Mechanical properties of CO2 corrosion scale formed at different temperatures and their relationship to corrosion rate

The mechanical properties of CO2 corrosion scale formed on P110 tubing steel at different temperatures were investigated by nanoindentation, Vickers' indentation and tensile test. The results showed that hardness, elastic modulus, fracture toughness and bonding strength of the CO2 corrosion scale initially decreased and then increased with increasing the film formation/exposure temperature with the minimum values all presented at 100 degrees C. This trend runs inversely to that of the corrosion rate of P110 carbon steel with increasing the temperature. A scanning electron microscope was also utilised to analyse the morphology of corrosion scale. In addition, the relationship between the mechanical properties of CO2 corrosion scale and the corrosion rate of P110 tubing steel at the corresponding temperature is discussed.