Bell style annealing furnace

Bell-type annealing is a traditional annealing process for cold-rolled steel wire coils. The cold rolled strip steel can be reached these purposes, such as reducing the hardness of steel, eliminating the cold process hardening, improving steel’s performance and recovering steel’s plastic deformation ability by recrystallization annealing. During annealing, some convector plates should be applied among steel coils, and the protection cover (inner cover) is covered. The shielding gas is filled into the inner cover, the heating bell (outer cover) is put and the steel strip is heated to a certain temperature and then be cooled after being kept warm for a while. The pure hydrogen gas is used as the annealing medium for the full hydrogen gas bell-type annealing furnace (BAF), which can make the steel coil a bigger heat conductivity coefficient in the radial direction increasing the heat transfer rate inside of the steel coil, reducing temperature difference between inside and outside of steel coil during heating up and to get better mechanical performance. Using pure hydrogen gas, the lubricant on the steel’s surface can be more easily to evaporate because of no decarburization and recarburization, to insure the steel surface to be bright and clean. Since the hydrogen gas has small density, the heat transfer rate is high, which can reduce the energy consumption and increase the production capacity.