CN108456766B - Aluminum chloride molten salt for rapidly and continuously heating thin strip steel and heating method thereof - Google Patents
Aluminum chloride molten salt for rapidly and continuously heating thin strip steel and heating method thereof Download PDFInfo
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- CN108456766B CN108456766B CN201810611840.XA CN201810611840A CN108456766B CN 108456766 B CN108456766 B CN 108456766B CN 201810611840 A CN201810611840 A CN 201810611840A CN 108456766 B CN108456766 B CN 108456766B
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- 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
- C21D1/34—Methods of heating
- C21D1/44—Methods of heating in heat-treatment baths
- C21D1/46—Salt baths
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- 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
- C21D1/26—Methods of annealing
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- 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
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
- C21D9/58—Continuous furnaces for strip or wire with heating by baths
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Abstract
An aluminum chloride molten salt for rapidly and continuously heating thin strip steel and a heating method thereof are disclosed, wherein the molten salt is composed of aluminum chloride and any one or two of potassium chloride or sodium chloride, and the melting point of the molten salt is 110-240 ℃. The salt bath heating is adopted, the liquid salt is in direct contact with the steel strip, the heating speed is high, the temperature and oxidation controllability is high, and the heated steel strip has uniform temperature and small deformation. The liquid salt completely covers the steel plate, the heating is uniform, and the steel plate stress caused by the temperature difference is greatly reduced, so that the deformation of the steel plate is caused. The liquid salt completely covers the strip steel, so that the strip steel is isolated from oxygen in the heating process, and the oxidation is reduced.
Description
Technical Field
The invention belongs to the technical field of heat treatment heating molten salt, and particularly relates to aluminum chloride molten salt for quickly and continuously heating thin strip steel and a heating method thereof.
Background
Modern cold rolled electrical steel production requires annealing. The current annealing is completed by a continuous annealing furnace, and the general annealing is directly heated by gas combustion and then heated by a completely isolated radiant tube. The protective gas (nitrogen-hydrogen mixed gas) for the cold-rolled electrical steel continuous annealing furnace prevents (reduces) the phenomena of surface oxidation, internal oxidation and internal nitridation under the high-temperature condition, and improves the performance of the cold-rolled electrical steel. The protective gas maintains positive pressure to prevent the external gas from entering the furnace.
The heating speed of the continuous annealing of the cold-rolled electrical steel has obvious influence on the performance of a final product, and the product performance can be improved due to the high heating speed. In addition, the oxidation degree also has a remarkable influence on the product performance, which is particularly remarkable on high-grade electrical steel.
In order to increase the heating rate of electrical steel, Japanese patent application laid-open No. 5-59441(JPH0559441A, 1993.03.09) utilizes the electrical resistance of electrical steel strip, and the electrical resistance heats the electrical steel to a temperature required for recrystallization. However, the contact resistance of the connection point of the electric circuit fluctuates greatly due to the movement and the shape of the electrical steel, so that the steel strip cannot be heated uniformly.
Similarly, Japanese patent No. CN02814192.X- "ultrahigh magnetic flux density single-oriented electrical steel sheet having excellent high magnetic field iron loss and coating properties and method for producing the same" of New day iron requires a heating rate of > 100 ℃/s, actually 300 ℃/s or 400 ℃/s, before decarburization annealing in order to obtain oriented silicon steel having high magnetic induction and low iron loss. Japanese patent No. CN 200780014827.6-method for producing grain-oriented electrical steel sheet with high magnetic flux density and CN 200780018947.3-method for producing grain-oriented electrical steel sheet with high magnetic flux density similarly require heating rate, and induction heating is required for rapid heating.
In the heat treatment (lump) of a tool or a die made of high-speed steel or the like, the japanese patent CN200880011115.3 "continuous annealing method and continuous annealing apparatus for a steel strip having a curie point" of new japanese iron employs salt bath heating in order to ensure uniformity (prevention, reduction of deformation), prevention of oxidation, and rapidity of heating. Because the workpieces treated by the heat treatment are small, the volume of the salt bath furnace is small, and the salt is static. Meanwhile, the heating time is long for the dissolution of carbides in the steel. Because the heat treatment temperature of the workpiece is higher, the melting point of the salt bath is also high.
In the continuous heating of the steel strip, the temperature of the steel strip is related to the temperature of the heating furnace and the running speed (time). Therefore, the temperature of the steel strip is influenced by a plurality of factors, the fluctuation is large, and the control of the oxidation state is difficult.
The high-speed heating in the heat treatment process of the electrical steel can improve the magnetic performance, but because the steel has a Curie point (ferromagnetic disappearance temperature), when the heating temperature of the steel strip is improved by adopting induction heating, the efficiency of the induction heating above the Curie point temperature is greatly reduced, and the heating speed is restricted. However, the heating rate of other methods is difficult to increase, and a new high-rate heating method is required.
The salt bath heating of tool steel is performed for small workpieces and is not adaptable to continuous strip heating (melting point, oxidation, heating time, fluidity, etc.). The fluidized bed heating of the tool steel utilizes conductive powder and is electric heating.
At present, a continuous annealing production line is mostly adopted for cold-rolled electrical steel, the thickness of an annealed product is generally 0.50mm, 0.35mm, 0.3mm, 0.25mm, 0.2mm and the like, the width is generally 1000 mm-1250 mm, and the running speed is more than 100 m/min; in order to realize higher heating speed, the front end of a common annealing line heating furnace adopts non-oxidation heating (NOF), and the strip steel is heated by adopting an open fire combustion mode, the heating speed is generally controlled to be dozens of ℃ (20-30 ℃/s), the requirement for further improving the product quality cannot be met, and in addition, the surface oxidation of the strip steel is inevitably caused, and the performance (particularly the iron loss) of the strip steel is reduced; the improved heating mode adopts radiant tube heating (RTF), but the heating speed is obviously reduced (less than or equal to 20 ℃/s). By adopting the two heating methods, thermal stress is often caused due to uneven heating, and the strip shape is influenced.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides an aluminum chloride molten salt for rapidly and continuously heating thin strip steel and a heating method thereof, aiming at improving the heating effect and improving the magnetic property of the electrical steel strip after passing through the molten salt continuous heat treatment line.
In order to achieve the purpose, the invention adopts the technical scheme that:
an aluminum chloride molten salt for rapidly and continuously heating thin strip steel is composed of aluminum chloride and any one or two of potassium chloride or sodium chloride, and the melting point of the molten salt is 110-240 ℃.
The molten salt consists of aluminum chloride and potassium chloride, and the content of the aluminum chloride in each mole of the molten salt is 0.4-0.7 mole.
When the content of the aluminum chloride is between 0.5 and 0.7 mol, the melting point of the molten salt is 130 ℃; when the content of the alumina is between 0.4 and 0.5 mol, the melting point of the molten salt is 240 ℃.
The molten salt consists of aluminum chloride and sodium chloride, and the content of the aluminum chloride in each mole of the molten salt is 0.42-0.65 mole.
When the content of the aluminum chloride is between 0.5 and 0.65 mol, the melting point of the molten salt is 110 ℃; when the content of aluminum chloride is between 0.42 and 0.5 mol, the melting point of the molten salt is 150 ℃.
The invention also provides a method for heating the thin strip steel by adopting the aluminum chloride molten salt, which comprises the steps of heating the aluminum chloride molten salt to the annealing temperature, spraying the aluminum chloride molten salt onto the strip steel from the strip steel outlet end of the heating furnace, enabling the sprayed heated molten salt to move in the reverse direction with the strip steel, immersing the strip steel by the molten salt, and finally enabling the molten salt to flow out from the strip steel inlet end of the heating furnace and enter a molten pool.
Preferably, a molten salt inlet arranged at the strip steel outlet end of the heating furnace and the molten pool are heated and conveyed through a circulating heating conveying system. The circulation heating conveying system comprises a molten salt conveying pipeline, an inlet and an outlet of the molten salt conveying pipeline are respectively connected with a molten salt inlet and an outlet of the heating furnace, and the system further comprises a molten salt preheater and a molten salt heater group which are sequentially arranged from the inlet end to the outlet end of the molten salt conveying pipeline.
The molten salt heater group comprises a gas heater and an electric heater, wherein the gas heater is used for heating the molten salt preheated by the preheater, and the electric heater is used for further heating the molten salt heated by the gas heater.
The molten salt preheated by the preheater is guided into the molten salt heater group through the molten salt pump to be heated, and then the molten salt is guided into the inlet of the heating furnace from the outlet of the molten salt conveying pipeline.
The molten salt pump is arranged on a conveying pipeline between the preheater and the gas heater.
In the method, the molten salt is heated to 600-900 ℃ outside the furnace, is conveyed through a pipeline, and is sprayed onto the strip steel at the outlet of the heating furnace in the continuous annealing furnace through a nozzle. The heated molten salt and the strip steel move in the reverse direction, and the strip steel is immersed by the molten salt. The rapid heat exchange is completed by the contact of the electrical steel strip and the molten salt. Meanwhile, the temperature of the strip steel is not higher than the temperature of the molten salt entering the heating furnace of the continuous annealing furnace. And then molten salt flows into a molten pool from a molten salt outlet arranged at the strip steel inlet end of the heating furnace, and liquid salt in the molten pool flows to a molten salt inlet of the strip steel continuous heating furnace after being heated, so that heating and cooling circulation is formed, and continuous heating of the strip steel is completed.
The invention has the beneficial effects that: the salt bath heating is adopted, the liquid salt is in direct contact with the steel strip, the heating speed is high, the temperature and oxidation controllability is high, and the heated steel strip has uniform temperature and small deformation. The liquid salt completely covers the steel plate, the heating is uniform, and the steel plate stress caused by the temperature difference is greatly reduced, so that the deformation of the steel plate is caused. The liquid salt completely covers the strip steel, so that the strip steel is isolated from oxygen in the heating process, and the oxidation is reduced. The method can realize the reduction of rapid heating and oxidation, and improve the magnetic property of the annealed strip steel. Because the surface oxidation is reduced, the annealing temperature can be subsequently increased, the iron loss is reduced, and the surface quality of the product is improved.
Drawings
The description includes the following figures, the contents shown are respectively:
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic diagram of the structure of the purification device of the present invention.
Labeled as:
1. the device comprises a strip steel, 2, a heating furnace, 3, a soaking furnace, 4, a preheater, 5, a molten salt pump, 6, a gas heater, 7, an electric heater, 8, a nozzle, 9, an inlet pipe, 10, a container, 13 and a vacuum device.
Detailed Description
The following detailed description of the embodiments of the present invention will be given with reference to the accompanying drawings for a purpose of helping those skilled in the art to more fully, accurately and deeply understand the concept and technical solution of the present invention and to facilitate its implementation.
Electrical steel strips are manufactured by smelting, continuous casting, hot rolling, and then acid pickling and cold rolling to the thickness and width of the finished product, and annealing is required to obtain the required properties. The invention provides a molten salt of liquid in a wide temperature range, and the magnetic property of electrical steel after the molten salt is subjected to continuous heat treatment. The molten salt is described in detail below:
an aluminum chloride molten salt for rapidly and continuously heating thin strip steel, which consists of aluminum chloride and any one or two of potassium chloride or sodium chloride, and has a melting point of 110-240 ℃. The low-melting-point salt is formed by the aluminum chloride molten salt, the low-melting-point salt has a good heating effect, and the magnetic property of the electrical steel after the molten salt is subjected to continuous heat treatment.
As a preferred aluminum chloride molten salt, the molten salt is composed of aluminum chloride and potassium chloride, and the aluminum chloride is contained in an amount of 0.4 to 0.7 mol per mol of the molten salt. When the content of the aluminum chloride is between 0.5 and 0.7 mol, the melting point of the molten salt is 130 ℃, because the melting point of the molten salt is low, the strip steel entering the annealing furnace to be cooled can cause the crystallization of the salt to be rapidly melted, the liquid molten salt can obtain high heating speed, and the magnetic property is improved by about 15 to 18 percent compared with the strip steel processed by the existing heating method; when the content of the aluminum oxide is between 0.4 and 0.5 mol, the melting point of the molten salt is 240 ℃, and because the melting point of the molten salt is low, the crystals of the salt caused by the strip steel entering the annealing furnace and cooled in the annealing furnace can be rapidly melted, and the liquid molten salt can obtain high heating speed.
As a second preferred aluminum chloride-based molten salt, the molten salt is composed of aluminum chloride and sodium chloride, and the aluminum chloride content is 0.42 to 0.65 mol per mol of the molten salt. When the content of the aluminum chloride is between 0.5 and 0.65 mole, the melting point of the molten salt is 110 ℃, because the melting point of the molten salt is low, the strip steel entering the annealing furnace to be cooled can be rapidly melted to form salt crystals, the liquid molten salt can obtain high heating speed, and the magnetic property is improved by about 8 to 10 percent compared with the strip steel processed by the existing heating method; when the content of the aluminum chloride is between 0.42 and 0.5 mol, the melting point of the molten salt is 150 ℃, because the melting point of the molten salt is low, the crystals of the salt caused by the strip steel entering the annealing furnace and cooled in the annealing furnace can be rapidly melted, and the liquid molten salt can obtain high heating speed.
The invention also provides a method for heating the thin strip steel by adopting the aluminum chloride molten salt, which comprises the steps of heating the aluminum chloride molten salt to the annealing temperature, spraying the aluminum chloride molten salt onto the strip steel from the strip steel outlet end of the heating furnace, enabling the sprayed heated molten salt to move in the reverse direction with the strip steel, immersing the strip steel by the molten salt, and finally enabling the molten salt to flow out from the strip steel inlet end of the heating furnace and enter a molten pool.
Preferably, a molten salt inlet arranged at the strip steel outlet end of the heating furnace and the molten pool are heated and conveyed through a circulating heating conveying system. As shown in fig. 1, the circulation heating conveying system comprises a molten salt conveying pipeline, a molten salt preheater 4 and a molten salt heater group which are sequentially arranged from the inlet end to the outlet end of the molten salt conveying pipeline, an inlet and an outlet of the molten salt conveying pipeline are respectively connected with a molten salt inlet and an outlet of a heating furnace 2, high-temperature liquid molten salt is filled in the heating furnace, an annealed electrical steel strip is completely covered by the molten salt in the heating furnace, and the heated electrical steel strip is uniformly heated (easily controlled by a plate shape) and has a very high heating speed due to good heat conductivity of. The molten salt preheated by the preheater is guided into the molten salt heater group through the molten salt pump 5 to be heated, and then is guided into the inlet of the heating furnace from the outlet of the molten salt conveying pipeline.
The molten salt heater group comprises a gas heater 6 for heating the molten salt preheated by the preheater 4 and an electric heater 7 for further heating the molten salt heated by the gas heater 6. Preferably, the molten salt pump is arranged on a conveying pipeline between the preheater and the gas heater.
The molten salt is matched with the heating process to heat the salt bath, so that the heating speed is high, the temperature is uniform, and the steel strip is prevented from being oxidized. The salt bath heating result of the molten salt is adopted, so that the iron loss of the product subjected to continuous annealing is reduced, the magnetic induction is high, and the surface quality is improved. Specifically, after the molten salt in the heating furnace 2 is preheated by the preheater 4 (the waste gas discharged by the heating furnace is adopted, the molten salt flowing through the heat exchanger is heated for the first time by the heat exchanger to improve the energy utilization efficiency, the heating temperature is relatively low), the molten salt is sent to the gas heater 6 by the molten salt pump 5 to be heated (coal gas and natural gas can be used as combustion media to be combusted in the heat exchanger, the process that the molten salt passes through the external loop of the heat exchanger is indirectly heated by heat conduction, the heating temperature is close to the temperature required by the process), then the molten salt is directly heated by the electric heater 7 to accurately raise the temperature of the molten salt to the annealing process temperature of the electrical steel thin strip, and the molten salt is conveyed to, and the molten salt is sprayed on the steel strip (the steel strip is ensured to accurately reach the process temperature when being led out from the heating furnace, the reverse flow of the steel strip and the molten salt in the heating furnace is accelerated, and the preheating and heating effects of the steel strip in the heating furnace are improved). The molten salt flows in a reverse direction to the strip inlet. The strip is heated during operation, while the molten salt is cooled. And cold molten salt is sent into the preheater from a molten salt outlet arranged at the strip steel inlet end, the heating process is circulated, the heating circulation of the molten salt is completed, and continuous and rapid heating of the continuous strip steel is realized.
By adopting the method, the cold-rolled thin electrical strip steel 1 passes through the continuous annealing furnace, because the heating furnace is filled with high-temperature molten salt, the steel strip is quickly preheated by the molten salt in the heating furnace 2 and is heated to the annealing process temperature, then the steel strip is annealed in the soaking furnace 3 in a heat preservation way, and the annealed steel strip leaves the annealing furnace to complete the subsequent process. In the continuous annealing furnace, the heating furnace 2 and the soaking furnace 3 are isolated and connected through a furnace throat, high-temperature airtight protection is performed in the furnace throat, the molten salt of the steel strip can be blown off, and the surface of the steel strip is ensured to have no molten salt when entering the annealing furnace. In the heating furnace, the flow direction of the molten salt is opposite to the movement direction of the steel strip, the annealed electrical steel strip is completely covered by the salt bath of the heating furnace, and the steel strip is heated by transferring heat to the low-temperature steel strip by means of the high-temperature molten salt, so that the temperature of the steel strip is quickly raised to the annealing process temperature; because the thermal conductivity of the molten salt is good, the heated electrical steel strip is heated uniformly (the shape of the strip is easy to control), and the heating speed is very high.
As shown in fig. 2, in order to remove volatile substances such as moisture in the molten salt, maintain the non-oxidizing property of the molten salt, and substantially prevent the oxidation of the electrical steel strip when the electrical steel strip is heated, it is preferable to provide a purification apparatus, a purification apparatus vessel 10, and a vacuum apparatus 13 for evacuating the interior of the vessel 10 in the above circulation heating and conveying system, wherein an inlet of the vessel 10 is connected to a molten salt outlet of the heating furnace 2 through an inlet pipe 9, and an outlet of the vessel 10 is connected to a molten salt heating line through an outlet pipe.
By adopting the purification device, the molten salt after the steel strip is heated in the electrical steel continuous annealing furnace is discharged into the container 10 through the introducing pipe 9, volatile substances such as water and the like in the molten salt are discharged under the vacuum maintaining condition, and the purity of the molten salt discharged from the molten salt discharge port is maintained. The vacuum tube interface on the container 10 is connected to a vacuum device via a vacuum tube. The molten salt after vacuum purification is discharged from the discharge port. Then the steel strip enters a molten salt heating circulation system to be heated and then is sent into a heating furnace to heat the steel strip. The vacuum device can be realized by adopting the existing vacuum equipment, such as a vacuum suction filter and the like. The discharge port of the container is preferably provided with a filter structure to prevent the molten salt from being discharged through the vacuum tube.
Preferably, the inlet duct 9 is tangential to the vessel wall. Or the introducing pipe is obliquely connected with the container wall, and the inclination angle is 0-5 degrees. The fused salt entering the container rotates on the wall of the container and then slowly falls down, so that the time of exposing the fused salt in vacuum is increased, and the purity of the fused salt is improved.
Specific preferable examples of using the above molten salt are as follows:
example 1
The composition of salt heated by salt bath of molten salt is KCl and AlCl31 mole of molten salt, AlCl3The molar content is 0.48, and the molar content of KCl is 0.52. Mixed KCl and AlCl3Heated to 880 ℃ outside the furnace to obtain a homogeneous salt solution. The 880 ℃ salt solution is sprayed onto the electrical steel strip required to be heated from the outlet of the heating section of the electrical steel continuous heating furnace to heat the steel strip to 880 ℃, then the steel strip flows into a molten pool, the molten salt flows to the inlet of the heating section of the electrical steel continuous heating furnace after being heated by an external pipeline, the temperature of the steel strip is reduced and increased by reversely flowing the molten salt, and then the molten salt is discharged outside the furnace to be heated and cooled to form a heating and cooling cycle.
The melting point of the molten salt was 240 ℃. The crystals of the salt formed by the strip steel entering the annealing furnace and cooled can be melted rapidly. Liquid molten salts enable high heating rates to be achieved.
The chemical components are as follows: rapidly heating 0.27mm electrical steel strip of 0.0025% C, 3.13% Si, 0.20% Mn, 0.0008% S, 1.05% Al, 0.0020% N, 0.01% Sn, and the balance Fe and inevitable impurities, cooling and coating the steel strip after keeping the temperature of 980 ℃ in a soaking section for a period of time to obtain a final product, namely a product P1.0/100053.1W/kg, magnetic induction B50Is 1.668T.
Example 2
The composition of salt heated by salt bath of molten salt is KCl and AlCl31 mole of molten salt, AlCl3The molar content is 0.65, and the molar content of KCl is 0.35. Mixed KCl and AlCl3Heated to 850 ℃ outside the furnace to obtain a homogeneous salt solution. The 850 ℃ saline solution is sprayed onto the electrical steel strip required to be heated from the outlet of the heating section of the electrical steel continuous heating furnace to heat the steel strip to 850 ℃, then the steel strip flows into a molten pool, the molten salt flows to the inlet of the heating section of the electrical steel continuous heating furnace after being heated by an outer pipeline, the temperature of the steel strip is reduced and increased by reversely flowing the molten salt, and then the molten salt is discharged outside the furnace to be heated and cooled to form a heating and cooling cycle.
The melting point of the molten salt was 130 ℃. No or very little crystals are formed on the surface of the strip entering the annealing furnace and can be melted rapidly. Liquid molten salts enable high heating rates to be achieved.
The electrical steel strip in the embodiment 1 is rapidly heated by the molten salt in the embodiment, and then the steel strip is cooled and coated after being kept at the soaking section of 980 ℃ for a period of time to obtain a final product, namely a product P1.0/100053.6W/kg, magnetic induction B50Is 1.660T.
Example 3
The composition of salt heated by salt bath of molten salt is NaCl and AlCl31 mole of molten salt, AlCl3The molar content is 0.525, and the molar content of KCl is 0.475. Mixed KCl and AlCl3Heated to 870 ℃ outside the furnace to obtain a homogeneous salt solution. The 870 ℃ salt solution is sprayed onto the electrical steel strip required to be heated from the outlet of the heating section of the electrical steel continuous heating furnace to heat the steel strip to 87 ℃, then flows into a molten pool, the molten salt flows to the inlet of the heating section of the electrical steel continuous heating furnace after being heated by an external pipeline, the temperature of the steel strip is reduced and increased by reversely flowing the molten salt, and then the molten salt is discharged outside the furnace to be heated and cooled to form a heating and cooling cycle.
The melting point of the molten salt is 150 ℃ because of its low melting point. The crystals of the salt formed by the strip steel entering the annealing furnace and cooled can be melted rapidly. Liquid molten salts enable high heating rates to be achieved.
The electrical steel strip in the embodiment 1 is rapidly heated by the molten salt in the embodiment, and then the steel strip is cooled and coated after being kept at the soaking section of 980 ℃ for a period of time to obtain a final product, namely a product P1.0/100053.4W/kg, magnetic induction B50It was 1.661T.
Comparative example 1
Heating the electrical steel strip in the embodiment 1 to 980 ℃ by adopting radiant tube heating (RTF), then entering a temperature equalizing section to keep the temperature at 980 ℃, cooling and coating after keeping the temperature for a period of time to obtain a final product, namely a product P1.0/100056.3W/kg, magnetic induction B50Is 1.652T.
The invention is described above with reference to the accompanying drawings. It is to be understood that the specific implementations of the invention are not limited in this respect. Various insubstantial improvements are made by adopting the method conception and the technical scheme of the invention; the present invention is not limited to the above embodiments, and can be modified in various ways.
Claims (5)
1. A method for heating thin strip steel by adopting aluminum chloride molten salt is characterized in that the molten salt is composed of any one or two of aluminum chloride and potassium chloride or sodium chloride, the melting point of the molten salt is 110-; set up purifier among the circulation heating conveying system, purifier includes the container and is used for carrying out the vacuum apparatus of evacuation to the container inside, and the import of container passes through the inlet tube and is connected with the fused salt exit linkage of heating furnace, and the discharge port of container passes through the discharge pipe and is connected with fused salt heating pipeline, is equipped with filtration at the discharge port of container.
2. The method of claim 1, wherein the molten salt is composed of aluminum chloride and potassium chloride, and the aluminum chloride is contained in an amount of 0.4 to 0.7 mol per mol of the molten salt.
3. The method for heating thin steel strip using molten salt of aluminum chloride according to claim 2, wherein the melting point of the molten salt is 130 ℃ when the content of aluminum chloride is between 0.5 and 0.7 mole per mole of molten salt; when the content of the aluminum chloride is between 0.4 and 0.5 mol, the melting point of the molten salt is 240 ℃.
4. The method of claim 1, wherein the molten salt is composed of aluminum chloride and sodium chloride, and the aluminum chloride is contained in an amount of 0.42 to 0.65 mol per mol of the molten salt.
5. The method of claim 4, wherein the melting point of the molten salt is 110 ℃ when the aluminum chloride content is between 0.5 and 0.65 mole per mole of the molten salt; when the content of aluminum chloride is between 0.42 and 0.5 mol, the melting point of the molten salt is 150 ℃.
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