CN109332625B - Casting method for improving stopper rod flow control Al deoxidized steel nozzle blockage - Google Patents
Casting method for improving stopper rod flow control Al deoxidized steel nozzle blockage Download PDFInfo
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- CN109332625B CN109332625B CN201811324962.7A CN201811324962A CN109332625B CN 109332625 B CN109332625 B CN 109332625B CN 201811324962 A CN201811324962 A CN 201811324962A CN 109332625 B CN109332625 B CN 109332625B
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- 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
- B22D11/18—Controlling or regulating processes or operations for pouring
Abstract
The invention relates to a casting method for improving the blockage of a stopper rod flow control Al deoxidized steel nozzle. When the stopper rod is used for controlling the flow to cast the aluminum deoxidized molten steel, the stopper rod is kept stable in the casting starting stage, and the molten steel can flow downwards; starting a shaking mode 5min after casting to form molten steelIn a wave form, Al2O3The similar impurities are not easy to be adsorbed on the inner wall of the nozzle, thereby improving the nozzle nodulation. Through research, the nozzle is enriched with Al with the increase of the casting time2O3The inclusion is increased. Therefore, the shaking frequency and amplitude of the stopper rod are preferably smaller in the early stage of the casting, and the shaking frequency and amplitude of the stopper rod are required to be larger in the later stage of the casting. The stopper rod jitter frequency and amplitude are key factors of the invention. Experiments show that the plug rod has overlarge shaking frequency and amplitude, which can cause molten steel to generate turbulence, the liquid level of the crystallizer fluctuates greatly, slag entrapment is caused, and the casting blank quality is greatly influenced; if the jitter frequency and amplitude of the stopper rod are too small, the stopper rod does not play a role in preventing the water gap from being blocked.
Description
Technical Field
The invention relates to the ferrous metallurgy industry, in particular to a casting method for improving the blockage of a stopper rod flow control Al deoxidized steel nozzle.
Background
In the production process of continuous cast steel with stopper rod flow control, the blockage accidents of the upper nozzle and the lower nozzle of the tundish are frequently encountered, so that the final casting is carried out in advance, the operation rate of a casting machine is reduced, and the production cost can be increased by frequently replacing the nozzles. Most seriously, the blockage adhered in the water gap can cause bias flow and crystallizer liquid level fluctuation, so that the casting blank generates surface quality defects. The plugs stripped by the scouring may be caught in the molten steel or float up to the mold flux, thereby causing defects in the quality of the cast slab. There are two main cases of nozzle clogging: firstly, cold steel is blocked; secondly, the enrichment of refractory metal oxides leads to the clogging of the nozzle. The blockage of the cold steel is easy to solve, and the normal operation can be kept in the process operation as long as the temperature is adjusted. The important difficulty of the water gap blockage caused by the flow control of the stopper rod is to solve the problem of the water gap blockage caused by the enrichment of refractory metal oxides.
In recent years, many studies on the problem of the nodulation of the continuous casting nozzle at home and abroad have been reported, and the following four nodulation types are summarized: alumina type nodules, calcium aluminate type nodules, calcium sulfide type nodules, and magnesium aluminate spinel type nodules. Along with the difference of varieties, smelting and casting processes, nozzle nodules are also greatly different, and the nozzle nodules are also different at different parts.
Aiming at the problem of water gap blockage, a plurality of measures are taken at home and abroad at present, a plurality of good process flows are formed, and effective improvement measures can be provided for solving the water gap blockage. The following methods can be summarized:
1) the molten steel is subjected to Ca treatment. In the case of Al2O3 inclusions which are likely to occur in molten steel, the Ca treatment can convert Al2O3 having a high melting point into calcium aluminate having a low melting point to change the form of oxide inclusions, but when the Ca treatment is performed on molten steel containing high aluminum, calcium aluminate having a high melting point is generated and the nozzle is easily clogged if the amount of Ca added is insufficient.
2) Preventing the secondary oxidation of the molten steel. The final contamination degree of the continuous cast slab depends on the secondary oxidation degree of the molten steel. The cleanliness of the continuous casting billet is improved, namely endogenous and foreign impurities are reduced, if good protective pouring measures are not taken, molten steel inevitably contacts with air, secondary oxidation is caused, the content of dissolved aluminum in the steel is reduced, and particularly, the problem of nozzle nodulation is easily caused when Al-containing steel such as SPHC and the like are produced.
3) Improve the argon blowing effect of the stopper rod and prevent the water gap from being blocked. The flow of argon of the stopper rod has direct influence on the anti-blocking effect of the nozzle and the steel quality. The flow is too small, and the anti-blocking effect is not ideal; the larger the flow is, the better the anti-blocking effect is, but the overlarge argon flow can cause the liquid level fluctuation in the crystallizer to be overlarge, and the phenomena of slag entrapment or secondary oxidation and the like can occur when the liquid steel is exposed in the air. Therefore, the selection of the argon flow should comprehensively consider the two contradictory factors, and the optimal argon flow should not only ensure good anti-blocking effect, but also ensure no adverse effect on steel quality.
4) To improve nozzle construction and optimize nozzle material. The prior solution to nozzle clogging mainly focuses on the control of nozzle material, structure and inclusion type. The method starts from the mechanical control aspect of the stopper rod, does not additionally increase or change molten steel inclusions, does not put higher requirements on the material of the water gap, and causes cost increase.
Al is easily generated in Al-deoxidized steel2O3And (4) inclusion-like substances. Such inclusions are easily concentrated at the nozzle during casting. As casting time increased. The number of enriched inclusions increases. The invention controls the shaking frequency and amplitude of the stopper rod to cause the molten steel to form fluctuation, so that Al is caused2O3The similar impurities are not easy to be adsorbed on the inner wall of the nozzle, thereby improving the nozzle nodulation.
Disclosure of Invention
In order to solve the problems, the invention provides a casting method for improving the nozzle blockage of stopper rod flow control Al deoxidized steel, which can effectively improve the nozzle blockage condition in the molten steel casting process.
The technical scheme adopted by the invention is as follows: a casting method for improving the blockage of a stopper rod flow control Al deoxidized steel nozzle comprises the following steps:
1) the ladle enters a rotating tower, a long nozzle is installed in place, and molten steel enters a tundish through the long nozzle;
2) when the tundish molten steel reaches 45t, lifting the stopper rod to enable the stopper rod to reach a normal casting opening degree (the opening degree is the proportion of the opening area of the stopper rod to the inner circle area of the water port and is represented by the lifting height of the stopper rod in production), and enabling the molten steel to flow into a crystallizer;
3) controlling the liquid level in the crystallizer, and casting a casting blank;
4) within 5min of casting, the molten steel is in a turbulent flow state, and the shaking mode of the stopper rod is not started at the moment;
5) and starting a stopper rod shaking mode after 5 min;
6) and after the molten steel in the three furnaces is cast, increasing the shaking frequency of the stopper rod until the casting of the whole furnace is finished, wherein the pulling speed is unchanged in the casting process.
Preferably, in the step 2), the casting opening degree is in the range of 60-80%.
Preferably, in the step 3), the distance between the molten steel and the upper opening of the copper plate of the crystallizer is 100 +/-5 mm, the casting pulling speed is 1-1.2 m/min, and the thickness of a casting blank is 230 mm.
Preferably, in the step 5), the stopper rod is shaken vertically up and down, the shaking frequency is 1-1.5 HZ, and the shaking amplitude is 1-1.5 mm.
Preferably, in the step 6), the stopper rod shaking mode is vertical shaking, the shaking frequency of the stopper rod is 2-2.5 HZ, and the shaking amplitude is 1.5-2 mm.
The beneficial effects obtained by the invention are as follows: when the stopper rod is used for controlling the flow to cast the aluminum deoxidized molten steel, the stopper rod is kept stable in the casting starting stage, and the molten steel can flow downwards; starting a shaking mode 5min after casting to cause molten steel to fluctuate, so that Al2O3The similar impurities are not easy to be adsorbed on the inner wall of the nozzle, thereby improving the nozzle nodulation.
Through research, the nozzle is enriched with Al with the increase of the casting time2O3The inclusion is increased. Therefore, the shaking frequency and amplitude of the stopper rod are preferably smaller in the early stage of the casting, and the shaking frequency and amplitude of the stopper rod are required to be larger in the later stage of the casting. The stopper rod jitter frequency and amplitude are key factors of the invention. Experiments show that the stopper rod has overlarge jitter frequency and amplitude, molten steel is turbulent, the liquid level fluctuation of the crystallizer is large, slag entrapment is caused, and great influence is caused on the quality of a casting blank, and when the jitter frequency of the stopper rod exceeds 4HZ or the jitter amplitude of the stopper rod exceeds 3mm, the liquid level of the crystallizer is greatly fluctuated, and the quality of the casting blank is influenced. If the jitter frequency and amplitude of the stopper rod are too small, the stopper rod does not play a role in preventing the water gap from being blocked. Meanwhile, the control of the argon flow of the stopper rod has great influence on the jitter frequency and amplitude of the stopper rod, and the influence on the molten steel flow and the inhibition effect on the enrichment of impurities should be considered at the same time.
Drawings
FIG. 1 is a schematic view of a stopper rod flow control tundish;
reference numerals: 1. a stopper rod mechanical arm; 2. a tundish wall; 3. a stopper rod; 4. molten steel; 5. a water feeding port; 6. a slide plate; 7. a water outlet.
Detailed Description
The invention will be further described with reference to the following drawings and specific embodiments.
A casting method for improving the blockage of a stopper rod flow control Al deoxidized steel nozzle comprises the following steps:
1) the ladle enters a rotating tower, a long nozzle is installed in place, and molten steel enters a tundish through the long nozzle;
2) the tundish capacity is 60t, when the tundish molten steel reaches 45t, the stopper rod is lifted to achieve a normal casting opening degree (the opening degree is the proportion of the opening area of the stopper rod to the inner circle area of the water port and is represented by the lifting height of the stopper rod in production), the casting opening degree range is 60-80%, and the molten steel flows into the crystallizer;
3) controlling the height of the liquid level in the crystallizer, wherein the distance between the molten steel and the upper opening of the crystallizer copper plate is 100 +/-5 mm, the casting pulling speed is 1-1.2 m/min, and the thickness of a casting blank is 230 mm;
4) within 5min of casting, the molten steel is in a turbulent flow state, and the shaking mode of the stopper rod is not started at the moment;
5) starting a stopper rod shaking mode after 5min, wherein the stopper rod shaking mode is vertical shaking up and down, the shaking frequency is 1-1.5 HZ, and the shaking amplitude is 1-1.5 mm;
6) and increasing the shaking frequency of the stopper rod after casting the molten steel in the three furnaces, wherein the shaking mode of the stopper rod is vertical shaking, the shaking frequency of the stopper rod is 2-2.5 HZ, the shaking amplitude is 1.5-2 mm, and the pulling speed is unchanged in the casting process until the casting of the whole furnace is finished.
By implementing the method, the blockage condition of the Al deoxidized steel nozzle is greatly improved. The following table shows the casting conditions under different conditions.
Example one
The middle package capacity is 60t, and when the argon blowing flow of the stopper rod is 5L/min, the stopper rod shaking mode is not started within 5min of pouring. And starting a stopper rod shaking mode after 5min, wherein the shaking mode is vertical shaking. The jitter frequency of the stopper rod is 1HZ, and the jitter amplitude is 1 mm. After the three-furnace molten steel is cast, the shaking frequency of the stopper rod is increased to 2HZ, and the shaking amplitude is 1mm until the whole furnace casting is finished.
Example two
The middle package capacity is 60t, and when the argon blowing flow of the stopper rod is 5L/min, the stopper rod shaking mode is not started within 5min of pouring. And starting a stopper rod shaking mode after 5min, wherein the shaking mode is vertical shaking. The jitter frequency of the stopper rod is 1.5HZ, and the jitter amplitude is 1.5 mm. After 3 furnaces of molten steel are cast, the shaking frequency of the stopper rod is increased to 2.5HZ, and the shaking amplitude is 2mm until the whole furnace casting is finished.
EXAMPLE III
The middle package capacity is 60t, and when the argon blowing flow of the stopper rod is 10L/min, the stopper rod shaking mode is not started within 5min of pouring. And starting a stopper rod shaking mode after 5min, wherein the shaking mode is vertical shaking. The jitter frequency of the stopper rod is 1.2HZ, and the jitter amplitude is 1.5 mm. After the three-furnace molten steel is cast, the shaking frequency of the stopper rod is increased to 2HZ, and the shaking amplitude is 2mm until the whole furnace casting is finished.
Example four
The middle package capacity is 60t, and when the argon blowing flow of the stopper rod is 10L/min, the stopper rod shaking mode is not started within 5min of pouring. And starting a stopper rod shaking mode after 5min, wherein the shaking mode is vertical shaking. The jitter frequency of the stopper rod is 1HZ, and the jitter amplitude is 1.5 mm. After 3 furnaces of molten steel are cast, the shaking frequency of the stopper rod is increased to 2.5HZ, and the shaking amplitude is 2mm until the whole furnace casting is finished.
The foregoing shows and describes the general principles and principal structural features of the present invention. The present invention is not limited to the above examples, and various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the claimed invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (1)
1. A casting method for improving the blockage of a stopper rod flow control Al deoxidized steel nozzle comprises the following steps:
1) the ladle enters a rotating tower, a long nozzle is installed in place, and molten steel enters a tundish through the long nozzle;
2) the tundish capacity is 60t, when the tundish molten steel reaches 45t, the stopper rod is lifted to enable the stopper rod to reach the normal casting opening degree, the casting opening degree range is 60-80%, and the molten steel flows into the crystallizer;
3) controlling the liquid level in the crystallizer, and casting a casting blank; the distance between the molten steel and the upper opening of the crystallizer copper plate is 100 +/-5 mm, the casting pulling speed is 1-1.2 m/min, and the thickness of a casting blank is 230 mm;
4) within 5min of casting, the molten steel is in a turbulent flow state, and the shaking mode of the stopper rod is not started at the moment;
5) and starting a stopper rod shaking mode after 5 min; the shaking mode of the stopper rod is vertical shaking up and down, the shaking frequency is 1-1.5 HZ, and the shaking amplitude is 1-1.5 mm;
6) and increasing the shaking frequency of the stopper rod after casting the molten steel in the three furnaces, wherein the shaking mode of the stopper rod is vertical shaking, the shaking frequency of the stopper rod is 2-2.5 HZ, the shaking amplitude is 1.5-2 mm, and the pulling speed is unchanged in the casting process until the casting of the whole furnace is finished.
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| CN113134587B (en) * | 2020-01-17 | 2022-11-18 | 宝山钢铁股份有限公司 | Method for judging water gap blockage and dissolution loss through stopper rod opening degree variation trend |
| CN114264786B (en) * | 2021-11-29 | 2024-01-12 | 马鞍山钢铁股份有限公司 | Casting blank quality evaluation method and system based on continuous casting tundish immersion nozzle falling-off nodulation |
| CN114346191B (en) * | 2021-12-08 | 2023-08-18 | 鞍钢股份有限公司 | Method for preventing heavy alarm of steel leakage forecasting system during quick water gap change of thick slab |
| CN114619003A (en) * | 2022-03-25 | 2022-06-14 | 中冶南方连铸技术工程有限责任公司 | Small square billet continuous casting process for improving aluminum-containing steel nodulation |
| CN115369215A (en) * | 2022-07-29 | 2022-11-22 | 邯郸钢铁集团有限责任公司 | Method for reducing inclusion cracking defect in large-thinning-amount deep drawing forming IF steel |
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| JPS6293062A (en) * | 1985-10-17 | 1987-04-28 | Nisshin Steel Co Ltd | Preventing method for adhesion of inclusion to tandish stopper head and nozzle |
| JPS62263858A (en) * | 1986-05-12 | 1987-11-16 | Kobe Steel Ltd | Control system for driving device of tundish stopper |
| JPH0679757B2 (en) * | 1989-12-04 | 1994-10-12 | 新日本製鐵株式会社 | Mold level control method |
| JPH1110301A (en) * | 1997-06-27 | 1999-01-19 | Nippon Steel Corp | Stopper device for controlling high accurate flow rate and continuous casting method using it and device therefor |
| JP2002254146A (en) * | 2001-03-02 | 2002-09-10 | Nippon Steel Corp | Continuous casting device and method |
| DE102010012062A1 (en) * | 2010-03-19 | 2011-09-22 | Sms Siemag Ag | Device and method for closing a discharge opening of a metallurgical vessel |
| KR20130002509A (en) * | 2011-06-29 | 2013-01-08 | 현대제철 주식회사 | Apparatus for preventing inclusion from adhering and producing on stopper of tundish |
| CN105710328A (en) * | 2014-12-05 | 2016-06-29 | 重庆永林机械设备有限公司 | 30MnSi continuous casting process |
| CN106955984B (en) * | 2016-01-08 | 2019-04-23 | 宝山钢铁股份有限公司 | Handle the autocontrol method of continuous casting channel blockage |
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