Influence of machined surface characteristics on a duplex stainless steel corrosion resistance

The aim of this study is to analyze the influence of machined surface characteristics on localized corrosion in synthetic sea water. The studied material is a duplex stainless steel. Mechanical surfaces are finished by turning, grinding or burnishing after turning or after grinding. Potentio-dynamic tests show an increase of pitting potential for grinded and burnished samples. In turning, residual stresses are positive because of the elevation of temperature during machining. Grinding improves surface roughness and introduces tensile residual stresses often less important than in turning. Burnishing gives excellent surface roughness and compressive residual stresses. So, this last mechanical treatment is the best for improving corrosion resistance.