The influence of microstructure and chemical composition of carbon and low alloy steels in CO2 corrosion. A state-of-the-art appraisal

The importance of chemical composition and microstructure on CO2 corrosion of carbon and low alloy steels has been widely recognized, but different aspects are still uncertain and contradictory results can be found in the literature. This is mainly due to the complexity of the problem and the difficulty to describe the involved mechanisms. The chemical composition and the microstructure are not independent variables; the same microstructure can be obtained with different chemical compositions and vice versa. Some authors report the effect of one of these parameters without taking into account that the other has been also modified. However, test conditions also vary widely, making them almost impossible to compare. As a consequence of the situation depicted above, it is evident that a more systematic work is required to clarify the mechanisms involved and to develop a selection criterion for the available information. The aim of the present work is to review and discuss the available information about the effect of microstructure and composition of carbon and low-alloyed steel on corrosion resistance in CO2 environments. The influence of these parameters on the efficiency of corrosion inhibitors is also considered.