Fracture mechanics-based testing was used to quantify the stress-corrosion cracking and corrosion fatigue behavior of a precipitation-hardened martensitic stainless steel (Custom 465-H950) in full immersion chloride-containing environments at two applied electrochemical potentials. A plateau in the cycle-based crack-growth kinetics (da/dN) was observed during fatigue loading at low ΔK and [Cl − ] at and above 0.6 M. Evaluation of the fracture morphology and frequency dependence of this plateau behavior revealed an intergranular fracture surface morphology and constant time-dependent growth rates. These data strongly support a controlling stress-corrosion cracking mechanism occurring well below the established K ISCC for quasi-static loading. Low-amplitude cyclic loading below ΔK TH (i.e., "ripple loads") is hypothesized to enable time-dependent intergranular-stress-corrosion cracking to occur below the K ISCC via mechanical rupturing of the crack-tip film and enhancement of the H embrittlement-based SCC mechanism.

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