Characteristics features of wear in tools made of high-speed steels with surface engineered coatings: II: Study of surface engineered high-speed steel cutting tools by AES, SIMS and EELFAS methods

Abstract

Changes in chemical composition and fine (at atomic level) structure characteristics of surfaces during the life time of cutting tools were investigated by using AES, SIMS and EELFAS methods. High-speed steels M2 and T15 with coatings incorporating ion nitriding and (Ti, Cr) nitride CAPDP (cathode arc plasma deposition process) were used. It was found that, under the wear conditions studied (such as cutting of medium carbon steels), some components of the protective hard coating dissociated, forming quasi-oxide amorphous films. This shows the parallel developing processes of: 1. Dissociation of chemical compound in coating material (Ti, Cr) N and intensive diffusion (absorption) of nitrogen into chip. 2. Creation on tool surface of stable amorphous protecting quasi-oxide TiO films. The discovered changes in chemical and phase composition of contact surfaces of the “tool-workpiece” tribopair improve service characteristics of the cutting tool and promote its adaptation to service conditions (named “self-organization”). The adaptation observed is expressed more on steel T15 with high heat resistance and leads to a significant increase of tool life.