Properties Of Magnesium Alloy Sheets Research Articles

Fracture behavior of AZ31B magnesium alloy under high-temperature ultrasonic-assisted shearing with related ductile-brittle transformation mechanism

A wide width is one of the fundamental requirements for magnesium alloy sheets to fulfill the lightweight needs of the aerospace and rail transportation industries. Nevertheless, ensuring the dimensional integrity of wide-format magnesium alloy sheets is a challenge in most manufacturing facilities. Simultaneously, processing operations are susceptible to encountering production issues, including but not limited to significant loss of raw materials, elevated costs, environmental contamination, and safety risks. Therefore, to fulfill the operational demands of the hot rolling finishing line for wide sheets made of magnesium alloy, the present study employed ultrasonic-assisted shearing (UAS) to carry out a high-temperature shearing test investigation on the AZ31B magnesium alloy sheet. In this research, we employed scanning electron microscopy, optical microscopy, and a micro-hardness tester to investigate the relationship between ultrasonic amplitude and fracture behavior, deformation mechanism, and mechanical properties of magnesium alloy sheets following exposure to ultrasonic vibration. The fracture morphology of the sheet fracture demonstrates that the behavior of the magnesium alloy sheet fractures under ultrasonic vibration changes from ductile fracture under conventional shearing to brittle fracture under ultrasonic-assisted shearing. The primary cause of this transformation between ductile and brittle is the effect of ultrasonic vibration on the material's internal energy. High-energy ultrasonic amplitude action causes magnesium to absorb a significant amount of ultrasonic energy. This results in an increase in the number of dynamic re-crystallization grains in the material organization, a decrease in the number of twins, and significant refinement of the grains. The sheet's hardness also changes along the rolling and normal directions, with a uniform distribution. The magnesium alloy sheet's fracture quality is optimal when the ultrasonic amplitude is 10 μm in the UAS process. This treatment results in notable enhancements in the section's straightness and brightness. Our study aims to advance the mass manufacturing of wide-format magnesium alloy sheets by investigating a cost-effective and high-yield technique for shearing magnesium alloy sheets.

Local twinning behavior of ZK61m magnesium alloy sheet under multiaxial stress during drawing-pressing with Erichsen test machine

In order to find a more effective method to preset twins and to explore the microstructure and twin evolution of magnesium alloy sheet under multi-axial stress state deformation, drawing-pressing deformation with Erichsen test machine is used as a sheet processing method to process ZK61m magnesium alloy sheet in this experiment. During repeated drawing-pressing deformation, the central area of the plate was subjected to annular tensile and compressive stress. In the process of deformation under unidirectional force, the slip direction of some grains is in hard orientation and it is difficult for the slip to operate, while the annular tensile and compressive stress state will provide the grains with multidirectional slipping options. Electron back-scattered diffraction (EBSD) technique was used to analyze the microstructure of magnesium alloy plates with different drawing-pressing times and different positions from local deformation center to edge. In this study, the complex circumferential force environment will weaken the anisotropy of deformation structure during repeated drawing-pressing, and the effect of prefabricated twins is more obvious. Based on the modified generalized Schmid factor (GSF) analysis, it is easier to show a variety of twin variation behaviors within a grain during Erichsen deformation. After the plate is deformed by Erichsen processing, the mechanical properties of magnesium alloy sheet have also been effectively improved.

Izboljšanje mikrostrukture in mehanskih lastnosti pločevine iz Mg zlitine z novo metodo iztiskanja

Izboljšanje mikrostrukture in mehanskih lastnosti pločevine iz Mg zlitine z novo metodo iztiskanja

Mechanical Behavior Characterization of Magnesium Alloy Sheets at Warm Temperature

AbstractMagnesium (Mg) alloy sheet has received increasing attention in automotive, transportation, and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. To better understand the warm forming properties of magnesium alloy sheet, an accurate description of the mechanical behavior at elevated temperature is required.In this paper, both uniaxial tensile tests and uniaxial compression tests were carried out at warm temperature for Mg AZ31B alloy sheets. The tensile tests were conducted under various strain rates and material orientations, while the compression tests only considered different material orientations. Based on the orthotropic yield criterion for hexagonal close packed (HCP) metals proposed by Cazacu et al., 2006, a viscoplasticity model has been developed to describe the initial yield anisotropy and asymmetry hardening behavior in tensile and compression of Mg sheet. This model was incorporated into ABAQUS through a user-defined material subroutine. The numerical results show a good agreement with experimental data in a large range of deformation.

Effects of rolling rate on microstructure and mechanical properties of Mg sheets

Abstract This study investigates the effects of rolling rate on the microstructure and mechanical properties of magnesium alloy sheets. AZ31 plates were rolled at speeds of 5, 10, 20 and 30 r · min−1 at room temperature. Optical microscopy, micro-hardness testing, and X-ray diffraction were carried out to characterize the material microstructure. Results show that the number of twin grains increases as the rolling rate increases. Simultaneously, the micro-hardness of the samples decreases, and the (0 001) basal texture is weakened. These results suggest the use of high rolling speed to practically reduce the formation of unfavorable basal texture in manufacturing magnesium alloy sheets.

Effects of Annealing Treatment on the Microstructure and Mechanical Properties of Magnesium Alloy Sheets

The microstructure of magnesium alloy sheets (nominal composition Mg–6Zn–Y in at. %) was investigated with the Optical Microscope (OM), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) technique after the annealing treatment. Tensile test at room temperature was performed to show the influence of annealing treatment on mechanical properties. Experimental results indicate that there are a large number of twin crystals appearing in microstructure of the extruded Mg-Zn-Y alloy sheet at 350 °C. The distinct icosahedral phase appears on the α-Mg matrix in granular form and the strength gets largely improved to the maximum. The uniform distribution of isometric crystal contributes to the best elongation at the annealing temperature of 400 °C.

Tailor-Welded Blanks Manufactured and Stamping Properties of Magnesium Alloy

Magnesium alloy tailor-welded blanks(MTWBs) of AZ31 and AZ80 sheet had been manufactured by gas tungsten arc welded(GTAW), which the thickness were 0.8mm. The welding properties of Magnesium alloy sheet had been analyzed, and the technology parameters of GTAW were determined by experiment study, which was that welding thread being Φ2.0mm, welding electricity 50A, welding voltage 9V, welding rate 12—13cm/min. The research results presented that the grain in welded seam was isometric crystal, and the grains were branching crystal in heat-affected zone (HAZ). For MTWBs of AZ31and AZ80 sheet which the thickness was 0.8mm, the forming parameters were that the forming temperature of AZ31 being 190-220°C, and forming temperature of AZ80 being 310°C-350°C, and the temperature of tools is 180°C~200°C.

Effects of processing variables on melt cleanliness of AZ31B magnesium alloy investigated by quantitative evaluation of Fe and non-metallic inclusions

Impurities such as Fe, Ni and Cu and non-metallic inclusions such as oxides, nitrides, carbides, sulfides and fluorides are harmful to the quality and various properties of magnesium alloy sheets produced by twin-roll casting. In this study, the changes of the content of Fe and non-metallic inclusions in AZ31B magnesium alloys with melt temperature and isothermal holding time were quantitatively evaluated using EPMA and the metallographic method. The Fe content did not increase above the Fe content in the raw material, which implies that the dissolution of Fe from a steel crucible was suppressed effectively. The content of non-metallic inclusions, mainly consisting of oxide, fluoride and Fe-rich intermetallic compounds, did not change remarkably with the melt temperature but it increased with the isothermal holding time due to the continuous oxidation of the magnesium alloy melt on the melt surface.

Texture evolution and mechanical properties of AZ31B magnesium alloy sheets processed by repeated unidirectional bending

Commercial AZ31B magnesium alloy sheets have poor plasticity and stamping formability at room temperature owing to strong basal texture. In this study, a method termed ‘repeated unidirectional bending’ (RUB) was applied to improve the mechanical properties of magnesium alloy sheets by controlling the texture. The evolution of the texture and mechanical properties of the sheets during RUB and annealing were systematically investigated. In the sheets that underwent RUB, the c-axis tended to become inclined from the normal direction (ND) towards the rolling direction (RD), and the { 1 0 1 ¯ 2 } extension twinning was activated during bending. When a sheet that had undergone RUB was annealed at 260 °C, the mechanical ductility at room temperature was improved considerably because the texture components became more dispersed along the RD, and work hardening was also eliminated by annealing.

Effect of Equal-Channel Angular Rolling Pass on Microstructure and Properties of Magnesium Alloy Sheets

The objective of this study was to determine the effect of rolling pass on AZ31 magnesium alloy sheets, which were produced by a new concept process, so-called equal-channel angular rolling process. Processing that causes continuous shearing deformation leads to a shifting of the crystal orientation from basal plane to non-basal plane. Compared with the as-received specimens, a lower yield strength and a higher ductility of the specimens produced by equal-channel angular rolling in tensile tests at ambient temperature were presented because of the non-basal crystal orientation. Drawability was also improved greatly.

Mechanical Properties of Magnesium Alloy Sheets Produced by Semi-Solid Roll Strip Casting

Mechanical Properties of Magnesium Alloy Sheets Produced by Semi-Solid Roll Strip Casting