METHOD TO TREAT SMALL SIZE INSTRUMENTS OF HIGH SPEED AND HEAT RESISTANT STEELS Russian patent published in 1995 - IPC

FIELD: instrument production. SUBSTANCE: method to treat small size instruments of high speed and heat resistant steels includes oxidation at 0.8 - 10 Hg mm pressure, 580 - 600 C in atmosphere of pyrolysis of ethanolamine and aniline in equal amount, further cementation in the same atmosphere at 940 - 980 C with 1.4 - 1.8 C per cent of carbon potential followed by hardening at 150 - 200 C/min cooling rate, 10^-2-10^-4 Hg mm pressure. Items are installed in the equipment of ceramic holder, with working surface upward. Vacuum furnace heated up to the temperature of oxidation may be used to load the instrument in it. 0.75 portion of total instrument length is installed in the equipment of heat resistant aluminium/boron/nitride ceramic. Post oxidation heating is performed up to cementation temperature for 1 - 1.5 h at increased carbonizer flow rate of up to 80-180 cm³/h .. In so doing, cooling may be performed in inert gas, and carbonizer may comprise additionally carbamate sodium. EFFECT: high strength instrument. 7 cl, 1 tbl, 1 dwg