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Influence of gas atomization parameters of alloy KhN60M on the characteristics of powder for laser surfacing

The object of the study was alloy powders KhN60М (EP367; 06Kh15N60М1). An overview of methods for manufacturing products from heat-resistant alloy KhN60M with an analysis of their advantages and disadvantages is given. It is shown that in comparison with injection molding and hot pressing of powders from high-alloyed special steels and alloys, additive technologies allow to obtain products of complex shape with a high level of physical and mechanical properties and material utilization. The low casting properties of the alloy under study cause the research of the atomization to meet the requirements for size, shape, morphology and fluidity of powders for additive technologies. The goal of the work was to study the effect of argon pressure during gas atomization on the physical, chemical, technological properties of powders for laser surfacing, obtained from alloy KhN60М. The technology of gas spraying of liquid melt with argon on a VIGA 2B laboratory atomizer at a temperature of 1560 °C and varying the pressure of the spraying gas in the range of 22–25 mbar was used for the manufacture of metal powder KhN60М. To select the atomization parameters, the melt viscosity values were calculated using the finite element method and its temperature dependence was constructed. The calculations were made with the ProCAST computer modeling system for casting processes. The shape and size of particles, the grain size composition were investigated using laser sedimentation, electron and optical microscopy. Quantitative metallography data were processed using the VideoTest 4 software. Fluidity of powders was measured. It was found that with increasing pressure of the spraying gas, the proportion of spherical particles increased and the fluidity of the powders improved; Feret diameter, average particle size, and d50 values did not change significantly. An experimental dependence of the increase in the yield of the powder of the target fraction (40–80 μm) with a decrease in the volume of the spray gas supply was obtained. An inversely proportional dependence of the fraction of spherical particles on the fraction of the desired cut was established. The results of the study make it possible to predict the values of the output parameters of powders during the atomization of steel KhN60M. Characteristics of powders of the –80+40 μm fraction with a shape factor of 0.99 and a yield point of 14–15 g/s make it possible to use them for the manufacture of products using additive technologies.