METHOD OF THERMAL ANTIFLOCCULATIVE TREATMENT OF FORGINGS Russian patent published in 2005 - IPC

FIELD: metallurgy.

SUBSTANCE: the invention is pertaining to metallurgy, in particular, to a method of antiflocculative thermal treatment of the large-sized items including forgings made out of carbonaceous, low-alloyed and intermediate-alloyed steels. A problem for solution of which the invention is directed to is reduction of duration of the thermal treatment at the expense of taking into account of the actual contents of hydrogen in an initial metal and a diameter of a forging. For the solution of the problem in view they realize heating of forgings in a furnace after forging up to the temperature of 660... 700°C, keeping the under this temperature with consequent cooling to the temperature of 240... 260°C. At that preliminary before the forging heating in the furnace they are chilled in the open air to the temperature of 250 - 350°C, and duration of their heating in the furnace depends on a diameter of a forging at the initial contents of hydrogen in the metal. Then cooling of the forging is conducted with a speed of 5... 20°C/hour. Duration of the forgings staying in the furnace makes 5 - 7 minutes per 1 mm of a forging diameter at the initial contents of hydrogen equal to 0.00035...0.00050 % (3.5...5 cm³ / 100 g). At that duration of a forging holding in the furnace reduce by 0.35 minutes per 1 mm of a forging diameter at reduction of the initial contents of hydrogen in the metal by 0.00001 %. At treatment of the intermediate-alloyed and the high-alloyed structural steels the forgings duration in the furnace is conducted with an intermediate super-cooling to the temperature of 200... 300°C in the midpoint of the duration. At that the cooling rate is not regulated, and the duration makes 7...9 minutes per 1 mm of a forging diameter at the initial contents of hydrogen in metal of 0.00035...0.00050 % (3.5...5 cm³ / 100 g) and reduce by 0.45 minutes per 1 mm of a forging diameter at reduction of the contents of initial hydrogen in the metal by 0.00001 %. The method thermal antifloculative treatment of forgings with a change of their duration of staying in the furnace depending on a diameter and the initial contents of hydrogen in the metal allows, not worsening of the forgings quality to significantly reduce duration antifloculative treatment at the expense of optimization of time of treatment depending on a diameter of a forging and the actual contents of hydrogen in the metal. It will allow to increase productivity of the thermal-treating furnaces and to reduce fuel consumption for the heat treatment of a unit of production.

EFFECT: the invention allows to significantly reduce duration pf the thermal antifloculative treatment of forgings without worsening of their quality, to increase the thermal-treating furnaces productivity, to reduce fuel consumption per a unit of production.

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