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The paper aims to study comparatively the fretting behavior in gross slip regime of fretting both under grease lubrication and dry condition and to investigate the mechanism of palliation of fretting wear with grease lubrication.

All fretting tests were carried out on high‐temperature fretting devices with standard GCr15 bearing steel ball against 45 steel flat and against GCr15 bearing steel flat contact pairs. The wear scar was examined by optical microscope, surface profiler and the confocal laser scanning microscope as well as energy dispersive X‐ray spectroscopy.

Compared with dry condition, the coefficient of friction and wear are decreased drastically and wear occurs mainly at the early stage of fretting under grease lubrication. The palliation effect of grease lubrication is closely associated with the amount of oil separated from the grease, the low‐oxidation corrosion and high‐hardness white layer. However, the bubbles which expelled from the contact edges have little influence on fretting wear.

The tested greases do not contain any additives for preventing possible misinterpretations of the results, but it is necessary to investigate the influence of different lubricant additives added to grease on friction and wear at different fretting conditions.

The research reveals that the palliation effect of grease lubrication on fretting wear is related closely to the amount of oil separated from the grease. The bigger penetration and more susceptible greases, which are easier to separate from the base oil, should be taken into account for palliation of fretting wear.

The presented results help to understand the palliation mechanism of grease lubrication and could be useful for designers of engineering assembly for which fretting wear is an issue.

This paper aims to investigate the fretting wear mechanism of an Al-Li alloy at room temperature, the tangential fretting wear tests were carried out.

The effects of displacement amplitude and fretting frequency on the tangential fretting wear characteristics were mainly investigated. The experimental data obtained are analyzed and compared.

The results indicated that the fretting friction coefficient increased with the increase of displacement amplitude. As the displacement amplitude increased, the wear scar morphology changed significantly, mainly in terms of delamination debris and furrow scratches. The wear mechanism changed from initial mild wear to more severe oxidative wear, adhesive wear and abrasive wear.

This paper extends the knowledge into mechanical tight connections. The conclusions can provide theoretical guidance for the fretting of mechanical tight connections in the field of automotive lightweight and aerospace.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2019-0490/

This study aims to understand the multiaxial fretting fatigue, wear and fracture characteristics of 35CrMoA steel under the elliptical loading path.

By keeping the contact pressure and torsional shear cyclic stress amplitude unchanged; the axial cyclic stress amplitude varied from 650 MPa to 850 MPa. The fretting fatigue test was carried out on MTS809 testing machine, and the axial cyclic strain response and fatigue life of the material were analyzed. The fretting zone and fracture surface morphology were observed by scanning electron microscope. The composition of wear debris was detected by energy dispersive X-ray spectrometer.

In this study, with the increase of axial stress amplitude, 35CrMoA steel will be continuously softened, and the cyclic softening degree increases. The fretting fatigue life decreases unevenly. The fretting scars in the stick region are elongated in the axial direction. The area of fracture crack propagation zone decreases. In addition, the results indicate that wear debris in the slip region is spherical and has higher oxygen content.

There were few literatures about the multiaxial fretting fatigue behavior of 35CrMoA steel, and most scholars focused on the contact pressure. This paper reveals the effect of axial cyclic stress on fretting fatigue and wear of 35CrMoA steel under the elliptical loading path.

The paper deals in some detail with the fretting wear behaviour of mild steel from room temperature to 600°C in an air atmosphere. The general mechanism of fretting for mild steel is discussed both at the lower temperatures and also at higher temperatures where normal oxidative processes become involved in the fretting mechanism. Both surface metallographic observations and surface SEM observations are presented in support of the wear processes involved. It is shown that there is a well defined wear transition temperature occurring in the region of 200°C together with the possibility of a second transition temperature occurring between 500 and 600°C. Finally, some consideration is given to the activation energy for tribo‐oxidation under fretting conditions and the manner in which the rate controlling factor changes from adhesion to oxidation as the temperature of wear increases.

The objective of this paper is to study the effect of a commercial lubricant, which contains a 50‐50 mixture of zinc diamyldithiocarbamate and petroleum oil, on the fretting corrosion of tin‐plated copper alloy contacts.

The change in contact resistance as a function of fretting cycles was used to assess the effectiveness of the lubricant in preventing the fretting corrosion of tin‐plated contacts. The surface profile, surface roughness, extent of fretting damage and extent of oxidation of the contact zone were assessed by a laser scanning microscope and surface analytical techniques to correlate the change in contact resistance with fretting cycles.

The lubricant film provides a surface coverage of 6.76±1 mg/cm² and it easily establishes metallic asperity contact between the mated tin‐plated contacts. The contact resistance of lubricated contacts remains stable for several thousand fretting cycles. Lubricated contacts reach a threshold value of 0.1 Ω around 100,000 cycles, whereas unlubricated contact reaches this value around 13,500 cycles itself. For lubricated contacts, the extent of mechanical wear of the tin coating is significantly reduced. As a result, they experience a lesser damage at the contact zone and exhibit a smoother profile. The formation of tin oxide is not appreciable and there is no oxide accumulation at the contact zone even at 380,000 cycles. The lubricant is very effective in delaying the fretting wear during the initial stages and in preventing the oxidation and accumulation of oxidation products at the contact zone in the later stages.

Metallic dialkyldithiocarbamates are useful anti‐wear and extreme pressure additives for lubricating oils. Dithiocarbamates improve the antioxidant properties of the lubricants and are effective in reducing the wear and increasing the friction‐reducing and load‐carrying ability of the base stock. The use of molybdenum dithiocarbamate as a grease additive is found to be effective in reducing fretting corrosion of ball bearings under random rotary vibrating conditions. The effect of dithiocarbamate containing lubricant oils or greases on the fretting corrosion of electrical contacts has not far been studied. The paper explores the effect of a lubricant that contains a 50‐50 mixture of petroleum oil and zinc diamyldithiocarbamate on the fretting corrosion of tin‐plated contact.

The purpose of this paper is to study the effect of surface salt spray duration on the fretting wear and electrochemical corrosion behaviors of Inconel 690 alloy.

A high-temperature steam generator was applied to salt spray test samples, a fretting wear rig was used to realize the damage behavior tests, an electrochemical workstation was applied to analysis the changes of each sample’s corrosion dynamic response before and after fretting wear.

The thickness of the oxide film that formed on sample surface was increased with the salt spray duration, and somewhat it could act as lubrication during the fretting wear process; however, the corrosive chloride would accelerate the fretting mechanical damage behavior.

In a salt steam spray condition, the fretting tribo-corrosion behaviors of Inconel 690 alloy surface was studied.

The purpose of this study is to investigate the microstructure of fretting wear behavior in 6061-T6 aluminum alloy. The fretting wear of blind riveted lap joints of 6061-T6 aluminum alloy plates, which are widely used in aircraft construction, was investigated. Fretting damages were investigated between the contact surface of the plates and between the plate and the rivet contact surface.

Experiments were carried out using a computer controlled Instron testing machine with 200 kN static and 100 kN dynamic load capacity. Max package computer program was used for the control of the experiments. Fretting scars, width of wear scars, microstructure was investigated by metallographic techniques and scanning electron microscopy.

It was found that fretting damages were occurred between the plates contacting surface and between the plate and rivet contact surface. As load and cycles increased, fretting scars increased. Fretting wear initially begins with metal-to-metal contact. Then, the formed metallic wear particles are hardened by oxidation. These hard particles spread between surfaces, causing three-body fretting wear. Fretting wear surface width increases with increasing load and number of cycles.

The useful life of many tribological joints is limited by wear or deterioration of the fretting components due to fretting by oscillating relative displacements of the friction surfaces. Such displacements are caused by vibrations, reciprocating motion, periodic bending or twisting of the mating component, etc. Fretting also tangibly reduces the surface layer quality and produces increased surface roughness, micropits, subsurface microphone.

Quantitative fretting wear prediction is of practical significance for industrial components. This study aims to establish a fretting wear model considering the formation of tribolayers and provide better fretting wear prediction.

Based on the characteristics for the formation of tribolayers, the ratio of fretting amplitude to nominal contact area length in the fretting direction is used to characterize their formation and contribution to the wear volume. The wear volume is then associated with the product of the friction energy and the ratio of fretting amplitude to nominal contact area length.

Better prediction in the wear volume can be achieved with the proposed fretting wear model by taking the formation of tribolayers into consideration.

The contribution of the formation of tribolayers to the wear volume is considered in the model and better prediction can be achieved.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2023-0004/

The first part of this paper appeared in our November/December issue and dealt with fretting wear behaviour of mild steel from room temperature to 600°C in air. The general mechanism for fretting is discussed at all temperatures where normal oxidative processes become involved. The nature of fretting wear is also covered and the effects of temperature are described. In this part of the paper, the discussion is continued to include triboxidation, delamination theory, atmospheric environment, transition temperatures, activitation energy and other factors affecting the influence of temperature on fretting.

This paper aims to study the influence of load and environment medium on the fretting behavior of SAF 2507 SDSS.

In this study, the effect of load on the fretting behavior of SAF 2507 SDSS in air and sea water were studied. The fretting wear tests under different loads were conducted with a ball-on-flat contact configuration. The friction coefficient, wear volume, surface morphology and oxidation component were determined.

With the increase of applied load, the friction coefficient decreases both in air and sea water. The fretting mechanism is gradually transformed from partial slip regime to slip regime in air while the fretting counterparts are all in the state of gross slip in sea water. In sea water, the friction coefficient is lower while the wear loss is higher compared with that in air.

This research suggests that the fretting behavior of SAF 2507 SDSS is related to load and environment medium.

The results may help us to choose the appropriate load under different environments.

The main originality of the research is to reveal the fretting behavior of SAF 2507 SDSS under different loads in air and sea water, which would help us to realize fretting behavior of SAF 2507 SDSS is controlled by the combination of applied load and lubricating environment.

The peer review history for this article is available at: http://dx.doi.org/10.1108/ILT-08-2019-0335.