Study of corrosion resistance of chromium-nickel steel in calcium-hypochlorite solution

Abstract

The purpose of this paper is to study the corrosion resistance of different samples bf chromium-nickel steel in calcium-hypochlorite solution, by potentiodynamic method. Corrosion resistance of Cr-Ni special steels is tested with fast electrochemical methods: numerical method of linear polarization, and polarization resistance method. Numerical method of linear polarization, whose results were obtained by potentiodynamic measurement and when processed by computer, appeared to be very useful, because, the influence of subjective factor is eliminated, and it is the fastest way to obtain the corrosion current intensity. Due to higher Ca(OCl)(2) concentration, pH value of the solution is also higher as well as active chlorine concentration and corrosion activity of the medium. Quantitative method of determining the corrosion resistance leads to the conclusion that the steels tested in 50 wt.% Ca(OCl)(2) suspension are less resistant, in 1 wt.% Ca(OCl)(2) solution are more resistant than in 10 wt.% Ca(OCl)(2) solution. URANUS B6 showed the best corrosion resistance of all tested chromium - nickel steels in all the three tested media. This is probably due to higher Cr and Ni content, as well as the presence of additional alloyed elements like Mo and Co.