The effect of fretting frequency on fretting corrosion behavior between Alloy 690TT heat-exchanger tube and 405 stainless steel plate in simulated secondary water of pressurized water reactor nuclear ...power plants was investigated. The wear volume and wear coefficient of 690TT tube increased initially and then decreased with increasing frequency, while wear volume and wear coefficient of corresponding 405 SS plate gradually increased. The mechanisms of friction and wear were analyzed in detail. The friction coefficient and the total dissipated energy deceased with increasing frequency, which is related to crack initiation and propagation. Moreover, wear mechanism changed from abrasive wear to oxidative wear and delamination as the stress increased. Finally, a predictive model of service life of 690TT tube was proposed.
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•Wear scar profile of 690TT tube is in “W” shape while it is in “U” shape for 405 SS plate.•Wear volume of 690 TT tube increases initially and then decreases with the increasing of frequency.•The main wear mechanism is affected by the local stress distribution.•An assessment model is proposed to predict the service life of 690TT tube in fretting process.
Fretting wear behaviors of Alloy 600MA in dry air and deionized water conditions were investigated. Results indicated that partial slip regime (PSR) and gross slip regime (GSR) were separated in ...running condition fretting map (RCFM). In deionized water, the boundary of PSR/GSR shifted into lower amplitude. In material response fretting map (MRFM), the cracking and particle detachment were characterized. In dry air, white etching layer (WEL) transformation resulted in the crack propagation in PSR and the formation of wear debris layer (WDL) in GSR. In deionized water, WEL was more difficult to be formed, resulting in shorter crack and smaller thickness of WDL. In nanostructured WDL, there were non-stoichiometric oxides of NiO, (Ni,Fe)(Fe,Cr)2O4 and Cr2O3 for dry air. The unoxidized phase of (Ni, Cr, Fe) coupled with non-stoichiometric oxides existed in WDL for deionized water.
•Fretting wear behaviors of Alloy 600MA in air and deionized water were studied.•The boundary of PSR/GSR in deionized water shifted into the lower amplitude.•In dry condition, white etching layer (WEL) resulted in the crack propagation.•WEL in deionized water resulted in the shorter crack and smaller thickness of WDL.•WDL had non-stoichiometric oxides for dry air and (Ni, Cr, Fe) for deionized water.
Fretting as a damaging way of the surface in contact is known for over 80 years. In the last 20 years there have been important achievements in the experimental research, understanding and ...description of the mechanisms that lead to this phenomenon. As fretting mechanisms can be discussed in close relation with many other aspects (egmovement, materials, contact, geometry, load, test device dynamics etc), and general presentation will be followed .
A running condition fretting map of 690 alloy tubes against 405 stainless steel plates was established through various fretting tests at room temperature. Three fretting regimes were observed: ...partial slip regime (PSR), mixed regime (MR), and gross slip regime (GSR). In the PSR, slight damage associated with the lowest friction coefficient (COF) and an adhesion layer due to adhesive wear were detected. In the GSR, severe damage corresponding to a higher COF and delamination were observed. In the PSR, Fe2O3 may be one of the main components of the wear particles. The spinel oxides of NiCr2O4 and/or FeCr2O4 may have existed in the debris layer in the MR and GSR.
•The evolution of wear damage of 690 alloy was investigated under various fretting conditions.•The spinel oxides of NiCr2O4 and/or FeCr2O4 might have existed in the debris layer in MR and GSR.•PPM was useful to remove debris covering on 405 SS to acquire more precise wear loss.
Ce travail de recherche se concentre sur la compréhension de l’usure du Ti-6Al-4V et la compétition entre l’usure et les mécanismes de fissuration sous sollicitations de fretting et fretting fatigue. ...Il existe de nombreuses applications où le fretting et le fretting fatigue sont les causes de rupture de système, on pourra citer les turboréacteurs d’avions ou encore les axes de train. Les sollicitations cycliques dues au fonctionnement des systèmes produisent des micro-déplacements entre les pièces, typiques du fretting. Ces travaux se concentrent sur l’usure, la prise en compte des débris d’usure dans l’interface et leurs influences sur l’amorçage et la propagation des fissures. Pour répondre à ce problème, des études expérimentales et numériques ont été menées en parallèle.Dans un premier temps, une étude numérique et expérimentale sur la compétition entre usure et amorçage a été réalisée sur le Ti-6Al-4V. Deux configurations de contact ont été étudiées, cylindre/plan et poinçon/plan. L’étude du poinçon/plan a mis en évidence la nécessité de prendre en compte la rotation du contact dans la prévision des phénomènes d’amorçage. Une méthodologie basée sur le suivi de marqueurs a permis de mesurer expérimentalement la micro-rotation entre les échantillons en contact. L’incorporation de cette rotation dans les simulations numériques a permis de mettre en évidence son influence sur les phénomènes de fissuration. Ainsi une bonne simulation des phénomènes compétitifs entre l’usure et l’amorçage de fissure a pu être réalisée et des cartes de fretting ont été déterminées. Ces cartes présentent les domaines d’endommagement en fonction des conditions de sollicitation d’un contact.Cette première partie a mis en évidence que l’usure n’était pas simulée avec exactitude. L’usure est dépendante des conditions d’essais, en d’autres termes, sa cinétique n’est pas constante quelles que soit les sollicitations. Pour mieux comprendre les mécanismes mis en jeu dans le contact homogène du Ti-6Al-4V, une étude paramétrique a été menée et met en évidence 2 mécanismes principaux d’usure, l’abrasion et l’adhésion. Ces deux mécanismes ont été associés, à l’aide d’analyses MEB, respectivement aux phénomènes d’oxydation des surfaces et aux transferts métalliques interfaciales. Une vitesse d’usure distincte est associée à chacun des mécanismes et une loi globale prenant en compte tous les paramètres d’essais étudiés est proposée. Cependant, l’observation des traces d’usure expérimentales a montré la nécessité de prendre en compte les débris dans l’interface pour pouvoir simuler les profils d’usure. Ces derniers ont un effet de concentrateur de contrainte au centre du contact, ceci tend à augmenter la profondeur d’usure et à réduire l’extension latérale du contact. Un algorithme est proposé afin de pouvoir ajouter les débris dans les simulations d’usure et permet d’obtenir des profils d’usure avec une erreur de moins de 10%.Finalement, à l’aide du modèle complet d’usure avec les débris et de fissuration, la prévision des durées de vie en fretting fatigue a pu être réalisé. Nous montrons que la méthode développée permet d’estimer de manière adéquate la réponse en fretting fatigue d’un panel varié de conditions de chargements constants. Ainsi, la carte de fretting fatigue est établie, Cette carte donne, pour un contact donné, les domaines d’amorçage, de rupture et d’activation de l’usure en fonction des chargements macroscopiques de fretting et de fatigue, est établie.
This research work focuses on the comprehension of the Ti-6Al-4V wear and the competition between wear and crack processes under fretting and fretting-fatigue solicitations. There are many applications where fretting and fretting fatigue cause system failure, such as aircraft engines or train shafts. The cyclic solicitations, due to the system functioning, produce micro-displacements between parts, which are typical of fretting. Here, we are focusing on wear, taking into account debris layers in the contact interface and their effects on crack nucleation and propagation. To answer this problem, experimental and numerical studies have been carried out.First, an experimental and numerical approach on the competition between wear and crack nucleation was performed on Ti-6Al-4V. Two contact configurations were studied, cylinder/plane and punch/pane. The punch/plane study showed the necessity of taking into account the contact rotation in the crack nucleation prediction. A methodology, based on the markers tracking, allows us to measure experimentally the micro-rotation between the two bodies in contact. The incorporated rotation in the numerical simulations confirms its influence on the crack nucleation. Hence, good simulations of competitive phenomena could be performed, and fretting maps were drawn. Fretting maps introduce damage domains as a function of solicitation conditions of the contact.This previous part has shown that wear was not well simulated. Wear depends on test conditions, in other words, its rate is not constant whatever the solicitations. To better understand the mechanisms involved in the homogeneous contact of Ti-6Al-4V, a parametric test campaign was led. This work, confirmed by SEM analysis, showed 2 principal wear mechanisms, respectively oxidation and metallic transfer between surfaces. A distinct wear rate can be related to each mechanism, thus a global law taking into account all test parameters is proposed. Nevertheless, the observed experimental wear scar demonstrates the necessity to take into account the debris layer in the contact interface in order to simulate wear profiles. These layers have a concentrator effect on stresses in the inner part of the contact, resulting in an increase of wear depth and a reduction of lateral contact extension. A new algorithm is proposed to add debris layer in the wear simulation and enables us to predict simulated wear profiles with an error below 10 %.Finally, helped by the global model with wear, debris layer and crack process, the lifetime can be predicted in fretting fatigue. We show that the developed methods allow adequate estimation of the fretting fatigue cracking response for a various panel of constant loadings. Hence, the fretting fatigue map is established. The map describes, for a given contact, the cracking nucleation domain, failure domain and activation of wear domain as a function of macroscopic fretting and fatigue loadings.
The fretting-corrosion performance of 6082 aluminum alloy in 3.5% NaCl solution was investigated in this work. The effects of displacements (5–50 μm) and loads (10–80 N) were considered. A running ...condition fretting map (RCFM) was established, which was composed of partial slip regime (PSR), mixed fretting regime (MFR), and slip regime (SR). In PSR and MFR, the worn surface could be divided into the outer micro-slip zone and the central sticking zone and the wear mechanism was mainly adhesive wear with slight corrosion. In SR, the whole contact surface was in slip, and the wear mechanism was mainly severe abrasive and corrosive wear. Compared to the static corrosion, the corrosion of 6082 alloys in MFR and SR was accelerated. However, the corrosion in PSR was weakened, which may result from the lackage of oxygen in the contact zone. The wastage level, the dominant mechanism of fretting corrosion, and synergy between corrosion and wear under different loads and displacements were quantitatively analyzed, and micro-abrasion-corrosion maps were constructed.
•The running condition fretting map of 6082 alloy was constructed.•Oxygen deficiency in contact area led to corrosion reduction in PSR.•The wear mechanism of PSR and MFR was mainly adhesive wear, and that of SR was abrasive and corrosive wear.•Identified the synergy of wear and corrosion, and the main mechanism and level of material degradation.•Micro-abrasion-corrosion maps were established to assess fretting corrosion.
In this paper, a global-local fretting design methodology for the pressure armour layer of flexible marine risers is outlined. This includes global dynamic riser analysis, geometrical and analytical ...sub-models and local nub-groove contact finite element analysis. Furthermore, a fretting test rig is developed and utilised to quantify coefficient of friction and wear coefficient under representative nub-groove loading conditions. The combination of the global-local computational methodology and experimental characterisation of pressure armour wire material allows for the development of running condition fretting maps. This identifies design criteria for critical riser global curvatures that are associated with minimum number of cycles to failure. The design methodology presented in this paper is applied to a realistic riser design study, using extreme sea-state loading conditions. In this case study, the predicted pressure armour fretting fatigue lives are found to be in the same range as the plain fatigue lives of the tensile armour layer.
•Global-local fretting design methodology for the pressure armour layer of flexible marine risers.•Global dynamic riser analysis, geometrical and analytical sub-models and local nub-groove contact finite element analysis.•Development and utilisation of a fretting rig to quantify friction and wear coefficients under representative nub-groove loading conditions.•Identification of design criteria for critical riser global curvatures associated with minimum number of cycles to failure.•Realistic riser design study, using extreme sea-state loading conditions.
To simulate the variational working conditions of the titanium fastener in the aero-engine, variable cycle fretting wear tests were carried out for normal loading (80/40 N), frequency (100/30 Hz), ...displacement amplitude (80/40 µm) and operating temperature (500/350 °C) in a self-lubricating composite coating on TC21 titanium alloy substrate, and the fretting wear behavior and wear mechanism were thoroughly investigated. The results shows that the coefficient of friction (COF) and the wear volume present a significant difference under variable cycle fretting conditions. The specimen exhibits a relatively stable COF under variable operating temperature. Whereas for the specimen under variable displacement amplitude presents a lowest wear volume. The adhesive wear is mainly found in the specimens under variable normal loading and frequency. Whereas for the specimens under variable displacement amplitude and operating temperature, abrasive wear and oxidation wear is mainly dominated, respectively. The dissipated energy calculation results demonstrate that the variable displacement amplitude and operating temperature have greater impact on the fretting wear behavior. The microstructure analysis in the cross-section of specimens reveals that the sub-surface is composed of amorphous-nano crystalline layer, plastic deformation layer and the origin coating. Additionally, the wear mechanism of the specimens under variable fretting conditions were deeply revealed. This work can provide essential information on fretting behavior and mechanism under the variational working conditions.
•The fretting wear behavior and mechanism of a composite coating were investigated under variable cycle fretting conditions.•The variation of displacement amplitude has a significant effect on fretting wear.•The amorphous-nano crystalline layer provides a protective role and suppresses wear effectively.•This work can provide essential information on fretting behavior and mechanism under the variational working conditions.
Some power transmission components are subject to the fretting corrosion failure mode, which results in rapid wear of mating surfaces or premature fatigue crack initiation. Fretting corrosion is ...generated by micro-movements of surfaces in contact. In mechanical transmissions, it is found in particular on shrink-fit connections (bearing rings, for example) and on key and spline connections when they are misaligned or not with the well design fit.
The sectoral board for mechanical transmissions and rolling bearings and CETIM is investigating the potential of technical solutions (materials, heat treatment, lubrication, etc.) to prevent fretting. This article presents a study of the impact of thermal and thermochemical heat treatments of steels used in power transmissions on the appearance, morphology and intensity of corrosion fretting.
Among the materials and heat treatments commonly used in mechanical transmissions (NF EN 683, ISO 6336-5), the following variants were studied: through-hardened steels (42CrMo4, 100Cr6), surface-hardened steels (42CrMo4), case-hardened steels (20MnCr5) and nitrided steels (42CrMo4). These variants are compared using a standardized ASTM G204 test, which involves oscillating a pressurized, lubricant-free pin (100Cr6) on a plate (the tested variant) for 24 hours. The peak-to-peal slip amplitude range is set at 50µm or 100µm. Tangential forces during testing, then the volume loss of pin and plate after testing, were measured, analysed and compared. The experimental study reveals wear resistance and depend on heat and thermochemical treatment as well as slip amplitudes. Through hardened 100Cr6 has better fretting resistance than nitrided 42CrMo4 for 50µm amplitude, but the results are completely reversed at 100µm amplitude.
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