EP4144459A1 - Procédé de réduction de fissures de surface d'une ébauche de coulée à l'aide d'une phase de ferrite - Google Patents

Procédé de réduction de fissures de surface d'une ébauche de coulée à l'aide d'une phase de ferrite Download PDF

Info

Publication number
EP4144459A1
EP4144459A1 EP21829482.5A EP21829482A EP4144459A1 EP 4144459 A1 EP4144459 A1 EP 4144459A1 EP 21829482 A EP21829482 A EP 21829482A EP 4144459 A1 EP4144459 A1 EP 4144459A1
Authority
EP
European Patent Office
Prior art keywords
casting slab
casting
surface layer
ferrite
temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP21829482.5A
Other languages
German (de)
English (en)
Other versions
EP4144459A4 (fr
EP4144459B1 (fr
Inventor
Yingchun Wang
Guodong Xu
Rongjun Xu
Zhengjie FAN
Xiaoming RUAN
Yan Wang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Baoshan Iron and Steel Co Ltd
Original Assignee
Baoshan Iron and Steel Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Baoshan Iron and Steel Co Ltd filed Critical Baoshan Iron and Steel Co Ltd
Publication of EP4144459A1 publication Critical patent/EP4144459A1/fr
Publication of EP4144459A4 publication Critical patent/EP4144459A4/fr
Application granted granted Critical
Publication of EP4144459B1 publication Critical patent/EP4144459B1/fr
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • 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
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
    • 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
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
    • B22D11/1246—Nozzles; Spray heads
    • 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
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/128—Accessories for subsequent treating or working cast stock in situ for removing
    • B22D11/1287—Rolls; Lubricating, cooling or heating rolls while in use
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/84—Controlled slow cooling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/60—Aqueous agents
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C21D1/667—Quenching devices for spray quenching
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite

Definitions

  • the present invention relates to the technical field of continuous casting, and specifically relates to a method for reducing surface cracks of a casting slab by ferrite phase.
  • the internal quality problems of the casting slab are mainly manifested in inhomogeneous compositions, looseness, shrinkage cavities, cracks and other defects, while the external quality problems include slag inclusion, cracks and other defects. As these defects will be inherited in subsequently rolled products, casting slabs with excellent internal and external structures are desired.
  • the formation of cracks in the casting slab is a result of the combined effect of metallurgical and mechanical factors in the continuous casting process. Whether cracks appear in the casting slab depends on the structure performance of steel, metallurgical behavior of solidification, process parameters of the casting machine and operating status of equipment. Controlling the structure of the casting slab is one of the effective ways to improve the comprehensive properties of the material.
  • the as-cast structure of the casting slab is typically controlled by controlling the supercooling degree of molten steel, electromagnetic stirring, or adding nucleating agent such as aluminum, titanium or a rare earth element.
  • the surface layer structure of the casting slab can also be controlled by changing the cooling rate and the heating process of the casting slab.
  • Patent CN110653352A in order to eliminate surface cracks of the casting slab caused by ferrite, a row of cooling water nozzles with small spray angles are added in front of the straightening section and Narrow-area strong cooling is provided to eliminate proeutectoid ferrite on the surface to control surface cracks of the casting slab.
  • intensive cooling quenching is also used to eliminate precipitation of ferrite and carbonitride on the surface layer of the casting slab, so as to avoid embrittlement and improve the plasticity of the casting slab, thereby reducing surface cracks of the casting slab.
  • Patent CN105478704B lifting devices of secondary-cooling water spraying frame are established, which can achieve dynamic control of secondary-cooling water cooling area and automatic adjustment of water flow rate. In this way, secondary-cooling water would not cool the corner of the casting slab directly and avoid corner cracks caused by extremely low temperature or temperature change.
  • the present invention aims to provide a method for reducing surface cracks of a casting slab by ferrite phase, which forms high-proportion ferrite structure on the surface layer of the casting slab to reduce surface cracks of the casting slab.
  • the method can not only control the surface layer structure of the casting slab, but also improve the plasticity of the surface layer of the casting slab, and reduce surface cracks of the casting slab.
  • a method for reducing surface cracks of a casting slab by ferrite phase wherein in the process of the continuous casting, a surface layer temperature of a casting slab is controlled to keep at the austenite-to-ferrite transition temperature for a long time, thereby obtaining a high-proportion ferrite phase so that the proportion of the ferrite phase on a surface layer of the casting slab reaches 35% or more before a straightening point of a casting machine.
  • the casting slab is formed by a steel with a carbon content of 0 ⁇ C ⁇ 0.25%; controlling the surface layer temperature of the casting slab to keep the temperature within the austenite-to-ferrite transition temperature so that the proportion of the ferrite phase on the surface layer of the casting slab reaches 35% or more before the straightening point of the casting machine.
  • smelted steel is solidified in a mold to form a solid casting slab having a certain thickness, and at this time, the temperature of the casting slab is 1000-1250°C. Later, the casting slab is cooled and transported by a supporting roller while cooling. After bending, the casting slab enters the bow section, and is further transported to the straightening point of the casting machine for straightening; then the casting slab passes through a horizontal section of the casting machine for complete solidification and is transported out of the casting machine.
  • the control of the surface temperature of the casting slab is carried out before the casting slab reaches the straightening point of the casting machine.
  • the solidified casting slab passing through the mold has a relatively high temperature, which can be cooled by cooling water to keep the surface layer temperature of the casting slab within the austenite-to-ferrite transition temperature. Cooling rate can be determined by a continuous cooling characteristic CCT curve of the steel.
  • the present invention focuses on controlling the surface layer temperature of the casting slab to maintain the temperature within the range of austenite-to-ferrite transition temperature, so as to achieve the transformation from austenite to ferrite. It is found through research that the proportion of the ferrite phase on the surface layer of the casting slab needs to reach 35% or more before the straightening point of the casting machine. After satisfying this condition, the casting slab with the desired phase proportion can enter the straightening point of the casting machine, and straightening the slab into a horizontal casting slab.
  • the exact time to cool the casting slab or keep the temperature within the range of the austenite-to-ferrite transition temperature may be adjusted according to production conditions, as long as the proportion of the ferrite phase on the surface layer of the casting slab before the straightening point of the casting machine is 35% or more.
  • the surface layer of the casting slab refers to a portion with a casting slab thickness of 10 mm or less. Controlling the proportion of the ferrite phase on the surface layer of the casting slab to 35% or more, and controlling the surface layer temperature of the casting slab are both performed to the portion with a casting slab thickness of 10 mm or less.
  • the range of cooling rate of the casting slab to the ferrite phase is determined by a continuous cooling characteristic CCT curve of the steel.
  • the casting slab is cooled within the range of cooling rate, so that the surface layer temperature of the casting slab is lowered into the range of the austenite-to-ferritete transition temperature and maintained within the above temperature range.
  • the surface layer temperature of the casting slab is controlled in an bow section of the casting machine to keep within the range of the austenite-to-ferrite transition temperature.
  • the range of cooling rate for the ferrite phase of the steel is 3-0.05°C/s according to the continuous cooling characteristic CCT curve of the steel.
  • the cooling rate range is 3-0.1°C/s and more preferably of 1.5-0.08°C/s.
  • the cooling rate can be controlled by configuring parameters in the program model and is conducive to keeping the temperature of the casting slab in the vicinity of the phase transition temperature of ferrite, so as to facilitate the formation of the ferrite.
  • the surface layer temperature of the casting slab is controlled, so that the proportion of the ferrite phase on the surface layer of the casting slab reaches 35%-100%, preferably 35%-75% before the straightening point of the casting machine.
  • the proportion of ferrite enables the surface layer of the casting slab to obtain good plasticity.
  • the time for forming the proportion of the ferrite is easier to satisfy and control.
  • the surface layer of the casting slab is kept within an austenite-to-ferritete transition temperature range of 900°C-600°C and held for 0.44-35 min.
  • the surface layer temperature of the casting slab is controlled by cooling water.
  • the cooling described herein is a cooling that maintain temperature.
  • first cooling the cooling that cooled the surface layer temperature of the casting slab to the austenite-to-ferritete transition temperature
  • second cooling the cooling that maintain the temperature at the austenite-to-ferritete transition temperature
  • the surface layer temperature of the casting slab can be maintained by spraying cooling water (that is, the second cooling mentioned above). This is because the central temperature of the casting slab is relatively high, and if no cooling is carried out, the heat of the center will be transferred to the surface layer of the casting slab and increase the surface layer temperature of the casting slab. Therefore, the surface layer temperature of the casting slab can be controlled by the cooling water.
  • the flow rate of the cooling water required for the surface layer temperature of the casting slab to keep within the range of the austenite-to-ferritete transition temperature is calculated by a continuous casting online model.
  • the model is a common model in the art, and the continuous casting online model of the present invention is a continuous casting and secondary cooling online model, whereby the surface temperature of the casting slab is calculated according to the heat transfer principle in combination with continuous casting process conditions, such as molten steel temperature, casting slab casting speed, and cooling water.
  • the model can calculate the flow rate of the cooling water required for different areas of the casting slab according to a target temperature set by the process, so as to control the temperature of the casting slab.
  • the flow rate of spraying water can be calculated by the continuous casting and secondary cooling online model, then water is sprayed to cool and control the surface layer temperature of the casting slab within a predetermined range.
  • the water spraying flow rate of cooling water for the second cooling can be suitably controlled within a range of 0-0.87 L/kg (including 0 and 0.87), which can control the surface layer temperature of the casting slab within the range of austenite-to-ferrite transition temperature.
  • the unit L/kg of the water spraying flow rate refers to a water spraying volume required by steel in unit mass.
  • the surface layer of the casting slab is kept at the austenite-to-ferrite transition temperature for a long time by the cooling water, and a secondary cooling nozzle is used to spray water to the surface layer of the casting slab for cooling, so as to control the surface layer temperature of the casting slab.
  • uniform cooling can be achieved at a small water volume (0-0.62 L/kg).
  • non-water spraying cooling can be adopted, that is, keeping at the air cooling state, which is also referred to as dry cooling.
  • dry cooling can also be used if a low second cooling rate is required.
  • the model will reduce the water spraying flowrate to avoid decrease of the surface layer temperature of the casting slab.
  • the model will use air cooling to keep the surface temperature of the casting slab.
  • the supporting roller of the bow section of the casting machine is cooled internally. Specifically, cooling water can be fed to the inside of the supporting roller to control the surface temperature of the supporting roller to 550°C or less, so as to prevent a bow section from being damaged.
  • the bow section here may also be referred to as the bow section.
  • cooling water is used to control the surface layer temperature of the casting slab before the straightening section of the casting machine, so that the surface temperature of the casting slab is kept constant in the vicinity of the austenite-to-ferrite transition temperature for a long time.
  • a secondary cooling nozzle with good atomization effect and uniform spraying is required A nozzle that can conduct uniform spraying cooling under the condition of a small water volume is especially needed.
  • dry cooling that is, no secondary cooling water is sprayed for continuous casting, is required for the casting slab to keep the temperature constant.
  • the supporting roller of the bow section needs good internal cooling, so as to avoid damages of supporting roller and bearing of the bow section caused by high temperature of the casting slab.
  • a continuous casting model is needed to control the surface layer temperature of the casting slab online and in real time.
  • many casting machines have been equipped with a continuous casting online control model. By means of this model, the amount of cooling water required for the surface layer temperature of the casting slab can be configured.
  • a ferrite layer is formed on the surface layer of the casting slab, by which the plasticity of the surface layer structure of the casting slab can be improved because of the high plasticity of ferrite as the proportion of ferrite in the surface layer structure of the casting slab increases, thereby reducing cracks generated at the inner surface of the casting slab due to tensile stress at the straightening section.
  • the surface layer temperature of the casting slab after leaving the mold is in high temperature area, generally at 1000-1250°C.
  • the surface layer structure of the casting slab at the moment is in austenite region.
  • the steel has relatively high plasticity at the case of single phase and would not generate cracks.
  • the temperature of the surface layer structure of the casting slab decreases continuously.
  • the transformation of the austenite in the casting slab to proeutectoid ferrite belongs to diffusion type phase transition.
  • the proeutectoid ferrite first nucleates at an initial austenite grain boundary and grows along the grain boundary.
  • the ferrite in the grain starts to nucleate.
  • a relatively coarse proeutectoid ferrite film has been formed at the initial austenite grain boundary.
  • the structure is subjected to the straightening tensile stress that will lead to cracks on the ferrite film at the austenite grain boundary, and the cracks gradually spread in the later stage.
  • the proportion of the ferrite in the structure of the casting slab is low, which is less than 35%, the proeutectoid ferrite film easily causes stress concentration to form cracks, but if the proportion of the ferrite exceeds 35%, the stress concentration will not occur, which can avoid cracks.
  • Thermodynamic and dynamic factors i.e., temperature and duration, both affect the precipitation proportion of the ferrite.
  • Phase transition temperatures at different cooling rates are obtained according to the continuous cooling characteristic CCT curve of the steel.
  • the ferrite can be formed in steel within a cooling rate of 3-0.05°C/s and a temperature range of 900°C-600°C. If the surface layer temperature of the casting slab is controlled in the vicinity of the phase transition temperature for a long time, a large amount of ferrite will be formed on the surface layer of the casting slab.
  • the holding time for the present invention is 0.44-35 min. When the proportion of the ferrite exceeds 35%, the plasticity of the structure of the casting slab will be significantly improved, which can avoid cracks.
  • One innovation of the present invention is that the method keeps the surface temperature of the casting slab constant in the vicinity of the austenite-to-ferritete transition temperature for a long time.
  • the present invention has the following beneficial technical effects:
  • the method of the present invention controls the surface layer temperature of the casting slab in the bow section of the casting machine, so that the surface layer temperature of the casting slab is constant in the vicinity of the phase transition temperature of the steel for a long time, and a large number of ferrite phases can be formed on the surface of the casting slab through the process.
  • the casting slab with the high-proportion ferrite phase passes through the straightening section of the casting machine, since there are a large number of ferrite phases in the structure, the tensile stress of the inner surface of the casting slab will not be concentrated at the grain boundary, and will not tear the grain boundary, thus avoiding the surface cracks of the casting slab.
  • This technology is very helpful to improve the surface plasticity of the casting slab, while reducing the surface cracks of the casting slab and improving the surface quality of a product.
  • a continuous cooling characteristic CCT curve of steel is tested or calculated to obtain a range of the first cooling rate of the steel that forms ferrite, which is 3-0.05°C/s, and austenite-to-ferritete transition temperature at a different cooling rate, which is 900°C-600°C.
  • the temperature is kept at 900°C-600°C for 0.44-35 min, and the process is completed before the straightening point.
  • a CCT curve of steel in Embodiment 1 below shows the relationship between the evolution of steel structure, the temperature and the time at several cooling rates.
  • the austenite-to-ferritete transition temperature at a certain cooling rate, and the time for forming a certain proportion of ferrite can be obtained from the figure.
  • the X-axis in the figure represents the cooling time
  • the Y-axis represents the temperature
  • multiple curves similar to a parabola in the figure represent the cooling rates.
  • the area marked with F in the figure is the area where ferrite is formed; the area marked with P in the figure represents pearlite; and the area marked with B in the figure represents bainite.
  • the cooling rates contained in area F is the range of cooling rate that can from ferrite.
  • the austenite-to-ferritete transition temperature can also be obtained, which is 560-620°C.
  • the holding time of the austenite-to-ferritete transition temperature in Embodiment 1 it is obtained in the present invention according to research determination that a holding time of 0.44-35 min can ensure the proportion of the ferrite phase on the surface of the casting slab to reach 35% or more.
  • Embodiment 1 Steel 1 includes 0.08% of C, 0.14% of Si, 1.69% of Mn, 0.41% of Cr, 0.02% of Mo, and the balance of iron and inevitable impurities.
  • the cooling rate range where ferrite can be formed is less than 0.1°C/s.
  • the present embodiment adopts 0.1°C/s as the cooling rate.
  • the austenite-to-ferritete transition temperature is 620°C and the holding time is 11.67 min, so that a ferrite proportion of more than 35% can be formed on the surface layer of the casting slab. This process is completed before the straightening point. After the production, it can be determined that more than 35% of ferrite is formed by observing the casting slab specimen through metallographic microscope and calculation.
  • Embodiment 2 Steel 2 includes 0.16% of C, 0.07% of Si, 1.04% of Mn, 0.88% of Cr, 0.02% of Ti, and the balance of iron and inevitable impurities.
  • the cooling rate range where ferrite can be formed is 0.1-3°C/s, wherein the austenite-to-ferritete transition temperature is 750°C at a cooling rate of 0.1°C/s, and 630°C at a cooling rate of 3°C/s.
  • cooling is carried out at a cooling rate of 0.2°C/s, then the surface layer temperature of the casting slab is kept at 720°C for 10 min. This process is completed before the straightening point. After the production, it can be determined that more than 35% of ferrite is formed by observing the casting slab specimen through metallographic microscope and calculation.
  • Embodiment 3 Steel 3 includes 0.077% of C, 0.09% of Si, 1.45% of Mn, 0.03% of Cr, 0.01% of Mo, and the balance of iron and inevitable impurities. According to continuous cooling characteristics, the cooling rate range where ferrite can be formed is 0.1-3°C/s.
  • the austenite-to-ferritete transition temperature is 790°C at a cooling rate of 0.1°C/s, and 730°C at a cooling rate of 3°C/s.
  • cooling is carried out at a cooling rate of 0.3°C/s, then the surface layer temperature of a casting slab is kept at 780°C for 7.22 min. This process is completed before the straightening point. After the production, it can be determined that more than 35% of ferrite is formed by observing a casting slab specimen is observed through a metallographic microscope and calculation.
  • Embodiment 4 Steel 4 includes 0.09% of C, 0.17% of Si, 0.83% of Mn, 0.02% of Cr, and the balance of iron and inevitable impurities. According to continuous cooling characteristics, the cooling rate range where ferrite can be formed is 0.1-3°C/s.
  • the austenite-to-ferritete transition temperature is 830°C at a cooling rate of 0.1°C/s, and 780°C at a cooling rate of 3°C/s.
  • cooling is carried out at a cooling rate of 0.5°C/s, then the surface layer temperature of a casting slab is kept at 820°C for 5.67 min. This process is completed before the straightening point. After the production, it can be determined that more than 35% of ferrite is formed by observing a casting slab specimen and calculation.
  • Comparative example 1 Steel in Comparative example 1 includes 0.077% of C, 0.09% of Si, 1.45% of Mn, 0.03% of Cr, 0.01% of Mo, and the balance of iron and inevitable impurities. Casting is performed by a conventional process. After leaving the mold, the casting slab is cooled. The surface temperature of the casting slab at an outlet of the mold is 1200°C. The surface temperature of the casting slab gradually decreases by secondary cooling water in the bow section and reaches to 750°C when the casting slab enters the straightening point. At the moment, in the structure of the surface of the casting slab, ferrite is precipitated at the austenite grain boundary, as shown in Fig. 1A . Tensile stress is generated on the surface of the casting slab due to straightening, forming cracks at the position where the ferrite is precipitated in the austenite grain boundary.
  • Fig. 1A and Fig. 1B show cooled casting slabs after the casting slabs of the steel in Comparative example 1 and Embodiment 3 pass through the straightening point, then the percentages of the microstructures of the surfaces of the casting slabs are measured.
  • the microstructure of the surface of the casting slab in Comparative example 1 is mainly austenite, and the content of ferrite is only 8%. Therefore, stress concentration is easily caused at the ferrite and forms cracks under the action of external force.
  • the casting slab is kept at 780°C at the cooling rate of 0.3°C/s and holding for 7.22 min. 95% of ferrite will be formed on the surface of the casting slab when the casting slab enters the straightening point. Stress concentration will not occur in such structure under external force, and the ferrite has good plasticity, so that no cracks are formed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Continuous Casting (AREA)
EP21829482.5A 2020-06-25 2021-06-25 Procédé de réduction de fissures de surface d'une ébauche de coulée à l'aide d'une phase de ferrite Active EP4144459B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202010592850.0A CN113843403B (zh) 2020-06-25 2020-06-25 一种利用铁素体相改善铸坯表面裂纹的方法
PCT/CN2021/102405 WO2021259376A1 (fr) 2020-06-25 2021-06-25 Procédé de réduction de fissures de surface d'une ébauche de coulée à l'aide d'une phase de ferrite

Publications (3)

Publication Number Publication Date
EP4144459A1 true EP4144459A1 (fr) 2023-03-08
EP4144459A4 EP4144459A4 (fr) 2023-08-30
EP4144459B1 EP4144459B1 (fr) 2024-10-02

Family

ID=78972051

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21829482.5A Active EP4144459B1 (fr) 2020-06-25 2021-06-25 Procédé de réduction de fissures de surface d'une ébauche de coulée à l'aide d'une phase de ferrite

Country Status (5)

Country Link
EP (1) EP4144459B1 (fr)
JP (1) JP2023530911A (fr)
KR (1) KR20230015949A (fr)
CN (1) CN113843403B (fr)
WO (1) WO2021259376A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114672628B (zh) * 2022-03-30 2023-03-14 东北大学 一种基于连铸机末端的板坯表面淬火系统与工艺
CN114734014B (zh) * 2022-03-31 2024-01-19 东北大学 一种微合金钢板坯角部裂纹控制的冷却方法及系统
CN114850423B (zh) * 2022-05-21 2023-05-23 湖南华菱湘潭钢铁有限公司 一种中碳锰钢连铸大方坯角部裂纹的控制方法

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3058079B2 (ja) * 1996-02-23 2000-07-04 住友金属工業株式会社 鋼の連続鋳造方法
JP2010082638A (ja) * 2008-09-30 2010-04-15 Jfe Steel Corp 連続鋳造鋳片の製造方法
CN101722287B (zh) * 2008-11-03 2012-07-18 攀钢集团研究院有限公司 连铸铸坯的冷却方法及包括该方法的连铸钢坯的生产方法
JP5381468B2 (ja) * 2009-07-30 2014-01-08 新日鐵住金株式会社 連続鋳造機内の二次冷却方法
JP5884479B2 (ja) * 2011-01-31 2016-03-15 Ｊｆｅスチール株式会社 鋼の連続鋳造方法
CN102228968B (zh) * 2011-06-20 2014-01-22 重庆大学 一种实现高强度低合金钢连铸坯直接送装的方法
JP5920192B2 (ja) * 2012-03-01 2016-05-18 Ｊｆｅスチール株式会社 鋼の連続鋳造方法
CN102861890A (zh) * 2012-09-19 2013-01-09 中冶南方工程技术有限公司 降低微合金钢板坯角部横裂纹的二次冷却方法
CN104399923B (zh) * 2014-11-18 2016-07-06 钢铁研究总院 一种生产特厚板连铸坯的方法
CN108138277B (zh) * 2015-08-11 2020-02-14 杰富意钢铁株式会社 高强度钢板用原材料、高强度钢板及其制造方法
CN105478704B (zh) 2016-01-04 2018-03-23 河北钢铁股份有限公司邯郸分公司 防止微合金钢铸坯连铸角裂缺陷的系统及其使用方法
CN108393456B (zh) * 2017-02-05 2019-10-29 鞍钢股份有限公司 一种q345b厚板铸坯组织控制方法
CN107695313B (zh) 2017-08-22 2019-10-11 中冶连铸技术工程有限责任公司 一种解决铸坯边角裂纹的方法及喷嘴布置方法
CN110756756B (zh) * 2019-10-10 2021-06-01 山东钢铁股份有限公司 一种降低热送铸坯表面裂纹生成率的方法
CN110653352A (zh) 2019-11-06 2020-01-07 湖南华菱湘潭钢铁有限公司 由先共析铁素体引发的铸坯表面裂纹的控制方法

Also Published As

Publication number Publication date
KR20230015949A (ko) 2023-01-31
CN113843403B (zh) 2023-01-20
CN113843403A (zh) 2021-12-28
EP4144459A4 (fr) 2023-08-30
EP4144459B1 (fr) 2024-10-02
WO2021259376A1 (fr) 2021-12-30
JP2023530911A (ja) 2023-07-20

Similar Documents

Publication Publication Date Title
EP4144459B1 (fr) Procédé de réduction de fissures de surface d'une ébauche de coulée à l'aide d'une phase de ferrite
CN103305770B (zh) 一种薄带连铸550MPa级高强耐大气腐蚀钢带的制造方法
CN100473731C (zh) 高张力钢板的制造方法
CN103305760B (zh) 一种薄带连铸550MPa级高强耐候钢制造方法
CN102002628A (zh) 一种低碳钢薄板的制造方法
CN103361569A (zh) 一种超低温耐候结构钢板及其生产方法
CN110616361A (zh) 一种免退火渗氮用钢的生产方法
CN109609840A (zh) 一种180～200mm厚度合金结构钢27SiMn及其生产工艺
JP2020525652A (ja) 材質ばらつきが少なく表面品質に優れた超高強度熱延鋼板及びその製造方法
CN104342598A (zh) 一种600MPa级别汽车大梁用热轧钢带的生产方法
CN102234742B (zh) 一种直缝焊管用钢板及其制造方法
US11648608B1 (en) Secondary cooling control method for reinforcing surface solidification structure of microalloyed steel continuous casting bloom
KR100450611B1 (ko) 표면품질이 우수한 마르텐사이트계 스테인레스강의 연주주편제조방법
CN105603302A (zh) 350mm直径的34CrMo圆管钢坯及其冶炼方法
CN105568166A (zh) 350㎜直径的34CrMo圆管钢坯及其炼铸方法
JP2011225953A (ja) 高強度鋼板、およびこの高強度鋼板の素材である鋳片の連続鋳造方法、ならびに高強度鋼板の製造方法
KR20170011808A (ko) 주조방법
CN110885916A (zh) 一种90°折弯不开裂的热轧普碳钢的生产方法
Li et al. Research Status and Control Measures of Transverse Cracks for Micro-alloyed Continuous Casting Billet
JP4238950B2 (ja) Ｂ含有オーステナイト系ステンレス鋼連続鋳造スラブの製造方法
CN106676427A (zh) 耐大气腐蚀型钢钢水和含钒钛氮耐大气腐蚀型钢及其生产方法
JPH09253814A (ja) 鋳片表面割れの抑制方法
CN106676428A (zh) 耐大气腐蚀型钢钢水和含铌氮耐大气腐蚀型钢及其生产方法
CN106676398A (zh) 含钒钛氮耐大气腐蚀型钢钢水和耐大气腐蚀型钢及其生产方法
CN116833244A (zh) 一种1800兆帕高强度钢混晶的热加工工艺

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20221128

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

A4 Supplementary search report drawn up and despatched

Effective date: 20230802

RIC1 Information provided on ipc code assigned before grant

Ipc: C21D 1/84 20060101ALI20230727BHEP

Ipc: B22D 11/128 20060101ALI20230727BHEP

Ipc: B22D 11/124 20060101ALI20230727BHEP

Ipc: B22D 11/22 20060101AFI20230727BHEP

17Q First examination report despatched

Effective date: 20230814

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

RIC1 Information provided on ipc code assigned before grant

Ipc: C21D 1/667 20060101ALN20240516BHEP

Ipc: C21D 1/62 20060101ALN20240516BHEP

Ipc: C21D 1/60 20060101ALN20240516BHEP

Ipc: C21D 9/00 20060101ALI20240516BHEP

Ipc: C21D 1/84 20060101ALI20240516BHEP

Ipc: B22D 11/128 20060101ALI20240516BHEP

Ipc: B22D 11/124 20060101ALI20240516BHEP

Ipc: B22D 11/22 20060101AFI20240516BHEP

RIC1 Information provided on ipc code assigned before grant

Ipc: C21D 1/667 20060101ALN20240517BHEP

Ipc: C21D 1/62 20060101ALN20240517BHEP

Ipc: C21D 1/60 20060101ALN20240517BHEP

Ipc: C21D 9/00 20060101ALI20240517BHEP

Ipc: C21D 1/84 20060101ALI20240517BHEP

Ipc: B22D 11/128 20060101ALI20240517BHEP

Ipc: B22D 11/124 20060101ALI20240517BHEP

Ipc: B22D 11/22 20060101AFI20240517BHEP

INTG Intention to grant announced

Effective date: 20240607

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 602021019703

Country of ref document: DE