Influence of surface treatment on the pitting corrosion behaviour of high alloyed stainless steels in a chloride solution

The pitting corrosion behaviour of the austenitic stainless steel alloys 31 and A 351 with different surface treatments in a technical MgCl2 solution was investigated. Potentiometric current density-potential measurements wer e carried out, and critical repassivation temperatures were determined, usi ng a galvanometric method. Pickled, ground, abrasively blast cleaned and sh ot-peened surfaces, respectively, were analysed concerning roughness, resid ual stress, work hardening and near-surface structure. The effects of the s urface properties on the local corrosion behaviour was investigated. Basica lly, with increasing roughness, amount of residual stress and work hardenin g, one can see a tendency to decreasing resistance against pitting corrosio n. On the other hand, those effects are superimposed by special properties of the passive layer, e.g., caused by pickling, or from the processing-spec ific surface texture.