Mechanical properties and corrosion behaviour of ultrafine-grained AA6082 produced by equal-channel angular pressing

Hockauf, Matthias; Meyer, Lothar; Nickel, Dominik; Alisch, G.; Lampke, Thomas; Wielage, B.; Krüger, Lutz

doi:10.1007/s10853-008-2724-9

Cited by 69 publications

(43 citation statements)

References 29 publications

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“…The reduced corrosion depth after ECAP was already indicated by several authors [11][12][13][14][15]17]. Contrary results were reported for Al-Ni and Al-Cu alloys containing other second phases [6].…”

Section: Pit Morphologymentioning

confidence: 81%

“…Finally, the corrosion resistance of UFG materials processed by accumulative roll bonding shows similarly contrasting results [18,19]. Table 1 presents the reviewed literature together with own results [13,14] demonstrating little consensus in the influence of ECAP processing on the corrosion behavior of aluminum alloys even within the same alloy. Certainly, the main challenge of corrosion studies in this regard is the lack of a standardized material condition suitable as benchmark for evaluating the effect of ECAP processing on the corrosion behavior.…”

Section: Introductionmentioning

confidence: 98%

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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: Pit Morphologymentioning

confidence: 81%

Section: Introductionmentioning

confidence: 98%

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

Nickel

Dietrich

Mehner

et al. 2015

Metals

Self Cite

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“…For SPD materials, corrosion behavior such as general [10][11][12][13][14][15][16][17][18][19][20], intergranular [21][22][23] and pitting corrosion [21,[24][25][26][27][28][29][30][31][32] of UFG aluminum and aluminum alloy [17,21,22,24,25,[29][30][31][32], copper and copper alloy [11,15,19,28] as well as stainless steels [10,12,18,23,27] and magnesium [13,14,16,20] processed by SPD, and corrosive environment dependence [33][34][35] have been reported. For example, corrosion resistance of aluminum alloys has mostly been reported to ...…”

Section: Introductionmentioning

confidence: 99%

Effects of Strain Energy and Grain Size on Corrosion Resistance of Ultrafine Grained Fe-20%Cr Steels with Extremely low C and N Fabricated by ECAP

Rifai

Miyamoto

Fujiwara

2015

International Journal of Corrosion

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Effect of strain energy and grain size on corrosion resistance of ultrafine grained (UFG) Fe-20%Cr steels with extremely low C and N fabricated by equal channel angular pressing (ECAP) was investigated. UFG structures of initial grain size of 144 nm exhibited the typical three-stage softening comprising recovery, recrystallization, and grain growth. Potentiodynamic polarization measurements were carried out with a conventional three-electrode cell to evaluate pitting potential. Pitting potential in 1000 mol⋅m −3 NaCl solution was nobler in UFG state, but pitting potential started to decrease monotonously at lower temperature compared to hardness. The degradation of corrosion resistance in the early stage of annealing is attributed to stability change of passivation by recovery of dislocation structures inside grains and in nonequilibrium grain boundaries. We therefore conclude that nobler potentials of UFG states were realized by not only grain size reduction but also defective deformation-induced UFG.

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“…Increased homogeneous surface energy distribution of UFG materials has been proposed as the main source for the enhanced resistance to pitting [12]. A heightened pit initiation resistance has been reported for UFG Al5052 [13], Al5083 [6], Al6082 [14] subjected to the short-term corrosion testing.…”

Section: Introductionmentioning

confidence: 99%

Significant Corrosion Resistance in an Ultrafine-Grained Al6063 Alloy with a Bimodal Grain-Size Distribution through a Self-Anodic Protection Mechanism

Oskooie

Asgharzadeh

Sadighikia

et al. 2016

Metals

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Abstract:The bimodal microstructures of Al6063 consisting of 15, 30, and 45 vol. % coarse-grained (CG) bands within the ultrafine-grained (UFG) matrix were synthesized via blending of high-energy mechanically milled powders with unmilled powders followed by hot powder extrusion. The corrosion behavior of the bimodal specimens was assessed by means of polarization, steady-state cyclic polarization and impedance tests, whereas their microstructural features and corrosion products were examined using optical microscopy (OM), scanning transmission electron microscopy (STEM), field emission scanning electron microscopy (FE-SEM), electron backscattered diffraction (EBSD), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques. The bimodal Al6063 containing 15 vol. % CG phase exhibits the highest corrosion resistance among the bimodal microstructures and even superior electrochemical behavior compared with the plain UFG and CG materials in the 3.5% NaCl solution. The enhanced corrosion resistance is attributed to the optimum cathode to anode surface area ratio that gives rise to the formation of an effective galvanic couple between CG areas and the UFG matrix. The operational galvanic coupling leads to the domination of a "self-anodic protection system" on bimodal microstructure and consequently forms a uniform thick protective passive layer over it. In contrast, the 45 vol. % CG bimodal specimen shows the least corrosion resistance due to the catastrophic galvanic corrosion in UFG regions. The observed results for UFG Al6063 suggest that metallurgical tailoring of the grain structure in terms of bimodal microstructures leads to simultaneous enhancement in the electrochemical behavior and mechanical properties of passivable alloys that are usually inversely correlated. The mechanism of self-anodic protection for passivable metals with bimodal microstructures is discussed here for the first time.

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Mechanical properties and corrosion behaviour of ultrafine-grained AA6082 produced by equal-channel angular pressing

Cited by 69 publications

References 29 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

Effects of Strain Energy and Grain Size on Corrosion Resistance of Ultrafine Grained Fe-20%Cr Steels with Extremely low C and N Fabricated by ECAP

Significant Corrosion Resistance in an Ultrafine-Grained Al6063 Alloy with a Bimodal Grain-Size Distribution through a Self-Anodic Protection Mechanism

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