Abstract
Corrosion rate in different steel grades (including oilfield pipeline steels) is determined by the presence of non-metallic inclusions (NMI) in steels. Specifically, the effect of different inclusions on the quality of steels depends on their characteristics such as size, number, morphology, composition, and physical properties, as well as their location in the steel matrix. Therefore, the optimization and control of NMI in steels are very important today to obtain an improvement of the material properties of the final steel products. It is well known that a Ca-treatment of liquid steels in ladle before casting is an effective method for modification of non-metallic inclusions for improvement of the steel properties. Therefore, the NMI characteristics were evaluated in industrial steel samples of low carbon Ca-treated steel used for production of oil-pipelines. An electrolytic extraction technique was used for extraction of NMI from the steel samples followed by three-dimensional investigations of different inclusions and clusters by using SEM in combination with EDS. Moreover, the number and compositions of corrosion active non-metallic inclusions were estimated in hot rolled steel samples from two different heats. Finally, the corrosion resistance of these steels can be discussed depending on the characteristics of non-metallic inclusions present in the steel.
Highlights
The increasing energy consumption and demands for oil and natural gas requires safe and effective possibilities to transport them under high pressure for long distances to customers
An electrolytic extraction technique was used for extraction of non-metallic inclusions (NMI) from the steel samples followed by three-dimensional investigations of different inclusions and clusters by using scanning electron microscope (SEM) in combination with energy dispersive spectroscopy (EDS)
The chemical compositions of steel samples taken from both heats after hot rolling are given in
Summary
The increasing energy consumption and demands for oil and natural gas requires safe and effective possibilities to transport them under high pressure for long distances to customers. (1) the content of alloying elements (chromium, nickel and copper), which are involved in the formation of protective films of corrosion products on the steel surface, (2) the steel microstructure, and (3). The presence of components in the steel structure that cause an increased levels of stress as well as contribute to the destruction of protective films. Such components of the structure include, in particular, non-metallic inclusions (NMI) of unfavorable chemical compositions, and isolation of excess phases, including nanoscale phases. The content of chromium, nickel, and copper, which is necessary to ensure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
