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The slow strain rate test was used to study the effect of a number of corrosive soil electrolyte components and corrosion inhibitors on the liability of pipe steel X70 to stress corrosion cracking in weakly acidic and neutral media simulating the electrolyte under delaminated coatings on underground pipelines. The electrochemical behavior of X70 pipe steel in the presence of some corrosion inhibitors was studied. It was shown that inhibitors of metal anodic dissolution can considerably improve the cracking resistance of pipe steel.

An investigation of the effect of hydrogen peroxide (H 2 O 2 ) on corrosion crack growth can be considered as a necessary stage in a study of the SCC of pipeline steels in the presence of dissolved oxygen and other oxidants. It was found that the presence of hydrogen peroxide at a low concentration (5 mM) results in a deceleration of the crack growth. With an increase in the concentration of H 2 O 2 , the crack growth rate increases. The change in the steel corrosion rate at various H 2 O 2 concentrations agrees with the dependence of the crack growth rate on the oxidant concentration. The conclusion has been made that the crack growth in a weakly acidic electrolyte (pH 5.5) is determined by the metal dissolution process. Hydrogen charging of the metal indirectly affects the crack growth by increasing the surface coverage with hydrogen, which decreases the steel dissolution rate.

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The effect of a series of organosilanes and their mixtures with corrosion inhibitors on the anticorrosion properties of polymer and paint coatings on steel, namely, on the adhesive characteristics of the coatings and corrosion behavior of the metal in the presence of coatings modified with organosilanes, corrosion inhibitors, and their mixtures, is studied. It is shown that mixtures of 1,2,3-benzotriazole (BTA) with vinyltrimethoxysilane (VTMS) or aminoethylaminopropyltrimethoxysilane—diaminosilane (DAS) inhibit the local dissolution and underfilm corrosion of carbon steel, and the potential of local depassivation shifts by 0.3–0.4 V. Here, compact polymer-like layers that are strongly bound to the metal surface are formed on the surface of steel. Corrosion and mechanical tests of the samples of pipe steels with different types of inhibiting compositions are conducted. The effect of the inhibitors on the crack growth under static loading in a model soil electrolyte (pH of 5.5) and on the crack resistance of steel under slow tension in an NS-4 model underfilm electrolyte (pH of 7.0) is evaluated. The tests are performed in media free from and containing hydrogen sulfide. It is shown that the best inhibiting properties are manifested by the mixtures of corrosion inhibitors with organosilanes. Comparative laboratory and bench tests for the adhesive strength, water resistance, and resistance to cathodic detachment of the adhesive junctions obtained upon applying the modified polymer and paint coatings onto the surface of steel are performed. It is found that introducing a mixture of organosilane and a corrosion inhibitor improves the adhesive properties of polymer and paint coatings.