The Effect of the Surface Topography of High-Speed Steel Cutting Blades Made Using Various Methods on Their Technological and Functional Properties

Indication of the proper scope of application of high-speed steels (HSS) produced by conventional methods and powder metallurgy for cutting tool blades requires a thorough assessment of their properties in various cutting conditions. According to common knowledge, the properties of tools made of both types of steel are largely determined by the arrangement of carbide phases. It turns out, however, that the surface morphology of the cutting blades is at least as important for their operational properties. This was already indicated by the preliminary research of the authors of the article, in which it was found that the surface topography significantly affects their durability depending on the applied value of the cutting speed in dry machining conditions and in the presence of a cooling lubricant. As it turned out, contrary to the literature data, blades made of sintered HSS do not have better service properties in all cutting conditions than blades made by conventional methods (e.g., in forging and hot rolling processes). Hence, it was necessary to determine the justified range of use of both types of steel for cutting blades. Cutting blades with a similar chemical composition from conventional high-speed steel and those produced in the powder metallurgy process were tested. Wear curves were determined on the basis of the tests. On this basis, for the assumed value of the blunting index, the tool life of the cutting edges was determined during the cutting of selected structural steel, commonly used for high-strength machine parts. Tests of the cutting ability of the blades were carried out without and with the use of a cooling--lubricating liquid. In order to correctly interpret the obtained results of the wear and durability tests of the cutting edges, verification tests were carried out. A detailed analysis of the research material made it possible to determine the recommended range of applicability of conventional and sintered HSS for the tested case.