Corrosion Resistance of Domex 700 Steel After Combined Surface Treatment in Chloride Environment

Nowadays is a trend to use high strength structural materials, especially high strength steels. The most positive advantage of the high strength steels is a reduction of the total constructions and machines weight by reducing the thickness of supporting cross section while retaining the required characteristics (e.g. tensile strength, yield strength, ductility, etc.). However, the usage of high strength steels does not lead to increase of corrosion resistance of steel constructions and machines. A proper selection of surface treatments combination can increase the corrosion resistance of high strength steels by several times. The purpose of this paper was to evaluate the effect of various surface treatment combinations (grinding, phosphating and shot peening) on corrosion resistance of Domex 700 high strength steel by electrochemical tests. The selected electrochemical environment was 0.1 M NaCl which corresponds to chloride concentration in seaside atmosphere. Electrochemical characteristics were determined by linear polarization tests (LP). From the obtained results it is clear, that the surface pretreatment by shot peening deteriorates the corrosion resistance of HSLA Domex 700 steel and subsequently created phosphate layer too.