Process for case-hardening metallic materials in low-pressure case-hardening systems comprises case-hardening phases carried out at specific partial pressures and diffusion phases carried out at permanently or temporarily raised pressures

摘要

Process for case-hardening metallic materials in low-pressure case-hardening systems (vacuum case-hardening systems) uses hydrocarbons as carbon donors or hydrocarbons in a mixture with other gases. The partial pressure of the process during the case-hardening phases is up to 50 mbar, and in diffusion phases the pressure is raised throughout the entire process or temporarily to minimize nitrogen removal. Preferred Features: The process consists of one or more case-hardening phases and diffusion phases. The case-hardening phase proceeds with a defined carbon flow throughout the entire process and the pressure is raised to 50 mbar to 2 bar throughout the entire process or temporarily. To prevent nitrogen removal the case-hardening phase is carried out at a higher process pressure of between 50 mbar and 2 bar.