Method for Controlling Subcutaneous Bubble Defects of Medium Carbon Steel Wide and Thick Slabs

Abstract

The invention discloses a method for controlling hypodermic bubble defects of a wide and thick slab of medium carbon steel. In the casting process, crystallizer protecting slag with alkalinity of 1.0-1.1 is used; the cooling strength of the bent section is controlled between 0.18-0.23 kg / L; the deformation is controlled to be 0.60 mm / m-0.70 mm / m under light pressure. A solid stopper rod is used, the argon blowing pressure of the middle ladle circular seam is 0.20-0.30 MPa, and the argon blowing flow is 2-4 L / min. According to the invention, the hypodermic bubble defects of the wide and thick slab of medium carbon steel can be effectively controlled, the cleaning amount of the casting blank in the later stage is reduced, the cleaning-free is achieved, meanwhile, the rejection rate of the rolled material is reduced, and the production cost is reduced; the system has the advantages of completeness and strong operability, can be rapidly popularized and promoted in production lines, and hasremarkable benefits.

Description

technical field [0001] The invention relates to a continuous casting method, in particular to a method for controlling subcutaneous air bubble defects of medium carbon steel wide and thick slabs. Background technique [0002] In the process of continuous casting billet production, due to the process, equipment and other reasons, it is easy to cause subcutaneous air bubble defects in the continuous casting billet. There are two possible reasons for the formation: (1) Mold mold powder due to excessive fluctuations in the liquid level of the mold Particles are entangled in the molten steel and caught by the primary shell, forming subcutaneous slag; (2) The argon blown in the tundish protection pouring may also enter the molten steel and be captured by the solidification front, resulting in subcutaneous bubbles. These two kinds of defects are difficult to distinguish during the slab sampling inspection process, and may even coexist together. In actual production, it is found th...

AI Technical Summary

Problems solved by technology

Bubble defects under the slab skin seriously affect the surface quality of the rolled material, and must be cleaned thoroughly before entering the next process, which not only increases the labor load of workers, reduces the metal yield, but also reduces the hot delivery rate of the cast slab

[0003] In order to avoid bubble-like defects, it is generally believed that it is more effective to use solid stopper rods and reduce the amount of protective gas blown into the tundish. However, when the above methods are used in actual production, bubble-like defects will still appear in medium carbon steel slabs