CN114082912A - HPB300 square billet crack control method - Google Patents
HPB300 square billet crack control method Download PDFInfo
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- CN114082912A CN114082912A CN202111349109.2A CN202111349109A CN114082912A CN 114082912 A CN114082912 A CN 114082912A CN 202111349109 A CN202111349109 A CN 202111349109A CN 114082912 A CN114082912 A CN 114082912A
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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
- B22D11/16—Controlling or regulating processes or operations
- B22D11/20—Controlling or regulating processes or operations for removing cast stock
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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
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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Abstract
The invention discloses an HPB300 square billet crack control method, which relates to the technical field of steel metallurgy steelmaking continuous casting, and comprises the steps of carrying out HPB300 square billet continuous casting operation by adopting a constant casting speed process, cooling by adopting an even cooling mode, controlling the temperature of a tundish, optimizing four-section cooling strength proportion in secondary cooling water, improving the purity of molten steel, controlling refining soft blowing time, promoting floating of inclusions, carrying out narrow component control in the process, adopting a soft pressing technology, and redesigning the components of the molten steel; the method can achieve the effects of reducing crack defects, improving the low-power quality, reducing steel leakage and stripping accidents and greatly improving the production pulling speed by adjusting corresponding equipment parameters and process parameters under the condition of not increasing equipment investment.
Description
Technical Field
The invention relates to the technical field of steel metallurgy steelmaking continuous casting, in particular to a HPB300 square billet crack control method.
Background
In the production process of the HPB300 steel, as the carbon content is close to a peritectic reaction area, when the pulling speed reaches more than 4.0m/min, the accidents of stripping and steel leakage easily occur, further, when a macroscopic sample is taken for detection, macroscopic cracks are serious, the rating reaches more than 8.0, and rolling scabbing and steel piling and rotting accidents are caused by the cracks;
at present, when the HPB300 steel grade is produced, the casting machine is an R9M arc casting machine, a crystallizer copper pipe with the length of 155mm and double-row-foot rollers are used, the type of the nozzle is a full hydraulic pressure nozzle, the covering slag is low-carbon covering slag produced by certain domestic large-scale covering slag, and the produced square billet is detected in low power under the conditions of the existing equipment and process parameters, so that the crack defect is obvious, the low-power quality is poor, and the production efficiency is low; therefore, the invention provides a method for controlling the cracks of the HPB300 square billet, which aims to overcome the defects in the prior art.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a method for controlling cracks of an HPB300 square billet, which adopts a constant-pulling-speed pouring process to carry out continuous casting operation of the HPB300 square billet, improves the homogenization of the internal quality of a casting blank, can avoid the problems that the surface temperature rises due to strong cooling to cause stress and cracks at the front edge of the internal solidification of the casting blank, can effectively avoid the problems that the thickness of the blank shell is reduced, the strength is reduced, columnar crystals are developed and thick due to high-temperature molten steel pouring, and the defects of the casting blank and production accidents caused by overhigh and overlow pouring temperatures due to the fact that the temperature of a tundish is controlled to be 15-25 ℃, and can avoid the problem that the cracks of the casting blank are aggravated due to larger reduction by adopting a light reduction technology.
In order to achieve the purpose, the invention provides the following technical scheme:
an HPB300 billet crack control method comprises the following steps:
the method comprises the following steps: adopting a constant-pulling-speed pouring process to carry out continuous casting operation on the HPB300 square billet, and stably controlling the continuous casting pulling speed to be 4.2-4.4m/min in the process of adopting the constant-pulling-speed pouring process;
step two: in the process of drawing, the drawing speed and the water quantity are controlled and selected, the casting blank is cooled in a uniform cooling mode in the running process, and meanwhile, the brittle temperature interval of the casting blank is avoided when the casting blank is straightened;
step three: in the HPB300 square billet continuous casting operation, the temperature of a tundish is controlled to be 15-25 ℃, the centering operation of the tundish is strictly controlled, the centering deviation of a water gap is ensured, and the invasion depth of the water gap is controlled to be 80-100 mm;
step four: optimizing the cooling strength ratio of the four sections in the secondary cooling water, and adaptively adjusting the strength of the secondary cooling water to ensure that the cooling effect achieved by each section of the secondary cooling water is gradually weakened;
step five: improving the purity of molten steel, reducing the quantity of non-metallic inclusions, controlling the total oxygen amount to decrease and controlling the size of the non-metallic inclusions to decrease;
step six: controlling refining soft blowing time, promoting floating of inclusions, carrying out narrow component control in the process, fully carrying out heat preservation and covering on molten steel in a tundish, preventing the molten steel from contacting with air, fully absorbing floating silicate and aluminate inclusions in the process, and reducing the content of the inclusions in the molten steel;
step seven: adopting a soft reduction technology, controlling the pressure of the hot blank at 4-6Mpa, adjusting the width of the foot roll to 140 mm;
step eight: redesigning the components of the molten steel, reducing the influence of harmful elements and carbon elements on the solidification state of the molten steel, and controlling the content of Mn element in the molten steel to be 0.55-0.65%.
The further improvement lies in that: the first step further comprises the step of analyzing the sub-production line with the longest execution time on the HPB300 square billet production line, taking the sub-production line as a target factor, and then adjusting the corresponding working time of all the sub-production lines on the whole HPB300 square billet production line by combining the target factor to form the optimized constant-pulling-speed pouring process.
The further improvement lies in that: the first step also comprises controlling temperature drop in the constant-pulling-speed pouring process, and reducing the temperature drop by additionally arranging a heat-insulating cover on the steel ladle, reasonably selecting a covering agent and improving the baking process of the steel ladle and the tundish.
The further improvement lies in that: and the first step further comprises checking equipment on the HPB300 square billet production line, including checking whether the guide roller has the problems of deformation, rotation and loosening dislocation, checking whether each fan-shaped part is dislocated or not, checking whether the spray ring is deformed or not, checking whether the cooling nozzle is blocked or not, and formulating the upper limit of the steel passing amount through statistical analysis to strictly forbid the overdimension of the crystallizer.
The further improvement lies in that: and controlling the straightening temperature of the casting blank to be between 920 and 980 ℃ when the casting blank is straightened in the step two.
The further improvement lies in that: the cooling intensity coefficients of the four sections of cooling intensity ratios in the second cold water in the fourth step are respectively 7.2, 6.8, 3.0 and 2.5.
The further improvement lies in that: and fifthly, when the purity of the molten steel is controlled, adding silicon-aluminum-barium to perform deoxidation treatment in the tapping process, and further controlling the total oxygen amount T [ O ] value to be reduced.
The further improvement lies in that: and step eight, adjusting the alkalinity of the casting powder to be more than 0.95.
The invention has the beneficial effects that: according to the invention, the continuous casting operation of the HPB300 square billet is carried out by adopting a constant-pulling-speed pouring process, the homogenization of the internal quality of the casting blank is improved, the stress generated at the solidification front edge of the casting blank by the surface temperature rise caused by strong cooling can be avoided by optimizing the cooling strength ratio of four sections in secondary cooling water, cracks can be generated, the problems of thickness reduction of the blank shell, strength reduction, developed and thick columnar crystals and production accidents caused by overhigh and overlow pouring temperatures due to high-temperature molten steel casting can be effectively avoided by controlling the temperature of a tundish to be 15-25 ℃, and the problem that the cracks of the casting blank are aggravated by larger reduction can be avoided by adopting a light reduction technology;
the method can achieve the effects of reducing crack defects, improving the low-power quality, reducing steel leakage and stripping accidents and greatly improving the production pulling speed by adjusting corresponding equipment parameters and process parameters under the condition of not increasing equipment investment.
Drawings
FIG. 1 is a schematic flow chart of the method of the present invention.
Detailed Description
In order to further understand the present invention, the following detailed description will be made with reference to the following examples, which are only used for explaining the present invention and are not to be construed as limiting the scope of the present invention.
According to fig. 1, the present embodiment provides a method for controlling cracks in an HPB300 billet, comprising the following steps:
the method comprises the following steps: adopting a constant-pulling-speed pouring process to carry out continuous casting operation on the HPB300 square billet, and stably controlling the continuous casting pulling speed to be 4.3m/min in the process of adopting the constant-pulling-speed pouring process;
analyzing the sub-production line with the longest execution time on the HPB300 square billet production line, taking the sub-production line as a target factor, and then adjusting the corresponding working time of all the sub-production lines on the whole HPB300 square billet production line by combining the target factor to form an optimized constant-pulling-speed pouring process;
the method also comprises the steps of controlling temperature drop in the constant-pulling-speed pouring process, and reducing the temperature drop by additionally arranging a heat-insulating cover on the steel ladle, reasonably selecting a covering agent and improving the baking process of the steel ladle and a tundish;
the method also comprises the steps of checking equipment on the HPB300 square billet production line, including checking whether a guide roller has the problems of deformation, rotation and loosening dislocation, checking whether each fan-shaped part is dislocated or dislocated arc, checking whether a spray ring is deformed or rotated, checking whether a cooling nozzle is blocked, formulating an upper limit of the steel passing amount through statistical analysis, and strictly forbidding the overdimension of the crystallizer;
step two: in the process of drawing, the drawing speed and the water quantity are controlled and selected, the casting blank is cooled in a uniform cooling mode in the running process, meanwhile, the casting blank is straightened, the brittle temperature interval of the casting blank is avoided, and the straightening temperature of the casting blank is controlled to be 950 ℃ when the casting blank is straightened;
step three: in the HPB300 square billet continuous casting operation, the temperature of a tundish is controlled to be 20 ℃, the centering operation of the tundish is strictly controlled, the centering deviation of a water gap is ensured, and the invasion depth of the water gap is controlled to be 90 mm;
step four: optimizing the cooling intensity ratio of the four sections in the secondary cooling water, and adaptively adjusting the intensity of the secondary cooling water to ensure that the cooling effect achieved by each section of the secondary cooling water is gradually weakened, wherein the cooling intensity coefficients of the cooling intensity ratio of the four sections in the secondary cooling water are respectively 7.2, 6.8, 3.0 and 2.5;
step five: improving the purity of molten steel, reducing the quantity of non-metallic inclusions, adding Si-Al-Ba to deoxidize in the tapping process, further controlling the total oxygen amount to reduce and controlling the size of the non-metallic inclusions to reduce;
step six: controlling refining soft blowing time, promoting floating of inclusions, carrying out narrow component control in the process, fully carrying out heat preservation and covering on molten steel in a tundish, preventing the molten steel from contacting with air, fully absorbing floating silicate and aluminate inclusions in the process, and reducing the content of the inclusions in the molten steel;
step seven: adopting a soft pressing technology, controlling the pressure of the hot blank to be 5Mpa, adjusting the width of a foot roller, and adjusting the width of the foot roller to be 140 mm;
step eight: redesigning the components of the molten steel, reducing the influence of harmful elements and carbon elements on the solidification state of the molten steel, controlling the content of Mn element in the molten steel to be 0.60 percent, and adjusting the alkalinity of the covering slag to be more than 0.95.
The invention has the beneficial effects that: according to the invention, the continuous casting operation of the HPB300 square billet is carried out by adopting a constant-pulling-speed pouring process, the homogenization of the internal quality of the casting blank is improved, the stress generated at the solidification front edge of the casting blank by the surface temperature rise caused by strong cooling can be avoided by optimizing the cooling strength ratio of four sections in secondary cooling water, cracks can be generated, the problems of thickness reduction of the blank shell, strength reduction, developed and thick columnar crystals and production accidents caused by overhigh and overlow pouring temperatures due to high-temperature molten steel casting can be effectively avoided by controlling the temperature of a tundish to be 15-25 ℃, and the problem that the cracks of the casting blank are aggravated by larger reduction can be avoided by adopting a light reduction technology;
the method can achieve the effects of reducing crack defects, improving the low-power quality, reducing steel leakage and stripping accidents and greatly improving the production pulling speed by adjusting corresponding equipment parameters and process parameters under the condition of not increasing equipment investment.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (8)
1. An HPB300 square billet crack control method is characterized in that: the method comprises the following steps:
the method comprises the following steps: adopting a constant-pulling-speed pouring process to carry out continuous casting operation on the HPB300 square billet, and stably controlling the continuous casting pulling speed to be 4.2-4.4m/min in the process of adopting the constant-pulling-speed pouring process;
step two: in the process of drawing, the drawing speed and the water quantity are controlled and selected, the casting blank is cooled in a uniform cooling mode in the running process, and meanwhile, the brittle temperature interval of the casting blank is avoided when the casting blank is straightened;
step three: in the HPB300 square billet continuous casting operation, the temperature of a tundish is controlled to be 15-25 ℃, the centering operation of the tundish is strictly controlled, the centering deviation of a water gap is ensured, and the invasion depth of the water gap is controlled to be 80-100 mm;
step four: optimizing the cooling strength ratio of the four sections in the secondary cooling water, and adaptively adjusting the strength of the secondary cooling water to ensure that the cooling effect achieved by each section of the secondary cooling water is gradually weakened;
step five: improving the purity of molten steel, reducing the quantity of non-metallic inclusions, controlling the total oxygen amount to decrease and controlling the size of the non-metallic inclusions to decrease;
step six: controlling refining soft blowing time, promoting floating of inclusions, carrying out narrow component control in the process, fully carrying out heat preservation and covering on molten steel in a tundish, preventing the molten steel from contacting with air, fully absorbing floating silicate and aluminate inclusions in the process, and reducing the content of the inclusions in the molten steel;
step seven: adopting a soft reduction technology, controlling the pressure of the hot blank at 4-6Mpa, adjusting the width of the foot roll to 140 mm;
step eight: redesigning the components of the molten steel, reducing the influence of harmful elements and carbon elements on the solidification state of the molten steel, and controlling the content of Mn element in the molten steel to be 0.55-0.65%.
2. The HPB300 billet crack control method of claim 1, wherein: the first step further comprises the step of analyzing the sub-production line with the longest execution time on the HPB300 square billet production line, taking the sub-production line as a target factor, and then adjusting the corresponding working time of all the sub-production lines on the whole HPB300 square billet production line by combining the target factor to form the optimized constant-pulling-speed pouring process.
3. The HPB300 billet crack control method of claim 1, wherein: the first step also comprises controlling temperature drop in the constant-pulling-speed pouring process, and reducing the temperature drop by additionally arranging a heat-insulating cover on the steel ladle, reasonably selecting a covering agent and improving the baking process of the steel ladle and the tundish.
4. The HPB300 billet crack control method of claim 1, wherein: and the first step further comprises checking equipment on the HPB300 square billet production line, including checking whether the guide roller has the problems of deformation, rotation and loosening dislocation, checking whether each fan-shaped part is dislocated or not, checking whether the spray ring is deformed or not, checking whether the cooling nozzle is blocked or not, and formulating the upper limit of the steel passing amount through statistical analysis to strictly forbid the overdimension of the crystallizer.
5. The HPB300 billet crack control method of claim 1, wherein: and controlling the straightening temperature of the casting blank to be between 920 and 980 ℃ when the casting blank is straightened in the step two.
6. The HPB300 billet crack control method of claim 1, wherein: the cooling intensity coefficients of the four sections of cooling intensity ratios in the second cold water in the fourth step are respectively 7.2, 6.8, 3.0 and 2.5.
7. The HPB300 billet crack control method of claim 1, wherein: and fifthly, when the purity of the molten steel is controlled, adding silicon-aluminum-barium to perform deoxidation treatment in the tapping process, and further controlling the total oxygen amount T [ O ] value to be reduced.
8. The HPB300 billet crack control method of claim 1, wherein: and step eight, adjusting the alkalinity of the casting powder to be more than 0.95.
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| CN114871401A (en) * | 2022-05-25 | 2022-08-09 | 山东莱钢永锋钢铁有限公司 | Method for rapidly treating casting blank stripping |
| CN115070002A (en) * | 2022-06-09 | 2022-09-20 | 安阳钢铁股份有限公司 | Method for accurately controlling width of continuous casting billet |
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