FORMATION OF NANOSURFACES OF STAINLESS STEELS WITH INCREASED CORROSION RESISTANCE DUE TO JET ELECTROLYTE-PLASMA TREATMENT

The work is aimed at studying the corrosion properties of stainless steels after reducing the Ra surface roughness parameter by jet electrolyte-plasma treatment. The studies were conducted using electron and atomic force microscopy and standard corrosion tests. During the study, the reduction of the Ra surface roughness parameter and the surface morphology of the samples were examined for stainless steels 20Kh13, 08Kh18N9T, AISI 304, AISI 310, AISI 316L, and the nickel heat-resistant alloy EP648. The initial surface of the samples was obtained by rolling, sawing with a mechanical hacksaw, SLM technology and electroplasma jet
technology. For the first time, it was shown that the average surface height Sa can be reduced to an extremely low value of 11.800 nm by combining dimensional and finishing processing of stainless steel. An electrostatic calculation of the electric field strength on the surface defects of the anode was performed. It has been shown that the surface roughness parameter Ra can be reduced to an extremely low value of Ra 0.004 μm on a base length of 10 μm, which leads to a decrease in the number of microdefects and an increase in the Gibbs free energy, as well as a 3.6-fold decrease in the corrosion current density. The increased corrosion resistance achieved through the combined use of electroplasma and jetting technologies can be used for the treatment of stainless steels used in the oil and gas industry, such as pipelines, process vessels,
valves, turbine blades.