Effect of extrusion conditions on grain refinement and fatigue behaviour in magnesium alloys

Uematsu, Yoshihiko; Tokaji, Keiro; Kamakura, Mitsutoshi; Uchida, K.; Shibata, Hideaki; Bekku, Norikatsu

doi:10.1016/j.msea.2006.06.117

Cited by 147 publications

(95 citation statements)

References 9 publications

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“…The fatigue limits were about 70% of the 0.2% proof strengths in all of the specimens. Several authors 1,2,5) have reported that fatigue limits obtained from the fatigue tests with R ¼ À1 correspond to about 60% of 0.2% proof strengths in AZ31B alloys. The ratio (fatigue limit/0.2% proof strength) in this study was about 10% higher than those in the references.…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3][4] However, the studies on the effect of the grain size on the fatigue properties in the Mg alloys are still quite limited. 5,6) Uematsu et al 5) have reported the effects of the grain size smaller than 10 mm on the fatigue properties in extruded AZ31B alloys. The AZ31B alloys with different grain sizes were prepared by controlling the conditions of the extrusion, and the grain sizes are 7.4 mm, 2.9 mm and 2.1 mm.…”

Section: Introductionmentioning

confidence: 99%

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Relationship between Fatigue Strength and Grain Size in AZ31 Magnesium Alloys

et al. 2008

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The effects of the grain size on the fatigue fracture behaviors in extruded AZ31B alloys were investigated. The mean grain sizes are 4.7 mm in F-specimen, 15 mm in M-specimen and 23 mm in C-specimen, respectively. The fatigue tests with R ¼ À1 were carried out with a plane fatigue bending machine, which was originally developed for thin sheet specimen. S-N curves show that the fatigue limit of the F-, the M-and the C-specimens were estimated as 160 MPa, 150 MPa and 150 MPa, respectively. The F-specimen had the highest fatigue limit in the present alloys. On the other hand, the fatigue life in low cycle region of the F-specimen is shorter than those of the M-and C-specimens. Striation-likepatterns were observed on the fracture surfaces in all of the specimens, although the grain sizes were different. Twin was not observed in the Fspecimen, but it was near the crack in the C-specimen. Consequently, twinning under the fatigue test depends on the grain size, and it affects the fatigue life of AZ31B alloys.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Relationship between Fatigue Strength and Grain Size in AZ31 Magnesium Alloys

et al. 2008

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“…Depending on their texture, wrought magnesium alloys show unique deformation behavior such as mechanical anisotropy, [2][3][4] pseudoelasticity in compression and tension loading-unloading, [4][5][6][7][8] and asymmetricity of stress-strain hysteresis loops in strain controlled low-cycle fatigue tests [9][10][11][12][13][14] and even in load controlled high-cycle fatigue tests, 4,9) etc. The orientation dependence of fatigue crack propagation behavior of magnesium single crystals, [15][16][17] and the effect of grain size [18][19][20][21] and texture [22][23][24][25] on fatigue properties of polycrystalline magnesium alloys have been reported in previous works. However, the effect of texture on the fatigue crack propagation behavior of textured polycrystalline magnesium alloys is still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Crack Propagation Behavior of Textured Polycrystalline Magnesium Alloys

et al. 2010

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This paper describes the fatigue crack propagation behavior of rolled and extruded AZ31B magnesium alloys (grain size: approximately 20 and 15 mm, respectively). Fatigue crack propagation tests were performed on center cracked plate tension specimens at a stress ratio of R ¼ 0:1 and a frequency of 10 Hz at room temperature. Loading axes were parallel to the rolling and extrusion directions; fatigue cracks propagated parallel to the transverse direction (L-T specimen of rolled AZ31B), parallel to the short transverse direction (L-S specimen of rolled AZ31B), and perpendicular to the extrusion direction (E-R specimen of extruded AZ31B). The crack growth rate (da=dN) of the L-S specimen was approximately 10 times lower than that of the L-T specimen in the examined stress intensity factor (ÁK) range. Fracture surfaces of the L-T and L-S specimens showed many steps parallel and perpendicular, respectively, to the macroscopic crack growth direction. The plot of the da=dN versus the ÁK range for the E-R specimen shows two regimes with different slopes in the examined ÁK range. The fracture surface was covered by various directional steps independent of macroscopic crack growth direction, and the fracture surface roughness at low ÁK was larger than that at high ÁK. SEM-EBSD observations revealed that the c-axis direction is unfavorable for the fatigue crack propagation in rolled AZ31B magnesium alloy. Free deformation twins were observed around the fatigue crack path in the L-T, L-S, and E-R specimens.

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“…Such a difference is connected with grain refinement, which is very effective for improving the fatigue strength. 23 Another fact that plays an important role during fatigue testing is the texture. Due to the preferential orientation of the basal planes parallel to the extrusion direction, there is an anisotropy between hardening for tensile and compressive loading.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

The effect of thermo-mechanical processing on the structure, static mechanical properties and fatigue behaviour of pure Mg

Kubásek¹,

Vojtěch²,

Dvorský³

2017

Mater. tehnol.

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Magnesium alloys find important applications in automotive, aircraft and space industries. Magnesium itself is also a key component in biodegradable metallic materials considered for applications in medicine. Although there are many studies that include the mechanical behaviour of pure Mg and its alloys after different thermomechanical processing, there is a huge impact of the processing method on the observed properties. Based on these facts, predicting the final properties is difficult. This paper deals with the preparation of pure Mg using a classic extrusion method with a low extrusion ratio, slow extrusion rate and low temperature. These parameters were selected to prevent an excessive grain size and to obtain optimal mechanical properties. The prepared materials were subsequently heat treated under different conditions and the relations between the grain size, texture strength and mechanical properties were studied. As well as static mechanical tests in tension and compression, fatigue tests were also performed. Finally, the obtained data were fitted using the Hall-Petch relation and the results were compared with the literature. The observed results confirmed the significant effect of processing on the mechanical properties with a strong impact on the Hall-Petch behaviour. Keywords: magnesium, mechanical properties, texture, Hall-Petch relation Magnezijeve zlitine so pomembne za uporabo v avtomobilski, letalski in vesoljski industriji. Magnezij je tudi klju~na komponenta v biorazgradljivih kovinskih materialih za uporabo v medicini.^eprav obstaja mnogo {tudij, ki vklju~ujejo mehansko obna{anje~istega Mg in njegovih zlitin po razli~nih termomehanskih obdelavah, je velik vpliv metode obdelovanja na opazovane lastnosti. Na osnovi tega je te`ko napovedovati kon~ne lastnosti. Ta~lanek obravnava pripravo~istega Mg s klasi~no metodo ekstruzije z majhnim razmerjem ekstruzije, majhno hitrostjo ekstruzije pri nizki temperaturi. Ti parametri so bili izbrani, da se prepre~i prekomerna rast zrn in da se dose`e optimalne mehanske lastnosti. Pripravljeni material je bil pozneje toplotno obdelan pri razli~nih pogojih in {tudirane so bile odvisnosti med velikostjo zrn, teksturo in mehanskimi lastnostmi. Razen stati~nih mehanskih preizkusov, nateznih in tla~nih, so bili izvedeni tudi preizkusi utrujanja. Na koncu so bili dobljeni podatki primerjani s Hall-Petchevim razmerjem in dobljeni rezultati so bili primerjani s podatki iz literature. Dobljeni rezultati so potrdili mo~an vpliv obdelave na mehanske lastnosti, z mo~nim vplivom na Hall-Petchevo razmerje.

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Effect of extrusion conditions on grain refinement and fatigue behaviour in magnesium alloys

Cited by 147 publications

References 9 publications

Relationship between Fatigue Strength and Grain Size in AZ31 Magnesium Alloys

Relationship between Fatigue Strength and Grain Size in AZ31 Magnesium Alloys

Fatigue Crack Propagation Behavior of Textured Polycrystalline Magnesium Alloys

The effect of thermo-mechanical processing on the structure, static mechanical properties and fatigue behaviour of pure Mg

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