Corrosion Properties Characterization of 06Cr18Ni10Ti, 08Cr18Ni10Ti Steels and 42CrNiMo Alloy under Conditions Simulating Primary Coolant of Pressurized Water Reactor

Abstract

The article presents an analysis of the corrosion properties of structural materials for primary circuit of light-water reactors. Results of autoclave testing of austenitic stainless steels 06Cr18Ni10Ti, 08Cr18Ni10Ti and chromium–nickel alloy 42CrNiMo in a model environment of primary coolant at a temperature of 350 ° C and a pressure of 16.5 MPa are presented. Corrosion resistance is estimated by the rate of mass change and the appearance of the samples, the microstructure of the oxide films, and the amount of metal that entered into reaction with the corrosion environment. As established, the samples of the 42CrNiMo alloy, in contrast to the Cr18Ni10Тi steel samples, are oxidized with a mass gain of 9 mg / dm 2 for 10 000 hours of testing. The mass index of stainless-steels’ corrosion during the same exposure time almost did not change and is of 0– − 2 mg / dm 2 . The reflectivity of the surface of the samples is decreased slightly, the oxide film is firmly attached to the metal substrate; there is no local corrosion or deposits that indicates the high corrosion resistance of the studied materials. The study of the morphology of the oxide-films’ surface reveals that compact pyramidal-shaped microcrystalline precipitates grow during autoclaving. The corrosion products are chemically removed from the surface of the samples to evaluate the corrosion damage of the studied materials. As shown