In this study, corrosion products of a Cr-bearing low-alloy (LA) steel and the conventional low-carbon (LC) steel with intact mill scale at the steel-concrete interface were investigated by means of backscattered electron (BSE) images. Furthermore, the effect of mill scale properties and corrosion inducing methods (long-term natural exposure to chloride solution and accelerated corrosion by chloride electromigration) on the distribution and penetration of corrosion products was compared. Complex interactions were highlighted between the corrosion products and the mill scale of LC and LA steels at the steel-concrete interface. In addition, different corrosion patterns of both steels were evident when subjected to different corrosion inducing methods.