Change in corrosion of stainless steel in boiling nitric acid solution with Cr or V ions

Motooka, Takafumi; Yamamoto, Masahiro ; Ueno, Fumiyoshi  ; Kato, Chiaki   ; Ishijima, Yasuhiro 

It is well known that stainless steels rapidly corrode in nitric acid solutions included oxidizing ions. But the time effect of oxidizing ions on corrosion has been rarely studied. In this repot, the change in corrosion rate with time was investigated using Cr(VI) and V(V) species. Corrosion test of SUS304L stainless steel was conducted in boiling nitric acid solutions. Quantitative analysis of test solutions was done before and after corrosion tests. Corrosion rate of stainless steel in high concentration nitric acid solution with Cr(VI) was rapidly decreased and Cr(VI) was reduced to Cr(III). Corrosion rate of stainless steel in nitric acid solution with V(V) and the amount of V(V) were not greatly changed with time. It was concluded that the corrosion of a stainless steel in nitric acid solutions included Cr(VI) was greatly affected by concentration of nitric acid and test time, and the corrosion of a stainless steel in nitric acid solutions included V(V) was not affected by test time.