Corrosion Behaviour of Dual-Phase High Carbon Steel—Microstructure Influence

Dual-phase high carbon steel is widely used in mining and in chemical industry applications in highly abrasive environments due to its excellent hardness and abrasion resistance. In recent years, the use of less expensive but more corrosive solutions in industrial processes has become more common. As a result, detailed understanding of the corrosion behaviour of dual-phase high carbon steel is needed; an issue that has, to date, been little-studied. This study investigates in detail the corrosion behaviour of dual-phase high carbon steel in a sodium chloride solution at different times, at the macro- and nano-scale, using various techniques. Using scanning electron microscopy (SEM) and 3D laser-scanning confocal microscopy, the corrosion behaviour of this important industrial steel was investigated at the micro-scale, then by using atomic force microscopy (AFM) it was further investigated at the nano-scale. The results reveal preferential corrosion attack on the retained austenitic phase, rather than the martensite phase, which is due to the carbon partitioning between martensite and austenite in this grade of steel