A solution to the problem of hot-rolled bubbles

Abstract

The present invention belongs to the field of continuous casting in steelmaking, and relates to a solution to the problem of hot coil bubble defects. During the normal production process of continuous casting, the argon flow rate of the tundish stopper rod is controlled at 3 - 5 L / min. When replacing the tundish submerged nozzle, the argon of the tundish stopper rod is turned off; when controlling the alignment and immersion depth of the tundish nozzle, it is ensured that the molten steel level in the mold does not roll over; among them, the alignment deviation < 5 mm, and the immersion depth is 140 - 160 mm; when the change value of the tundish stopper rod opening > 5 mm, information is fed back to the steelmaking process, and the wire feeding amount of molten steel calcium treatment is adjusted in a timely manner to avoid the phenomenon of molten steel loss control caused by tundish nozzle blockage or nozzle flushing. Through this technical solution, the present invention can avoid the entrainment of mold powder and the secondary oxidation of molten steel, and achieve the purpose of reducing hot coil bubble defects.

Description

Technical Field

[0001] The present invention belongs to the field of continuous casting in steelmaking and relates to a method for solving the problem of hot coil bubble defects. Background Art

[0002] The situation where bubble defects appear in hot coils after rolling continuous casting billets often occurs, and there are many influencing factors, such as: argon gas of the continuous casting tundish stopper rod for protective casting, replacement of the tundish submerged nozzle during the continuous casting process, alignment of the tundish submerged nozzle during the continuous casting process, submerged depth of the tundish submerged nozzle during the continuous casting process, and fluctuations in the molten steel level in the continuous casting mold. These factors are ignored or not well understood by continuous casting workers, and the key points for improvement have not been found. The mold powder in the continuous casting mold is involved in the continuous casting billet, resulting in bubble defects in the hot coil. At the same time, after taking measures such as controlling the deoxidation of molten steel, reducing the leakage of the converter hood, and improving the baking effect of the continuous casting tundish, there are still many bubble defects in the hot coil. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a method for solving the problem of hot coil bubble defects, avoiding the involvement of mold powder, avoiding secondary oxidation of molten steel, and reducing hot coil bubble defects.

[0004] To achieve the above purpose, the present invention provides the following technical solution: A method for solving the problem of hot coil bubble defects, comprising the following steps:

[0005] S1, The hot metal from the blast furnace is smelted in a BOF converter to become molten steel, poured into a ladle, and processed through a refining process;

[0006] S2, The processed molten steel is transported to the continuous casting pouring platform for casting. The molten steel flows from the ladle into the tundish, and then through the tundish submerged nozzle into the mold, and is cooled into a continuous casting slab in the mold and the continuous casting secondary cooling zone;

[0007] S3, The continuous casting slab is sent to a rolling mill and rolled into a hot coil.

[0008] Optionally, in step S2, during the normal production process of continuous casting, the argon gas flow rate of the tundish stopper rod is controlled at 3 - 5 L / min.

[0009] Optionally, when replacing the tundish submerged nozzle, the argon gas of the tundish stopper rod is closed.

[0010] Optionally, control the alignment and submerged depth of the tundish submerged nozzle to ensure that the molten steel level in the mold does not roll over; among which the alignment deviation < 5 mm, and the submerged depth is 140 - 160 mm.

[0011] Optionally, when the change value of the tundish stopper rod opening > 5 mm, feedback information to the steelmaking process and timely adjust the wire feeding amount of molten steel calcium treatment to avoid the phenomenon of tundish submerged nozzle blockage or washing the nozzle resulting in out - of - control steel loss.

[0012] The beneficial effects of the present invention are as follows: the present invention provides a solution to the bubble defects of hot coils, the bubble defects of hot coils are reduced after the continuous casting billet is rolled, and the waste loss is reduced.

[0013] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. DETAILED DESCRIPTION

[0014] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0015] A solution to the bubble defect of hot coil, when used, includes the following steps:

[0016] S1, molten iron from blast furnace is smelted in BOF converter to become molten steel, which is poured into ladle and processed by refining process;

[0017] S2, the treated molten steel is transported to the continuous casting steel pouring platform for casting, the molten steel flows from the ladle into the tundish, and then flows into the crystallizer through the tundish water inlet, and is cooled in the crystallizer and the continuous casting secondary cooling zone to form a continuous casting slab;

[0018] S3, the continuously cast slab is sent to the rolling mill and rolled into hot coils by the rolling mill.

[0019] In this embodiment, during the normal continuous casting production process, the argon flow rate of the middle plug rod is controlled at 3-5L / min. (In the original production plan, the argon flow rate of the plug rod is controlled at 10-15L / min. A large flow rate will cause the protective slag in the crystallizer to be involved, which is not well understood.)

[0020] In this embodiment, when the tundish outlet is replaced, the argon gas of the tundish plugging rod is turned off. (There is no provision in the original production plan, and the inclusion of protective slag is ignored, which is a lack of understanding.)

[0021] In this embodiment, the centering (deviation <5mm) and the immersion depth (140-160mm) of the tundish water inlet are controlled to ensure that the molten steel level in the crystallizer does not roll over. (The centering deviation of the original production plan was within 10mm, the immersion depth of the tundish water inlet was 120-140mm, and the molten steel level in the crystallizer rolled over, ignoring the adverse consequences of the molten steel level rolling over in the crystallizer.)

[0022] In this embodiment, when the change in the opening of the tundish stopper rod is greater than 5mm, information is fed back to the steelmaking process to timely adjust the wire feeding amount for calcium treatment of molten steel to avoid the phenomenon of uncontrolled steel flow caused by blockage of the tundish water inlet or the water washing inlet. (There is no provision in the original production plan. When the tundish water inlet or the water washing inlet is found to be blocked, the problem is already very serious, the molten steel flow field changes, and the protective slag in the crystallizer will be drawn into the molten steel.)

[0023] The bubble defect rate of hot-rolled coils in a certain steel plant reached 0.20%. After implementing this technical solution, the bubble defect rate of hot-rolled coils was reduced to below 0.10%.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for solving the problem of hot-rolled bubbles, characterized in that, It includes the following steps: S1. The hot metal from the blast furnace is smelted in a BOF converter to become molten steel, which is poured into a ladle and processed through a refining process. S2. The processed molten steel is transported to the continuous casting pouring platform for casting. The molten steel flows from the ladle into the tundish, and then through the tundish nozzle into the mold. It is cooled into a continuous casting slab in the mold and the secondary cooling zone of the continuous casting. During the normal production process of continuous casting, the argon flow rate of the tundish stopper rod is controlled at 3 - 5 L / min. Control the alignment and submerged depth of the tundish nozzle to ensure that the molten steel level in the mold does not roll over; among them, the alignment deviation < 5 mm, and the submerged depth is 140 - 160 mm. When it is necessary to replace the lower tundish nozzle, close the argon gas of the tundish stopper rod. When the change value of the tundish stopper rod opening > 5 mm, feedback information to the steelmaking process and timely adjust the wire feeding amount of calcium treatment of molten steel to avoid the phenomenon of out - of - control steel loss caused by tundish nozzle blockage or washing of the nozzle. S3. The continuous casting slab is sent to the rolling mill and rolled into a hot coil.