AZ31 Magnesium Alloy Research Articles

Effects of water cooling of friction stir welding of magnesium alloy stiffness joint

This study presents a comparative analysis of friction stir welding (FSW) and underwater friction stir welding (UFSW) of AZ31 magnesium alloy in T-configuration, emphasizing the effects on heat distribution, material properties, and mechanical performance. Simulation results revealed a more uniform heat distribution in both welding techniques, with the hottest area on the advancing side. The maximum temperatures recorded at the shoulder-workpiece contact were 404 °C for FSW and 349 °C for UFSW, a 13.6 % reduction in UFSW. Material velocity at the trailing edge was 63 mm/s for FSW and 42 mm/s for UFSW, showing a 34 % decrease due to lower heat generation in UFSW. Strain rates were 450 s⁻¹ for FSW and 420 s⁻¹ for UFSW. Grain size in the stir zone was 26 micrometers for FSW and 21 micrometers for UFSW, a 19 % reduction. Ultimate tensile strength (UTS) increased by 6 % in the skin direction and 12.8 % in the flange direction for UFSW compared to FSW. SEM analysis indicated enhanced ductility in UFSW fractures. These results demonstrate UFSW's superiority in improving thermal management, microstructural properties, and mechanical performance of welded joints.

On the heterogeneous microstructure and strengthening mechanisms in a laser welding AZ80 magnesium alloy

This study investigates the microstructural characteristics and mechanical properties of a laser welded AZ80 magnesium alloy. The welding process led to the formation of coarse-grained fusion zone (FZ), where a secondary phase formed continuous network. Mg17Al12 precipitation and coarsening of grain boundaries occurred in the heat affected zone. The welded joint exhibited excellent mechanical properties with a yield strength of 202 MPa and a joint efficiency of 92%. The microstructure analysis via EPMA and EBSD in conjunction with synchrotron X-ray diffraction analysis reveals that precipitates and increased dislocation density in the fusion zone are primary strengthening mechanisms for the laser welded AZ80 Mg alloy.

Forming limit analysis of magnesium alloy sheet metal forming process at elevated temperatures

Abstract Magnesium alloys are valued by industry for their lightweight structures. Magnesium alloy are mainly produced by warm forming because the sheet formability is poor at room temperature. The mechanical properties of magnesium alloy AZ31, such as stress-strain curves and damage values at different elevated temperatures, were obtained by this study using a computerized screw universal testing machine. Freudenthal fracture criteria were used to obtain the forming limit at distinct temperatures. The forming limit analysis proceeded during the sheet metal forming process at various elevated temperature. The fracture’s forming load, stroke, and position were determined for different working temperatures of the sheet metal forming process for AZ31, using a finite element simulation combined with the ductile fracture criteria. Finally, the predicted values were compared with the experimental results during the sheet metal forming process. The simulation results agreed with the experimental values for the fracture forming load, stroke, and position of the sheet metal forming process. The feasibility of the present method was confirmed to predict forming limit during the sheet metal forming process for different elevated temperatures. A finite element analysis for forming limit prediction would be beneficial to the design of sheet metal processes for AZ31 magnesium alloys.

Development of Mg-3Al-0.5Zn-0.4Mn-1Gd Alloys as a Clavicle Bone Implant Material: A Literature Review

Abstract Magnesium alloys are widely used as implant materials such as Magnesium-Aluminium, Magnesium-Mangan, Magnesium-Zirconium, and others. These alloys still need further research regarding the mechanical properties of the alloy materials, resistance to corrosion rate, and anti-toxic properties to the human body. This article reviews the Magnesium alloy AZ31 (Magnesium-3Al-1Zn-0.4Mn) with the addition of the Gadolinium element as a candidate for the implant of the clavicle bone. The novelty of the proposed research is the change in composition in the form of a reduction of 0.5% Zn and the addition of 1% Gd. Furthermore, anodizing and coating treatment is implemented to improve the mechanical stability of the alloy. This alloy is supposed to improve the physical, mechanical, and chemical properties of magnesium. The addition of gadolinium can increase the mechanical strength, creep resistance, and rate of corrosion resistance.

Corrosion Inhibition of AZ31-xLi (x = 4, 8, 12) magnesium alloys in sodium chloride solutions by aqueous molybdate

Corrosion of lithium-containing AZ31 magnesium alloys AZ31-xLi (x = 4, 8, and 12 wt%) has been examined in 0.05 M NaCl solution with and without 10–150 mM of Na2MoO4 inhibitor. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and dynamic electrochemical impedance spectroscopy (DEIS) measurements were used to correlate the phase composition and microstructure of the alloys with their corrosion propensity and effectiveness of the molybdate inhibitor, giving high inhibition efficiency (>85%) at concentrations higher than ca. 35 mM. Post-corrosion microstructure, Raman, and X-ray photoelectron spectroscopy analyses allowed to provide the inhibition mechanism of AZ31-xLi alloys by molybdate ions.

Behaviour of AZ91 magnesium alloy in tension and torsion: experimental investigations and numerical modelling

Abstract This study is concerned with the evaluation of the most appropriate plasticity model for simulating the behaviour of the AZ91 magnesium alloy in terms of accuracy and analysis times, based on experimental data obtained from tensile and torsion tests. The material was supplied in ingot form, was subsequently cut using and automated saw and ISO 6892 round specimens were obtained through lathing. The test data was used to calibrate three hardening functions, namely the multi-linear hardening, Johnson-Cook power law hardening and the Ramberg Osgood plasticity model, with the former determining the best results.

Microstructure Evolution and Mechanical Behavior of AZ31 Magnesium Alloy Sheet with Bimodal Texture under Bending Deformation

Microstructure Evolution and Mechanical Behavior of AZ31 Magnesium Alloy Sheet with Bimodal Texture under Bending Deformation

Prediction of wear amounts of AZ91 magnesium alloy matrix composites reinforced with ZnO-hBN nanocomposite particles by hybridized GA-SVR model

Prediction of wear amounts of AZ91 magnesium alloy matrix composites reinforced with ZnO-hBN nanocomposite particles by hybridized GA-SVR model

Production of AZ80 magnesium alloy wires: influence of heat treatment on microstructure and properties after twin-roll casting

AbstractTwin-roll casting (TRC) of magnesium sheets has already been analysed in numerous ways. The installation of a pilot plant for the twin-roll casting of magnesium wire at the Institute of Metal Forming, TU Bergakademie Freiberg, has opened up a further area for research. The principle of twin-roll casting of wire is comparable, although the microstructure development is different because of the resulting process-specific solidification and forming conditions. In this work, wire was produced for the first time from the magnesium alloy AZ80 using the TRC process. The microstructure consists of dendritic areas, twins, deformed areas and recrystallised grains. A non-basal texture with low intensity is developed, which is retained even after heat treatment. A temperature of 450 °C and a holding time of 1 h have been shown to be favourable for heat treatment to achieve a uniform grain structure. On the basis of the microstructure and texture analysis, the responsible recrystallisation mechanisms were discussed. Finally, mechanical properties at room temperature were presented and compared with extruded and cast material from the literature.

Quantitative evaluation of local strain distribution induced by deformation twins and triggering effect of deformation twinning on neighboring grains in polycrystalline AZ31 magnesium alloys

{101‾2}<1‾011> deformation twinning commonly occurs in Mg/Mg alloys. In their polycrystals, however, twinning is not always activated at locations with high Schmid factor for {101‾2}<1‾011> twinning. It is believed that twinning behavior in polycrystalline Mg/Mg alloys can be understood with a consideration of interaction between adjacent twins as well as local deformation behavior on a micro- and meso‑structural scale. In this study, we theoretically estimate local plastic strain within twins by transforming coordinates and then compare it with that experimentally obtained from digital image correlation (DIC) analysis for understanding the reason for non-Schmid twinning in polycrystalline-Mg alloys. The theoretically estimated strain of twins was found to be in good agreement with the DIC-strain value. Furthermore, it was observed that the variant selection of twin can be explained by the compatibility parameter m’, rather than Schmid factor, suggesting that twin activation in polycrystalline-Mg is strongly influenced by adjacently appeared twins.

Simulation of recrystallization grain growth in AZ61 magnesium alloy based on GA and 3D CA

In this paper, the Arrhenius constitutive model (GA-Arrhenius) optimized by genetic algorithm (GA) is established, and the dynamic recrystallization (DRX) grain growth process of AZ61 magnesium alloy during hot deformation is simulated by three-dimensional cellular automata (3D CA), and the morphological evolution and grain boundary migration of recrystallized grains are reproduced. The results show that the GA-Arrhenius model accurately predicts the rheological behavior of the material, while the 3D CA model effectively describes the formation and growth mechanism of grains during DRX.

Nanocrystallization and precipitation behavior evolution of AZ80 magnesium alloy during multi-directional compression

In response to the growing demand for high-performance magnesium alloys in the aerospace and transportation industries, researchers conducted a study on the AZ80 magnesium alloy. The primary objective was to achieve a nanocrystalline structure in the alloy through severe plastic deformation using low-strain multi-directional compression at room temperature. Subsequently, an aging treatment was performed to induce the transformation of the structure into a stable state. The study aimed to investigate the morphology and mode of the second phase precipitation in the magnesium alloy after undergoing severe plastic deformation. The research findings revealed that the application of multi-directional and multi-pass compression during room temperature deformation of the magnesium alloy effectively prevented instability and fracture. Moreover, this process facilitated the accumulation of larger true strain. As the number of compression passes increased, deformation twins became increasingly denser, particularly in the intersecting areas. Consequently, ultrafine high-angle grain structures were preferentially formed in these regions. Furthermore, the number of fine-grained areas gradually increased with each deformation pass. After ΣΔε 5.12, the grain size was refined to a range of 100–200 nm. Additionally, the aging treatment following severe plastic deformation brought about a significant change in the traditional lamellar precipitation mode of the second phase Mg17Al12 in the magnesium alloy. Instead, spherical precipitation occurred.

On the Creation of a Material Bond between L-PBF-Manufactured AZ91 and Ti-6Al-4V Components in the Context of Medical Applications.

Within the scope of these investigations, the feasibility of a material bond between Ti-6Al-4V and the magnesium alloy AZ91 is analyzed. Ti-6Al-4V is frequently used for implants due to its biocompatibility, corrosion resistance, and specific strength. However, depending on the surface quality, the attachment behavior of the bone to the implant varies. Magnesium implants promote the regeneration of bone tissue and biodegrade as the bone tissue heals. Combining the properties of both materials in one implant enables a reduced implant volume and increased stability. For this reason, this study aims to demonstrate the feasibility of creating a material bond between the materials Ti-6Al-4V and AZ91. For this purpose, Ti-6Al-4V truncated cones and AZ91 sleeves were produced using the additive manufacturing process of laser powder bed fusion (L-PBF). The as-built sleeves were then pressed onto machined truncated cones. Since zinc serves as a lubricant and has good diffusion properties with the materials used as a result of heat treatment, a comparison was made between zinc-coated and the as-built Ti-6Al-4V samples. This showed that a bond was created after hot isostatic pressing and that the push-out force could be increased by more than 4.5 times. Consequently, a proof of feasibility was demonstrated, and a high potential for applications in medical technology was shown.

Enhanced Cyclically Stable Plasticity Model for Multiaxial Behaviour of Magnesium Alloy AZ31 under Low-Cycle Fatigue Conditions.

Magnesium alloys, particularly AZ31, are promising materials for the modern automotive industry, offering significant weight savings and environmental benefits. This research focuses on the challenges associated with accurate modelling of multiaxial cyclic plasticity at small strains of AZ31 under low-cycle fatigue conditions. Current modelling approaches, including crystal plasticity and phenomenological plasticity, have been extensively explored. However, the existing models reach their limits when it comes to capturing the complexity of cyclic plasticity in magnesium alloys, especially under multiaxial loading conditions. To address this gap, a cyclically stable elastoplastic model is proposed that integrates elements from existing models with an enhanced algorithm for updating stresses and hardening parameters, using the hyperbolic tangent function to describe hardening and ensure a stabilised response with closed hysteresis loops for both uniaxial and multiaxial loading. The model is based on a von Mises yield surface and includes a kinematic hardening rule that promises a stable simulation of the response of AZ31 sheets under cyclic loading. Using experimental data from previous studies on AZ31 sheets, the proposed model is optimised and validated. The model shows promising capabilities in simulating the response of AZ31 sheet metal under different loading conditions. It has significant potential to improve the accuracy of fatigue simulations, especially in the context of automotive applications.

Enhancement strength of AZ91 magnesium alloy composites reinforced with graphene by T6 heat treatment and equal channel angular pressing

Enhancement strength of AZ91 magnesium alloy composites reinforced with graphene by T6 heat treatment and equal channel angular pressing

Effect of HVOF parameter on titanium oxide (TiO2) coating characteristics on AZ81 magnesium alloy

High-velocity oxy-fuel (HVOF) coating to enhance the erosion, wear, and corrosion-resistant properties crucial for orthopedic applications. HVOF is distinguished for its capability to provide surfaces with a dense and superior finish. Porosity and hardness serve as vital process variables in assessing performance. This current study aims to optimize HVOF process parameters to minimize porosity values in titanium oxide (TiO2) coatings applied on AZ81 magnesium substrate. Oxygen flow, liquefied petroleum gas (LPG) flow, coating material feed rate, and spray distance were selected due to their significant impact on the coating quality. Statistical techniques such as response surface methodology (RSM), analysis of variations, and design of experiments (DoE) were employed to obtain the necessary results. The findings indicate that LPG flow has the most significant influence on coating quality, followed by standoff distance, oxygen flow rate, and feed rate. The coating obtained using optimal spray parameters exhibits a lower surface porosity of 0.86 vol.% and achieves a greater hardness of 922 HV. This has been confirmed through validation via the response graph. Consequently, the optimized parameters for TiO2 deposit entail an oxygen flow rate of 266 lpm, an LPG flow rate of 68 lpm, a powder feed rate of 35 g/min, and a spray distance of 236 mm. KEY WORDS: High-velocity oxy-fuel, Response surface methodology, Porosity, Hardness, AZ81 Magnesium alloy, Titanium oxide Bull. Chem. Soc. Ethiop. 2024, 38(6), 1869-1886. DOI: https://dx.doi.org/10.4314/bcse.v38i6.28

Corrosion inhibition of AZ31 magnesium alloy in 3.5 % NaCl by green corrosion inhibitor: Maleic hydrazide derivative

A novel maleic hydrazide derivative containing multiple active groups (NOMAM) has been synthetized and characterized. Electrochemical tests revealed that it can provide effective protection for AZ31 magnesium alloys in 3.5 % NaCl. The best inhibition was achieved at 0.2 g·L−1. The observation results of the surface morphology also confirmed its excellent corrosion inhibition performance. Density functional theory (DFT) calculations and molecular dynamics simulations (MDS) revealed that maleic hydrazide derivative molecules adsorb onto magnesium alloy surfaces via a combination of physisorption and chemisorption with heteroatoms as active sites. The complexes formed by derivative molecules with Mg2+, together with the deposited Mg(OH)2, form protective barriers at the interface. The synthesized derivative has many advantages, such as low cost, simple processing and low toxicity. This study can contribute to the search for green corrosion inhibitors for magnesium alloys.

Influence of Uric Acid on the Corrosion Behavior of AZ31 Magnesium Alloy in Simulated Body Fluid

Influence of Uric Acid on the Corrosion Behavior of AZ31 Magnesium Alloy in Simulated Body Fluid

Grain size dependence of twin nucleation in magnesium alloys

Twinning plays a prominent role in the plastic deformation of low-symmetry crystals such as magnesium alloys. However, the capture of twin nucleation has been challenging since the process is rapid and difficult to predict, making it impossible to observe directly. Because of this, the understanding of the fundamental twinning mechanism through experiments and simulation techniques incorporating twinning has progressed slowly. In this study, a quantitative analysis integrating an in-situ three-point bending experiment and crystal plasticity modeling was conducted on the twin nucleation in AZ31 magnesium alloys with different grain sizes. The threshold for triggering twin nucleation has been quantified. The prediction ability of three widely used criteria for twin nucleation, i.e., geometrically necessary dislocation (GND) density, von Mises stress, and stored energy density, is evaluated. The results suggest that only the stored energy density is able to capture the twin nucleation location accurately in all the considered grain sizes. The critical value exhibits an exponential reduction with the increase in grain size. Based on the quantitative analysis, the mechanism of the grain size effect on twin nucleation is proposed.

Influence of Zinc Chloride Exposure on Microstructure and Mechanical Behavior of Age-Hardened AZ91 Magnesium Alloy.

The AZ91 magnesium alloy was subjected to a complex treatment involving age hardening (supersaturation and artificial aging) and simultaneous surface layer modification. The specimens were supersaturated in contact with a mixture containing varying concentrations of zinc chloride, followed by cooling either in air or water. After supersaturation, the specimens were subjected to artificial aging and then air-cooled. This process resulted in the formation of a surface layer made of zinc-rich phases. The thickness and microstructure of the surface layer were influenced by the process parameters, namely, the zinc chloride content in the mixture and the cooling rate during supersaturation. The treated specimens exhibited favorable tensile strength and greater elongation compared to the as-cast AZ91 alloy, with values comparable to those of the alloy subjected to standard T6 tempering. No cracking of the layer was observed under moderate deformation, though greater deformation resulted in the formation of cracks, primarily in the areas containing the Mg5Al2Zn2 intermetallic phase. The produced layer demonstrated strong metallurgical bonding to the AZ91 substrate.