APPLICATION OF CR-BASED PVD COATINGS OF DIFFERENT THICKNESSES FOR RETARDING HYDROGEN EMBRITTLEMENT OF STEEL

In the context of active development of alternative energy sources, the problem of hydrogen embrittlement of critical structural elements undoubtedly requires attention. Deterioration of strength characteristics of structural materials in contact with hydrogen-containing media significantly increases the requirements for their reliability and reduces the technical and economic feasibility of using hydrogen. This paper presents the results of metallographic studies and mechanical tests of experimental St20 steel samples with a barrier coating with thickness of≈2 μm and ≈4 μm on the basis of chromium (Cr), applied using PVD (Physical Vapour Deposition) technology. Analysis of morphology and structure of the coating, as well as fractograms of the fracture surface of the experimental samples showed the absence of structural changes during hydrogenation of the samples. According to the results of tensile tests, the positive effect of using barrier coatings of greater thickness was noted. Experimental samples with barrier coating of greater thickness showed less deterioration of strength characteristics, compared to the control hydrogenated sample without barrier coating. We observed a twofold decrease in the rate of deterioration of strain values and a fourfold decrease in the rate of deterioration of the tensile strength.