INVESTIGATION OF INHIBITOR INFLUENCE ON CORROSION BEHAVIOR OF STRUCTURAL STEELS

Abstract

The article considers the effect of a nitrogen-containing inhibitory additive on the corrosion indicators of structural steels (Steel 20, 30ХГСА, 40ХН2МА, 18Х2Н4ВА). The effectiveness of the inhibitor was studied by conducting corrosion tests in a solution of 3% sodium chloride using gravimetric and electrochemical methods. The results of determining the current density and corrosion potential testify to the inhibition of the corrosion process after surface treatment of steels in an emulsion of cutting fluid used for machining parts. The introduction of a heterocyclic nitrogen-containing compound into the emulsion promotes surface passivation and enhances the inhibitory effect. Due to the introduction of additives for carbon steel 20, it is possible to reduce the corrosion current density by 2.5 times compared to machined samples and by 1.6 times compared to samples processed in an emulsion of cutting fluid without additives. After holding the studied steels in a solution of 3% sodium chloride a decrease in the iron content and an increase in the oxygen content are observed in the surface layer. For alloyed steels the surface is enriched with chromium. The results of gravimetric studies indicate that after processing the samples in a 3% emulsion of cutting fluid with the addition of a nitrogen-containing compound, the mass loss is reduced by almost 2.5 times for steels 20 and 18X2H4ВA, by 1.7 times in 30ХГСА, and by 1,3 times in 40XH2MA compared with samples after machining. The use of an inhibitor provides an increase in the duration of interoperational storage after machining of parts made from the investigated structural steels.