High-speed steels Service conditions: High contact stresses Bending and twisting loads Heating of cutting edges Surface abrasion with chips Vibrations
Requirements for material: High-speed steels Requirements for material: High hardness (HRC 62-68) High wear resistance Sufficient strength Sufficient toughness Heat resistance (red-hardness) is an ability to keep cutting properties upon long heating
Composition of high-speed steels Grade (Russian system) Alloying elements, % С Cr W Mo V Co Р18 0.7-0.8 3.8-4.4 17-18.5 0.5-1.0 1.0-1.4 - Р6М5 0.82-0.9 5.5-6.5 5.0-5.5 1.7-2.1 Р6М5К5 3.8-4.3 6.0-7.0 4.8-5.8 1.7-2.2 4.8-5.3
High-speed steels : secondary hardness arises in the process of tempering, in the issue of partial martensite decomposition and precipitation of dispersed carbides (carbide fines)
High-speed steels : Heat treatment includes quenching from high temperature and triple tempering Stage Cooling Triple tempering heating in hot medium
High-speed Steel Structure (grade Р6М5, Russian classification system) Annealed steel Quenched steel Tempered steel carbides martensite primary carbides tempered martensite secondary carbides