The oil drilling and gas production industries has been making increasing use of stainless steels because of their good combination of mechanical propriety and corrosion resistance and economically-viables alloys for onshore and offshore pipeline applications. These materials usually exhibit excellent corrosion resistance, toughness and weldability. However, of all the different types of corrosion, localized pitting corrosion is the most difficult process to control. The present work studies the effect of the cooling rate on corrosion of martensitics stainless steels 13Cr-4Ni-0,02C and 13Cr-2Ni-0,1C. It was observed that higher cooling rate led to the formation of a finer microstructure and with dendritics structures presence. The corrosion rate was determined by immersion tests and it was observed that the higher cooling rate, the higher the corrosion rate for the studied steels. Pitting density, pitting depth, and corrosion rates were all higher for 13Cr-2Ni-0,1C steel. This is due to its more refined microstructure and more dendritics structures that can act as nucleation sites for the corrosion process.
stainless steel; pitting; solidification rate; immersion test
