Microstructure and hardness of carbon and tool steel quenched with high-frequency currents

In the course of high-temperature treatment with high-frequency currents (HFC) in the range from 600 to 1300 °C, carbon and tool steels are strengthened. After the heat treatment the hardness reaches 64-70 HRC for carbon steel (carbon content 0.4-0.5%) and 68-71 HRC for tool steel 1.3343 (R6M5 steel analogue with 0.9-1.0% C content, W – 5-6 wt%, Mo – 3.5-5.3 wt%, V – 1.3-1.8 wt%, Cr – 3.8-4.3 wt%, Mn+Si – 0.5-1 wt%, Fe – balance). The resulting structure is a carbide network, and in the case of tool steel – complex carbides around a high-strength martensitic phase.