The corrosion fatigue behavior of extruded az80 t5 magnesium alloy has been investigated in three different environments. The fatigue crack propagation behavior of asextruded az31b magnesium alloy welded joint and heat affected zone have been studied. Relationship between fatigue strength and grain size in az31 magnesium alloys masayuki tsushida1,2. Sem observations to fracture surfaces revealed that for all alloys, the fatigue crack mostly initiated at the surface or subsurface of samples failed within 106109 cycles. An investigation of the fatigue crack propagation fcp behavior of the asextruded magnesium alloy az80 was made by means of the constant load. The current work investigated the effect of shot peening sp on high cycle fatigue hcf behavior of the hotextruded zk60 magnesium alloy. The corrosion morphologies of asextruded magnesium alloy am60 in 3. Effect of temperature and relative humidity on fatigue crack propagation behavior of az61 magnesium alloy j. Sem observation to the fatigue crack initiation sites for the ascast mg7gd5y1nd0. May 25, 2009 an investigation of the fatigue crack propagation fcp behavior of the as extruded magnesium alloy az80 was made by means of the constant load amplitude fatigue test, scanning electron microscope sem, transmission electron microscopy tem and auger electron spectroscopy aes. Visualization of microstructural factors resisting the crack propagation in mesosegregated highstrength lowalloy steelj.
The hotextruded magnesium alloy zk60 nominal composition in wt. Mg10gd3y, az31 and az80, and zk60 alloy, and reported that the surface modifications with sp generated effective compressive stresses which shifted the fatigue crack nucleation site from the surface to subsurface regions, thus improving the. The three kinds of the asextruded az31b alloys were used in this study. Sp can significantly improve the fatigue life of the zk60 alloy. High cycle fatigue property and micro crack propagation. The creep behavior of the ti40al16nb alloy and the effect of the minor addition of sc are investigated by creep tests at 1073 k under constant load from 200 to 280 mpa. The formation of fatigue crack in an extruded mg alloy am60 relates to the almn particles. Tensile and fatigue behaviour of wrought magnesium alloys. A study on very high cycle fatigue properties of low. The principal purpose of this paper is to find the influence of maximum fatigue load on the probabilistic aspect of fatigue crack propagation life at a specified grown crack in magnesium alloys. Han, influence of load frequency and ageing heat treatment on fatigue crack propagation rate of as extruded az61 alloy.
Han, influence of load frequency and ageing heat treatment on fatigue crack propagation rate of asextruded az61 alloy. Influence of chemical liquids on the fatigue crack growth of. In this work, the effect of precompression along the extrusion direction on the straincontrolled lowcycle fatigue behavior of an extruded az31 magnesium alloy was investigated. In the present study, using the investment casting process, scaffolds of the magnesium mg alloy lae442 with two different and defined pore sizes, which had on average a diameter of 400. Stress corrosion cracking and liquid metal embrittlement. The influence of material factors including microstructure,metallurgy,corrosive media,mean stress,temperature on fatigue properties of magnesium alloys are analyzed.
The morphology, components, and phase compositions of the chemical depositions at the fatigue crack tip were analyzed by employing scanning electron microscopy sem, energy dispersive spectroscopy eds, and xray diffraction xrd, respectively. The crack propagation behavior of the alloy was analyzed by optical microscopy. Almn phase is the source of fatigue crack initiation in air. Influence of chemical liquids on the fatigue crack growth. After sp at the optimum almen intensities, the fatigue strength at 10 7 cycles in the as extruded referred to as zk60 and the t5 agingtreated referred to as zk60t5 alloys. Corrosion fatigue behavior of extruded magnesium alloy. The fatigue crack growth behavior of an az31 magnesium alloy was investigated by comparing the effect of zirconate and phosphate chemical liquids. In addition, the gear oil lubrication could lead to the flaking off of the epoxycoated layer. Fatigue test was carried out on az31b magnesium alloy. A critical discussion on influence of loading frequency on fatigue crack propagation behavior for extruded mgalzn alloys. Low cycle fatigue properties and cyclic deformation behavior. Compact tension ct of the notch direction parallel tl, vertical lt, and inclined at 45 to the.
Property improvement in light metals using shot peening. The current work investigated the effect of shot peening sp on high cycle fatigue hcf behavior of the hot extruded zk60 magnesium alloy. Introduction as magnesium alloys are very attractive materials because of their extreme light weight, high speci. Low cycle fatigue behavior of asextruded az31 magnesium alloy. The extruded am60 has an inhomogeneous microstructure characterized by. For instance, liu et al, wagner et al, and fouad et al have applied sp on mgbased alloys, e. The fatigue behavior and fatigue limits of standard and subsize specimens were observed.
Fatigue behaviour and fractography of extruded az80. Therefore, fatigue crack initiates at the edge of the hole, and it propagates perpen. Sem observation to the fatigue crack initiation sites for the as cast mg7gd5y1nd0. Surface characteristics and high cycle fatigue performance. Jul 01, 2010 the corrosion fatigue behavior of extruded az80t5 magnesium alloy has been investigated in three different environments. Surface characteristics and high cycle fatigue performance of. The creep curve of the alloy with high nb contents does not exhibit a steadystate region, and the minor addition of sc added to the alloy has no effect on minimum creep rate. Sn properties obtained in both rotating bending and axial loading were compared with each other. Property improvement in light metals using shot peening jean k.
The fatigue crack propagation rate of asextruded az31b magnesium alloy was studied. Compact tension ct of the notch direction parallel tl, vertical lt, and inclined at 45 to the extrusion direction was investigated. Journal of chinese society for corrosion and protection. Low cycle fatigue properties and cyclic deformation. Abstractthe aim of this paper is to assess the veryhighcycle fatigue vhcf behaviour of a magnesium alloy zk60. However, it is different from that of as extruded magnesium alloy am60 in 3.
A critical discussion on influence of loading frequency on. Low cycle fatigue behavior of extruded az31b magnesium alloy. Fatigue crack initiation of rolled az31b magnesium alloy in air and nacl solution was investigated. The objective of this investigation is to evaluate the low cycle fatigue properties of asextruded magnesium az31 alloy and study its cyclic deformation behavior based on the twinning effect and the variation of the dislocation density. Az80 magnesium alloy can serve as structural material since it has good mechanical properties and relatively low price, but studies on fatigue properties of az80 magnesium alloy are concentrated on the effect of surface treatment, fatigue crack propagation or fatigue properties in high cycle fatigue regime, information about the cyclic. Influence of microstructure on tensile properties and fatigue crack growth in extruded magnesium alloy am60. Corrosion fatigue behavior of extruded magnesium alloy az80. This paper summarizes the studies on fatigue properties of magnesium alloys in recent years. In air, fatigue crack of mg alloy az80 initiates at the inclusions in the surface and subsurface. The theory of crack initiation and crack propagation is expounded. Fatigue tests were conducted under axial loading at a stress ratio of. Effect of precompression deformation on the strain. Towards understanding twinning behavior near fracture surface in magnesiumj. Considering the fact that crack initiation of magnesium alloy is a surface phenomenon controlled by aspects as residual stress level near the surface, the existence of compressive residual stresses in surface region results in an improvement of fatigue properties 5, 6.
The experiments of fatigue crack propagation are carried out in laboratory air under different conditions of the maximum fatigue loads to obtain the. Understanding mechanical and fatigue behavior of a wrought. Effect of yttrium content on the ultrahigh cycle fatigue. Corrosion pits are often the initiation sites for cf cracks. In order to investigate the fatigue properties of extruded magnesium alloy in very highcycle regime, rotary bending fatigue test was performed in ambient atmosphere at room temperature using the hourglass shaped specimens of az80 alloys extruded fspecimen and treated by an artificial aging after extrusion t5specimen.
Mar 01, 2009 samples prepared from as extruded az61 plates were utilized in an axial fatigue crack propagation test. Fatigue crack propagation behavior of an asextruded. An investigation of the fatigue crack propagation fcp behavior of the asextruded magnesium alloy az80 was made by means of the constant load amplitude fatigue test, scanning electron microscope. The experimental results indicate that the crack propagation direction is parallel to the extrusion direction for tl and lt specimens, whereas the specimen inclined. The results demonstrated that the fcp rates of the az61. Even the increase of humidity, in air or argon leads to an increase of the fatigue crack propagation rate in az91, az61and am60, showing a very high sensitivity of magnesium alloys to humidity.
The effects of electromagnetic vibration on macrosegregation in az80 magnesium alloy billets have been investigated experimentally. Compact tensions ct of welded joint ltw and heat affected zone welded joint is parallel tlh and vertical lth to the extruded direction were researched. Sep 08, 2015 for instance, liu et al, wagner et al, and fouad et al have applied sp on mgbased alloys, e. Present and development of research on fatigue properties. An investigation of the fatigue crack propagation fcp behavior of the asextruded magnesium alloy az80 was made by means of the constant load amplitude fatigue test, scanning electron microscope sem, transmission electron microscopy tem and auger electron spectroscopy aes. The influences of the artificial ageing heat treatment or microstructure and loading frequency on fcp rates were discussed.
After precompression deformation occurred, the tensile yield strength decreased, whereas the tensile yield strength and ultimate tensile strength increased gradually. Many authors 9 have illustrated the influence of several environmental media on fatigue crack propagation rates of magnesium alloys. An investigation of the fatigue crack propagation fcp behavior of the as extruded magnesium alloy az80 was made by means of the constant load amplitude fatigue test, scanning electron microscope. Compared with other alloys, the alloy with y content of 2 wt% has the highest fatigue strength and its value is 105 mpa. Fatique crack propagation behavior of an asextruded magnesium alloy az80, journal of material science engineering a. In order to use a low flammability magnesium alloy as structural components, very high cycle fatigue properties of this alloy amca602 were investigated. An investigation on fatigue crack propagation fcp behavior of as extruded magnesium alloy az61 was made. The morphology, components, and phase compositions of the chemical depositions at the fatigue crack tip were analyzed by employing scanning electron microscopy sem, energy dispersive spectroscopy. Fatigue crack propagation behavior of asextruded az31b mg. While in nacl solution, crack initiated from surface damage which was produced by. Recent progress and development in extrusion of rare earth. The mechanism for fatigue behavior evaluation was discussed. Keeffect of temperature and relative humidity on fatigue crack propagation behavior of az61 magnesium alloy mater.
The mechanical properties of the epoxy coating layer are lower than that of magnesium alloy, which is the main reason for the fatigue crack initiation on the epoxy coating layer. The extrusion ratio of about 14 was applied to produce the extruded bar with external diameter of 26. Surface treatments for controlling corrosion rate of. Fatigue fracture mechanism of az31b magnesium alloy and. The corrosion fatigue behavior of extruded az80t5 magnesium alloy has been investigated in three different environments. Stress corrosion cracking and liquid metal embrittlement in. Effect of roller burnishing on the high cycle fatique performance of the highstrength wrought magnesium alloy az80, journal of scripta materiallia, pp. Fatigue crack propagation behavior of an asextruded magnesium alloy az80. After sp at the optimum almen intensities, the fatigue strength at 10 7 cycles in the asextruded referred to as zk60 and the t5 agingtreated referred to as zk60t5 alloys. Fatigue behavior of az91d magnesium alloy and its composite reinforced with sic.
While fatigue crack propagation data obtained directly using the notched fracture mechanics type samples in the recontaining mg alloys are still lacking in the literature so far, fatigue crack propagation mechanisms could be seen fig. Kaplan, hi, jn hryn, bb clow, eds 2000 magnesium technology 2000 tms, warrendale, pa. Influence of maximum fatigue load on probabilistic aspect. Keeffect of temperature and relative humidity on fatigue crack propagation behavior of az61 magnesium alloy mater sci forum, 546549 2007, pp.
Results indicate that the fatigue crack initiates from an area consisting of many distributed facets, while the region of early crack propagation is characterised by parallel traces, based on a fractographic analysis. In air, the cracked second phases were responsible for crack initiation. The processing maps based on the dynamic material modeling dmm were constructed, which is useful to analyze the deformation mechanism and the destabilization mechanism of az80. Influence of maximum fatigue load on probabilistic aspect of. The pitting corrosion morphologies for as extruded magnesium alloy am60 in 3. The alsc alloy specimens fracture as a result of shear band formation and crack propagation within the shear band.
The effect of ph values on corrosion of am60 and the role of almn particles in corrosion were discussed. Effect of precompression deformation on the straincontrolled. Influence of microstructure on tensile properties and fatigue crack growth in extruded magnesium alloy am60, international journal of fatigue, 32, 2010. Through these studie s, it was not clear to exist the fatigue limit on sn curve of extruded magnesium alloy up to 10 7 cycles. Fatigue characteristics of an extruded az61 magnesium alloyj. Low cycle fatigue behavior of the extruded az80 magnesium.
The objective of this investigation is to evaluate the low cycle fatigue properties of as extruded magnesium az31 alloy and study its cyclic deformation behavior based on the twinning effect and the variation of the dislocation density. A study on processing map and flow stress model of az80. Zeng, rongchang, han, enhou, ke, wei, dietzel, wolfgang, kainer, karl ulrich and atrens, andrejs 2010 influence of microstructure on tensile properties and fatigue crack growth in extruded magnesium alloy am60. The microstructure, mechanical properties and fatigue crack propagation fcp of extruded magnesium alloy am60 were investigated and compared with rolled am60.
A rationale for deformation twinning in nanocrystalline magnesium and magnesium az80 alloy suveen n. Figure 22 shows typical fractographs near the crack initiation site and in the crack propagation area of the fatigued samples of gw103k alloy in different states at a total strain amplitude of 0. Veryhighcycle fatigue crack initiation and propagation. Relationship between fatigue strength and grain size in.
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