Intergranular Cracking of Irradiated Thermally Sensitized Type 304 Stainless Steel in High-Temperature Water and Inert Gas Available to Purchase

Specimens of solution-annealed (SA), commercial-purity type 304 (UNS S30400) stainless steel (SS) with a high carbon content were thermally sensitized by heat treatment in a two-step process: a high-temperature sensitization at 1,023 K followed by a low-temperature sensitization at 773 K. The specimens then were irradiated to 3 x 10²³ n/m² (E > 1 MeV) at 563 K in boiling pure water. After irradiation, the materials were tensile tested at room temperature (RT) and at 563 K in inert gas and then tensile tested by the slow strain rate (SSR) method in 563 K water with different dissolved oxygen (DO) concentrations and in inert gas. Results were compared with those for unirradiated sensitized materials. The irradiated thermally sensitized SS revealed intergranular cracking (IGC) when tensile tested at RT and at 563 K in argon gas. Intergranular stress corrosion cracking (IGSCC) susceptibility of thermally sensitized specimens in high-temperature water of different DO concentrations was enhanced by neutron irradiation. A hypothetical model was proposed to interpret the enhanced IGC susceptibility. The model consisted of three cracking mechanisms: IGSCC (conventional SCC), irradiation-assisted SCC (IASCC, or enhanced SCC), and IGC (mechanical IGC).