On the fatigue strength of uncoated and DLC coated 7075-T6 aluminum alloy

Baragetti, Sergio; Borzini, Emanuele; Božić, Željko; Arcieri, Emanuele Vincenzo

doi:10.1016/j.engfailanal.2019.04.035

Cited by 45 publications

(18 citation statements)

References 66 publications

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“…Therefore, low temperature coatings should be preferred, particularly if deposited on light alloys, as confirmed in a study on the contribution of type of coating and deposition temperature on 7075-T6 aluminum alloy [8]. The deposition of DLC coatings has been found to globally reduce the fatigue strength of 7075-T6 aluminum alloy within the number of cycles range 200,000-10,000,000 [9][10][11][12]. Another study which testifies to the doubtful contribution of PVD coatings on fatigue strength, better RCF strength, is presented in [13], where a more uniform damage-load diagram was obtained for uncoated spur gears compared to the coated components.…”

Section: Introductionmentioning

confidence: 90%

Finite Element Analysis and Experiments for Predicting Fatigue and Rolling Contact Fatigue Behavior of Spur Gears

Baragetti

2022

Period. Polytech. Mech. Eng.

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This paper presents the Finite Element (FE) analyses carried out with the aim to predict the tooth root fatigue and Rolling Contact Fatigue (RCF) behavior of spur gears, in terms of crack propagation maximum number of cycles. The combination of different materials, i.e. steel and titanium, and surface treatments, i.e. case-hardening and application of surface layers by Physical Vapor Deposition (PVD), are investigated. The residual stresses induced by the deposition of the coating are modelled. The stress intensity is described by linear elastic relations based on the crack tip opening displacement and the crack propagation in the case-hardened spur gears is described with the help of mathematical models. Experiments are carried out to evaluate tooth damage under RCF for different treated gears. The best solutions in terms of bulk material – treatment combination among the ones investigated are identified, also highlighting innovative possibilities which can guarantee appreciable performance.

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Section: Introductionmentioning

confidence: 90%

Finite Element Analysis and Experiments for Predicting Fatigue and Rolling Contact Fatigue Behavior of Spur Gears

Baragetti

2022

Period. Polytech. Mech. Eng.

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“…The uneven stress distribution on the interface between film and substrate easily induces the film cracking, spalling, or other failures 20 . DLC films deposited directly on aluminum alloy and ceramic materials have poor adhesion, because these materials are hard to bond with carbon ions 21,22 . Some materials like titanium, silicon, and chromium have good affinity with carbon to generate microcarbides on the interface when depositing DLC films 23,24 .…”

Section: Introductionmentioning

confidence: 99%

“…20 DLC films deposited directly on aluminum alloy and ceramic materials have poor adhesion, because these materials are hard to bond with carbon ions. 21,22 Some materials like titanium, silicon, and chromium have good affinity with carbon to generate microcarbides on the interface when depositing DLC films. 23,24 These carbide bonds can greatly improve the adhesion of DLC films.…”

Section: Introductionmentioning

confidence: 99%

The influence of Ti plasma etching pre‐treatment on mechanical properties of DLC film on cemented carbide

Huang

Yuan

et al. 2021

Surface & Interface Analysis

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The pre-treatment of substrate surface had been a key part of DLC film preparation to improve mechanical and tribological properties. Ti plasma etching pre-treatment was investigated in this paper as a new effective surface pre-treatment method to substitute transition layer. This pre-treatment used high-energy Ti plasma to impact substrate surface. Ti plasma etched the substrate to a depth of 407 nm and increased the roughness from 1.36 to 40.39 nm. A trace layer of substrate, together with cobalt, oxides, and other impurities, was removed. Ti plasma broke some top WC crystals and combined with the free carbon ions separating from the substrate. A DLC film was deposited on the etched surface. Compared with DLC films deposited on the untreated substrate and Ti transition layer, the DLC film on the Ti plasma etched substrate had best adhesion strength of 34.14 N. The three DLC films had the same sp 3 bonding carbon content, but Ti plasma etching treatment could promote the formation of sp 3 bonds on the interface of substrate and DLC film. This DLC film had low friction coefficient of 0.12 and low wear rate of 5.11 Â 10 À7 mm 3 / mÁN. In summary, Ti plasma etching pre-treatment could significantly improve the adhesion of DLC film and keep its excellent tribological properties.

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“…As partículas contendo o constituinte Fe e Si mostraram um efeito prejudicial nas propriedades de fadiga pois são consideradas impurezas que podem formar inclusões nas ligas dessa série, ou seja, influenciam diretamente a tenacidade e resistência a fadiga. As trincas por fadiga nucleadas nestas inclusões ou nas partículas intermetálicas próximas à superfície propagam-se até a falha(BARAGETTI et al, 2019). Contrariamente a isso, o Mg2Si não foi relatado como locais de iniciação de trinca(FINTOVÁ et al, 2020).…”

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“…Por outro lado, as trincas e os defeitos podem surgir durante o pré-tratamento de superfície e no processo de anodização. Já se sabe, por exemplo, que a anodização com ácido sulfúrico da liga de alumínio 7075-T73 oferece redução de 60% na vida à fadiga(BARAGETTI et al, 2019).Em aplicações aeronáuticas, a corrosão por pite e intergranular podem surgir na superfície das estruturas, resultando em falha por fadiga de corrosão. Alguns métodos de deformação plástica na superfície são aplicados para melhorar as propriedades da camada superficial das estruturas expostas a esses ambientes como mostrado no estudo realizado na liga de alumínio 7B50, pertencente à série de ligas Al-Zn-Mg-Cu.…”

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Obtenção, caracterização microestrutural e comportamento mecânico de ligas de alumínio da série 7xxx extrudadas para aplicações automotivas

Hattori¹

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HATTORI, Carolina S. Manufacturing, microstructural characterization, and mechanical behavior of extruded 7xxx series aluminum alloys for automotive applications, 2021. Tese (Doutorado em Tecnologia Nuclear) -Instituto de Pesquisas Energéticas e Nucleares -IPEN-CNEN/SP, São Paulo.Due to the increasingly strict legislation regarding CO2 emissions, one of the automakers' options is the use of lighter materials. This lightness issue brought even more attention to the aluminium alloys that are already widely used in the automotive industry for several applications, mainly the traditional alloys of the 5xxx and 6xxx series.In view of the industry's competitive scenario, it is necessary to develop structural alloys with high mechanical strength, such as those of the 7XXX series, which are the focus of this study. This study aims to obtain two new aluminium alloys 7108 and 7046, by extrusion, to characterize the microstructure in each stage of the manufacturing process and to analyse the mechanical behaviour in tension and fatigue. Initially, the two alloys billets were casted for further development of the extrusion process, in two different extruded profile geometries, in order to define the main process parameters and the heat treatments. The microstructures of the extruded profiles of alloys 7108 and 7046 are formed by second phase particles rich in Al-Fe-Si and fine precipitates rich in Al-Zn-Mg dispersed in an aluminium matrix. The strength limit of alloy 7046 showed a result 36% higher than alloy 7108, proving the influence of the amount of precipitates formed.For the 7046 alloy, all the maximum stress levels performed better in the fatigue properties compared to the 7108 alloy, and a significant improvement in the fatigue properties was noted due to the polishing of the specimens. On the fracture surfaces, a region with a smaller crack propagation area and a more extensive rupture region due to mechanical overload are observed. The crack propagation region is characterized by plastic deformation and the presence of striations perpendicular to the growth direction.

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On the fatigue strength of uncoated and DLC coated 7075-T6 aluminum alloy

Cited by 45 publications

References 66 publications

Finite Element Analysis and Experiments for Predicting Fatigue and Rolling Contact Fatigue Behavior of Spur Gears

Finite Element Analysis and Experiments for Predicting Fatigue and Rolling Contact Fatigue Behavior of Spur Gears

The influence of Ti plasma etching pre‐treatment on mechanical properties of DLC film on cemented carbide

Obtenção, caracterização microestrutural e comportamento mecânico de ligas de alumínio da série 7xxx extrudadas para aplicações automotivas

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