STUDIES ON THE INFLUENCE OF METALLURGICAL VARIABLES ON THE STRESS-CORROSION BEHAVIOR OF AISI-304 STAINLESS-STEEL IN SODIUM-CHLORIDE SOLUTION USING THE FRACTURE-MECHANICS APPROACH

Stress corrosion data on a nuclear grade AISI type 304 stainless steel in a boiling solution of 5M NaCl + 0.15M Na2SO4 + 3 mL/L HCl (bp 381 K) for various metallurgical conditions of the steel are presented in this article. The metallurgical conditions used are solution annealing , sensitization, 10 pct cold work, 20 pct cold work, solution annealin g + sensitization, 10 pct cold work + sensitization, and 20 pct cold w ork + sensitization. The fracture mechanics approach has been used to obtain quantitative data on the stress corrosion crack growth rates. T he stress intensity factor, K-I, and J integral, J(I), have been used as evaluation parameters. The crack growth rates have been measured us ing compact tension type samples under both increasing and decreasing stress intensity factors. A crack growth rate of 5 x 10(-11) m/s was c hosen for the determination of threshold parameters. Results of the op tical microscopic and fractographic examinations are presented. Acoust ic signals were recorded during crack growth. Data generated from acou stic emissions, activation energy measurements, and fractographic feat ures indicate hydrogen embrittlement as the possible mechanism of crac king.