Process method for controlling inclusion occurrence rate of continuous casting sheet billet

Abstract

The invention discloses a process method for controlling the inclusion occurrence rate of a continuous casting slab. The process method comprises the following steps: (1) cleaning an inner cavity of a tundish; (2) controlling the adding amount of casting powder; (3) slag is dredged before butt joint; (4) the pouring ton of the tundish is increased; (5) the throwing speed is normatively increased; and (6) automatic liquid level control is started, specifically, automatic crystallizer liquid level control is started as early as possible, and nonmetallic substances are prevented from being involved in molten steel to form inclusions due to large fluctuation of manually controlled crystallizer liquid level. The method has the advantages that non-metallic inclusions in the slab can be greatly reduced, the occurrence rate of the inclusions of the continuous casting slab is controlled, the quality of the continuous casting slab is stable and reliable, and economic benefits are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a process method for controlling the incidence of inclusions in continuous casting slabs. Background Art

[0002] Inclusions are one of the important reasons for steel quality defects, and they cannot be eliminated during the steel rolling process. If the size of the inclusions is too large, surface quality defects will occur during the rolling process, which cannot meet the requirements of users, resulting in steel downgrading and severe steel being judged as scrap, causing huge economic losses to the company. In order to effectively control the incidence of inclusions in continuous casting slabs, it is urgent to design an effective and feasible process technology method. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the existing slab has a high inclusion rate and is prone to quality defects. A process method for controlling the inclusion incidence rate of continuous casting slabs is provided, which can significantly reduce the non-metallic inclusions inside the slab, control the inclusion incidence rate of the continuous casting slab, and achieve stable and reliable quality of the continuous casting slab.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: A process method for controlling the incidence of inclusions in continuous casting slabs, the specific steps are as follows: (1) Clean the inner cavity of the tundish: Before installing and using the tundish, check the inner cavity of the tundish, clean up the fallen slag and other non-metallic foreign matter, and keep the inner cavity of the tundish clean; (2) Control the amount of protective slag added: strictly control the amount of protective slag added to the tail furnace, stop the automatic slag adding equipment half a furnace ahead of time for the last furnace of all docking furnaces, and start slagging in advance after the ladle is closed to ensure that the protective slag in the crystallizer is melted cleanly; (3) Slag removal before docking: Before docking, crush the slag shell and slag blocks near the copper plate in the crystallizer, and use a special slag removal tool to remove the broken slag blocks from the crystallizer: (4) Increase the ton of tundish pouring: control the weight of molten steel in the tundish during docking, and determine the pouring start time based on the weight of molten steel in the tundish; (5) Standardize the drawing speed: when the length of the slab reaches 0.1m after docking, increase the drawing speed to 0.2m / min; when the length of the slab reaches 0.2m, increase the drawing speed to 0.3m / min; when the length of the slab reaches 0.3m, increase the drawing speed to 0.4m / min; (6) Enable automatic liquid level control: Enable automatic liquid level control in the crystallizer as early as possible to prevent large fluctuations in the liquid level of the crystallizer caused by manual control, which may cause non-metallic materials to be drawn into the molten steel and form inclusions.

[0005] Furthermore, in the step (4), pouring is started when the weight of the molten steel in the tundish reaches more than 6 tons.

[0006] Furthermore, in the step (5), when the slab length reaches 0.7 m, the pulling speed is increased to 0.6 m / min.

[0007] Furthermore, in the step (5), starting from 2 minutes later, the speed is increased every 30 seconds until it reaches the normal throwing speed.

[0008] Furthermore, in the step (5), the speed is increased every 30 seconds starting from 2 minutes until it reaches 1.1 m / min.

[0009] Furthermore, in the step (6), when the casting speed reaches 0.2 m / min, automatic control of the crystallizer liquid level is enabled.

[0010] In the technical scheme of the present invention, by adopting methods such as cleaning the inner cavity of the tundish, controlling the amount of protective slag added, removing slag before docking, increasing the casting tonnage of the tundish, standardizing the casting speed, and starting automatic liquid level control as soon as possible, the non-metallic inclusions inside the slab are greatly reduced, the inclusion incidence rate of the continuous casting slab is well controlled, the quality of the continuous casting slab is stable and reliable, the huge economic losses caused by the non-metallic inclusions inside the slab are reduced, and considerable economic benefits are brought to the steel enterprises. DETAILED DESCRIPTION Example

[0011] In order to make the present invention more clear, a process method for controlling the incidence of inclusions in continuous casting slabs of the present invention is further described below. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0012] In this embodiment, taking the continuous casting machine for continuous casting of 220mm thick slab as an example, the specific steps are as follows, which are characterized in that: (1) Before installing and using the tundish, check the inner cavity of the tundish, clean up the fallen slag and other non-metallic foreign matter, and keep the inner cavity of the tundish clean; (2) Strictly control the amount of protective slag added to the tail furnace. Stop the automatic slag adding equipment halfway through the last furnace of all the connecting furnaces. Start slagging in advance after the ladle is closed to ensure that the protective slag in the crystallizer is melted cleanly. (3) Before docking, crush the slag shell and slag blocks near the copper plate of the crystallizer, and use a special slag removal tool to remove the broken slag blocks from the crystallizer; (4) Control the tonnage of the tundish during docking, and start pouring when the weight of the molten steel in the tundish reaches more than 6 tons; (5) After docking, when the slab length reaches 0.1m, the pulling speed is increased to 0.2m / min, when the slab length reaches 0.2m, the pulling speed is increased to 0.3m / min, when the slab length reaches 0.3m, the pulling speed is increased to 0.4m / min, when the slab length reaches 0.7m, the pulling speed is increased to 0.6m / min, and after 2min, it is increased every 30s until it is increased to 1.1m / min; (6) When the casting speed reaches 0.2 m / min, the automatic control of the crystallizer liquid level is enabled to prevent the large fluctuations in the crystallizer liquid level caused by manual control, which may cause non-metallic materials to be drawn into the molten steel to form inclusions.

[0013] After tracking and using the method of the present invention for 6 months, the incidence of slab inclusions has been well controlled, the non-metallic inclusions inside the slab have been greatly reduced, and the slab quality defects and economic losses caused by the non-metallic inclusions inside the slab have been effectively avoided, achieving the production goal of high quality and high profit of continuous casting products.

[0014] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A process for controlling the incidence of inclusions in continuous casting slabs, characterized in that: (1) Clean the inner cavity of the tundish: Before installing and using the tundish, check the inner cavity of the tundish, clean up the fallen slag and other non-metallic foreign matter, and keep the inner cavity of the tundish clean; (2) Control the amount of protective slag added: strictly control the amount of protective slag added to the tail furnace, stop the automatic slag adding equipment half a furnace ahead of time for the last furnace of all docking furnaces, and start slagging in advance after the ladle is closed to ensure that the protective slag in the crystallizer is melted cleanly; (3) Slag removal before docking: Before docking, crush the slag shell and slag blocks near the copper plate in the crystallizer, and use a special slag removal tool to remove the broken slag blocks from the crystallizer: (4) Increase the ton of tundish pouring: control the weight of molten steel in the tundish during docking, and determine the pouring start time based on the weight of molten steel in the tundish; (5) Standardize the drawing speed: when the length of the slab reaches 0.1m after docking, increase the drawing speed to 0.2m / min; when the length of the slab reaches 0.2m, increase the drawing speed to 0.3m / min; when the length of the slab reaches 0.3m, increase the drawing speed to 0.4m / min; (6) Enable automatic liquid level control: Enable automatic liquid level control in the crystallizer as early as possible to prevent large fluctuations in the liquid level of the crystallizer caused by manual control, which may cause non-metallic materials to be drawn into the molten steel and form inclusions.

2. The process for controlling the incidence of inclusions in continuous casting slabs according to claim 1, characterized in that: In the step (4), pouring is started when the weight of the molten steel in the tundish reaches more than 6 tons.

3. The process for controlling the incidence of inclusions in continuous casting slabs according to claim 1 or 2, characterized in that: In the step (5), when the slab length reaches 0.7 m, the pulling speed is increased to 0.6 m / min.

4. The process for controlling the incidence of inclusions in continuous casting slabs according to claim 3, characterized in that: In the step (5), starting from 2 minutes later, the speed is increased every 30 seconds until it reaches the normal throwing speed.

5. The process for controlling the incidence of inclusions in continuous casting slabs according to claim 3, characterized in that: In the step (5), the speed is increased every 30 seconds starting from 2 minutes until it reaches 1.1 m / min.

6. The process for controlling the incidence of inclusions in continuous casting slabs according to claim 1 or 2, characterized in that: In the step (6), when the casting speed reaches 0.2 m / min, the automatic control of the crystallizer liquid level is enabled.