Strengthening the Surface Layer of Tools with State-of-the-Art Technologies

Abstract

Increasing both the service life and the wear resistance of the tool by surface hardening is an urgent issue. Its solution contributes to a significant increase in the performance of products. Available methods of surface hardening of tools, based on coating or changing the surface condition, are becoming increasingly important due to the complexity of the operation of products. Plates made of the T5K10 (85%WC–6%TiC–9%Co) and T15K6 (79%WC–15%TiC–6%Co) hard alloys as well as cylindrical samples made of the W6Mo5Cr4V2 and W18Cr4V high-speed steels are used for the study. Studies have shown that, after processing the T15K6 alloy plates with a pulsed magnetic field, the cutting tool life improved by more than 200% as compared to the untreated ones. The proposed method will increase the strength of carbide plates and stabilize the physical and mechanical properties of the cutting tool. For tools made of alloy steels, the hardening treatment is carried out by the boron method in pastes with nanodisperse powders. As shown, the thickness of the boride layer for high-speed steels increases with the duration of the process; however, its growth rate depends on the composition of the steel. An increase in the holding time of the chemical and thermal treatment leads to the growth of boride layers. The layer thickness changes quadratically (as a second-degree polynomial) with duration time. A feature of formation of diffusion layers is revealed. The dependences of both the surface hardness and the thickness of boride layer on the borating time for high-speed steels are also shown. Studies have shown that boriding in a nanodisperse medium can significantly increase the wear resistance of steels. The method of expert assessments of the maximum values of the surface properties of the studied steels is carried out. As shown, it is more rational to use W6Mo5Cr4V2 steel as a cutting tool after hardening the surface layer by boriding in a nanodisperse boron-containing powder. The proposed processing method demonstrates the prospects of using it to improve the performance of products. In addition, this method of hardening can significantly increase the wear resistance of materials (by ≈ 3.38–3.75 times) as compared to steels without processing.

Keywords

• hard alloy
• high-speed steel
• surface hardening
• magnetic pulse treatment
• boriding
• hardness
• wear resistance