METHOD OF ANNEALING OF HIGH SPEED STEEL Russian patent published in 2008 - IPC C21D9/22 C21D1/26 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to methods of thermo treatment before plastic deformation of stocks out of high speed steel. To cut down rejects at lengthwise screw rolling without cracks at the cutting edge of a tool at annealing there is performed thermo cycling with heating at each cycle for 5-20° below point A_c3 and cooling in cycles at 5-20°C lower point A_c1, then there is performed ageing at temperatures of heating and cooling within 1.5-3 hrs, at that the number of cycles is not less, than two. Further intermediate cooling of metal is carried out up to a temperature of 130°-145°C below point A_c1 and ageing within 1.5-3 hrs at this temperature with additional thermo cycling; at that the following is performed: heating to temperatures of 35-50°C below point A_c1, for 45-60°C below point A_c1, for 55-70°C below point A_c1, in each cycle correspondingly; then cooling is carried out in each cycle to the temperature equal to the ageing temperature at intermediate cooling. Duration of ageing at heating and cooling temperatures is 1.5-3 hrs. Slow down cooling is executed in the furnace at a rate not more, than 10-15°C per hour to the temperature of 700-715°C and at a rate of not more, than 50-60°C per hour to the temperature of 600°C, then the final cooling in the open air is performed.

EFFECT: development of efficient and defect-free method of high speed steel annealing.

2 cl, 7 ex, 7 dwg, 1 tbl