Surface hardening of small-size drills made of high-speed steel by chemical-thermal treatment with formation of tungsten nitrides

The effect of the combined CTT process with saturation of small-size drills made of high-speed steels R6M5 (P6M5 - Russian name) and R6M5K5 (P6M5K5 - Russian name) with tungsten and nitrogen on the surface layer structure and tool durability has been investigated. By spectral analysis it was found that when iron-based drill alloys were jointly saturated with tungsten and nitrogen in the pulsed mode, diffusion layers of various thicknesses containing dispersed inclusions identified as tungsten nitrides were formed. As a result of the treatment, the hardness of the surface layer increases. The microhardness on the surface can increase to 15 GPa, which depends on the volume fractions of strengthening nitrides. Surface hardening leads to a significant increase in the durability of drills when cutting holes in various structural materials.