Mechanism and Kinetics of Formation of Intermetallic Layers on the Surface of Steel Press Molds in Casting of Silumins

Criteria for Evaluating the Manufacturability of Steels when Cutting with an Edge Tool

“…To ensure satisfactory machinability on machining lines, a stable and identical "ferrite-pearlite" microstructure is required throughout the forgings cross-section, which ensures the formation of short chips and excludes increased wear and premature failure of the cutting tool. The processing method provides for austenitization at 940 -950 [ °C], uniform cooling to a temperature of Ar1 - (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) [ °C] and holding time with a step-down decrease in temperature in the range of 680 -600 [ °C] until the completion of diffusion transformation, followed by cooling in air. The developed technology makes it possible to stably obtain on forgings from low-carbon alloy steels, including steel 18HGR, a microstructure of the "ferrite + pearlite" type, hardness within 156-207 HB and banding no more than 2 points.…”

“…To obtain reliable information about the manufacturability of steel in various cutting operations, an important condition is to conduct metallophysical studies of the workpieces to be processed and to establish a connection between the machinability and indicators of the physical and mechanical properties of the material. The key point of such studies is the determination of criteria for the microstructure and properties of the alloy, which are responsible for the machinability by cutting workpieces on automatic lines [8][9][10][11][12][13][14][15][16].…”

“…Figure 2 -Indicators of the microstructure of steel, limiting the machinability by cutting steel workpieces: a -banding; b, c, d -non-pearlite transformation products (b -bainite and c, d -martensite (M); e -lack of clear grain boundaries; f, g, h -presence of carbides; g -microhardness of pearlite HV> 350; h -microhardness ferrite HV> 200 On the basis of the obtained results of a comprehensive study, the technology of heat treatment of forgings from low-carbon alloy steels has been developed and substantiated, based on the individualization of technological parameters of isothermal annealing, which allows you to control the structure formation of steel, taking into account the inheritance of the microstructure of a metallurgical nature, and acquired in mechanical engineering technologies.The processing method provides for austenitization at 940 -950 [ °C], uniform cooling to a temperature of Ar1 -(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) [ °C] and holding time with a step-down decrease in temperature in the range of 680 -600 [ °C] until the completion of diffusion transformation, followed by cooling in air. The developed technology makes it possible to stably obtain on forgings from low-carbon alloy…”