Strengthening Thermo-Cycling Heat Treatment Process of High-Speed Steels

The results of the examination of structure and properties of high-speed steels S 6-5-2, P6M5 (6% W, 5% Mo), P18 (18% W), P6M5K5 (6% W, 5% Mo, 5% Co) subjected to a specific strengthening thermo-cycling heat treatment are presented. The newly developed process results in a fine-grained heterogeneous microstructure (primary and secondary carbides, martensite and residual austenite) with spatially uniform distribution of the carbide grains. This brings about a 10–20% increase in the bending strength with the impact strength increased by the factor of 1.5–2.5, improves surface hardness by HRC 1–3 and the wear resistance of tools by the factor of above 2 as compared with standard heat treatments.