Nanotechnology in mechanical engineering: plasma modification of a thread-cutting tool

Abstract

The paper studies the process of plasma surface modification of a screw-threaded comb from Steel P6M5steel to form submicrocrystalline structure on the tool surface. Under certain technological conditions of plasma modification of the high-speed steel tool, the possibilities of additional increase of hardness and heat resistance are created due to the formation of the ultra-fine martensitic-carbide structure in the modified zone after the final tempering. Studies have shown that increase in the hardness and heat resistance of the cutting edges of the Steel P6M5 comb in plasma modification result from the action of substructural, dislocational and solid-hardening mechanisms of strengthening. In the structure of the modified zone, extremely dispersed carbide particles (about 100 nm) are formed that act as barriers and prevent the growth of austenitic grain and, consequently, martensite crystals at high-speed hardening in both the liquid and solid phases. However, the degree of HV and K4r58 increase is not significant, and the increase in the content of residual austenite and, moreover, saturation of the solid solution with carbon and carbide-forming elements presuppose the effectiveness of the final bulk tempering and the solidification with the release of secondary carbides. The values of hardness and heat resistance of the cutting edges exceeding the level of plasma modification without surface melting for a massive tool of high speed steel are achieved and, accordingly, plasma processing with surface micromelting, called plasma micro-and nanostructurization. The degree of dispersion of the structure after the complex reinforcement is an order of magnitude higher than that of a plasma processing of a massive instrument, and is similar to that of a plasma processing with micromelting and 2-3 orders of magnitude higher than with a standard bulk heat treatment