Corrosion and hydrogenation of steels in solutions of mineral acids containing iron(III) salts

• Ya.G. Avdeev¹, L.V. Frolova¹, A.V. Panova¹, K.L. Anfilov² and Yu.I. Kuznetsov¹

¹ A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119071 Russian Federation
² Federal State Budgetary Educational Institution of Higher Education “Bauman Moscow State Technical University” (Kaluga Branch), Bazhenov str. 2, Kaluga, 248000 Russian

Abstract: The pickling and washing processing solutions of sulfuric acid accumulate Fe(III) cations in the course of operation, mainly as a result of the dissolution of scale and mineral deposits. Fe(III) cations significantly worsen the inhibitory protection of steels in contact with the acid. The corrosion and hydrogenation of low-carbon steel 08PS and high-strength steel 70C2XA in 2 M H₂SO₄, 2 M H₂SO₄+H₃PO₄ and 2 M H₃PO₄ solutions containing Fe(III) salts were studied within the temperature range from 25 to 60℃. The hydrogenation of steels in these media depends on the chemical composition of steel, anionic composition of the corrosive media, and concentration of Fe(III) salts in them, temperature, and the presence of a corrosion inhibitor in the medium. It was established that in the case of a potential danger of accumulation of Fe(III) salts in inhibited pickling sulfuric acid solutions that substantially increases their corrosiveness to steels, their replacement with H₂SO₄+H₃PO₄ mixtures inhibited by a formulation of IFKhAN-92, KSCN, and urotropine (in 9:1:400 molar ratio) is a promising step. Unlike a similar solution of H₂SO₄, the corrosion losses and hydrogenation of low-carbon and high-strength steels are insignificant even in the case of substantial accumulation of Fe(III) cations (up to 0.1 M).

Keywords: acid corrosion, corrosion inhibitors, triazoles, low-carbon steel, hydrogenation of steel, sulfuric acid, phosphoric acid, iron(III) sulfate, iron(III) phosphate

Int. J. Corros. Scale Inhib., 2020, 9, no. 1, 320-333 PDF (857 K)
doi: 10.17675/2305-6894-2020-9-1-21

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