Wrought Magnesium Alloys Research Articles

Cold Roll Forming Behavior of Wrought Magnesium Alloy with Tension - Compression Asymmetry

In recent years, the movement that banning the sale of gasoline cars and diesel vehiclesespecially in Europe and allowing only electric cars for passenger’s cars has been accelerated. Forexamples, Germany’s federal council, the Bundesrat, has passed a resolution calling for a ban oncombustion engine cars by 2030. If the ban were to go through, German citizens would only bepermitted to purchase electric or hydrogen-fueled cars. In Norway, until 2025 there is a movement tolegislation prohibiting the registration of new cars for passenger car gasoline and diesel cars.Beginning in 2025 in the Netherlands, a bill to prohibit the sale of new cars for gasoline and dieselvehicles was submitted to Congress. Under the circumstances, the growing demand for light weightproducts for automotive industries has been increased due to global trend of environmentalpreservation. Although requires of magnesium has risen dramatically, production of magnesium alloysheet remains still at a very low level in practical use. The aim of the study is to establish a guidelinefor roll design in the roll forming of wrought magnesium alloys to extend practical use of roll formedproducts of wrought magnesium alloys. A three-dimensional elasto-plastic analysis by finite elementmethod has been conducted to express exact roll forming behavior of wrought magnesium alloys thathave different stress-strain curves in tension and compression. A simple V-sections were formed by atandem six stands roll forming machine to demonstrate effectiveness of the simulation methods withdifferent stress-strain curves in the case of tension and compression. Also, spring back analysis hasbeen performed to investigate exact cold roll forming phenomenon for wrought magnesium alloysheets.

Magnesium fabricated using additive technology: Specificity of corrosion and protection

Direct laser deposition (DLD) technology was used to obtain magnesium (Mg) samples in this work. The morphology, composition, electrochemical and mechanical properties of the Mg specimens with and without protective layers were investigated using microhardness and scratch tests, SEM-EDX and XRD analysis, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and immersion tests. The localized corrosion processes on the DLD Mg sample surface were studied using scanning vibrating electrode technique (SVET) and scanning ion-selective electrode technique (SIET). Plasma electrolytic oxidation (PEO) method was applied to modify the DLD Mg material intended to be used as bioresorbable implants for bone repair applications. Composite polymer-containing layers were designed to increase the corrosion resistance of the protected material. It was established that the use of additive technology for the formation of the material does not require correction of the electrical modes of PEO, developed for wrought magnesium alloys. The formed coatings possess high adhesive strength and sufficiently increase the protective properties of the DLD samples in a 3 wt% NaCl solution.

Discontinuous and inhomogeneous strain distributions under monotonic and cyclic loading in textured wrought magnesium alloys

The present work investigates the deformation behaviour of strongly textured AZ31B wrought magnesium sheets under monotonic as well as cyclic mechanical loading. Of special focus is the distribution of strain, which is investigated employing optical strain field measurements on the specimen surfaces. Microstructural investigations of the material after loading provide detailed information on the underlying deformation characteristics. The investigations show that bands of twinned grains (BTGs) form up once twinning occurs. These BTGs consist of solely {101‾2} tension twins and are clearly delimited to the adjacent absolutely twin-free regions. Most importantly, strain fields are strongly inhomogeneous and discontinuous due to these BTGs with considerably higher compressive strain inside BTGs, both after monotonic and cyclic loading. During the first few load cycles, BTGs are observed to grow and the formation of new BTGs can occur. Additionally, a significant hardening is found during the first load cycles, most likely caused by residual twins and unretwinnable twins. However, material behaviour stabilizes after a few load cycles and remains approximately constant for most of a specimen's lifetime. The presented specific deformation characteristics are important for understanding and describing the material. Modelling the investigated material behaviour is not yet completely feasible with phenomenological constitutive models, which is why important modelling aspects are discussed.

Recent Advances in LPSO-Containing Wrought Magnesium Alloys: Relationships Between Processing, Microstructure, and Mechanical Properties

Development of strong and ductile lightweight magnesium (Mg) alloys has been the subject of enormous research breakthroughs since 2000. This review describes the most significant progress on the design and processing of high-strength wrought Mg alloys containing long-period stacking order (LPSO) phases. It first focuses on the typical atomic structure, transformation, and morphology of various LPSO phases, then explores the key contributions of thermomechanical processing techniques to the metallurgical structure, morphology, spatial dimension, and distribution of diverse LPSO phases and discusses the LPSO-derived strengthening mechanisms of Mg alloys. Finally, future research opportunities for LPSO-containing wrought Mg alloys are proposed on the basis of the mechanistic relationships between the evolution of LPSO phase particles and strengthening mechanisms.

Macro to nano: a microscopy study of a wrought magnesium alloy after deformation

This educational paper aims to assist physics teachers in explaining the concepts and principles of material composition and deformation by describing how to perform a microscopy investigation of a deformed wrought magnesium alloy test piece. By examining the changes taking place at the different length scales from macro to nano it is possible to understand how changes in the microstructure influence the macroscopic appearance and properties. The microscopy techniques employed for the investigation of each length scale—light microscopy, scanning electron microscopy and transmission electron microscopy—are explained along with the procedures of specimen preparation. A background is given to help teachers explain the microstructure of magnesium, the role of magnesium alloys in modern industrial and technological contexts and the historical developments of microscopy. The paper can also be used to assist teachers in laboratory courses to describe the principles and methods of scientific experiment. The work is fully referenced and a reading list is included, making it suitable as a teaching resource for academic courses or for solo study.

Improving the room-temperature formability of Mg-3Al-1Zn alloy sheet by introducing an orthogonal four-peak texture

Wrought magnesium alloy sheets suffered extrusion or rolling usually exhibit strong basal texture, which greatly degrades their mechanical performance, and thus, restrict their applications. In this study, a novel texture modification process based on employing in-plane precompression, prestretching and annealing was carried out on an extruded Mg-3Al-1Zn (AZ31) sheet to introduce an orthogonal four-peak distribution of basal texture. The results indicated that such an orthogonal four-peak texture could provide larger and more balanced Schmid factors for basal slip compared with that of the as-extruded sheet when the sheets subject to tension along different directions. As expected, the tensile yield strength was decreased and the ductility was increased effectively, suggesting a considerable improvement in uniaxial deformation ability. Additionally, the orthogonal four-peak texture could also provide more balanced mechanical properties along different directions and contribute to reducing the planar anisotropy. Erichsen tests showed that the Erichsen value of the sample with orthogonal four-peak texture increased up to ∼115% compared with that of the as-extruded sheet. This finding indicated that such a texture modification method was also highly conducive to enhancing the multiaxial stretch formability of the Mg sheets. The orthogonal four-peak texture modification was confirmed as an efficient way to improve the comprehensive mechanical performance of the Mg alloy sheets.

High-temperature dependency of elastic mechanical behavior of two wrought magnesium alloys AZ31B and ZK60A studied by resonant ultrasound spectroscopy

Resonant ultrasound spectroscopy (RUS) was used to study the elastic mechanical properties and internal friction of two wrought magnesium alloys, AZ31B and ZK60A, from 25 °C to 450 °C. Samples in the rolled, transverse, and normal directions were characterized at 50 °C intervals to determine the temperature dependency of elastic moduli and stiffnesses for each direction. The temperature dependencies represented as, dE/dT, dG/dT, dB/dT, dC11/dT, dC12/dT, and dC44/dT are provided herein. To evaluate the RUS technique for these type of alloys, Young's modulus was also determined by conventional static tension testing and the results were compared. From the same RUS experiment, the internal friction variation with temperature was calculated for both alloys. The linear coefficients of thermal expansion for each direction over the temperature range considered were determined, as they were needed to estimate sample dimension at elevated temperature for the RUS measurements.This study shows that RUS can be a convenient and accurate technique to supply quantitative elastic mechanical data and fill the existing gaps on light metals characterization.

Development of age-hardenable wrought magnesium alloy

Development of age-hardenable wrought magnesium alloy

Fatigue of ZEK100-F magnesium alloy: Characterisation and modelling

Fatigue and cyclic behaviour of rolled ZEK100-F magnesium alloy in rolling direction are investigated by conducting fully-reversed strain-control uniaxial tension-compression cyclic experiments at a wide range of strain amplitudes. The experimental alloy possesses less asymmetric (less skewed) hysteresis loops, and higher ductility at the room temperature, relative to other conventional wrought magnesium alloys, e.g., AZ31B-H24 and AM30. Cyclic straining at amplitudes less than 0.6% results in material softening, while at higher amplitudes cyclic hardening occurs. Through stress-control cyclic tests at stress ratios of 0 and −1, mean stress is shown to have an adverse effect on the fatigue life of rolled ZEK100-F alloy. Finally, strain- and energy-based fatigue life prediction models are assessed against generated constant and variable amplitude experimental data, and Jahed-Varvani energy-based approach is observed to give statistically better life predictions.

High Mechanical Properties of AZ91 Mg Alloy Processed by Equal Channel Angular Pressing and Rolling

Mechanical properties usually take precedence for wrought magnesium alloy when it would be used as a structure material. This paper proposed an approach that achieved high strength in AZ91 Mg alloy. The main procedure combined solution heat treatment, equal channel angular pressing (ECAP), and the subsequent low temperature rolling. After solution heat treatment and ECAP, the alloy had fine grains and excellent ductility, which benefited the following rolling at low temperature. By the following rolling (at 150 °C), the strength was further increased to ~432 MPa with a moderate ductility. This approach was proved effective in refining the grains and accumulating dislocations. The ultrahigh strength was attributed to the high density of dislocations and fine structure. The uniformly distributed fine precipitates also supplied precipitate hardening. Recrystallization that happened during rolling and annealing was the main reason for the moderate ductility.

Optimisation of Heat Treatment Process for Damping Properties of Mg-13Gd-4Y-2Zn-0.5Zr Magnesium Alloy Using Box–Behnken Design Method

High damping magnesium alloys have poor mechanical properties, so it is necessary to investigate the damping properties of high-strength wrought magnesium alloys to effectively reduce vibration and noise in mechanical engineering. The aim of this work is to improve the mechanical damping performance of a novel high-strength Mg-13Gd-4Y-2Zn-0.5Zr magnesium alloy by optimising the heat treatment process. The mechanical damping coefficient, considering not only damping capacity but also the yield strength, is selected as one of the evaluation indexes. The other evaluation index is the tensile strength. The solid solution and ageing treatment were optimised by Box-Behnken method, an efficient experimental design technique. Heat treatment experiments based on the optimal parameters verified that the best process is a solution at 520 °C for 10 h followed by ageing at 239 °C for 22 h. The damping coefficient reaches 0.296, which is 73.1% higher than that before heat treatment. There was a good agreement between the experimental and Box-Behnken predicted results. The microstructure, morphology and composition of the second phases after heat treatment were analysed by SEM, XRD and EDS. Due to the high content of alloying elements in Mg-13Gd-4Y-2Zn-0.5Zr alloy, there are a large number of second phases after heat treated. They mainly include layer, short rod-shaped, bulk long period stacking order (LPSO) Mg12YZn and granular Mg5Gd phases. It was found that the area fraction of the second phases has an extreme effect on the damping capacity and short rod-shaped LPSO can effectively improve the damping capacity of heat-treated Mg-13Gd-4Y-2Zn-0.5Zr alloy. The volume fraction of the second phases was analysed by ImageJ software. It was concluded that the smaller the area occupied by the second phases, the better the mobility of the dislocation, and the better the damping performance of the alloy. The statistical analysis results obtained using ImageJ software are consistent with the experimental results damping capacity.

Development of high-performance flame-retardant wrought magnesium alloys and evolution for application of the alloys to high-speed railway body

Development of high-performance flame-retardant wrought magnesium alloys and evolution for application of the alloys to high-speed railway body

Evolution of Texture during Hot Rolling of a New Magnesium Alloy

High-strength wrought magnesium alloys are one of the sought-after materials in the automotive sector owing to the demands for weight reduction in the automobiles due to fuel economy and CO2 emission. However, because of low room temperature strength and formability of Mg alloys, only a few applications in wrought form have been explored with these materials. In the present investigation, a high strength, good ductility and low cost wrought magnesium alloy with Mg-Sn-Zn composition have been developed and subjected to conventional wrought processing. Hot rolling was carried out at 350°C without homogenization and after homogenization at 300°C and 330°C. The phase stability, microstructure and texture of the alloy has been investigated for as-cast, homogenized and hot rolled conditions. The compositional and microstructural characterization was carried out by Electron Probe Micro-analysis (EPMA) and optical microscopy respectively. Texture evolution was investigated by X-ray diffraction method. A strong (0002) basal texture develops after hot rolling without homogenization. The (0002) basal texture has been weekend by splitting of poles and double peak distribution when hot rolling was carried out after homogenization.

Magnesium Twin-Roll Casting Technology for Flat and Long Products - State of the Art and Future

Due to their advantageous strength-weight ratio, good recyclability, excellent noise and vibration damping properties as well as excellent dent resistance, magnesium materials offer a variety of uses in modern lightweight structures. As a result, a comeback of magnesium alloys is to be seen in multiple industrial applications, especially in the automotive industry, as the potential for lightweight, cost-effective lightweight industrial construction associated with the lightest metallic engineering material helps to meet even stricter energy and environmental efficiency guidelines. Traditionally, casting processes have been the dominant magnesium manufacturing processes, but in the last decade, an increasing number of lightweight structural applications have been implemented with magnesium wrought alloys. In this paper, the current state of developments focusing the twin-roll casting (TRC) of semi-finished products of magnesium alloys will be presented. By reducing the number of process steps in combination with a unique microstructure, the near-net-shape TRC process offers new options to provide magnesium materials meeting current and future requirements for semi-finished products, constructions and moldings in terms of type, quantity and quality.

Reducing yield asymmetry and anisotropy in wrought magnesium alloys – A comparative study

Yield asymmetry in wrought magnesium alloys has been shown previously to be reduced by texture weakening and {101̅2} tensile-twin solid-solution strengthening due to rare-earth element (RE) additions. Yield asymmetry can also be reduced by grain-size reduction and precipitation strengthening. In this work these mechanisms were studied in several Mg-Sn-Zn-Al-Na(-Ca) alloys and a Mg-7 wt% Y (W7) alloy to rank their effectiveness. It was shown that texture weakening and tensile-twin solid-solution strengthening were the most effective asymmetry reducing mechanisms but were only achieved in the yttrium containing alloy. For yttrium-free alloys, grain-size reduction and precipitation strengthening must be utilised to overcome asymmetry and anisotropy produced by strong textures. Carefully designed precipitate populations were demonstrated to reduce both asymmetry (in the extrusion direction) and anisotropy. The power of crystal plasticity models, such as the visco-plastic self-consistent model, in aiding this design process has been demonstrated. However, achieving the desired precipitate populations in a practical alloy under realistic processing conditions is difficult. Grain-size reduction is more easily achieved and is effective in reducing asymmetry, but can only combat anisotropy successfully if an alloy is not hindered by an unfavourable wrought texture.

Special features of the weldability of a new wrought VMD16 magnesium alloy

ABSTRACTThe results of the investigation of the weldability of a new VMD16 magnesium alloy by automatic argon-shielded arc welding and friction stir welding are presented. The friction stir welding technology was investigated for the first time for the Russian magnesium wrought alloy. The data obtained in the studies of the phase composition and structure of the VMD16 alloy are presented. The experimental results show that the intermetallic phases (Mg, Zn)5REE (REE = rare-earth elements) and Zn2(Zr, REE)3 and the Laves phases ZrZn2, together with the fine-grained and equiaxed structure (the grain size 8–12 µm), result in a high level of the strength characteristics of the alloy and of welded joints in the alloy. It is also shown that the alloy is characterized by higher (two to six times) resistance to the formation of cracks in welding than the standard magnesium alloys MA2-1, MA2-1pch and MA20. The strength of the welded joints in the VMD16 alloy equals 0.85–0.88 of the strength of the parent material. Postweld heat treatment is not required.

Cylindrical cup deep drawing of ZEK100 sheet at elevated temperatures

Cylindrical cup deep drawing experiments are performed on as-received magnesium rare-earth alloyed ZEK100 rolled sheet between room temperature and 250 °C. All tests are performed using warm tooling comprising a 101.6 mm (4”) diameter cylindrical punch and smooth die and blank holder. Both isothermal and non-isothermal experiments are performed with a draw ratio of 2.25. Warm temperature formability of ZEK100 is investigated through determination of draw depths of cylindrical cups under isothermal and non-isothermal conditions. The effect of sheet anisotropy during deep drawing operation is investigated by measuring the earring profiles by means of digital imaging as well as sheet thickness from the center to the outer diameter in the rolling direction. It is found that ZEK100 sheets exhibit significantly better warm temperature drawing performance over commercial wrought magnesium alloy sheet – e.g. a full draw of 203.2 mm (8”) blanks of ZEKIOO-O was achieved with tool temperature of 150 °C compared to a full draw for AZ31B-O with a tool temperature of 225 °C. Temperature process windows are used to present a direct comparison of forming behavior between ZEK100 and AZ31B. The increased forming performance of ZEK100 at elevated temperatures is attributed to the weakened texture resulting from alloying with Zr and Nd, respectively, allowing for elevated slip activity at lower temperatures.

The Influence of Hot Forming on the Microstructure and Corrosion Behaviour of AZ31B Magnesium Alloys

The influence of the hot forming process of AZ31B wrought and twin roll cast (TRC) magnesium alloy sheets on the microstructure and corrosion behaviour have been evaluated. The corrosion behaviour was investigated by hydrogen evolution experiments in chloride-containing solution. Filiform-like corrosion was predominant attack to the AZ31 magnesium alloys, as observed by in-situ corrosion observation. The intermetallic particle existence and grain structure significantly influenced the corrosion rate. The dendritic structure of the as-cast TRC alloy was severely attacked, revealing that the as-cast alloy was highly susceptible to corrosion. The presence of twins in wrought alloy was found to act as a corrosion barrier, while the increase in grain size showed the high corrosion rate of the alloy.

Bending Behavior of a Wrought Magnesium Alloy Investigated by the In Situ Pinhole Neutron Diffraction Method

The tensile twinning and detwinning behaviors of a wrought magnesium alloy have been investigated during in situ four-point bending using the state-of-the-art high spatial resolution pinhole neutron diffraction (PIND) method. The PIND method allowed us to resolve the tensile twinning/detwinning and lattice strain distributions across the bending sample during a loading-unloading sequence with a 0.5 mm step size. It was found that the extensive tensile twinning and detwinning occurred near the compression surface, while no tensile twinning behavior was observed in the middle layer and tension side of the bending sample. During the bending, the neutral plane shifted from the compression side to the tension side. Compared with the traditional neutron diffraction mapping method, the PIND method provides more detailed information inside the bending sample due to a higher spatial resolution.

Concept of the highly strained volume for fatigue modeling of wrought magnesium alloys

Microstructural investigations and mechanical fatigue tests with in situ optical strain field measurement were performed on unnotched, notched, and bending AZ31B magnesium specimens. Twinned and twin-free regions are clearly delimited and compressive strain within twinned regions is much higher compared to the strain in twin-free regions. Furthermore, initial macroscopic cracks are observed to be always located within the twinned regions. Thus, only twinned regions are considered for fatigue modeling. To cover stress concentrations, stress gradients, different types of loading, and strongly inhomogeneous distribution of strain within bands of twinned grains all together, current fatigue lifetime description methods are insufficient. Hence, this work presents a newly developed method, referred to as the method of highly strained volume. The new method bases on the principals of the method of highly stressed volume, which is suitable for modeling the fatigue limit. This method uses the size of the highly strained volume and the effective strain amplitude in the highly strained volume to describe the number of cycles to failure. Based on results of 75 fatigue tests (strain amplitude: 0.30–1.17%, strain ratio: 1.47 to −0.431) the accurate description of the fatigue lifetime by the method of highly strained volume is demonstrated.