초록 ▼

Process for the heat treatment of low-alloy steels at temperatures higher than 600°C., such as annealing or heating before hardening, etc., said treatment being carried out in a protection atmosphere produced by the injection of nitrogen, hydrocarbon CxHy and optionally hydrogen, with a control of t

Process for the heat treatment of low-alloy steels at temperatures higher than 600°C., such as annealing or heating before hardening, etc., said treatment being carried out in a protection atmosphere produced by the injection of nitrogen, hydrocarbon CxHy and optionally hydrogen, with a control of the atmosphere. According to the invention, the composition of the residual species CH4, CO, H2O, and the temperature of the gaseous mixture in the furnace are controlled in order to control the carburization and the decarburization of the treated steels.

대표청구항 ▼

A process for heat treating a low alloy steel work piece, comprising heat treating said piece in a furnace to a temperature greater than 600°C. within a protective atmosphere containing N2, CH4 and CO not in thermodynamic equilibrium and having a relative proportion of CO/CH4 between 0.05 and 15 wit

A process for heat treating a low alloy steel work piece, comprising heat treating said piece in a furnace to a temperature greater than 600°C. within a protective atmosphere containing N2, CH4 and CO not in thermodynamic equilibrium and having a relative proportion of CO/CH4 between 0.05 and 15 with a residual content of CH4 lower than 2.5% and a residual content of CO lower than 2%, and injecting N2 and a hydrocarbon CxHy into the furnace to control said atmosphere, said injection of N2 and hydrocarbon CxHy being increased when a measured dew point DPm in the furnace is greater than a set dew point DPs calculated from a set flow Fs of transfer of the carbon between the work piece and the atmosphere through the surface of the work piece, said injection of N2 and hydrocarbon CxHy being maintained when DPm is equal to DPs, and said injection of N2 and hydrocarbon CxHy being reduced when DPm is less than DPs.