Abstract
The demand for pipeline steels has increased in the last several decades since they were able to provide an immune and economical way to carry oil and natural gas over long distances. There are two important damage modes in pipeline steels including stress corrosion cracking (SCC) and hydrogen induced cracking (HIC). The SCC cracks are those cracks which are induced due to the combined effects of a corrosive environment and sustained tensile stress. The present review article is an attempt to highlight important factors affecting the SCC in pipeline steels. Based on a literature survey, it is concluded that many factors, such as microstructure of steel, residual stresses, chemical composition of steel, applied load, alternating current (AC) current and texture, and grain boundary character affect the SCC crack initiation and propagation in pipeline steels. It is also found that crystallographic texture plays a key role in crack propagation. Grain boundaries associated with {111}∥rolling plane, {110}∥rolling plane, coincidence site lattice boundaries and low angle grain boundaries are recognized as crack resistant paths while grains with high angle grain boundaries provide easy path for the SCC intergranular crack propagation. Finally, the SCC resistance in pipeline steels is improved by modifying the microstructure of steel or controlling the texture and grain boundary character.
Highlights
The demand for energy has increased in recent decades which forced the industry to develop high resistance pipeline steels [1,2,3]
Based on the above-discussion, several factors playing a significant role on the stress corrosion cracking (SCC) susceptibility in pipeline steels are as follow: (1)
Microstructure of steel plays a key role on the SCC crack initiation and propagation
Summary
The demand for energy has increased in recent decades which forced the industry to develop high resistance pipeline steels [1,2,3]. Such steels show better mechanical properties and a higher corrosion resistance compared with normal carbon steels. These steels still suffer from two important failure modes including hydrogen induced cracking (HIC) and stress corrosion cracking (SCC) [4,5,6]. The microstructure of API X60 and X70 pipeline steels has been mainly composed of polygonal and acicular ferrite. The microstructure of L360NS pipeline steel has been composed of white blocky polygonal ferrite, gray irregular blocky quasi-polygonal ferrite and black blocky pearlite colony [10]
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