SURFACE CHARACTERIZATION OF STAINLESS-STEELS PREPARED WITH VARIOUS SURFACE TREATMENTS

In types 304 and 316, chromium was enriched in the surface oxide films, whereas nickel was enriched at the film/substrate interface. The degree of Cr-enrichment increased in the following order: mechanical polishing with emery paper in water less than chemical etching in mixed acid of 1%HF plus 10%HNO//3 less than electropolishing in mixed acid of CH//3COOH plus HClO//4 (20:1) less than chemical treatment in 10% HNO//3 or chemical passivation in 30%HNO//3. Enrichment of nickel had good correlation with enrichment of chromium.