Influences of Stress Ratios on Cyclic Stress Corrosion Crack Growth Characteristics of a High-strength Steel

Influences of stress ratios and stress cycle frequencies on cyclic stress corrosion crack growth characteristics of a high-strength steel have been investigated. The influences of stress ratios on crack growth rate under cyclic SCC are clearly distinguished between above and below KISCC. In the range of Kmax, KFSCC≤ Kmax < KISCC, a decrease of R causes not only an increase of da/dt but also a lowering of KFSCC. In this region crack growth rate is cycle-dependent, and the crack growth by a cyclic SCC is dominant. In high Kmax, Kmax≥ KISCC, time-dependent da/dt increases with an increase of R and the crack growth by a static SCC is dominant.