Mechanical Properties and Wear Resistance of Microarc Diffusion Coatings on Steel

The aim of the work is to study the influence of the structure and phase composition of diffusion coatings prepared by microarc surface alloying of steel with carbon, boron and carbide-forming elements on mechanical properties and wear resistance. Steel 20 specimens are subjected to Cr, Mo, V, W, B saturation, as well as multicomponent saturation with B+Cr, B+Mo, B+V, and B+W. Coating mechanical properties are evaluated by instrument cross-section indentation with recording and analysis of the deformation diagram during indenter loading and subsequent unloading. After single-component saturation coatings consist of a base within which carbide-type inclusions are located. The base is a solid solution of diffusant containing nanosize inclusions of iron carbides, borides, and alloying elements. After multicomponent saturation coatings consist of a base in the form of a dispersed ferrite-carbide mixture within which carbide and boride inclusions are located, as well as sections of boride eutectic. Coating mechanical properties are significantly higher than those of steel 20 in the initial condition. Hardness during indentation and the elasticity modulus of inclusions significantly exceed the same indices for the base layer. These results correspond to the indices for creep and the ratio of elastic and plastic components of work during instrument indentation. The best combination of mechanical properties is achieved with boromolybdenization. The relative wear resistance of steel after alloying with elements in the test combinations increases by a factor of 3.1–4.5. The best wear resistance is typical for coatings after joint saturation with boron and a carbide-forming element.