Properties Of AZ31B Magnesium Alloy Research Articles

Microstructure evolution and properties of novel AZ31B/SiCps composites prepared based on wire-arc directed energy deposition

The novel AZ31B/SiCps composite was prepared by wire-arc directed energy deposition (DED-Arc) method. The effects of SiCps content in the range of 1.0–3.0 wt% on grain orientation, average grain size, grain boundary angle distribution, and mechanical properties of AZ31B magnesium alloy were studied. The results showed that SiCps, as a reinforcing phase uniformly dispersed in the matrix, could effectively reduce the free energy of the α-Mg matrix, and promoted non-uniform nucleation as a heterogeneous nucleation point. At the same time, SiCps was also pushed to the grain boundary by the solid-liquid interface, hindering the columnar grain of epitaxial growth, which helped to reduce the subcooling of components at the grain growth front (ΔTcs = ΔTn-min). With the increase of SiCps mass fraction, the transformation of columnar crystals to equiaxed crystals was realized. The average grain size of the deposited specimen and the texture strength of the crystal face of the α-Mg matrix (0001) gradually decreased. Finally, the AZ31B magnesium alloy with a mass fraction of 2.0 wt% SiCps exhibited excellent mechanical properties with a tensile strength of 233.35 MPa and an elongation of 24.04%. The anisotropy of the deposited sample was converted to isotropy.

Influence of non-thermal effect caused by pulse current on AZ31B magnesium alloy deformation

This paper studied the influence of pulse current (PC) on the plastic deformation of pre-deformed AZ31B magnesium alloy. Compared to the sample subjected to no current (NC), the PC sample's fracture strain and uniform strain increased by respectively 21.5% and 10%, while its strength slightly decreased. The fracture strain of the PC sample was equal to that of the as-received sample, while yield strength improved by 56 MPa and yield to tensile strength ratio enhanced by 42%. The non-thermal effect caused by PC induced more dislocation motion, weakened the base texture, inhibited void nucleation, and promoted uniform deformation. These actions were critical factors for improving materials' plasticity. Overall, the comprehensive properties of AZ31B magnesium alloy were significantly enhanced by combining pre-deformation and PC treatment. The findings obtained in this research can be expanded to magnesium alloys.

Investigation on mechanical properties of AZ31B magnesium alloy manufactured by stir casting process

- Nanocomposites of AZ31B with varying compositions of nano-hydroxyapatite and nano alumina were cast by the stir casting process. The primary goal of this research is to investigate and assess if it is feasible to fabricate magnesium metal matrix nano-composites (MMNCs) utilizing the stir casting process for biomedical applications. In this study AZ31B used as matrix and nano alumina (Al2O3) and nano hydroxyapatite (nHA) as a reinforcement. Due to its low weight as a structural metal and excellent strength-to-weight ratio, magnesium is commonly employed in engineering designs in addition to the development of composite materials. Mg alloys are widely used in biomedical due to their lower density. The Brinell hardness test was conducted to examine materials made by casting and forging processes that have a structure which is too coarse or rough for another test. It was observed that AZ31B-5nHa among the others has the highest hardness number. Compression tests were conducted to check the behavior of the MMNC under an applied load. AZ31B-0.5(Al2O3)-0.3nHa among the others has the highest compressive strength. It was observed that adding nHA reinforcement in AZ31B affects the microstructure and mechanical characteristics of a nanocomposite made of magnesium metal matrix, including compressive strength, hardness, corrosion resistance and biocompatibility. This study aims to investigate the effects of reinforcement on a magnesium metal matrix nanocomposite's microstructure and mechanical properties.

The effect of friction stir process on the mechanical, tribological, and biocompatibility properties of AZ31B magnesium alloy as a biomaterial: A pilot study.

Recently, AZ31B magnesium alloy has been widely employed in automotive, aerospace, and bio implant industries due to its light-weight and biocompatibility properties. However, the equilibrium of ductility and strength of this material and the negativity brought by its poor wear behavior have limited its versatile use. Friction stir processing (FSP) has been commonly used as severe plastic deformation method for improving mechanical and tribological properties of metal sheets. The effect of this method on the biocompatibility of materials is a matter of curiosity that should be emphasized. So, the present study aims to investigate the effect of friction stir process on the mechanical, tribological, and biocompatibility properties of AZ31B magnesium alloy. It is observed that FSP enhanced the tensile properties of the alloy but decreased its elongation. It was determined that the base material exhibited ductile character on the fracture surface of the specimens, and mixed ductile/brittle fracture was evident with the FSP. In the FSP zone, the hardness value was improved by 17% compared to the base material. Also, the wear performance of the alloy enhanced in ambient air and Simulated Body Fluid (SBF) solution. Wear properties in SBF solution were better due to less adhesive bonds between the friction surfaces. This assessment was supported by SEM images of the wear path and surface of counter bodies. On the other hand, FSPed AZ31B alloy materials with improved strength properties were not cytotoxic for human gingival fibroblasts, and these results may suggest that the materials are safe for clinical uses.

Improvement of laser welded joint properties of AZ31B magnesium alloy to DP590 dual-phase steel produced by external magnetic field

External magnetic field was utilized to enhance laser welded joint properties of AZ31B magnesium alloy to DP590 dual-phase steel based on the joint structure with adding Sn powder prefabricated concave groove. The influence mechanism of external magnetic field on the plasma behavior of metal vapor, shape and size of grain in molten pool and improvement of joint performance were also revealed. The results suggested that the changes of joint property were closely related to the thermoelectric magnetic force (TEMF) generated by the interaction of metal vapor plasma and thermal current in molten pool. External magnetic field suppressed the shielding effect of metal vapor plasma on laser energy, increasing the absorption rate of laser energy, and the “bi-directional” metallurgical bonding of magnesium/steel interface was achieved. Simultaneously, grain size and distribution morphology were also reasonably controlled, hence, the mechanical performance of magnesium/steel joint was significantly improved by magnetic field.

Fatigue Properties of AZ31B Magnesium Alloy Processed by Equal-Channel Angular Pressing

A stent is employed to expand a narrowed tubular organ, such as a blood vessel. However, the persistent presence of a stainless steel stent yields several problems of late thrombosis, restenosis and chronic inflammation reactions. Biodegradable magnesium stents have been introduced to solve these problems. However, magnesium-based alloys suffer from poor ductility and lower than desired fatigue performance. There is still a huge demand for further research on new alloys and stent designs. Then, as fundamental research for this, AZ31 B magnesium alloy has been investigated for the effect of equal-channel angular pressing on the fatigue properties. ECAP was conducted for one pass and eight passes at 300 °C using a die with a channel angle of 90°. An annealed sample and ECAP sample of AZ31 B magnesium alloy were subjected to tensile and fatigue tests. As a result of the tensile test, strength in the ECAP (one pass) sample was higher than in the annealed sample. As a result of the fatigue test, at stress amplitude σa = 100 MPa, the number of cycles to failure was largest in the annealed sample, medium in the ECAP (one pass) sample and lowest in the ECAP (eight passes) sample. It was suggested that the small low cycle fatigue life of the ECAP (eight passes) sample is attributable to severe plastic deformation.

Effect of Peak Current Density on Tensile Properties of AZ31B Magnesium Alloy.

An investigation into the effects, including the athermal effect, of a pulsed current on AZ31B magnesium alloy was carried out. Different peak current densities were applied at the same temperature under uniaxial tensile testing. The results indicate that the stress reduction caused by the increasing peak current density is independent of temperature. The strain hardening coefficient also shows a similar trend. The fracture strain shows the optimum value due to the current crowding effect.

Effect of Symmetric and Asymmetric Rolling Processes on The Microstructure and Mechanical Properties of AZ31B Magnesium Alloy

Microstructure progression, in addition to excellent plasticity possessions of AZ31B-alloy procedure using four paths in asymmetric through various reductions, was studied to facilitate develops the deprived plasticity of alloy. The procedure was used for alloy of about 78μm grain size, with a prim thickness of 5mm. It was formed by using different ratios,1:1,1:1.4,1:1.8and1:2.2.The thinning were 20%,25%,30%, 35% to reduce thickness to 4.00mm, 3.750 3.500 And 3.2500 repetitively. The rolling method was completed by using equal rollers diameter at a constant temperature of 473 K and devoid of lubricating after heating the rollers to 373K; the method was finished through four routes. Path (U.D.), pattern “way was kept” stable and unmoved connecting continual passes; whereas pattern was turned 180o to direction connecting continual passes during path (R.D.); pattern (N.D.) was turned throughout 180° concerning the standard direction to the continual passes; pattern (H.Y.) was turned 180o to the rolling direction primary in addition to, subsequently turned 90° concerning the standard direction connecting continual undulating passes. A traditional rolling process was done under identical situations to evaluate the outcome; microhardness test was also completed. Visual microscopy was used to study of rolling parameters on the microstructure of the rolled pieces. The outcome of inspection explained to the alteration of the microstructure had been pretentious employing path, ratio and decrease area. At low proportion, large numbers of mirror image creation become visible, as reduction raises dynamical recrystallization happening on the identical twin and shear bands were encouraged. In contrast raised proportion caused a raise within the quantity of recrystallized grains furthermore improved the microstructure. Very fine grains construction had been improved while the alloy was rolled using H.Y. path at a proportion of (1: 1.8) and 25% decrease. Excellent plasticity possessions of patterns devoid of annealing were experienced in stress at 673.00 K along with next to room temperature at primary strain selection from 1 × 10−3 s−1 to 2.2×10−3 s−1.

Effect of surface mechanical attrition treatment on corrosion fatigue behavior of AZ31B magnesium alloy

Surface mechanical attrition treatment (SMAT) is considered as an effective technology to influence fatigue and corrosion resistance as these properties are largely related to surface structure and property. Despite the increasing number of studies that report the effects of SMAT on separate fatigue or corrosion behaviors, the impact of SMAT on fatigue property under corrosive environment is left unexplored. In this paper, the corrosion fatigue properties of AZ31B magnesium alloy before and after SMAT process are investigated. Hydrogen evolution tests and potentiodynamic polarization tests are carried out to obtain the corrosion resistance, and it is found that SMAT promotes corrosion rate. The surface roughness of SMATed specimen also increases, which accelerates corrosion rate. In terms of fatigue properties, the fatigue life of SMATed specimen is found to be higher, in both air and 3% NaCl solution. And the larger the size of stainless steel balls used during processing SMAT specimens, the longer the fatigue life. Under 3% NaCl corrosive environment, the beneficial effects induced by SMAT process gradually emerge with increasing stress amplitude during fatigue tests. Reduced fatigue life of SMATed specimen under corrosive environment is attributed to roughened interface between deformed surface layer and bulk material. Nevertheless, the crack initiation sites for SMAT specimens are the same in both air and NaCl solution, all located at the subsurface area.

Microstructure and Mechanical Properties of AZ31B Magnesium Alloy Prepared by Solid State Recycling

Abstract Machined chips of AZ31B magnesium alloy were consolidated by cold pressing followed by hot extruding at different processing temperatures and extrusion ratios. Compared with ingot extruding alloy, the influences of processing technique on mechanical properties of recycled alloys were analyzed from two main aspects involving the dynamic recrystallization microstructure and the bonding condition between chips. Results show that with the increasing extrusion temperature, the ultimate tensile strength and elongation to failure of the recycled alloys firstly increase and then decrease. The combined action of grain growth and improvement of the bonding between chips with the increasing extrusion temperature results in the variations of mechanical properties of the recycled alloy. With the extrusion ratio increasing from 4:1 to 44:1, the grain is refined, and the bonding between chips is enhanced. This contributes to the increased ultimate tensile strength of recycled alloy. Whereas elongation to failure decreases when extrusion ratio is higher than 25:1 due to the significant deformation strengthening.

Effect of Differential Speed Rolling Temperature into Mechanical Properties of AZ31B Magnesium Alloy

The received AZ31B magnesium alloy sheets of 2 mm in thickness were subjected to differential speed rolling (DSR) process performed on a mill, of which the rotation speed ratio of the lower roll and upper one is kept at constant 1.15, by using the different upper and lower roller diameters. The influence of the rolled sheet temperature on the microstructure of the specimens was examined by optical microscopy, and elongation-to-failure of tensile test at temperature 623 K and initial strain-rate range between 0.5×10-3 - 1.83×10-3 s-1 was measured. The present process was found to be effective to refine the grain size. Grain refinement became more marked and uniform. The sheet DSRed at 473K exhibited the highest values of 340% and 0.35 for elongation-to-failure and strain rate sensitivity (m) respectively.

On the modeling of asymmetric yield functions

A first degree homogeneous yield function is completely determined by its restriction to the unit sphere of the stress space; if, in addition, the function is isotropic and pressure independent, its restriction to the octahedric unit circle, the π -circle, is periodic and determines uniquely the function. Thus any homogeneous, isotropic and pressure independent yield function can be represented by the Fourier series of its π -circle restriction. Combinations of isotropic functions and linear transformations can then be used to extend the theory to anisotropic convex functions. The capabilities of this simple, yet quite general methodology are illustrated in the modeling of the yielding properties of AZ31B magnesium alloy.

Dry sliding wear behavior of ES-processed AZ31B magnesium alloy

The friction and wear properties of AZ31B magnesium alloy fabricated by a new severe plastic deformation called extrusion-shear (shorted for ES) have been investigated in dry sliding condition. Dry sliding tests for AZ31B magnesium alloy processed by direct extrusion have been performed and compared with that of the alloy prepared by ES process. The results show that the wear resistance of AZ31B alloy was improved by Extrusion-Shear process, compared with direct extrusion. This was mainly attributed to the grain size refinement in Extrusion-Shear process. The main wear mechanisms of both alloys are abrasion slight deformation, oxidation delamination and melting under different frequencies. The effective stresses for the surface region during wear process have been calculated by using FE (Finite Element) method. The simulation results indicates that a higher effective stress is accumulated in the direct extrusion alloy than in the ES alloy, which may cause a larger volumetric wear rate of AZ31B magnesium alloy.

The role of microstructure and texture in controlling mechanical properties of AZ31B magnesium alloy processed by I-ECAP

Mechanical properties of AZ31B magnesium alloy were modified in this work by various processing routes of incremental equal channel angular pressing (I-ECAP) followed by heat treatment. Possible strategies for improving ductility and strength of the alloy were investigated. Processing by routes A and BC showed that texture plays predominant role in controlling mechanical properties at room temperature. Four passes of I-ECAP by route C followed by annealing enhanced ductility up to 0.35 of true strain. It was found that tensile twinning was important in accommodating strain during tensile testing, which resulted in a very good hardening behaviour. The yield strength was improved to 300MPa by refining grain size to 0.8µm in I-ECAP at 150°C. The obtained structure and properties were shown to be stable up to 150°C. True strain at fracture was increased to 0.2 after annealing at 150°C without lowering strength.

Review the Effect of Welding Processes on the Comprehensive Mechanical Properties of Magnesium Alloy Joints

In this paper, the effect of welding processes such as friction stir welding (FSW), laser beam welding (LBW) and pulsed current gas tungsten arc welding (PCGTAW) on comprehensive mechanical properties of AZ31B magnesium alloy was reviewed. Among the three different welding processes, the LBW joints showed superior comprehensive properties to FSW and PCGTAW joints. The formation of very fine grains in weld region, higher fusion zone hardness, uniformly distributed finer precipitates were the main reasons for superior comprehensive mechanical performance of LBW joints compared to PCGTAW and FSW joints.

Improving the Mechanical Properties of Friction Stir Welded AZ31B Magnesium Alloy Flat Plates through Axial Force Investigation

In this paper, the effects of axial force on the mechanical properties of AZ31B magnesium alloy flat plates during the Friction Stir Welding (FSW) process were investigated by carrying out the tensile tests as per the American Society for Testing and Materials (ASTM) E8M-11 standards. The tensile test results indicated that the increase of the axial force greatly improved the tensile shear load (TSL) of the friction stir welded joints at a constant tool rotational speed of 800 rpm and welding speed of 50mm/min. Sound lap joints with low distortion, lack of cavity and high tensile strength were successfully obtained with an axial force of 5kN. However, the TSL of the friction stir welded joints decreased when the axial forces were 3kN and 4kN with the same constant tool rotational and welding speed.

The effects of detwinning on the mechanical properties of AZ31B magnesium alloy with different strain rates at 423 K

In order to investigate the effects of detwinning on the mechanical property of AZ31 extruded magnesium alloy at different strain rates, tensile tests were conducted on samples which had been subjected to pre-compression to 3% along the extrusion direction, with strain rates ranging from 10−1s−1 to 10−4s−1 at 423K. The results show that the strength decreases by decreasing the strain rate both on the as-received and on the pre-compressed specimens. Yield strength of pre-compressed alloy decreased comparing with as-received specimens in the whole strain rate range. Fracture elongation of undeformed specimens increased as the strain rate decreased. However, in pre-compressed materials it decreased when the strain rate ranged from 10−2s−1 to 10−4s−1. Changes in mechanical properties were mainly related to the softening orientation induced by the twins. Detwinning occurred during the inverse tensile deformation in the pre-compressed AZ31 alloy. Due to detwinning, DXR was delayed.

Electrochemical Performance of AZ31 Magnesium Alloy under Different Processing Conditions

In order to select a good cost-performance ratio magnesium alloy as anode material, the electrochemical properties of AZ31B magnesium alloy under different processing conditions were investigated by electrochemical workstation, optical microscope (OM), scanning electron microscopy (SEM) and energy dispersed spectroscopy (EDS). Extruded, rolled, cast-rolled and as-cast AZ31 magnesium alloys were prepared as the anode materials. The results show that under different processing conditions, the extruded alloy is the best cost-performance ratio anode material among the four alloys. It possesses the most negative equilibrium potential, the lowest corrosion current density and the smallest free corrosion rate indicating the highest electrochemical activity due to the uniform fine grains and the second phase. Its corrosiun products are loose, dispersing uniformly on the extruded anode surface, prone to falling off which decrease the polarization and increase the utilization of the anode. The electrochemical activity and the corrosion resistance of the rolled and the cast-rolled alloys are relatively low, compared with the extrude samples. Due to the coarse grains, as-cast defects and coarse second phase distributed along the grain boundaries, the as-cast alloy has unstable discharge curve and positive discharge potential. The corrosions of AZ31 magnesium alloy under different conditions are almost pitting corrosion.

Microstructure and Mechanical Properties of AZ31B Magnesium Alloy by Friction Stir Welding

Friction stir welded Mg AZ31B alloy have been investigated. Friction stir welding (FSW) is carried out at different rotational speeds of 900rpm, 1120rpm, 1400rpm and 1800rpm and with change of tool materials such as High speed steel (HSS) and Stainless steel (SS) at a constant welding speed of 40mm/min, tilt angle of 2.50 and axial force of 5 KN. It is observed In this study, the effect of tool material and rotational speed on microstructure and mechanical properties of that the joint fabricated using SS tool material at a rotational speed of 1120rpm obtained higher mechanical properties as compared to those of 900rpm, 1400rpm and 1800rpm and also to those of HSS material.

Characterization of Mechanical Properties and Microstructural Analysis of Friction Stir Welded AZ31B Mg Alloy Thorough Optimized Process Parameters

In this paper, a detailed investigation has been carried out to find out the impact of the process parameters including Tool rotational speed, welding direction at constant axial force and with a taper cylindrical pin profiled HSS tool during the Friction stir welding (FSW) of AZ31B magnesium alloy lap joints. This paper evaluates & examines in an elaborate manner, the influence of these FSW parameters in the microstructure & mechanical properties of AZ31B magnesium alloy. In short, AZ31B Mg alloys were friction stir welded by varying several different process parameters and the effects of these parameters on the joint quality, microstructure & mechanical properties were discussed comprehensively. This paper also experimentally proves & suggests the optimized process parameter values to be adopted for effective lap joining of AZ31B Magnesium alloys using FSW technique.