Influence of precipitates on low-cycle fatigue and crack growth behavior in an ultrafine-grained aluminum alloy

Hockauf, Kristin; Wagner, Martin F.‐X.; Halle, Thorsten; Niendorf, Т.; Hockauf, Matthias; Lampke, Thomas

doi:10.1016/j.actamat.2014.07.061

Cited by 64 publications

(34 citation statements)

References 67 publications

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“…Apart from grains and sub-grains defined by high-and low-angle boundaries, coherent regions are bounded by accumulated dislocations and are commonly assigned as cells. Cell sizes are averaged out at 180 nm in the extruded condition and typically range from 80 nm-170 nm for both matrix and shear bands of the ECAP condition, which is consistent with the published cell size data determined by STEM [32]. Interestingly, the mean cell size in the matrix region is smaller (≈100 nm) compared to the shear band with the largest cells in the region with the highest microstrain.…”

Section: Evolution Of Microstructuresupporting

confidence: 76%

“…ECAP processing enhances the fraction of low-and high-angle grain boundaries, the dislocation density and the fragmentation of strengthening precipitates of the studied aluminum alloy [23,32]. A bimodal grain size distribution and an increased dislocation density appear already after one ECAP pass in both matrix and shear bands [32].…”

Section: Pit Morphologymentioning

confidence: 99%

“…A bimodal grain size distribution and an increased dislocation density appear already after one ECAP pass in both matrix and shear bands [32]. The dislocations accumulate to a complex network of deformation induced cell boundaries [23].…”

Section: Pit Morphologymentioning

confidence: 99%

“…Apart from the AlFeSi phases, the solid solution matrix of the as-cast billet contains dissolved Mg and Si, which precipitate to fine β and β´ particles during quenching [29,30]. Certain observations show that the hardening precipitates in the studied AlMgSi0.5 alloy undergo fragmentation and change in coherency by ECAP [31,32].…”

Section: Evolution Of Microstructurementioning

confidence: 99%

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Effect of Strain Localization on Pitting Corrosion of an AlMgSi0.5 Alloy

Nickel

Dietrich

Mehner

et al. 2015

Metals

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Abstract:The corrosion susceptibility of an age-hardened aluminum alloy in different processing conditions, especially after a single pass of equal-channel angular pressing (ECAP), is examined. The main question addressed is how corrosive attack is changed by strain localization. For that purpose, an AlMgSi0.5 alloy with a strain localized microstructure containing alternating shear bands was subjected to potentiodynamic polarization on a macro-scale and micro-scale using the micro-capillary technique. Pitting potentials and the corrosion appearance (pit depth, corroded area fractions and volumes) are discussed with respect to microstructural evolution due to casting, extrusion and ECAP. Size, shape and orientation of grains, constituent particle fragmentation, cell size and microstrain were analyzed. Stable pitting of shear bands results in less positive potentials compared to adjacent microstructure. More pits emerge in the shear bands, but the pit depth is reduced significantly. This is attributed to higher microstrains influencing the stability of the passivation layer and the reduced size of grains and constituent particles. The size of the crystallographic pits is associated with the deformation-induced cell size of the aluminum alloy. OPEN ACCESSMetals 2015, 5 173

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Section: Evolution Of Microstructuresupporting

confidence: 76%

Section: Pit Morphologymentioning

confidence: 99%

Section: Pit Morphologymentioning

confidence: 99%

Section: Evolution Of Microstructurementioning

confidence: 99%

See 2 more Smart Citations

Effect of Strain Localization on Pitting Corrosion of an AlMgSi0.5 Alloy

Nickel

Dietrich

Mehner

et al. 2015

Metals

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“…These investigations show the well-known effect of the grain or particle size on the fatigue crack growth. The grain refinement through ECAP leads to a minimized amount of crack deflection and roughness-induced crack closure, which results in higher crack propagation rates and, therefore, in minor thresholds [11][12][13][14][15][16][17][18]. In reinforced materials, particle sizes larger than 2-5 µm have a contrary effect on crack propagation: by increasing crack deflection and roughness-induced crack closure, crack propagation rates are lowered [19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Influence of Particulate Reinforcement and Equal-Channel Angular Pressing on Fatigue Crack Growth of an Aluminum Alloy

Köhler

Hockauf²,

Lampke³

et al. 2015

Metals

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Abstract:The fatigue crack growth behavior of unreinforced and particulate reinforced Al 2017 alloy, manufactured by powder metallurgy and additional equal-channel angular pressing (ECAP), is investigated. The reinforcement was done with 5 vol % Al2O3 particles with a size fraction of 0.2-2 µm. Our study presents the characterization of these materials by electron microscopy, tensile testing, and fatigue crack growth measurements. Whereas particulate reinforcement leads to a drastic decrease of the grain size, the influence of ECAP processing on the grain size is minor. Both reinforced conditions, with and without additional ECAP processing, exhibit reduced fatigue crack growth thresholds as compared to the matrix material. These results can be ascribed to the well-known effect of the grain size on the crack growth, since crack deflection and closure are directly affected. Despite their small grain size, the thresholds of both reinforced conditions depend strongly on the load ratio: tests at high load ratios reduce the fatigue threshold significantly. It is suggested that the strength of the particle-matrix-interface becomes the critical factor here and that the particle fracture at the interfaces dominates the failure behavior.

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Low‐Cycle‐Fatigue Performance of Stress‐Aged EN AW‐7075 Alloy

et al. 2023

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The effect of a novel heat treatment, that is, aging under superimposed external stress, on the fatigue performance and microstructural evolution of a high‐strength aluminum alloy (EN AW‐7075) is presented. Stress aging, a combination of heat treatment and superimposed external stress, can enhance the mechanical properties of EN AW‐7075 under monotonic loading due to the acceleration of precipitation kinetics. Scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) reveal that a longer aging time and the presence of superimposed stress both promote the formation and growth of precipitates, that is, the precipitation of strengthening η´ precipitates. This is confirmed by differential scanning calorimetry (DSC) heating experiments of stressless and stress‐aged states. Furthermore, stress aging leads to a reduction of dimensions of precipitate‐free zones near grain boundaries. Cyclic deformation responses (CDRs) and half‐life hysteresis loops are evaluated focusing on the low‐cycle fatigue (LCF) performance of different conditions. A noticeable cyclic hardening seen in case of the specimens aged for a short time indicates the occurrence of dynamic strain aging (DSA). Eventually, stress aging allows for an enhancement of the monotonic mechanical properties of EN AW‐7075 without degrading the cyclic performance in the LCF regime.

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Influence of precipitates on low-cycle fatigue and crack growth behavior in an ultrafine-grained aluminum alloy

Cited by 64 publications

References 67 publications

Effect of Strain Localization on Pitting Corrosion of an AlMgSi0.5 Alloy

Effect of Strain Localization on Pitting Corrosion of an AlMgSi0.5 Alloy

Influence of Particulate Reinforcement and Equal-Channel Angular Pressing on Fatigue Crack Growth of an Aluminum Alloy

Low‐Cycle‐Fatigue Performance of Stress‐Aged EN AW‐7075 Alloy

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