Study on the Effect of Surface Finishing Methods on Pitting Corrosion Behavior of 304 Stainless Steel Alloy

In this study the effect of different surface finishing techniques on the pitting corrosion behaviour of a commercial 304 stainless steel alloy was investigated. Surface finishing methods were divided into two categories, i.e. mechanical and chemical. Mechanical treatment methods include power tooling such as grinding, emery paper brushing, stainless steel wire brushing and stainless steel shot blasting. Chemical treatment methods include chemical passivation (phosphoric acid, citric acid, nitric acid) and electro-cleaning (phosphoric acid and citric acid). Potentiodynamic polarization experiments were carried out in 3.5 wt. % NaCl solution at room temp. (20 $^{\circ}C$). The results showed that chemical treatment methods improved the corrosion resistance of stainless steel 304, measured in terms of pitting potential ($E_{pit}$). Corrosion resistance of the specimens was increased in the order of; electro-cleaning > manual passivation > mechanical cleaning. Surface of electro-cleaned specimens was smoother than rest of the surface treatment methods. Chrome content in chemically treated specimens was higher than in mechanically treated specimens as shown by EDX analysis.