THERMAL CALCULATIONS OF RAPID HEATING AND COOLING DURING TESTING THE TECHNOLOGY OF COMBINED SURFACE HARDENING OF WELDED PARTS WITH A WORKING PART MADE OF 15X11MF STEEL

Hardening of contacting surfaces is aimed at improving the material properties of components to ensure more efficient operation of mechanisms and devices. There are many surface modification technologies, such as: creating surfacing on the surface, creating coatings, forming surface layers using various techniques, and other technologies. Such technologies are aimed at improving the mechanical and tribological properties of materials and products made of them. Combined surface hardening using friction is a hardening method that can significantly improve the mechanical and tribological properties of materials. Thermal calculations of the process are an important aspect for controlling this hardening method. In this regard, there is an urgent need to perform thermal calculations of the process of rapid heating and cooling after heating during testing the technology of combined surface hardening of welded parts. the purpose of this work is to perform thermal calculations of the cycle of rapid heating and cooling after heating during surface hardening of welded parts with a working part made of 15X11MF steel. This steel grade is a structural alloy steel with increased corrosion resistance. Combined surface hardening was performed on a friction treatment unit. The source of heating in the combined surface hardening technology is the friction that occurs between the tool, a rotating steel disk, and the surface of the workpiece. To analyze the temperature distribution from the surface deep into the samples during combined surface hardening, the heat conduction problem was solved using the source method. The problem of heat conduction was solved in a coordinate system that moves with the heat source, i.e., with the contact surface The input parameters for calculating thermal phenomena during the combined surface hardening of the studied material were: a - thermal conductivity coefficient; λ - thermal conductivity coefficient; аф - actual value of the machining depth taken from the side where the microgroove was made; r is the radius of the disk; L is the length of contact between the disk and the sample surface during sample processing; y is the heat source criterion - the isotherm value of 150 °C, taken from the side where the grinding was performed. The result of thermal calculations according to the shape of the source is the temperature field from an instantaneous source of the corresponding shape. The temperature field is shown in the boundary plane of the sample plate section and demonstrates to what depth and temperature the sample was heated during processing To evaluate and analyze the thermal cycle of steel heating and cooling during machining, a corresponding heating-cooling graph was calculated and plotted, which makes it possible to calculate the actual cooling rate in the surface layer of the samples during machining. The expediency of applying this technology in terms of a high-speed method of heating and cooling the surface layer of the processed parts is shown. The data obtained make it possible to calculate the cooling rate of the surface after heating in the process of combined surface hardening, or the cooling rate at any depth of the part sample within the temperature field that occurs during its processing, which is planned infurther research.