CORROSION FATIGUE BEHAVIOUR OF STRUCTURAL MATERIALS IN VARIOUS ENVIRONMENTS CONTAINING H2S GAS

Corrosion fatigue strength of SUS 410J1 (13Cr stainless steel), and Ti-6Al-4V alloy in a steam and a humid air containing H{sub 2}S gas is discussed in terms of corrosion pits formed at the corrosion fatigue crack initiation area of base metal and weldment. Emphasis is placed upon the recent topics on corrosion fatigue crack propagation behavior of ship hull structural steels such as KA36 (TMCP) and KAS steel in a crude oil containing H{sub 2}S gas. It is demonstrated that the crack propagation rate in the base metal of KA36 (TMCP) and KAS steel is accelerated in a crude oil containing 400 ppm H{sub 2}S. It can be characterized that the environmental enhancement of the crack propagation rate in a sour crude oil depends on hydrogen evolved by reaction between the ship hull structural steels and H{sub 2}S gas in a crude oil. The further works recommended for study are touched on briefly.