attracted by many industries, such as electron and automobile [1]. However, magnesium alloy has a hexagonal close- packed (HCP) crystal structure, so it performs a poor formability. According to von Mises criterion, it needs five independent slip systems to activate the deformation. Nevertheless, the basal plane is the main slip plane which can only provide two basal slips and the non-basal slip systems cannot be activated at low temperature [2]. So, there are few slip systems to coordinate the deformation along the

Forming of Seat Bidet by AZ31 Magnesium Alloy through Stamping Process

In this paper, the forming of a seat bidet at 150°Cand 200°C by AZ31 magnesium alloy through the stamping process was conducted. The microstructure and the press technology were investigated. The results show that the lubrication and temperature have an important impact on the stamping forming. The seat bidet can be forming successfully by warm stamping. While the defect and fracture behavior mainly occurs at the corner of the seat bidet and the slant groove in the center.

Forming of the Battery Cell Packing in Extruded AZ31 Magnesium Alloys through Backward Extrusion

Mg batteries have received increasing attention mainly because of their high volumetric capacity (3832 mAhcm−3). In order to form type NO.5 cell packing for Magnesium battery the finite element simulation by Deform 3D was carried out. Then backward extrusion was conducted on an AZ31 magnesium alloy at 300°C. The results show that battery cell packing with the wall of 0.35 mm can be formed through backward extrusion with an AZ31 Mg alloys. A significant grain size refining was resulted from hot BE, however, the microstructure in different positions of the Mg cell packing was inhomogeneous. At bottom of the packing, the microstructure was formed by equiaxial and relatively coarse grains. The wall of the Mg cell packing was made of much finer grains.

Influence of Annealing Temperature on Microstructure and Properties of Warm-Rolled AZ31 Magnesium Alloy Sheets

Warm-rolled AZ31 alloy sheets were annealed at different temperatures ranging from 150 to 450°C. Effects of annealing temperature on microstructure and properties of warm-rolled AZ31 alloy sheets, especially the formability, were investigated. The results revealed that the Lankford value (r-value) and strain-hardening exponent (n-value) first increased and then became relatively steady with the increase of annealing temperature. The Erichsen value (IE) first increased and then decreased with the increase of annealing temperature and the AZ31 alloy sheets exhibited the highest IE of 3.02 mm when annealing at 250°C, which can be mainly attributed to a larger elongation, a lower r-value and a higher n-value.