METHOD OF REDUCTION THERMAL TREATMENT OF ITEMS MADE OUT OF HEAT RESISTANT CHROMIUM NICKEL ALLOYS Russian patent published in 2008 - IPC C22F1/10 C21D6/00 

FIELD: metallurgy.

SUBSTANCE: invention refers to a reduction thermal treatment of replaced parts of metallurgical furnace equipment, particularly to worn out furnace rollers. For reduction of initial physic mechanical properties of parts due to deep refining with carbon, nitrogen and sulphur and an optimum redistribution of excessive phases the said parts are heated to an austenisation temperature in two stages- at the first stage up to 900-1180°C at a rate of 15-20°C/h with a hold during 5-40 hours for decomposition of chromium carbides and partial decarbonisation, then up to 1200-1250°C with a hold during 5-10 hours for transition into a solid solution of more stable carbon nitride compositions at the base of tungsten and titanium and more complete decarbonisation, then a controlled cooling is performed, first slowly up to 300-400°C in a medium of highly purified and dried oxygen with a dew point not higher, than 50°C with a hold at that temperature in a non-corrosive medium for 2-10 hours and then at an open air. During the process of cooling an additional hold is carried out at 1000-1100°C during 4-6 hours.

EFFECT: reduction of physic mechanical properties of parts.

2 cl, 3 tbl, 4 dwg