Slow strain rate tests (SSRTs) and HNO3/Cr6+ corrosion tests of several types stainless steels irradiated to 5.3×1024n/m2 at about 573K, were conducted to evaluate the correlation between irradiation assisted stress corrosion cracking (IASCC) and radiation induced grain boundary segregation.
All the stainless steels tested failed intergranularly after neutron irradiation. Type 321 and 347 were less susceptible to IASCC than Type 304 and 316. IASCC susceptibility was mitigated by the addition of oversized elements for chromium (for example/ titanium and niobium).
Intergranular corrosion in the HNO3/Cr6+ tests was accelerated due to irradiation in commercial purity (CP) stainless steels, while high purity (HP) stainless steels were immune to corrosion. The occurrence of IASCC in both HP and CP stainless steels indicated that radiation induced impurities enrichment may not be the main contributor to IASCC.
IASCC susceptibility could be correlated to the austenite phase stability and steels of higher austenite phase stability seemed to be less susceptible to IASCC.