Thermodynamic foundations of the rational cutting modes choice under conditions of machining

Durability and tribological tests of standard grades of high-speed steels and experimental single-carbide hard alloys with modified cobalt binder, created on the basis of the standard VK8 grade, under conditions of friction and turning of structural steels 45 and 12Х18Н10Т were carried out. The experiments were carried out for various cutting speeds and friction in order to determine the dependence of the optimal modes from the point of view of reducing the wear rate for cutting materials with different structural and thermodynamic characteristics. It has been experimentally established that high-speed steels with high values of thermal entropy have greater wear resistance in comparison with low-entropy grades, and cutting (sliding) speeds corresponding to minimal wear rates are higher for them. For experimental hard alloys grades characterized by greater thermal entropy values of the binder lower wear rates at optimal cutting speeds compared to the base alloy were also recorded; the values of the optimal cutting speeds for these materials are also higher. Thus, high-entropy cutting materials allow machining at higher speeds, while reducing the wear intensity

Tribological properties of high-entropy high-speed steels under conditions of friction on stainless steel 12H18N9T

This paper is devoted to the study of tribological characteristics of standard grades of high-speed steels (HSS) under conditions of friction on stainless steel 12H18N9T without the use of a lubricant. The grades of HSS selected for research differ in the value of thermal entropy, which is considered as an integral characteristic of their chemical composition. The tests were carried out according to the "pin-disk" friction scheme. The following differences in the characteristics of the friction process have been experimentally established, depending on the value of the thermal entropy of the HSS. Frictional interaction of high-entropy HSS was characterized by increasing the thickness of dissipative structures over time. The forming intermediate layer has a shielding effect, protecting the surfaces of rubbing bodies from destruction, but at the same time it has a large shear resistance, due to which higher coefficients of friction were recorded. The process of friction of HSS grades with low values of thermal entropy is characterized by the convergence of contacting bodies over time. For this group of materials, lower coefficients of friction were recorded against the background of a significant change in the surface micro relief relative to the initial state

Tribological properties of experimental hard alloys in conditions of friction on structural steel without lubricant

Tribological properties of the experimental grades of high entropy hard alloys with modified binding phase on cobalt, which are characterized by minimal value of absolute t.m.f. to carbide phase, were experimentally investigated. It was established experimentally that new grades obtain better friction characteristics in comparison with the base alloy grade VK8 because friction processes of these materials in contact with structural steels are characterized by lower friction forces and lower temperatures in the friction zones. The ‘third body’ which is thicker than for the base alloy grade VK8, obtains a positive gradient of mechanical properties in friction zone, has a shielding effect, reduces the rate of generation of adhesive joints (welding bridges), and, perhaps, performs the role of dry lubrication

Tribological properties of experimental hard alloys in conditions of friction on structural steel without lubricant

Tribological properties of the experimental grades of high entropy hard alloys with modified binding phase on cobalt, which are characterized by minimal value of absolute t.m.f. to carbide phase, were experimentally investigated. It was established experimentally that new grades obtain better friction characteristics in comparison with the base alloy grade VK8 because friction processes of these materials in contact with structural steels are characterized by lower friction forces and lower temperatures in the friction zones. The ‘third body’ which is thicker than for the base alloy grade VK8, obtains a positive gradient of mechanical properties in friction zone, has a shielding effect, reduces the rate of generation of adhesive joints (welding bridges), and, perhaps, performs the role of dry lubrication