L. IN. Mironov and g. N. Shubin 40 studied the influence of the final annealing regime of cold -rolled transformer steel on the degree of perfection of the texture of the finished strip.
Checking the properties of steel with a content of 3% SI showed that with a contact electric heater, a strip at a speed of 300-200 ° CSCs up to 1000-1300 ° C without restraint occurs a complete recrystallization of steel and a significant increase in grain. At the same time, the degree of texture of the samples did not exceed 30% (instead of 90g after an annealing in the caps currently used).
The work carried out at the Verkh-Isetsky plant according to the final annealing by cold-rolling transformer steel in a laboratory-length stretch furnace at 900-1200 ° C with a tape speed that provides its exposure at these temperatures for 5-15 minutes, also confirmed that the annealing mode is obtained Low degree of perfection of texture.
A roll subject to high -temperature annealing after cooling has the shape of a spiral. To straighten the roll and obtain a flat strip, a vacation in lingering furnaces is carried out.
At 750-800 ° C, the strip is straightened, and then cools in the cooling chamber of this furnace in a flat state to room temperature, which ensures, after unwinding such a roll, obtaining a flat tape.
At the Novolipetsk Metallurgical Plant, experimental work was carried out on high -temperature annealing transformer steel in gas furnaces using the protective environment of the composition: 5% H2 and 95% N2. The annealing mode of the cage weighing 53-58 g was as follows: the temperature is 1100 ° C, the heating time and aging of the cage 82 hours, cooling under the cap 122 hours and under the muffle 64 hours, only 268 hours.
The magnetic properties of transformer steel 0.5 mm thick after annealing according to the specified regime were as follows: LO = 0.91 – 1 VTCG; P15 = 1.78-2.1 VTKG; B25 = 18000-19230 GS.
