An overview: Fatigue behaviour of ultrafine-grained metals and alloys

Höppel, Heinz Werner; Kautz, M.; Xu, Cheng; Murashkin, M. Yu.; Langdon, Terence G.; Valiev, Ruslan Z.; Mughrabi, H.

doi:10.1016/j.ijfatigue.2005.08.014

Cited by 205 publications

(131 citation statements)

References 27 publications

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“…[4,[6][7][8][9][10][11][12] Low-cycle fatigue testing of ECAE metals has led to the conclusion that the fatigue lives of these UFG metals are only 20 to 50 pct of their coarse grain conventional counterparts, although a recovery heat treatment of these metals increases their fatigue lives. [4] Research into monotonic properties has shown that processing methods greatly change the final mechanical properties of UFG materials, [12,13] so it is not possible to make generalized predictions regarding the fatigue behavior of all UFG materials based solely on data collected for ECAE materials. Therefore, the goal of this study was to examine the fatigue resistance and deformation mechanisms active during low-cycle fatigue testing of two UFG AA5083 alloys created by the high-energy ball milling process known as cryomilling.…”

Section: Ultra-fine-grain (Ufg) and Nanocrystallinementioning

confidence: 99%

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

Walley

Lavernia

Gibeling

2009

Metall Mater Trans A

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The cyclic deformation behavior of cryomilled (CM) AA5083 alloys was compared to that of conventional AA5083-H131. The materials studied were a 100 pct CM alloy with a Gaussian grain size average of 315 nm and an alloy created by mixing 85 pct CM powder with 15 pct unmilled powder before consolidation to fabricate a plate with a bimodal grain size distribution with peak averages at 240 nm and 1.8 lm. Although the ultra-fine-grain (UFG) alloys exhibited considerably higher tensile strengths than those of the conventional material, the results from plastic-strain-controlled low-cycle fatigue tests demonstrate that all three materials exhibit identical fatigue lives across a range of plastic strain amplitudes. The CM materials exhibited softening during the first cycle, similar to other alloys produced by conventional powder metallurgy, followed by continual hardening to saturation before failure. The results reported in this study show that fatigue deformation in the CM material is accompanied by slight grain growth, pinning of dislocations at the grain boundaries, and grain rotation to produce macroscopic slip bands that localize strain, creating a single dominant fatigue crack. In contrast, the conventional alloy exhibits a cell structure and more diffuse fatigue damage accumulation.

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Section: Ultra-fine-grain (Ufg) and Nanocrystallinementioning

confidence: 99%

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

Walley

Lavernia

Gibeling

2009

Metall Mater Trans A

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“…Further fatigue strength enhancement, especially in the HCF-regime, can be achieved by ultrafine grained (UFG) or nanocrystalline material (Höppel, 2002). Grain refinement as a hardening mechanism is especially attractive in maintaining sufficient ductility for cold forming processes.…”

Section: Fatigue Of Tin Bronzesmentioning

confidence: 99%

Properties of High Performance Alloys for Electromechanical Connectors

Kuhn¹,

Altenberger²,

Hölzl³

et al. 2012

Copper Alloys - Early Applications and Current Performance - Enhancing Processes

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“…The microstructural stability loss can occur during a thermal exposition 6,7 or mechanical loading (predominantly fatigue loading). 8,9 The instability can be manifested as grain coarsening connected with a decrease in the mechanical properties, which can be lower than the properties of an unprocessed, virgin material.…”

Section: Introductionmentioning

confidence: 99%

Microstructural changes of ECAP-processed magnesium alloy AZ91 during cyclic loading at different stress-amplitude levels

Štěpánek¹,

Pantělejev²,

Man³

et al. 2018

Mater. Tehnol.

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Microstructural changes of magnesium alloy AZ91 after fatigue loading in the EX-ECAP state were evaluated using EBSD. It was found that both the number fraction of low-angle boundaries and parameter KAM decreased after the testing at a stress amplitude of 160 MPa but started to increase with the increasing stress amplitude. This behaviour can be explained with a mutual influence of dislocation accumulation (which is stronger with a higher stress amplitude) and dynamic softening (which is weaker with a decreasing number of cycles/cycles to failure). The average grain size remained almost unchanged except at a stress amplitude of 180 MPa, which could have been caused by certain conditions allowing an ideal development of both mentioned phenomena. Keywords: magnesium alloy, ECAP, EBSD, fatigue loading V pri~ujo~em~lanku avtorji opisujejo ovrednotenje mikrostrukturnih sprememb magnezijeve zlitine AZ91 z EBSD metodo zaradi utrujanja po procesiranju z ECAP-postopkom. Ugotovili so, da se tako dele`malo kotnih mej kot tudi parameter razlik v kristalografski orientaciji kristalnih zrn (KAM; angl.: Kernel Average Misorientation) zni`ujeta po testiranju pri napetostni amplitudi toda pri~neta nara{~ati z nara{~ajo~o napetostno amplitudo. To obna{anje si je mo~razlo`iti z isto~asnim vplivom kopi~enja dislokacij, (ki je intenzivnej{e pri vi{jih napetostnih amplitudah) in dinami~nim meh~anjem, (ki je manj{e pri manj{em razmerju med dejanskim {tevilom ciklov in {tevilom ciklov do poru{itve). Povpre~na velikost kristalnih zrn je ostala skoraj nespremenjena pri napetostni amplitudi 180 MPa, kar je lahko posledica specifi~nih pogojev, ki omogo~ajo idealen potek obeh omenjeni pojavov (mehanizmov). Klju~ne besede: zlitina na osnovi magnezija, ekstremno mo~na plasti~na deformacija (SPD) dose`ena z enokanalnim pravokotnim procesiranjem (ECAP), preiskovalna metoda na osnovi uklona povratno sipanih elektronov (EBSD), utrujanje oz. dinami~no (cikli~no) obremenjevanje

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An overview: Fatigue behaviour of ultrafine-grained metals and alloys

Cited by 205 publications

References 27 publications

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

Properties of High Performance Alloys for Electromechanical Connectors

Microstructural changes of ECAP-processed magnesium alloy AZ91 during cyclic loading at different stress-amplitude levels

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