Effect of Non-Metallic Inclusion Chemical and Phase Composition on Corrosion Resistance of Carbon and Low Alloy Steels in Water Media Typical for Oilfield Pipeline Operating Conditions

Abstract

Results of studying the effect of the chemical and phase composition of non-metallic inclusions on the corrosion resistance of carbon and low-alloy steels in neutral aqueous media characteristic of the operating conditions of oilfield pipelines are presented. It is shown that the corrosivity of complex nonmetallic inclusions present in modern steels depends on their chemical and phase composition, the optimization of which can prevent an unfavorable effect of these inclusions on steel corrosion resistance under oilfield pipeline operating conditions. A method for reducing the corrosivity of non-metallic inclusions based on aluminum-magnesium spinel is its oxide component modification with calcium and/or titanium, which contribute to its conversion into a globular form. An increase in corrosivity of complex non-metallic inclusions, the oxide component of which consists of various components, and correspondingly a large amount of corundum among oxide components, results in a reduction of steel corrosion resistance. An increase in the content of calcium and magnesium oxides leads to a reduction in the corrosivity of complex inclusions. In producing steels with increased corrosion resistance for oil field pipelines it is advisable to provide production methods aimed at preventing formation of adverse types of non-metallic inclusions.