Evaluation of resistance against environmental cracking of reprocessing grade Zr in nitric acid solutions

The susceptibility to stress corrosion cracking (SCC) of zirconium weldments was examined by the slow strain rate tensile test (SSRT) and fatigue corrosion test(CF) in nitric acid solution. Zirconium have the susceptibility to SCC in nitric acid. On results of SSRT, the decrease rate of life lime became lower at boundary of HAZ1 and base material (HAZ2) than that of HAZ1 in C-type specimen. This has shown that the susceptibility to SCC becomes higher in HAZ2. However, the decrease rate of life time in L-type specimen was not clearly found in HAZ2. There is relationship between the rate of cleavage type fracture ares by SCC and the decrease rate of life lime. On result of CF, the crack propagation rate of C type specimens was higher than that of L type specimens both in air at room temperature and in boiling 3 N nitric acid. The reason for this difference is considered to be the crystal anisotropy caused from hcp type structure. In addition, the crack propagation rate in HAZ is higher than in base metal. (author)