SCC of Unirrradiated Stainless Steels and Ni Alloys in Hot Water

Stress corrosion crack growth rate evaluations show that all grades of stainless steels and nickel alloys are susceptible in high temperature water, whether O₂ or H₂ is high or low, the water is theoretical purity water or buffered or contaminated, the temperature lower or higher, etc.  This suggests that the underlying processes and mechanisms of crack advance are similar in these various alloys and environments.  SCC growth rate measurements performed in high temperature water showed ittle effect of grade / heat of stainless steel, martensite content or H₂ fugacity / permeation rate was observed, and large effects of yield strength, stress intensity factor, corrosion potential, and temperature.  Model “stainless steels” containing elevated Si showed high growth rates and little effect of corrosion potential or stress intensity factor.  The effects of cold work (surface cold work, bulk cold work, and weld shrinkage strain), irradiation hardening and metallurgical strengthening mechanisms, e.g., nitrogen additions or precipitation hardening appear to have a similar effect on SCC through their effect on yield strength.