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Influence of some minor elements on the corrosion behaviour of low alloy steels in sulfuric acid

Julien Hernaire, Patrice Berthod

The corrosion behaviours of fifteen low alloy steels were studied in a molar solution of sulphuric acid, using the classical electrochemical techniques. The studied steels are all of complex compositions but they contain less than two (and often one) percents of each alloying elements. They were synthesized from pure elements by induction foundry in inert atmosphere and the characterization of corrosion was performed according to the Stern- Geary and Tafel methods. Unsurprisingly all steels were in an active state, with lowpolarization resistances, corrosion potentials generally near -0.2 V/ HNE and current densities of corrosion just under 1mA/ cm². Nevertheless, some differences were seen between the corrosion parameters of some of these steels. The presence ofmolybdenum, niobium, tantalumand vanadium seems to lower the corrosion ratewhile the contrarywas observed for silicon and chromium. The influences of manganese and tungsten were not well established.