Effect of strain rate on the fatigue cavitation during continuous cycling of 12% Cr-Mo-V steel at 600 °C

Abstract

The effect of the strain rate on the low-cycle fatigue life of 12% Cr-Mo-V steel was investigated at 600 °C in air. Two different total strain rates of 4 × 10 −3 and 4 × 10 −5 s −1 of triangular waveform were selected for the strain rate effect investigation. In the higher plastic strain range, the fatigue life of 12% Cr-Mo-V steel is significantly decreased with decreasing strain rate. This is considered to be the result of the damage caused by fatigue cavitation under the slow strain rate (4 × 10 −5 s −1) condition. From thermal nucleation theory, the critical strain rate, ϵ dot c, for the nucleation of fatigue cavities was found to be dependent on the strain amplitude and the controlling strain rate, and for the strain amplitude of ±2.0−±1.0%, it is found to be in the range of 1.25 × 10 −3 − 3.23 × 10 −4 s −1 for a strain rate of 4 × 10 −3 s −1,, and about 8.79 × 10 −5−2.74 × 10 −5 s −1 for a strain rate of 4 × 10 −5 s −1, respectively.