In continuous casting production, the degradation of billet will lead to difficult delivery of order contract and increase enterprise cost. It is found that the deterioration of slab is caused by mould level fluctuation, submerged nozzle, middle and down casting speed (stripping ingot lifting speed, tail tank falling speed, tundish temperature, high dropping speed), weighing in tundish.
Measures to reduce reduced billet and increase yield of casting blank:
1, reduce the level fluctuation
Main causes of mould level fluctuation is the purity of molten steel is not enough, in order to improve the purity of molten steel, with top slag were modified, reduce the melting point of the slag, increasing the adsorption capacity decreased with increasing casting speed; at the same time, in order to alleviate the mold level fluctuation; in addition, using low level fluctuation protective casting argon flow condition.
2. Replace submerged nozzle
Because the transition slab itself is degraded in each billet, therefore, in order for the end of 3 cans of casting billet on transition tank replacement of the submerged nozzle, not only alleviate the clogging of submerged entry nozzle, and reduce the change of submerged nozzle caused by slab degradation.
3, reduce the casting speed
For the removal of the dummy bar lifting speed by one step in place up to target velocity, not in the removal of the dummy bar when the lifting speed or low speed to maintain the transition to the blank off dummy bar pouring in second cans after rising to the target speed; for the tail tank cast, slow down on the big the tank stopped after pouring, so when casting speed reduction is cast billet casting billet tail, tail itself is also reduced the number of downgrade billet, billet downgrade.
For casting tundish temperature caused by high speed machine, set up a regression model, the actual temperature out of refining refining theory of target temperature + = out temperature compensation. According to the calculation of the temperature out of the model operation, the tundish temperature qualification rate is improved, and the tundish temperature qualification rate has been greatly improved
4 、 control tundish liquid level is not less than 45t
For the package itself into shortage in package scale allowed, weighing value is too small, in the first tank pouring, will be quickly rose to the level in the package from the overflow port within 50mm, if the bag weighing less than 60t or higher than 65t, can be adjusted to weighing 60 ~ 65t, second blocks from the guarantee the cast, not because of no degradation of billet "(the first time for the default cast billet downgrade). In addition, the need to avoid, when the tundish in contact with the car, due to inertia, the middle package called a certain impact, affecting the accuracy of the package.
