The new Fe-Cr-Mo ferritic stainless steels are reviewed with an emphasis on corrosion behavior. The properties of commercial steels are outlined showing how these alloys can be divided into general purpose (18Cr-2Mo), moderately severe service (26Cr-1Mo), and premium service (29Cr-4Mo) materials. The stress corrosion cracking (SCC), intergranular corrosion, pitting, crevice corrosion, and general corrosion of the Fe-Cr-Mo ferritic stainless steels in general is discussed. The influence of nickel on the corrosion resistance and toughness of ferritic stainless steels is considered.

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A method for calculating the anodic polarization curves of binary alloys from those of their components is presented. Heterogeneous alloys can be treated as simple galvanic couples, but homogeneous alloys are subject to a modification of Tammann's concept of surface enrichment. Potentiostatic anodic polarization curves are used to compare the calculated and experimental curves. Data are presented for the tin‐zinc, cadmium‐zinc, iron‐chromium, titanium‐chromium, and iron‐titanium systems.

Immersion and applied current studies are used to investigate the pitting behavior of binary Fe-Cr alloys formed both by conventional melting techniques and by diffusion of chromium into mild steel (chromizing). Experiments on both sets of materials show that a chromium content of 28–30 percent is critical for elimination of room-temperature pitting corrosion. It is proposed that chromium acts to improve the pitting resistance of Fe-Cr alloys by stabilizing passivity, thus reducing pit initiation and slowing pit growth. The relationship between polarization measurements and pitting is discussed. It is shown that in a simple immersion test pitting occurs at potentials quite different from the “critical” potentials predicted by polarization measurements.