Status report: stress corrosion cracking of Ni-base and Ti alloys milestone No.wp267M4

Susceptibility to stress corrosion cracking (SCC) of two candidate alloys for the inner container of the multibarrier nuclear waste package was evaluated by using wedge-loaded, precracked, double-cantilever-beam (DCB) specimens and the slow-strain-rate (SSR) test technique. Materials tested included Alloy C-22 and Ti Gr-12. A deaerated 90 C acidic brine (pH {approx} 2.70) containing 5 weight percent NaCl was used as the test environment. Both DCB and SSR tensile specimens were machined from mill-annealed plate materials. No additional thermal treatments were given to these specimens prior to their being exposed to the test solution. The DCB testing was performed for periods ranging from one through eight months. The initial and final stress intensity factor (K{sub I} and K{sub f}) values were calculated using a standard fracture-mechanics equation. Fractographic evaluation of the broken DCB specimens was performed by using scanning electron microscopy (SEM) to analyze the characteristics of failures