Influences of Secondary Stress Fluctuations of Small Amplitude on Low-Cycle Corrosion Fatigue

Abstract

The influences of small superimposed stress fluctuations on low-cycle corrosion fatigue under trapezoidal waveform are varied by the susceptibility of the test materials to stress corrosion cracking (SCC). The corrosion-fatigue life of the materials which are insensitive to SCC is greatly diminished if small stress fluctuations are superimposed. The crack initiation is shortened somewhat by such a superposition. In materials sensitive to SCC, the corrosion-fatigue life is almost occupied by the crack growth period, and the crack rate greatly decreases with the superposition of small stress fluctuations under Kmax higher than KISCC. Under low Kmax which is nearly equal to KISCC, the similar characteristics to that of the materials insensitive to SCC are obtained. The effects of stress change on corrosion fatigue component and SCC component have been discussed.