Austenitic stainless steels are used extensively in commercial nuclear power plants. Under
irradiation some of the materials may undergo grain boundary enrichment in some of the minor
alloying elements or impurities. The objective of this research project was to characterize the
electrochemical behavior of stainless steels with different amount of chromium, nickel and
silicon. The amount of Si in the alloys were varied from ~1% to 5%, the amount of Cr varied
from 12% to 19% and the amount of Ni from 8 to 15%. The electrochemical studies were
performed using non-irradiated materials. The tests were carried out at 288°C in water
contaminated with chloride, fluoride or sulfate in the order of 100 ppm. Typical electrochemical
techniques such as polarization resistance, potentiodynamic polarization, and electrochemical
impedance spectroscopy were used. Little or no effect was found on the effect of Si and Cr on
the electrochemical behavior in high temperature water of the several types of stainless steel
tested. That is, electrochemical tests could not explain why a material containing 12%Cr +
15%Ni + 5%Si was highly susceptible to environmental cracking in high temperature water
while a material containing 19%Cr + 10% Ni + 2%Si was not susceptible to cracking under the
same conditions.
Keywords: Austenitic stainless steels, silicon, electrochemical behavior, high temperature water