Fatigue experiments have been conducted with high purity ferritic stainless steel Fe-26Cr-1Mo in air and corrosive solutions under plastic strain control. The results in air show that the cyclic hardening becomes more and more pronounced with increasing plastic strain amplitude and strain rate, Fatigue cracks usually initiate along the persistent slip bands in the cases of low strain amplitude and low cyclic strain rate, but cracks nucleant at the grain boundaries while the strain amplitude and strain rate are higher. Such behaviors can be explained according t the thermal activation theory of dislocations. A sensitive apparatus was specially developed for carrying out corrosion fatigue experiments under plastic strain control. The corrosion transient current could be accurately measured with this device. All corrosion fatigue experiments were performed within the potential range of passivity. Fatigue in 1M H_2SO_4 solution shows several interesting points. Firstly, a bump of current was found in the first half cycle when the tests started with tension. However, such behavior did not occur in the tests starting with compression. Secondly, at the strain amplitude above 2.8 * 10~(-3), there are two transient current peaks in one strain cycle. However, there is only one peak in one strain cycle when the strain amplitude is below 1.4 * 10~(-3).Thirdly, corrosion current began to decrease as soon as the cyclic handening reached saturation. Corrosion current behavior during fatigue in 1M Nacl solution was greatly different from that in 1M H_2SO_4 solution. Here, in one strain cycle, only one current peak could be found and the corrosion current increases continuously with cycling but the current amplitude remains unchanged. It was concluded that the current behavior in corrosion fatigue in 1M H_2SO_4 could be attributed to the repeated rupture of the passive film. However, in 1M Nacl solution, the corrosion fatigue behavior can not be interpreted by the model of film rupture. A model of distortion of passive film was proposed. It was suggested that the bump of current was caused by the increase of dielectric constant, which resulted from thinning solid passive film due to Poisson's effect. The decay of corrosion current at cyclic saturation regime was considered to be caused by the improvement of oxide film in quality during corrosion fatigue.
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