Effect of Alloy Composition on Pitting

The major alloying element contributing to resistance to pitting corrosion in iron- and nickel-base alloys is chromium. The effect of chromium in reducing both the critical current density and the passivating potential of iron in 1 N H2S04 is shown by the polarization curves of 

SEGMENT OF THE PERIODIC TABLE OF ELEMENTS H- BENEFICIAL, V = VARIABLE, O=N0 EFFECT X DETRIMENTAL. — = NOT INVESTIGATED 

Nickel has a very small effect on the anodic polarization behavior of iron, and hence, iron-nickel alloys are of minor significance as corrosion-resistant alloys. However, the addition of nickel to iron-chromium alloys (AISI 200 series) permits conversion of the latter as ferritic alloys to austenitic iron-chromium-nickel alloys (AISI 300 series). In 

Fig- 7.25 Critical pitting potentials for Fe-Cr alloys in 0.1 N NaCl at 25 °C. Redrawn from Ref 38 

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Effects of Alloy Composition on Pitting Corrosion Inhibition of Pitting Corrosion Crevice Corrosion... 

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