Influence of continuous ion beams on the changes in the morphology of surface layers and performance properties of a tungsten-free hard alloy of KNT16 grade

Abstract

Subject of research: the article studies the effect of continuous ion beams of Ar++Zr+ and N++Ti+ compositions, with ion energy E = 20 keV and radiation dose D = 5⸱1017 ion/cm2, on the change in morphology, microhardness and wear resistance during finishing turning processing of metal-cutting plates made of tungsten-free hard alloy grade KNT16 (TiCN-Ni-Mo). The purpose of the study: the development of technological modes of ion-beam processing aimed at improving the operational characteristics of metal-cutting tools from tungsten-free hard alloys of the TiCN-Ni-Mo system. Methods and objects of research: the object of research was metal-cutting plates made of tungsten-free hard alloy grade KNT16 in the initial state and after modification of their surface layers by continuous ion beams of Ar++Zr+ and N++Ti+. The change in the wear resistance of cutting inserts after ion modification was estimated by constructing kinetic curves of wear of the rear surfaces of the inserts during finishing turning of bars made of 40KhN steel. The microhardness of the samples was determined using a Shimadzu HMV-2 microhardness tester using the Vickers method. The change in surface morphology was assessed using atomic force microscopy on an Ntegra prima scanning probe microscope. Research results: using the method of atomic force microscopy, using the N++Ti+ beam as an example, it was shown that ion-beam treatment leads to selective sputtering of the binder phase in a thin surface layer of the irradiated hard alloy. It has been experimentally determined that ion modification contributes to an increase in the average service life of cutting inserts by 4060% compared to the initial ones during finishing turning of 40KhN steel in the normalized state. It has been established that ion irradiation with an Ar++Zr+ beam leads to an increase in the average value of the microhardness of the KNT16 alloy by ~ 20%, and with an N++Ti+ beam by ~ 10%. Physicochemical processes are proposed that are responsible for changes in the properties of metal-cutting inserts made of tungsten-free hard alloy KNT16 as a result of modifying its surface layers with ion beams.