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The initial crack under fretting condition occurs at lower stress amplitude and lower cycles of cyclic loading than that under plain fatigue condition. The fretting damage, for example, can be observed in fossil and nuclear power plant, aircraft, automobile and petroleum chemical plants etc. INCONEL alloy 690 is a high-chromium nickel alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. This alloy is used extensively in the industries of nuclear power, chemicals, heat-treatment and electronics. In this paper, the effect of fretting damage on fatigue behavior for INCONEL alloy 690 was studied. Also, various kinds of tests on mechanical properties such as hardness, tension and plain fatigue tests are performed. Fretting fatigue tests were carried out with flat-flat contact configuration using a bridge type contact pad and plate type specimen. Through these experiments, it is found that the fretting fatigue strength decreased about 43% compared to the plain fatigue strength. In fretting fatigue, the wear debris is observed on the contact surface, and the oblique micro-cracks are initiated at an earlier stage. These results can be used as the basic data in a structural integrity evaluation of heat and corrosion resistant alloy considering fretting damages.

The fretting fatigue behavior of the Ti811titanium alloy, as influenced by temperature, slip amplitude, and contact pressure, was investigated using a high-frequency fatigue machine and a home-made high-temperature apparatus. The fretting fatigue failure mechanisms were studied by observing the fretting surface morphology features. The results show that the sensitivity to fretting fatigue is high at both 350°C and 500°C. The higher the temperature is, the more sensitive the alloy is to fretting fatigue failure. Creep is an important factor that influences the fretting fatigue failure process at elevated temperature. The fretting fatigue life of the Ti811 alloy does not change in a monotonic way as the slip amplitude and contact pressure increase. This is due to the fact that the slip amplitude affects the action of fatigue and wear in the fretting process, and the nominal contact pressure affects the distribution and concentration of the stress and the amplitude of fretting slip at the contact surface, and thus further influences the crack initiation probability and the driving force for propagation.

Incoloy 800, which is used within steam generator tubes, is a heat resistant material since it is an iron-nickel-chromium alloy. However, construction of a systematic database is needed to receive integrity data defecting insurance of specific data about room and elevated temperature fretting fatigue behavior for Incoloy 800. Accordingly, this study investigates the specific change in fatigue limitations under the condition of the fretting fatigue as compared to that under the condition of the plain fatigue by performing plain and fretting fatigue tests on Incoloy 800 at 320°C, real operating temperature and at room-temperature, respectively. The change in the frictional force is measured during the fretting fatigue testing against the repeated cycle, and the mechanism of fretting fatigue is investigated through the observation of the fatigue-fracture surface.

An experimental investigation was conducted to examine the fretting fatigue behavior of physical vapor deposition-coated CrN film deposited on Ti-6Al-4V specimens contacted on both sides with pads of the same material. Behavior against the CrN-coated specimens was characterized through the determination of fretting fatigue strength up to 10⁷ cycles. Fretting damage of specimen surface was characterized by SEM and surface profilometer. The experimental results from the S–N tests indicate that the CrN coating is effective to improve the fretting fatigue strength until about 10⁶ cycles, but over 10⁶ cycles, the strength is lower than that of uncoated specimens. The enhanced fretting fatigue resistance can be attributed to the improved hardness of the CrN film due to change of bias voltage during the film deposition. It has also been concluded that below and about 10⁶ cycles, there is smaller influence of bias voltage on fatigue strength, whereas, over 10⁶ cycles, fatigue strength is clearly changed by bias voltage as well as contact pressure.

To improve the fatigue strength of the roller chain, the fatigue test is conducted by varying the press-fitting ratio between the pin and the holed plate. To model what occurs in a chain under load, a single plate specimen is prepared by press-fitting two pins into two holes at the ends of the plate. The FEM analysis is performed to obtain the stress amplitude and the average stress. The results, in both cases demonstrate that the fatigue strength is improved by the press-fit between the pin and the hole. The fatigue improvement mechanism is discussed based on the stress analysis.

In this study, the effect of contact pressure on fretting fatigue behavior of Al7075-T6 under cyclic normal contact loading is investigated. It is found that fretting fatigue life for the case of cyclic contact load was significantly less than that for constant contact load at the same axial and contact load levels, particularly for High Cycle Fatigue (HCF) conditions. The results showed that the fretting fatigue life decreased monotonically with the increase in normal contact load for all axial stresses. Examination of the fretting scars was performed using optical microscopy and numerical simulation was carried out using commercial finite element (FE) codes ABAQUS${}^{\text{®}}$ and FRANC2D/L${}^{{}^{\text{®}}}$ to calculate the crack propagation life. The crack initiation life was calculated by a combination of numerical and experimental results. Finally, the FE simulation was validated by a comparison between the numerical crack growth rate and the experimental measurement using replica.

Low wear resistance and high sensitivity to fretting fatigue (FF) damage limit the application of titanium alloys. In order to improve its wear resistance, surface plasma Zirconium (Zr) alloying is a candidate through solution strengthening with its property of infinite solid solution with $\alpha$–Ti and $\beta$–Ti. In this work, the plasma Zr metallurgy technique was used to improve the FF resistance of Ti6Al4V alloy combined with shot peening (SP), which is different from the combined treatments of the surface modification with high hardness and SP, and may explain the impacts of ductility and strength in improving FF resistance. The results indicate that the Zr metallurgy layer is composed of a Zr–Ti solid solution with low surface hardness and density, which induce the reduction of the fretting wear (FW) resistance and FF resistance of the Ti6Al4V alloy. Instead, when SP was used as the post treatment, the FW and FF behavior of the titanium alloy were increased obviously after prior plasma Zr metallurgy, especially to high cycle fatigue. This indicates that residual stress introduced by SP is beneficial for improving both FW and resistance.

The fretting fatigue behavior of the Ti811titanium alloy, as influenced by temperature, slip amplitude, and contact pressure, was investigated using a high-frequency fatigue machine and a home-made high-temperature apparatus. The fretting fatigue failure mechanisms were studied by observing the fretting surface morphology features. The results show that the sensitivity to fretting fatigue is high at both 350°C and 500°C. The higher the temperature is, the more sensitive the alloy is to fretting fatigue failure. Creep is an important factor that influences the fretting fatigue failure process at elevated temperature. The fretting fatigue life of the Ti811 alloy does not change in a monotonic way as the slip amplitude and contact pressure increase. This is due to the fact that the slip amplitude affects the action of fatigue and wear in the fretting process, and the nominal contact pressure affects the distribution and concentration of the stress and the amplitude of fretting slip at the contact surface, and thus further influences the crack initiation probability and the driving force for propagation.

A TiN/Ti composite coating was prepared on a Ti-811 titanium alloy substrate by an ion-assisted arc deposition (IAAD) technique with a view to improving the fretting fatigue resistance of the titanium alloy at elevated temperature. The composition distribution, bonding strength, micro-hardness, ductility, tribological properties, and fretting fatigue resistance at elevated temperature of the coating were investigated. The results indicate that the IAAD technique can be used to prepare a TiN/Ti composite coating with high hardness, good ductility, excellent bonding strength, and high load-bearing capability. The TiN/Ti composite coating can improve the resistance to wear and fretting fatigue of the Ti alloy at 350 °C because of the good toughness and high bonding strength of the IAAD TiN/Ti composite coating with excellent lubrication of Ti particles in the coating.