1993 年 33 巻 8 号 p. 877-883
Effect of dissolved oxygen concentration on fatigue crack growth behavior of a low alloy pressure vessel steel A533B CI. 1 in high temperature water was investigated. Fatigue tests were conducted at 561 K in water, of which DO concentration ranged from 1 to 8000 ppb including of BWR coolant condition. In a range of DO concentration below 1000 ppb fatigue crack growth rates (da/dN) showed independence on DO concentration, while above 1000 ppb striking DO dependence was observed, i.e. da/dN increased with increasing DO concentration. Corrosion products formed on the fracture surfaces were analyzed by an X-ray diffractometer. Magnetite was formed at all the levels of DO concentration, while hematite above 200 ppb and its X-ray diffraction intensity increased with increasing DO concentration.
Effect of DO concentration on corrosion potential of the material was also investigated and discussed with the environmentally assisted cracking by DO concentration of fatigue crack growth rate in high temperature water from the viewpoint of electrochemistry.
