Crack propagation behavior of stress corrosion cracking on zirconium in boiling nitric acid solution

Ishijima, Yasuhiro ; Kato, Chiaki   ; Yamamoto, Masahiro 

Zirconium has been utilized in chemical plant because of its superior corrosion resistance. But Stress corrosion cracking (SCC) susceptibility and black oxide film growth had been reported in some conditions. In order to clarify the relevance among SCC crack growth and oxide film formation of Zr in boiling nitric acid solution, constant load tests at potentiostatic condition were conducted. From the results, many cracks initiate under oxide film. Distribution of cracks was not change until 96 hr tested sample. In the 162 hr tested sample, SCC cracks grown over 10 m. These results suggest that the SCC mechanism of Zr in boiling nitric acid can attribute by tarnish rupture mechanism.