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Corrosion fatigue (CF) behavior of AISI 316L was investigated in a 3 pct NaCl aqueous solution at an R = − 1 stress ratio and a frequency of 60 Hz at room temperature. The test scale specimen was 7 cm2. The passive (0 mVRef), pitting (120 mVRef), and cathodic (− 1400 mVRef) polarization potentials were statically applied and recorded during CF tests until the samples were broken. The shaft material surface was treated with a ball burnishing (BB) process. By the results, the fatigue behavior of AISI 316L was affected by polarization potential and surface treatment. Under 0 mV potential charged tests for 5 × 105 cycles, BB treatment raised the CF strength of the shaft material from about 448 to 702 MPa with a percent 57 increase. Fractographic observations revealed that corrosion pits occurred during the experiments where anodic potential was applied and that transgranular surface fractures occurred in all cases.

The purpose of the present study was to investigate two and three-body wear resistance and hardness of eighth kinds of modern bulk-fill and resin-based composite materials — Grandio, Estelite Flow, Filtek bulk-fill, Charisma, Clearfil, Ultimate, Quadrant, and G-aenial. All samples were kept in distilled water for one week, and their Vickers hardness was determined before two- and three-body wear tests. The mean volume loss of all specimens after the wear tests was determined by the 3D profilometry. In addition, a random specimen was selected from each test group and scanning electron microscope images were taken for an analysis of wear tracks. The surface morphology of the Clearfil and Ultimate composite materials was damaged severely, whereas Grandio and Charisma had a very smooth surface after two-body wear tests. The lowest mean volume loss was measured in micro-fill Grandio two-body and three-body wear tests. The Filtek bulk-fill and resinbased composites showed similar two- and three-body wear behavior. For the composite materials considered, correlations between the filler volume loss, Vickers hardness, and two- and three-body wear resistances were found to be insignificant.

The present work deals with the effect of relative slip on fretting fatigue behaviour of 2014 Aluminium alloy with age-hardened conditions T4 and T6 in contact with a dissimilar mating material AISI 1045 steel, using a plane-on-plane configuration. There are a significant number of parameters influencing fretting fatigue behaviour. Relative slip value between the specimen and fretting pad is one of the most important factors. In the present study, the influence of relative slip was evaluated at different cyclic stress levels by using a fretting pad with a single pad span value of 10 mm. The results show the artificial temper T6 is more effective for improving the fretting fatigue life when compared with natural temper T4. This may be attributed to a higher microstructural barrier to the fretting fatigue crack nucleation and initiation, due to having lower values of relative slip with artificial temper T6.

The effect of a commercial hard anodizing on the fatigue property of 2014 Al alloy which has been solution heat treated and age hardened prior to the hard anodizing of approximately 10 μm in thickness have been investigated. The results indicated that fatigue life in high stress region for aluminium alloy samples hard anodized was shorter than that of the other material condition which has been solution heat treated and then age hardened (T6 heat treated), while the life in low stress region was longer than that of the material (T6 heat treated). However, such a coating to the aluminium substrate gives rise to a significant increase in fatigue strength of 107 cycle in comparison with the as cast condition, but a much less increase in comparison with T6 heat treated samples. From the microscopic point of view, it has been observed that fatigue fracture of samples hard anodized initiated in the coating in high stress region in opposition to low stress region in which fatigue fracture initiation started on the interface between coating and substrate.

The effect of tensile prestraining-induced residual stress on the fatigue life of notched steel parts was investigated. The study was performed on AISI 4140 steel. Rotating bending fatigue tests were carried out on semicircular notched specimens with different notch radii in the as-quenched and tempered conditions. Metallography of the specimens was performed by means of light optical microscopy. The finite-element method was used to evaluate the residual stress distribution near the notch region. Fatigue tests revealed fatigue life improvement for notched specimens, which changes depending on the notch radii and applied stress. Scanning electron microscopy was used to examine the fracture surfaces of the specimens.