Effect of hard anodize thickness on the fatigue of AA6061 and C355 aluminium

Rateick, Richard G.; Binkowski, T. C.; Boray, B. C.

doi:10.1007/bf00240794

Cited by 44 publications

(29 citation statements)

References 2 publications

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“…The data points were curve-fit to a logarithmic model, as it was proposed by Rateick et al [15] for the fatigue behaviour of EAO-coated specimens.…”

Section: Fatigue Performancementioning

confidence: 99%

“…For aluminium wrought alloys with a conventional grain size, it is known that, in spite of the benefits that are obtained in terms of corrosion and wear resistance, anodising has a detrimental effect on the fatigue life [1,2,[15][16][17][18][19]. This is mainly due to the brittle and porous nature of the coating and the presence of tensile residual stresses.…”

Section: Introductionmentioning

confidence: 99%

“…This is mainly due to the brittle and porous nature of the coating and the presence of tensile residual stresses. Under these conditions, cracks can easily form in the coating [15][16][17]19]. Assisted by the good adherence, they will more likely propagate into the substrate than along the interface [16,20] and thus lead to a fast progress of the fatigue damage.…”

Section: Introductionmentioning

confidence: 99%

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The effect of anodic oxide coating on the fatigue behaviour of AA6082 with an ultrafine‐grained microstructure

Hockauf¹,

Köhler²,

Händel³

et al. 2011

Materialwissenschaft Werkst

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In this work, the high-cycle fatigue behaviour of the precipitation hardening aluminium wrought alloy AA6082 was investigated for a conventionally-grained and an ultrafine-grained substrate condition, with each a hard and a soft electrolytic anodic oxide (EAO) coating. The investigations were focused on the susceptibility of the coatings to anodising-and fatigueinduced cracking of the coatings and its impact on the fatigue life. For both substrate materials, the fatigue strength of the coated specimens was significantly reduced compared to the uncoated materials. Considering the resistance to crack initiation in the coating, the soft-anodised coatings were found to be superior compared to the hard-anodised ones. Moreover, the coatings on the ultrafine-grained substrate showed an enhanced resistance to anodisinginduced as well as fatigue-induced cracking. However, it is supposed that the lower resistance to crack transition from the coating into the substrate is one of the most important factors which strongly limits the fatigue life of the EAO-coated specimens. This might be the reason why the fatigue strength of the ultrafine-grained substrates is relatively low, despite their higher resistance to crack initiation.Keywords: equal-channel angular pressing (ECAP) / electrolytic anodic oxidation (EAO) / high-cycle fatigue (HCF) / ultrafine-grained / Al-Mg-Si alloy / In dieser Arbeit wird die Ermüdungsfestigkeit der ausscheidungshärtbaren Aluminiumknetlegierung AA6082 an einen normalkörnigen sowie einem ultrafeinkörnigen Zustand mit jeweils einer hart-und einer weichanodisierten Schicht (electrolytic anodic oxiddation, EAO) untersucht. Die Untersuchungen sind darauf ausgerichtet, die Anfälligkeit der Schichten für Rissbildung, sowohl beim Anodisierprozess als auch bei der Ermüdungsbelastung, zu untersuchen und Verbindungen zur Ermüdungsfestigkeit herzustellen. Für beide Substratmaterialien ergibt sich für die beschichteten Zustände eine deutliche Verschlechterung der Ermüdungsfestigkeit. Dabei zeigen sich die hartanodisierten Schichten generell als deutlich rissanfälliger im Vergleich zu den weichanodisierten Schichten. Darüber hinaus kann im Vergleich der Substratzustände festgestellt werden, dass beide Schichttypen auf dem ultrafeinkörnigen Substrat einen erhöhten Widerstand gegen eine anodisierprozessbedingte oder ermüdungsbedingte Anrissbildung besitzen. Die Untersuchungen zeigen jedoch auch, dass vor allem der Widerstand gegen einen Übergang des Risses von der Schicht ins Substrat die Lebensdauer bestimmt. Für die beschichteten ultrafeinkörnigen Substrate könnte hier der Grund für deren relativ niedrige Ermüdungsfestigkeit liegen, die sich trotz des erhöhten Widerstandes gegen Anrissbildung ergibt.Schlüsselwörter: equal-channel angular pressing (ECAP) / elektrolytisch anodische Oxidation (EAO) / ultrafeinkörnig / Ermüdungsfestigkeit / Al-Mg-Si-Legierung /

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“…The data points were curve-fit to a logarithmic model, as it was proposed by Rateick et al [15] for the fatigue behaviour of EAO-coated specimens.…”

Section: Fatigue Performancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The effect of anodic oxide coating on the fatigue behaviour of AA6082 with an ultrafine‐grained microstructure

Hockauf¹,

Köhler²,

Händel³

et al. 2011

Materialwissenschaft Werkst

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“…Sadeler [6] performed fatigue tests on 2014 aluminum alloy which has been hard anodized and reported that the fatigue cracks nucleated within the hard coating and then propagated towards the substrate. Rateick et al [7] showed that anodization of wrought 6061-T6 alloy gave rise to an appreciable reduction in fatigue strength (60% debit) and the presence of cracks throughout the film is responsible for this degradation. They also reported that in case of cast C355-T6, anodization did not affect the fatigue strength significantly.…”

Section: Introductionmentioning

confidence: 99%

Effect of sealed anodic film on fatigue performance of 2214-T6 aluminum alloy

Shahzad

Chaussumier

Chieragatti

et al. 2012

Surface and Coatings Technology

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The aim of present study is to investigate the influence of anodic film, grown by sulfuric acid anodizing and sealed in nickel-acetate solution, on fatigue strength of aluminum alloy 2214-T6 by conducting axial fatigue tests at stress ratio 'R' of 0.1 and − 1. The influence of sealed anodic film is to degrade the stress-life (S-N) fatigue performance of the base material at all stress levels. Effects of pre-treatments like degreasing and pickling employed prior to anodizing were also studied and no influence of these pre-treatments was observed on fatigue life. The surface and cross-section observations of anodic film were made by scanning electron microscope (SEM) before and after fatigue tests. The surface observations have revealed cavities which resulted from dissolution of coarse Al 2 Cu particles during anodization and network of micro-cracks on anodic film surface which were initiated as a result of sealing process. Some of these micro-cracks were found to penetrate up-to substrate and have detrimental effect on subsequent fatigue strength. The decrease in fatigue life for anodized-sealed specimens as compared to bare condition has been attributed to decrease in initiation period and multi-site crack initiations. Multi-site crack initiation has resulted in rougher fractured surfaces for the anodized specimens as compared to bare specimens tested at same stress levels.

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“…For the adhesion of structurally significant items, chromic acid anodising (CAA) [1] and, to a lesser extent, phosphoric acid anodising (PAA) [2] are usually preferred options. However, the results of numerous studies [3,4,5,6] have shown that any form of anodising is potentially harmful to the fatigue and fracture properties of the underlying substrate material. Consequently, the benefits gained in terms of corrosion protection, or improved adhesive bonding properties, must always be weighed against the incurred penalty of a reduction to the fatigue strength of the component.…”

Section: Introductionmentioning

confidence: 99%

Fatigue and fracture assessment of toxic metal replacement coatings for aerospace applications

Cree

Devlin

Critchlow

et al. 2010

Transactions of the IMF

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The use of corrosion resistant, and adhesion promoting films and coatings is established industrial practice for many fatigue sensitive components and structures. However, recent environmental legislation restricting the use of a range of toxic heavy metals and their derivative processes, such as chromic acid anodising (CAA), has meant that a number of new coatings systems and pretreatments are currently being developed to replace the traditional processes still in use. Typical of these new systems are the boric acid-sulphuric acid anodising (BSAA) process which can be modified to provide excellent adhesive bonding properties; the sulphuric acid anodising process, which includes an additional electrolytic phosphoric acid deoxidizing stage (EPAD) to produce a duplex oxide layer, and the recently patented ACDC sulphuric acid anodising process which produces a two layered oxide film which can be tailored to produce different porosity volume fractions within each layer. This communication reports the preliminary findings of a study carried out to assess the fatigue response of Al2618:T6 aluminium alloys to these new processes. In contrast to CAA anodising, the initial results indicate that the EPAD and ACDC processes do not appear to have a significant affect on fatigue.

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Effect of hard anodize thickness on the fatigue of AA6061 and C355 aluminium

Cited by 44 publications

References 2 publications

The effect of anodic oxide coating on the fatigue behaviour of AA6082 with an ultrafine‐grained microstructure

The effect of anodic oxide coating on the fatigue behaviour of AA6082 with an ultrafine‐grained microstructure

Effect of sealed anodic film on fatigue performance of 2214-T6 aluminum alloy

Fatigue and fracture assessment of toxic metal replacement coatings for aerospace applications

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