Influence of Frequency on Corrosion Fatigue

Abstract

In order to clarify the influence of the speed of stress cycles on the fatigue strength under corrosion, the following three kinds of corrosion fatigue tests were carried out on the carbon steels : (1) the ordinary corrosion fatigue tests for the three kinds of frequency, by rotating-beam bending, (2) the corrosion fatigue tests in which the repeated stressing under corrosion and the pure corrosion without repeated stressing are alternatively applied, by rotating-beam bending, and (3) the corrosion fatigue tests of the two kinds of frequency, by repeated impact. These test results were summarized and discussed as follows : (1) The influence of speed of stress cycles on the fatigue strength under corrosion should be determined by both the time rate of deformation and the time of corrosion. (2) The coefficient of fatigue effect which determines the factors dominating failure under corrosion-fatigue was proposed as the following expression : k_f=-(d(logt))/(d(logN)) The reciprocal of this coefficient 1/k_f was termed as the coefficient of corrosion effect. The va1ue of k_f depends not only upon the kind of material but upon the applied stress level.