Fretting Corrosion

9 Key excerpts on "Fretting Corrosion"

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  eBook - ePub

  Mechanical Engineers' Handbook, Volume 1

  Materials and Engineering Mechanics

  • Myer Kutz(Author)
  • 2015(Publication Date)
  • Wiley

    (Publisher)

  Although there are some supporting data for such a procedure, 101 more investigation is required before it could be recommended as an acceptable approach for general application. If fretting wear at a support interface, such as between tubes and support plates of a steam generator or heat exchanger or between fuel pins and support grids of a reactor core, produces loss of fit at a support site, impact fretting may occur. Impact fretting is fretting action induced by the small lateral relative displacements between two surfaces when they impact together, where the small displacements are caused by Poisson strains or small tangential “glancing” velocity components. Impact fretting has only recently been addressed in the literature, 102 but it should be noted that under certain circumstances impact fretting may be a potential failure mode of great importance. Fretting Corrosion may be defined as any corrosive surface involvement resulting as a direct result of fretting action. The consequences of Fretting Corrosion are generally much less severe than for either fretting wear or fretting fatigue. Note that the term Fretting Corrosion is not being used here as a synonym for fretting, as in much of the early literature on this topic. Perhaps the most important single parameter in minimizing Fretting Corrosion is proper selection of the material pair for the application. Table 4 lists a variety of material pairs grouped according to their resistance to Fretting Corrosion. 103 Cross comparisons from one investigator's results to another's must be made with care because testing conditions varied widely. The minimization or prevention of fretting damage must be carefully considered as a separate problem in each individual design application because a palliative in one application may significantly accelerate fretting damage in a different application

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  Handbook of Lubrication and Tribology, Volume II

  Theory and Design, Second Edition

  • Robert W. Bruce(Author)
  • 2012(Publication Date)
  • CRC Press

    (Publisher)

  10 -1 10.1 Introduction Fretting may be defined as a friction-driven contact phenomenon in which damage occurs in the vicin-ity of the contact of two nominally clamped surfaces. In the presence of cyclic tangential loads, the two contacting bodies undergo small-scale, oscillatory, relative tangential motions known as “microslip.” This slipping motion may be localized so that the contacting surfaces do not exhibit global relative motion. Typical microslip amplitudes are on the order of 10–100 μ m. The physical mechanism of the damage involves a combination of wear, corrosion, and fatigue. These, in turn, are driven by high stress gradients near the contact and microslip. The resulting nucleated fretting crack may grow in the pres-ence of an external cyclic stress field, ultimately resulting in failure of the component. While fretting damage is very localized, it can have a huge impact on the fatigue life of an engineering component, reducing it by as much as 40%–60% (Waterhouse, 1972). Fretting was reported as early as 1911 by Eden et al. (1911), but Tomlinson (1927) is credited with the first experimental investigation using a machine to generate small relative rotations between two rings. The fact that fretting exacerbates fatigue and reduces life was noted by McDowell (1953). Early evolution of the friction coefficient was observed by Nishioka and Hirakawa (1969) and Endo and Goto (1976) and details of the fretting damage process and microwelding were described by Waterhouse and Taylor (1971) and Waterhouse (1972). Classical elastic contact mechanics began with the work of Hertz (1882), who modeled frictionless spherical contacts. Subsequently, important work done by Cattaneo (1938) and Mindlin (1949) provided the ability to analyze contacts in the presence of tangential forces. Elastic contact mechanics is a key tool to analyze fretting.

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  Bio-Tribocorrosion in Biomaterials and Medical Implants

  • Yu Yan(Author)
  • 2013(Publication Date)
  • Woodhead Publishing

    (Publisher)

  These effects are distinct fields of scientific study but they occur together to cause a material to wear. A typical example of mechanical experiments includes tangential load measurements. However, some electrochemical investigations have been carried out to understand the synergistic effects (Landolt et al., 2001 ; Ponthiaux et al., 2004). These synergies were investigated to understand corrosion, as both a mechanical and a coupled mechanical–electrochemical phenomenon (Jiang et al., 2002 ; Celis et al., 2006 ; Jiang and Stack, 2006 ; Diomidis et al., 2010). Fretting Corrosion is relevant to many industrial fields, such as nuclear power, food processing, marine engineering, and medicine. Focusing on Fretting Corrosion in the degradation of orthopedic implants, Waterhouse and Lamb (1980), Hoeppner and Chandrasekaran (1994) and Chandrasekaran et al. (1999) highlight its significant impact on the lifetime of implants. Corrosive products in physiological liquids are generated, due to Fretting Corrosion, between mineral-organic materials such as prosthetic materials and bone. This debris from the artificial joint could have a deleterious effect on the biocompatibility of the implant (Shettlemore and Bundy, 2001 ; Reclaru et al., 2002 ; Huang, 2003 ; Ingham and Fisher, 2005 ; Okazaki and Gotch, 2005). In the following sections, Fretting Corrosion of biomaterials in different joints, or generally in the human body, will initially be described with regard to medical issues. Fretting Corrosion will then be precisely defined mechanically and electrochemically, with the key points of Fretting Corrosion being highlighted and compared with sliding wear corrosion. Precise studies in laboratories are then presented to show the main characteristics of Fretting Corrosion in the biomedical field, i.e. crevice corrosion, protein effect, etc. Fretting Corrosion modeling will be discussed

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  Corrosion and Materials Selection

  A Guide for the Chemical and Petroleum Industries

  • Alireza Bahadori(Author)
  • 2014(Publication Date)
  • Wiley

    (Publisher)

  Other forms of erosion-corrosion damages are cavitation damage and Fretting Corrosion. The first is caused by the formation and collapse of vapor bubbles in a liquid near a metal surface and the second is due to contact areas between materials under load subjected to vibration and slip. It appears as pits or grooves in the metal surrounded by corrosion products. Fretting is also called “friction oxidation,” “wear oxidation,” “chafing,” and “false brinelling” (so named because the resulting pits are similar to the indentations made by a Brinell hardness test).

  2.11.7 Combating Erosion-Corrosion

  Five methods for prevention or minimization of damage due to erosion-corrosion are used. In order of importance they are:

  • Materials with better resistance to erosion corrosion
  • Design
  • Alteration of the environment
  • Coatings
  • Cathodic protection.

  2.12 Stress Corrosion Cracking

  Stress corrosion cracking (SCC) refers to cracking caused by the simultaneous presence of tensile stress and a specific corrosive medium.

  Many investigators have classified all cracking failures occurring in corrosive mediums as stress-corrosion cracking, including failures due to hydrogen embrittlement. These two types of cracking failures respond differently to environmental variables. To illustrate, cathodic protection is an effective method for preventing stress-corrosion cracking whereas it rapidly accelerates hydrogen-embrittlement effects. Hence the importance of considering stress-corrosion cracking and hydrogen embrittlement as separate phenomena is obvious.

  During stress-corrosion cracking, the metal or alloy is virtually unattached over most of its surfaces while fine cracks progress through it. This is illustrated in Figure 2.19 .

  Figure 2.19

  Branched cracks in stress-corrosion cracking.

  (Reproduced with permission from Daubert Cromwell.)

  Cross sections of SCC frequently show branched cracks. This river branching pattern is unique to SCC and is used in failure analysis to identify when this form of corrosion has occurred. This cracking phenomenon has serious consequences since it can occur at stresses within the range of a typical design.

  The two classic cases of stress-corrosion cracking are the “season cracking” of brass, and the “caustic embrittlement” of steel. Both of these obsolete terms describe the environmental conditions present that led to stress-corrosion cracking. While the effects of stress alone are well known in mechanical metallurgy (i.e., creep, fatigue, tensile failure) and corrosion alone produces characteristic dissolution reactions, the simultaneous action of both sometimes produces disastrous results.

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  Engineering Tribology

  • Gwidon Stachowiak, Andrew W Batchelor(Authors)
  • 2013(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  The corrosive contribution to fretting wear and fretting fatigue is in fact quite large compared to the mechanical contribution alone. For example, it was found that the fretting fatigue of an aluminium alloy in a vacuum is about 10–15 times that in air [47]. Viewing fretting as a F RETTING AND MINOR WEAR MECHANISMS 663 process dominated by corrosion, it would be expected that the wear rates would decrease with increased frequency of sliding since there is less time for a corrosion film to form. More information of the effect of combined corrosion and fretting on fatigue life can be found in [40]. Practical Examples of Fretting Many contacts that are nominally fixed suffer fretting in practice. These include most interference fits and devices subjected to vibration. The suppression of vibration is most important in the prevention of fretting wear and fretting fatigue. For example, in most railway wagon designs, steel wheels are press-fitted onto a steel axle. The rotation of the wheel and axle causes fretting and, more importantly, fretting fatigue. Interference fits of rotating assemblies therefore need to be carefully designed [5]. Heat exchangers provide a classical instance of a nominally static assembly which in fact suffers wear. Turbulent flow around the heat-exchange pipes causes them to vibrate against the baffle plates. Fretting wear and leakage may result. Assemblies of plates held together by rivets, i.e., air-frames, are also prone to fretting when vibration occurs. Typical examples of fretting occurring between the bearing outer ring and housing and in a riveted joint are shown in Figure 15.18. Bending Fretting movement Shaft Bearing Debris accumulation; loss of interference fit F IGURE 15.18 Examples of fretting occurring between two stationary surfaces due to oscillatory motion in a bearing assembly and in a riveted joint.

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  Fatigue of Metals

  • P. G. Forrest(Author)
  • 2013(Publication Date)
  • Pergamon

    (Publisher)

  C H A P T E R V I I C O R R O S I O N F A T I G U E AND F R E T T I N G C O R R O S I O N Corrosion fatigue CORROSIVE action on the surface of a metal may cause a general roughening of the surface and the formation of pits or crevices at certain points and this can result in a considerable loss in fatigue strength if the metal is subsequently subjected to fluctuating stresses. Much greater reductions in fatigue strength result, however, from the combined effect of both corro-sion and fluctuating stresses acting together than from either factor acting separately and the term corrosion fatigue is used to describe this behaviour. It is difficult to define corrosion fatigue precisely because corrosion can proceed in any oxidizing environment. Normal fatigue in air might there-fore be regarded, strictly, as corrosion fatigue and it has been demonstrated that the fatigue strength of a number of metals can be increased if the supply of air to the surface is restricted. For practical purposes, however, corrosion fatigue may be regarded as the effect of fluctuating stresses in a corrosive environment other than air. The process has been shown to be an electro-chemical one and, as discussed later, this accounts for its highly damaging effect. Reviews of corrosion fatigue behaviour have been written by Gough in 1932 [364], and more recently by Gilbert [365], Gould [366] and Evans [367]; Gilbert gives an extensive bibliography. Corrosion fatigue is a process quite distinct from stress corrosion cracking, which results from a steady stress acting in a corrosive environment. Stress corrosion occurs only in certain metals, generally after an incorrect heat-treatment [367], while most, if not all, metals are susceptible to corrosion fatigue. Corrosion fatigue accounts for a wide variety of failures in service, including, for example, marine propeller shafts, boiler and superheater tubes, turbine and pump components, and pipes carrying corrosive liquids.

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  Modern Physical Metallurgy and Materials Engineering

  • R. E. Smallman, R J Bishop(Authors)
  • 1999(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  S -values. The damage ratio (i.e. corrosion fatigue strength divided by the normal fatigue strength) in salt water environments is only about 0.5 for stainless steels and 0.2 for mild steel. The formation of intrustions and extrusions gives rise to fresh surface steps which form very active anodic sites in aqueous environments, analogous to the situation at the tip of a stress corrosion crack. This form of fatigue is influenced by those factors affecting normal fatigue but, in addition, involves electro-chemical factors. It is normally reduced by plating, cladding and painting but difficulties may arise in localizing the attack to a small number of sites, since the surface is continually being deformed. Anodic inhibitors may also reduce the corrosion fatigue but their use is more limited than in the absence of fatigue because of the probability of incomplete inhibition leading to increased corrosion.

  Fretting Corrosion, caused by two surfaces rubbing together, is associated with fatigue failure. The oxidation and corrosion product is continually removed, so that the problem must be tackled by improving the mechanical linkage of moving parts and by the effective use of lubricants.

  With corrosion fatigue, the fracture mechanics threshold ΔK th , is reduced and the rate of crack propagation is usually increased by a factor of two or so. Much larger increases in crack growth rate are produced, however, in low-frequency cycling when stress-corrosion fatigue effects become important.

  12.3 Surface engineering

  12.3.1 The coating and modification of surfaces

  The action of the new methods for coating or modifying material surfaces, such as vapour deposition and beam bombardment, can be highly specific and energy-efficient. They allow great flexibility in controlling the chemical composition and physical structure of surfaces and many materials which resisted conventional treatments can now be processed. Grain size and the degree of crystalline perfection can be varied over a wide range and beneficial changes in properties produced. The new techniques often eliminate the need for the random diffusion of atoms so that temperatures can be relatively low and processing times short. Scientifically, they are intriguing because their nature makes it possible to bypass thermodynamic restrictions on alloying and to form unorthodox solid solutions and new types of metastable phase.

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  Corrosion Prevention and Protection

  Practical Solutions

  • Edward Ghali, V. S. Sastri, M. Elboujdaini(Authors)
  • 2007(Publication Date)
  • Wiley

    (Publisher)

  Ludema (ed.), American Society of Mechanical Engineers, pp. 501–508, 1985. 77. Lim, S.C., Ashby, M.F., Brunton, J.H., Acta Metallurgica , 35 , 1343–1348 (1987b). 78. Lim, S.C., Ashby, M.F., Acta Metallurgica , 35 , 1–24 (1987a). The Forms of Corrosion 455 79. Hutchings, I.M., Tribology: Friction and Wear of Engineering Materials , CRC Press, Boca Raton, Florida, pp. 171–197, 1992. 80. Gopal, M., Jepson, W.P., Effect of Multiphase Flow on Corrosion, in Corrosion and Environmental Degradation , Wiley-VCH, Vol. 1, M. Schu ¨tze (ed.), pp. 265–284, 2000. 81. (a) Fischer, T.E., Anderson, M.P., Jahanmir, S., Salher, R., Wear , 124 , 133–148 (1988). (b) Quinn, T.F.J., Review of Oxidational Wear-Part I and II, Tribol. Inter. , 16 , 257–271; 305–315 (1983). 82. Guile, A.E., Juttner, B., Basic Erosion Process of Oxidized and Clean Metal Cathodes by Electric Arcs, IEEE Trans. Components, Hybrids, Manuf. Technol. , PS-8, pp. 259–269, 1980. 83. Bhushan, B., Davis, R.E., Thin Solid Film , 108 (2), 135–156 (1983). 84. Jones, D.A., Principles and Prevention of Corrosion , Prentice-Hall, Upper Saddle River, N.J., USA, 2nd edn, pp. 235–291; 343–356, 1996. 85. Van Dyke, M., An Album of Fluid Motion , The Parabolic Press, p. 107, 1982. 86. Douglas, J.F., Gasiorek, J.M., Swaffield, J.A., Fluid Mechanics , Pitman, p. 648, 1979. 87. Hurricks, P.L., The Mechanism of Fretting-A Review, Wear , 15 , 389–409 (1970). 88. ASM b, in Friction, Lubrication and Wear Technology , Vol. 18, P.J. Blau (ed.), ASM International, Ohio, USA, Waterhouse: pp. 242–256; Madsen: pp. 271–279, 1992. 89. Waterhouse, R.B., Fretting Wear, Proc.Int. Conf. on Wearof Materials , ASME, NY, pp. 17–22, 1981. 90. Uhlig, H.H., Corrosion et protection , Dunod, Paris, France, pp. 98–108, 136–143; CF pp. 148–157, 1970. 91. Almen, J.O., Fretting Corrosion, in The Corrosion Handbook , The Electrochemical Society, H.H. Uhlig (ed.), John Wiley & Sons, Inc., NY, pp. 590–597, 1948.

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  Wear of Advanced Materials

  • J. Paulo Davim(Author)
  • 2013(Publication Date)
  • Wiley-ISTE

    (Publisher)

  Implant surface damage is due to the fatigue mode wear damage process. The daily activities of patients apply cyclic contacts on the bearing surface and modular interfaces. The well-polished bearing surface maximizes the contact area and thus prevents local stress elevations. The secure oxide layers separate the two metal surfaces and avoid adhesion. The tapered surface on the femoral stem is brought into rough surface contact, so that the small contact areas will be subjected to local stress elevations and become plastically deformed. In addition, the relative displacement of two mating surfaces will break the oxide layer at contact points.

  If the process includes repeated contact loading, however, the mechanism has to be engaged in fatigue mode damage. Most of the commercial materials contain multiple defects. Some defects are dislocations due to void, inclusion and atoms missing in crystalline structure. During repeated contact loadings, the shear load causes dislocation mobility and such dislocations accumulates at the subsurface.

  Figure 5.3. The initiation of a subsurface crack by frictional contact stress and the stress intensity factor at the subsurface crack

  The dislocation pile-up creates micro-cracks which then coalesce and propagate (see Figure 5.3 ). Previous studies on the mechanism by which cracks are created below the surface due to a moving asperity, have illustrated that cracks propagate parallel to the surface due to the shear mechanism, while the cracking motion impacts the free surface due to a tensile mechanism. The location of the subsurface crack and friction coefficient are the major parameters involved in producing plate-shaped wear debris in ductile materials.

  5.2.2. Physiological corrosion of metals

  Metal corrosion is the process of degradation of metallic materials by reaction with their environment. Most metallic materials are susceptible to corrosive attack if they do not have a tenacious oxide layer on their surface. When the surface layer is permeable to oxygen and moisture, however, the process of corrosion will continue and lead to eventual failure. Among the various mechanisms of corrosion, metal corrosion is driven by electrochemical reactions – it includes a chemical reaction with electron transfer.

  During exposure to an aqueous environment, atoms on the metal surface undergo an anodic process, where electrons are released, leading to oxidation and the formation of metallic ions. The simultaneous oxidation and reduction processes, as shown in Figure 5.4 , produce the transformed metal ion Mn+ and the free electron en- . The free electrons move through the conductive metal to other surface sites. An anodic process involves oxidation of metal to an ion with a valence charge and the release of electrons. The metal ion (Mn+

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