Abstracto

Influence of the Si content in steels on their mechanical and chemical behaviors. Part 2: Properties in corrosion

Elodie Conrath, Patrice Berthod

The four ternary steels Fe-xSi-0.01C (x=1 to 2.5%) elaborated in the first part of this work to study the effect of the silicon content and the plastic deformation on hardness, and on high temperature oxidation at this can be encountered during hot-rolling, were considered to study the effects of the same parameters on the corrosion rate in acidic aqueous solution. The additional experiments done to complete the preceding ones for characterizing the various solicitations to which iron sheets can be exposed at the different steps of their manufacturing were cyclic polarization runs performed in a 2N sulphuric solution. A lot of parameters characterizing these curves were analyzed with regards to the Si content and to the plastically deformed state. The greatest influence on the results is due to the presence of 1% and more of silicon. This element lowers the corrosion rate in the active state and modifies the shapes of both the potentialincreasing part and the potential-decreasing part of the cyclic polarization curves by comparison with pure polycrystalline iron. The better resistance against active corrosion is an additional beneficial effect of silicon which improved hardness and compression resistance at room temperature as well as high temperature oxidation behaviour, as previously seen in the first part of this work.