Wear and Performance of Hard Alloys

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

“…Cutting depth was t = 0.5 mm, feed s = 0.15 mm/rev. Durability tests also were carried out when turning work pieces of heat-resistant steel 12H18N10Т by tool inserts made of experimental single-carbide hard alloys with modified cobalt binder [14] created on the basis of the standard HA grade VK8 (Table 2). These HA grades are characterized by high thermal entropy values of the binder together with small values of absolute thermo-EMF which increases the electrochemical stability of these materials, and also characterized by an improvement in a number of operational and tribotechnical characteristics in comparison with the base composition [15,16].…”

“…The value of the most rational cutting speed from the point of view of reducing the wear rates of the tool directly depends on the chemical composition, physical, mechanical and tribotechnical characteristics of the cutting tool material (CTM). As the integral characteristics of the chemical composition of such types of CTM as highspeed steels (HSS) and hard alloys their thermodynamic parameters -thermal entropy and absolute (relative) thermo-EMF -may be considered [14]. These characteristics are interrelated: high-entropy CTMs are characterized by low values of absolute (relative) thermo-EMF, which contributes to their greater resistance to oxidative wear [15].…”

Wear Resistance of Experimental Hard Alloys Grades with Co-Mo-Ti Binders upon Conditions of Friction without Lubricant on Stainless Steel

“…The proposed by authors of [4] partial substitution of cobalt in the binders by other metals implies a reduction in the cost of HA without reducing cutting and operational characteristics, and in some cases, improving individual properties of EHA in comparison with the base alloy VK8. So, the relative thermo-EMF of the proposed binders in relation to the carbide phase is lower, which increases the electrochemical stability of EHA [5]. Current environmental and economic requirements for the metal cutting processes imply a reduction or complete abandonment of the use of lubricating cooling liquids, which leads to an intensification of the wearing of cutting edges.…”

“…Studies have found that partial substitution of cobalt in a binder by Mo and Ti has led to a decrease in average friction rates. It was established that the greatest wear resistance and the best tribological characteristics were obtained for specimens of experimental grade 2.22 (5,65%Co+1,8%Mo+0,6%Ti). The process of friction for this pin material was characterized by the formation of secondary structures with high shielding properties, reducing of the adhesive interaction of materials, low volume wear intensity, minimal friction coefficient, as well as the least roughness of friction tracks on the counter body (disk).…”