Crack Growth Behavior of Type 304 Stainless Steel in Oxygenated 290 C Pure Water Under Low Frequency Cyclic Loading

Type 304 stainless steel crack growth behavior in oxygenated 290 C pure water was investigated under cyclic loading using fracture mechanics techniques. Crack growth rates, due to stress corrosion cracking (SCC) and corrosion fatigue (CF), were systematically measured as a function of the stress intensity factor, loading frequencies, loading wave forms, and a heat treatment. In solution annealed steel, only a transgranular cracking mode was observed, while, in sensitized steel, an intergranular cracking mode was observed at low frequencies. The crack growth rate for sensitized steel was basically described as a summation of the time dependent SCC growth rate and cycle dependent CF crack growth rate. However, during stress rise time, both SCC growth rate and CF growth rate were enhanced by a synergistic effect in combination with an aggresive environment and mechanical damage.