Purpose – This paper aims to clarify the corrosion behavior of two famous structural steels in sour environment. These steels have a vast application in oil and gas industries. The study aims to find the effect of different concentrations of sour solution on the origin of crack in these steels. Design/methodology/approach – After preparation of specimens, different sour solutions were made using the synthetic brine (according to National Association of Corrosion Engineers [NACE], Technical Committee Report 1D182) and various amounts of Na2S.9H2O and CH3COOH. The polarization test was done by Potansiostat apparatus model Zahner-IM6 at two temperatures, 25°C and 50°C. The corrosion current densities were obtained from the polarization curves. Finally, the corrosion products and hydrogen-induced cracking (HIC) were investigated by Tescan Vega II XMU scanning electron microscope (SEM) linked to a Rontec energy-dispersive X-ray spectroscopy (EDS) system. Findings – API 5L-X70 steel showed smaller corrosion current values than A516-Gr70 steel. The HIC cracks propagated parallel to the surface of A516-Gr70 steel in three solutions and confirmed the inappropriateness of this steel for sour environment applications. Originality/value – This paper studies the effect of sour environment on the behavior of two famous industrial steels at two temperatures by new method.

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