Constant Strain Rate Testing of Type 304 Stainless Steel in High Temperature Water—Part II: An Investigation of the Chloride Effect on Stress Corrosion Cracking

Constant strain rate tests of Type 304 stainless steel were continued in high temperatures with varying chloride ion concentrations up to 100 ppm. A strain rate of 5 × 10⁻⁴ minute⁻¹ was employed. The effects of dissolved oxygen content in the water, heat treatment, especially slight sensitization, and most importantly chloride ion concentration on the susceptibility of Type 304 stainless steel to stress corrosion cracking (SCC) were investigated. Fracture mode was discussed, and comparison of the constant strain rate test results with conventional constant load test results was done using a cracking index (I_CSRT). The comparison justified the constant strain rate testing technique clearly. Chloride ions promoted SCC of both annealed and sensitized Type 304 stainless steel in high temperature water containing high dissolved oxygen at 286 C. It was found that chloride levels of 0.2 or 1 ppm caused intergranular cracking of the slightly sensitized steel in high temperature water containing high dissolved oxygen. However, in high temperature water containing low dissolved oxygen, chloride ion additions up to 100 ppm did not influence SCC behavior of Type 304 stainless steel.