Temperature range of carbide phase formation and its effect on the mechanical properties of Kh12VMBF type steel

1. Carbide phases are formed in quenched steel Kh12VMBFR during tempering at 200–650°C. At 200–500°C metastable Fe3C is formed, in which chromium atoms are gradually substituted for iron atoms at 500°C and higher. At 500–650°C the carbide phase is notably enriched in chromium, molybdenum, and tungsten, with subsequent formation of M23C6. 2. Machine parts of steel Kh12VMBFR intended for prolonged operation should be quenched from 1050–1150°C and tempered at 650–750°C, depending on the strength required. Parts with high strength for short operation at temperatures up to 450°C should be tempered at 530–550°C after quenching.