CN112828254A - Method for controlling liquid level fluctuation of peritectic steel continuous casting crystallizer - Google Patents
Method for controlling liquid level fluctuation of peritectic steel continuous casting crystallizer Download PDFInfo
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- CN112828254A CN112828254A CN202011607673.5A CN202011607673A CN112828254A CN 112828254 A CN112828254 A CN 112828254A CN 202011607673 A CN202011607673 A CN 202011607673A CN 112828254 A CN112828254 A CN 112828254A
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- steel
- slag
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
- B22D11/111—Treating the molten metal by using protecting powders
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Continuous Casting (AREA)
Abstract
A method for controlling liquid level fluctuation of a peritectic steel continuous casting crystallizer comprises the following steps: (1) deoxidizing the converter steel tapping by adopting an aluminum ingot; (2) adding calcium carbide and silicon carbide to deoxidize and produce yellow white slag in LF refining, controlling the refining period to be more than or equal to 30min, and controlling the soft blowing time to be more than or equal to 10min, so as to ensure that impurities float up fully; (3) the slag surface of the tundish is covered by a low-carbon covering agent and carbonized rice hulls, and meanwhile, the tundish is covered by plastering and the slag overflow port is covered by rock wool to prevent the temperature of molten steel from being reduced and the slag surface from crusting; the tundish adopts an aluminum-carbon high-oxygen anti-corrosion stopper rod to prevent the liquid level fluctuation caused by corrosion of a common stopper rod; (4) the crystallizer adopts special covering slag for peritectic steel, and the flow of molten steel injected into the crystallizer is controlled to be 0.35-0.40 t/min, so that the molten steel quantity in the crystallizer is kept stable; by adopting the control method, the fluctuation quantity of the liquid level of the molten steel of the peritectic steel crystallizer can be controlled within +/-3 mm, the degradation rate of casting blanks and the rejection rate are greatly reduced, and the defect rate is controlled to be below 0.65 percent.
Description
Technical Field
The invention belongs to the technical field of molten steel smelting, and particularly relates to a method for controlling liquid level fluctuation of a peritectic steel continuous casting crystallizer.
Background
The fluctuation behavior of the free liquid level of the molten steel in the continuous casting crystallizer has serious influence on the quality of the continuous casting billet. When the free liquid level in the crystallizer fluctuates violently, the thickness distribution of the covering slag will change, and further secondary oxidation of molten steel and slag entrapment of the covering slag may occur, so that the quality of a casting blank is reduced. In addition, the fluctuation of the free liquid level of the molten steel is also a key factor influencing the high-pulling-speed smooth running and the production of high-quality products of continuous casting billets. More and more attention has been paid to how to reasonably control the free level fluctuation at the steel/slag interface in the crystallizer. The influence of the liquid level fluctuation of the liquid steel of the peritectic steel continuous casting crystallizer on the production is mainly reflected in that: (1) the safe production is influenced, the continuous casting furnace number of peritectic steel is reduced, and the risk of steel leakage of the sliding plate is brought; (2) leading to casting blank quality problems. Slag inclusion is easy to generate in the process of large fluctuation of the liquid level, and transverse cracking is easy to generate in the process of large speed reduction of the casting blank, so that serious influence is brought to the quality control of the casting blank.
When peritectic steel is cast, the fluctuation of the liquid level of molten steel in a continuous casting crystallizer happens occasionally, and when the liquid level fluctuates seriously, the fluctuation range is up to plus or minus 20mm, thus bringing great influence to the smooth running of casting. Therefore, the provided process method takes corresponding measures to control the fluctuation of the liquid level of the molten steel of the peritectic steel continuous casting crystallizer, and has important significance for ensuring the safe production of a continuous casting site and improving the quality of a casting blank.
Disclosure of Invention
The invention aims to provide a method for controlling the fluctuation of the liquid level of a peritectic steel continuous casting crystallizer, the fluctuation quantity of the liquid level of molten steel of the peritectic steel crystallizer can be controlled within +/-3 mm after the control method is adopted, the degradation rate of a casting blank is improved, the waste product is greatly reduced, and the defect rate is controlled to be below 0.65 percent.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for controlling liquid level fluctuation of a peritectic steel continuous casting crystallizer comprises the following steps:
(1) deoxidizing the converter steel tapping by adopting an aluminum ingot;
(2) adding calcium carbide and silicon carbide to deoxidize and produce yellow white slag in LF refining, controlling the refining period to be more than or equal to 30min, and controlling the soft blowing time to be more than or equal to 10min, so as to ensure that impurities float up fully;
(3) the slag surface of the tundish is covered by a low-carbon covering agent and carbonized rice hulls, and meanwhile, the tundish is covered by plastering and the slag overflow port is covered by rock wool to prevent the temperature of molten steel from being reduced and the slag surface from crusting; the tundish adopts an aluminum-carbon high-oxygen anti-corrosion stopper rod to prevent the liquid level fluctuation caused by corrosion of a common stopper rod;
(4) the crystallizer adopts the special covering slag for peritectic steel, and the flow of the molten steel injected into the crystallizer is controlled to be 0.35-0.40 t/min, so that the molten steel quantity in the crystallizer is kept stable.
Further, in the step (1), the adding amount of the aluminum ingot is 0.4-0.6 kg/t steel.
In the step (2), the addition amount of the calcium carbide is 0.4-0.5 kg/t steel; the addition amount of the silicon carbide is 0.6-0.8 kg/t steel.
In the step (3), the low-carbon covering agent covers the surface of the medium-carbon slag, and the carbonized rice hulls cover the low-carbon covering agent.
In the step (3), the using amount of the low-carbon covering agent is 0.15-0.30 kg/t steel, and the content of C in the low-carbon covering agent is controlled to be 0.05-0.1%; the usage amount of the carbonized rice hulls is 0.5-0.70 kg/t steel.
In the step (4), the special covering slag for peritectic steel mainly comprises the following components: SiO 22：30～35％、CaO：28～30％、Al2O3: 8-10%, C content: 14-17%, F: 2-3% of other oxides R2O: 4-6%; alkalinity of 0.8-0.9, viscosity of 1.1-1.3 Pa.S, melting point: 1150-1200 ℃.
The addition amount of the covering slag special for peritectic steel is 0.35-0.50 kg/t steel.
Further, for Q195 peritectic steel, the C content is controlled to be beyond 0.075-0.095%, and peritectic steel has the phenomenon that the liquid level of the steel in a peritectic region is easy to fluctuate during casting due to the characteristics of steel types. The fluctuation of the liquid level is the most serious when the mass percent of C is 0.075-0.095%, so that the carbon component Q195 needs to be controlled to avoid the interval as much as possible.
The technical scheme of the invention has the following beneficial effects:
(1) by adopting the control method, the fluctuation quantity of the liquid level of the molten steel of the peritectic steel crystallizer is gradually recovered to be within +/-3 mm from +/-10 mm, the degradation rate of casting blank and the rejection rate are greatly reduced, and the defect rate is controlled to be below 0.65% from more than 3.16%;
(2) the operation is simple and convenient, and the safety risks of bleed-out and the like are reduced;
(3) the liquid level is stable, and the product quality is improved;
(4) the process is reduced, waste is thrown, and the cost is reduced.
Detailed Description
The present invention will be described in detail with reference to examples.
Example 1
A method for controlling the fluctuation of the liquid level of a Q195 peritectic steel continuous casting crystallizer comprises the following steps:
1) controlling the mass percent of the element C of the Q195 peritectic steel to avoid the interval of 0.075-0.095%;
2) adding 0.4-0.6 kg/t of steel aluminum ingot into converter tapping for deoxidation;
3) in LF refining, adding 0.4-0.5 kg/t steel of calcium carbide and 0.6-0.8 kg/t silicon carbide for deoxidation to produce yellow white slag, controlling the refining period to be 25-35 min, and controlling the soft blowing time to be 8-15 min to ensure that impurities float sufficiently;
4) the tundish slag surface is covered by a low-carbon covering agent which is 0.15-0.30 kg/t steel and carbonized rice hulls which are 0.5-0.7 kg/t steel, the low-carbon covering agent covers the tundish slag surface, the carbonized rice hulls cover the low-carbon covering agent, meanwhile, the tundish ladle is covered by plastering, and the slag overflow port is covered by rock wool, so that the large slag surface can be prevented from crusting due to temperature drop of molten steel; the tundish adopts an aluminum-carbon high-oxygen anti-corrosion stopper rod;
5) the crystallizer adopts peritectic steel special-purpose covering slag, the component of which is SiO2：30～35％、CaO：28～30％、Al2O3: 8-10%, TC: 14-17%, F: 2-3% of other oxidesR2O: 4-6%; alkalinity R of 0.8-0.9, viscosity: 1.1-1.3 Pa.S, melting point: 1150-1200 ℃, the consumption is 0.35-0.50 kg/t steel, the flow of the molten steel injected into the crystallizer is controlled to be 0.35-0.40 t/min, and the molten steel quantity in the crystallizer is kept stable.
By adopting the control method in the embodiment, the fluctuation quantity of the liquid level of the molten steel of the peritectic steel crystallizer can be controlled within +/-3 mm; the casting blank degradation rate and the scrap rate are greatly reduced, and the defect rate is controlled to be below 0.65%.
Comparative example 1
C of Q195 peritectic steel: 0.075-0.095%; adding 0.3-0.5 kg/t of steel aluminum ingot into converter tapping for deoxidation; in LF refining, silicon carbide 0.8-1.0 kg/t steel is added for deoxidation and slagging, the refining period is controlled to be 20-30 min, and the soft blowing time is controlled to be 5-10 min; the secondary ladle slag surface is covered by carbonized rice hulls at a ratio of 0.6-0.8 kg/t, and meanwhile, the secondary ladle is covered by plastering mud and slag overflow port rock wool to prevent the slag surface from crusting due to temperature drop of molten steel; the middle package adopts a magnesium-carbon stopper rod.
By adopting the control method in the comparative example, the fluctuation quantity of the liquid level of the molten steel of the peritectic steel crystallizer is beyond +/-10 mm; the defect rate of the casting blank is controlled to be more than 3.16 percent.
The above detailed description of a method for controlling the level fluctuation of a peritectic steel continuous casting mold with reference to the embodiments is illustrative and not restrictive, and several embodiments can be cited within the limits thereof, so that variations and modifications thereof without departing from the general concept of the present invention shall fall within the protection scope of the present invention.
Claims (8)
1. A method for controlling liquid level fluctuation of a peritectic steel continuous casting crystallizer is characterized by comprising the following steps:
(1) deoxidizing the converter steel tapping by adopting an aluminum ingot;
(2) adding calcium carbide and silicon carbide to deoxidize and produce yellow white slag in LF refining, and controlling the refining period to be more than or equal to 30min and the soft blowing time to be more than or equal to 10 min;
(3) covering the surface of the tundish slag by using a low-carbon covering agent and carbonized rice hulls, covering the tundish slag by using plastering, and covering the slag overflow port by using rock wool; the tundish adopts an aluminum-carbon high-oxygen anti-corrosion stopper rod;
(4) the crystallizer adopts special covering slag for peritectic steel, and the flow of molten steel injected into the crystallizer is controlled to be 0.35-0.40 t/min.
2. The control method according to claim 1, wherein the amount of the aluminum ingot added in the step (1) is 0.4 to 0.6kg/t steel.
3. The control method according to claim 1, wherein in the step (2), the addition amount of the calcium carbide is 0.4-0.5 kg/t steel; the addition amount of the silicon carbide is 0.6-0.8 kg/t steel.
4. The control method according to claim 1, wherein in the step (3), the low-carbon covering agent is covered on the tundish slag surface, and the carbonized rice hulls are covered on the low-carbon covering agent.
5. The control method according to claim 1 or 4, wherein in the step (3), the amount of the low-carbon (C: 0.05-0.10%) covering agent is 0.15-0.30 kg/t steel; the usage amount of the carbonized rice hulls is 0.5-0.70 kg/t steel.
6. The control method according to claim 1, wherein in the step (4), the peritectic steel special mold flux mainly comprises the following components: SiO 22：30～35％、CaO：28～30％、Al2O3: 8-10%, C content: 14-17%, F: 2-3% of other oxides R2O: 4-6%; alkalinity of 0.8-0.9, viscosity of 1.1-1.3 Pa.S, melting point: 1150-1200 ℃.
7. The control method according to claim 1 or 6, wherein in the step (4), the addition amount of the covering slag special for peritectic steel is 0.35-0.50 kg/t steel.
8. The control method according to claim 1, wherein the C content of the Q195 peritectic steel is controlled to be other than 0.075% to 0.095%.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116493563A (en) * | 2023-06-28 | 2023-07-28 | 江苏永钢集团有限公司 | Crystallizer liquid level control system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116493563A (en) * | 2023-06-28 | 2023-07-28 | 江苏永钢集团有限公司 | Crystallizer liquid level control system |
| CN116493563B (en) * | 2023-06-28 | 2023-09-12 | 江苏永钢集团有限公司 | Crystallizer liquid level control system |
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Application publication date: 20210525 |