Study on Heat Treatment Effect on Corrosion of API 5L X52 steel in CO2 Environment

The objective of the present work is to study the effect of microstructure on X52 steel corrosion in CO2 environment. Based on API Specification 5L, pipe furnished to this specification may be as-rolled, normalized, normalized and tempered, subcritically stress relieved, subcritically age hardened or quenched and tempered. However, there is no specific type of heat treatment required by this specification standard. Thus, two types of heat treatment which are annealed and quenched and tempered will be use for this project. For this project, corrosion rates of both heat treated samples were examined using Linear Polarization method while microstructure and microhardness of these steels were examined by optical microscopy and hardness test, respectively. Experimental results have shown that quenched and tempered X52 steel has higher corrosion rate after 120 hour of immersion but it still has the highest strength compared to annealed X52 steel. Thus, it can be concluded that microstructure can influence the properties of materials and different heat treatment process can be used to obtain desired properties.