The effect of temperature on fatigue crack growth behaviour of a low alloy pressure vessel steel in a simulated BWR environment

Abstract Fatigue crack growth tests for a low alloy steel equivalent to ASTM A533 Grade B Class 1 were conducted under a simulated BWR environment in a temperature range from room temperature to 320°C. The frequency and the stress ratio were 1 cpm and 0.1, respectively. Two types of CT specimens with L-S and T-S orientations were employed. In situ monitoring crack length was continuously carried out by compliance method using LVDT. Complicated temperature dependences of fatigue crack growth rates were observed: the minimum growth rates were at 175°C, while those at 100°C showed the maximum enhancement by the environmental effect, which was approximately four times the maximum compared to the current air default line in ASME Code Section XI. Even the maximum enhancement of the crack growth rates at 100°C did not exceed the current water default lines. The discontinuities of the temperature dependences of fatigue crack growth rates under a simulated BWR condition were basically consistent with those under simulated PWR conditions.