Abstract
The features of obtaining coatings on carbon steel, structural steel St 3 are studied during diffusion metallization – simultaneous saturation of steel with boron, chromium and aluminum (boron chromium aluminizing), without the use of special heat treatment. The basic compositions of powder mixtures are established using the simplex lattice method, which make it possible to obtain boride structures of increased hardness, phases of a solid solution of boron, chromium and aluminum in Fe α and the predicted depth of the surface layer on the surface of carbon steel. The characteristic features of the microhardness formation of the surface layer of coatings are established depending on the composition of the saturating mixture. An important factor is established for the effect of aluminum on the microhardness of the surface layer in multicomponent systems. Its presence contributes to the formation of solid solutions. New data are obtained on the formation of surface layers during steel saturation with boron, chromium and aluminum, and the conditions for obtaining layers of high hardness and high ductility are determined. The optimal areas for the formation of coatings of various structures and depths by the simplex planning method are found. As optimization factors, let’s use the relative planes occupied by borides and solid solution, as well as the depth of the surface layers. It is clearly shown how the structure of surface layers changes depending on the quantitative relations between the components of saturating mixtures. The graphical dependences of the boride phase, the phase of the solid solution and the depth of the layer, on the composition of the saturating mixture during diffusion metallization (boron chromium aluminizing) allow to improve the process in order to obtain coatings with increased wear resistance on the surface of carbon steel
Highlights
The processes of complex saturation of products during chemical-thermal treatment have recently been increasingly used in industry, compared with single-component proces ses [1]
To identify the main types of structures that form on the surface of structural steel and analyze their hardness depending on the composition of the saturating mixture, a number of studies of boron chromium aluminizing process are carried out (Table 1)
It is found that in the process of diffusion metallization, depending on the composition of the powder mixture on the surface of structural steel, three types of layers are formed: the first is a boride of high hardness; the second is a solid solution of low hardness; the third is borides located in a solid solution of variable stiffness
Summary
The processes of complex saturation of products during chemical-thermal treatment have recently been increasingly used in industry, compared with single-component proces ses [1]. On the surface of metal products, which is able to impart cutting properties to products [5] This trend in science and industry can be traced in connection with the shortage and high cost of tool steels [6]. The solution to the problem of obtaining tools based on carbon, structural steels with deposited wear-resistant coatings requires special studies Factors that make it difficult to solve the problems posed are the indefinite types of structures, the depth and hardness of the surface layers during diffuse metallization to obtain various hardnesses on structural steel. The problem of obtaining coatings of a given structure, depth and different hardness on structural steel during diffuse metallization is relevant, requiring comprehensive study and analysis
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