New stainiess steels for sea water applications. Part. 1: Corrosion and mechanical properties of ferritic stainless steels

Two experimental ELI ferritic stainless steels (22 Cr – 2.5 Ni – 3 Mo and 22 Cr – 2.5 Ni – 3 Mo – Ti) prepared in laboratory and a commercial one (21 Cr – 3 Mo – Ti) were investigated. Electrochemical and laboratory exposure tests were carried out to define the localized corrosion resistance (pitting and crevice) of such steels in chloride solution. Intergranular and stress corrosion resistance was also evaluated. Room temperature tension tests and impact tests were performed. 22 Cr – 2.5 Ni – 3 Mo – Ti and 21 Cr – 3 Mo – Ti steels are immune to intergranular corrosion whatever temperature they are heat treated at and have the same pitting corrosion resistance as a function of temperature; crevice corrosion of 22 Cr – 2.5 Ni – 3 Mo is decidely better than in the commercial 21 Cr – 3 Mo – Ti. The experimental steels were immune to stress corrosion in hot chloride environment.