Abstract. The low-carbon steels offer economical properties of mean hardness, strength, and low corrosion resistance, but the steel can be welded without restrictions, usually. The structural low carbon steels have a ferritic-perlitic microstructure. The microstructure depends on the manufacturing technology and heat treatments of steel. This steel is not intended for heat treatment. However, due to the technological process, which is welding, the material often overheats. This overheating causes microstructure growth. The effect of larger grains of the steel microstructure is the reduction of its functional properties. Corrosion resistance is an essential factor in structural steel’s quality and application. The purpose of this article is to investigate corrosion resistance using weight loss and profile roughness parameters of typical structural steel in grade S235JR in 2.5% sulphuric acid solution in distilled water. Samples were tested after normalizing and superheating annealing. Corrosion tests show that continued corrosion characterizes tested steel in both corrosive environments. Roughness parameters for every one of the research times determine the size of steel corrosion.