CN111809028A - Heating process for avoiding surface defects of steel plate - Google Patents
Heating process for avoiding surface defects of steel plate Download PDFInfo
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- CN111809028A CN111809028A CN201910287496.8A CN201910287496A CN111809028A CN 111809028 A CN111809028 A CN 111809028A CN 201910287496 A CN201910287496 A CN 201910287496A CN 111809028 A CN111809028 A CN 111809028A
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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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
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
Abstract
The invention relates to a heating process for avoiding surface defects of a steel plate, which comprises the following specific process flows: producing a plate blank by a continuous casting machine, cutting the plate blank into a spray mark, heating the plate blank in a heating furnace, primarily rolling the plate blank, finely rolling the plate blank, coiling and baling and cutting a finished product; before the plate blank is heated in a heating furnace, the temperature of the plate blank is controlled, and the specific reaction conditions are as follows: the invention discloses a heating process for avoiding surface defects of a steel plate, which is used for controlling the surface temperature of a plate blank to be higher than Ar3 temperature or controlling the surface temperature of the plate blank to be lower than Ar1 temperature and higher than 200 ℃. And the iron scale on the surface of the steel plate is easier to remove, the carbonitride is fully dissolved in the heating process, the high-temperature plasticity of the steel is improved, and the surface defects of slag inclusion, cracks and the like of the rolled steel plate are avoided.
Description
Technical Field
The invention relates to a heating process for avoiding surface defects of a steel plate, and belongs to the technical field of metallurgical continuous casting.
Background
The process flow for rolling the continuous casting slab into the steel plate comprises the following steps: continuous casting machine producing plate blank → plate blank cutting spray mark → plate blank temperature control → plate blank heating furnace heating → plate blank blooming → plate blank finish rolling → coiling and baling → finished product cutting (steel plate).
The hot charging technology for the plate blank to enter the heating furnace is a great breakthrough of the continuous casting technology, not only can save energy and reduce consumption, but also has profound significance for the reformation of the traditional industrial structure, and greatly improves the comprehensive economic benefit in the continuous casting production process. However, the prior art for realizing hot charging of slab has great difficulty, because many steel grades have strong sensitivity to the charging temperature, and the surface defects of rolled steel are easily formed when the charging temperature is too high or too low, so that the surface quality and the internal quality of a hot coil are difficult to control.
In addition, the heating process of the plate blank in the heating furnace has profound influence on the uniformity of the quality and the mechanical property of the hot coil product, the heating process of the plate blank directly influences the microstructure and the grain size of the final product, and the improper heating and soaking temperature and the overlong heating and soaking time are root causes influencing the larger fluctuation of the performance of the final product.
At present, the control research on the surface crack defects of the steel plate mostly focuses on smelting, ladle refining, hot rolling process, recrystallization, thermomechanical rolling, deformation compression optimization, cold rolling process and the like, but the recognition and attention degree of surface temperature control before the plate blank is loaded into a heating furnace and heating process control of the plate blank of the heating furnace are insufficient.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a heating process for avoiding the surface defects of a steel plate, and aims to solve the problems in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a heating process for avoiding surface defects of a steel plate comprises the following specific process flows: producing a plate blank by a continuous casting machine, cutting the plate blank into a spray mark, heating the plate blank in a heating furnace, primarily rolling the plate blank, finely rolling the plate blank, coiling and baling and cutting a finished product; before the plate blank is heated in a heating furnace, the temperature of the plate blank is controlled, and the specific reaction conditions are as follows: controlling the surface temperature of the slab to be higher than the Ar3 temperature or controlling the surface temperature of the slab to be lower than the Ar1 temperature and higher than 200 ℃.
The method for controlling the surface temperature of the slab to be higher than the Ar3 temperature comprises the following specific steps: the secondary cooling of the slab in the continuous casting machine is controlled by weak cooling, the transportation process of the slab adopts heat preservation measures, and the slab is placed into a heating furnace 5 hours after being cut.
The weak cold control comprises the following specific steps: and a weak cooling process with low water ratio and low cooling strength is adopted in the secondary cooling process of the slab, and the surface temperature of the slab leaving the continuous casting machine is controlled to be higher than the Ar3 temperature.
The concrete steps of the heat preservation measures adopted in the slab transportation process are that a heat preservation cover is covered or the slab enters the heat preservation box in the slab transportation process, and the surface temperature of the slab entering the heating furnace is controlled to be higher than the Ar3 temperature.
The method comprises the following steps of controlling the surface temperature of the plate blank to be lower than Ar1 and higher than 200 ℃, and comprises the following specific steps: (1) forcibly cooling the hot-charged plate blank which is loaded into the heating furnace 5 hours after the plate blank is cut; (2) and (4) carrying out heat preservation and slow cooling on the cold-charged plate blank which is not required to be loaded into the heating furnace within 5 hours after the plate blank is cut.
The forced cooling steps are as follows: and carrying out water spraying and cooling on the slab from the horizontal section to the position before cutting for three times.
The heat preservation and slow cooling steps are as follows: and (4) placing the slab into a heat preservation pit or a heat preservation cover for slow cooling.
And heating the plate blank in a heating furnace, and controlling the heating time of the plate blank in the heating furnace to be 250 +/-10 min.
The slab is heated in a heating furnace, when the slab is heated, the heat load of the heating furnace moves forward, the heating section heats up quickly, and the heating temperature of the first heating section is controlled to be 1060 +/-30 ℃; the heating temperature of the second adding section is 1160 +/-10 ℃; slowly heating in the soaking section and making the tapping temperature less than 1210 +/-10 ℃.
And when the slab leaves the heating furnace and enters the primary rolling procedure, the outlet of the primary rolling R2 is opened for reverse descaling.
The primary rolling is repeated rolling of the plate blank back and forth, and when the reverse rolling is carried out, the reverse pass descaling at the outlet of the primary rolling R2 is opened to remove the scale and other impurities on the surface of the plate blank.
The reaction principle of the invention is as follows:
1. controlling the surface temperature of the slab loaded into the heating furnace to avoid the (Ar 3-Ar 1) temperature interval of steel grade
Ar3 and Ar1 are the transformation point temperatures of steel heat treatment, and are the most commonly used symbols and terms in metallurgy and metal materials science.
The temperature of the plate blank loaded into the heating furnace has direct and obvious influence on the energy consumption of the heating furnace and the subsequent steel plate quality, and the high-temperature hot loading of the plate blank not only can greatly reduce the energy consumption, improve the metal yield and shorten the production period, but also has great superiority in the aspects of production efficiency, production cost reduction and the like. However, the surface temperature of the slab charged into the furnace must be controlled to avoid the (Ar 3-Ar 1) temperature interval of the steel grade.
The reason why the temperature range (Ar 3-Ar 1) of the steel grade is avoided for controlling the surface temperature of the slab loaded into the heating furnace is that when the loading temperature of the slab is in the temperature range (Ar 3-Ar 1) of the steel grade, the macroscopic structure of the slab basically does not change and remains in the heating process, so a large amount of nitrides remain on the grain boundary after heating, and although the existence of the nitrides can play a role of inhibiting the growth of crystal grains, the high-temperature plasticity of the blank is also seriously reduced, so that the surface crack of the rolled steel plate occurs, as shown in figure 2.
The low-temperature charging is carried out, the temperature of the plate blank loaded into the heating furnace is lower than the Ar1 temperature but higher than 200 ℃ because the iron scale charged at the high temperature is easier to remove in a certain temperature range, and researches show that the plate blank is charged at the high temperature (not less than 200 ℃) in a certain temperature range, so that the energy consumption and the heating time of the heating furnace are saved, and the iron scale on the surface is easier to remove due to the large grain size of the iron scale. Therefore, the surface temperature of the low-temperature charging plate blank cannot be lower than 200 ℃, otherwise, the scale cannot be removed cleanly, and the slag inclusion defect on the surface of the steel plate is caused, as shown in figure 2.
It should be noted that the temperature ranges (Ar 3-Ar 1) are different for different steel types, and all steel types cannot be in the same temperature range.
2. The heating time of the plate blank in the heating furnace is controlled to be 250 +/-10 min, so that the plate blank is ensured to be fully heated and not to be over-fired
The slab heating process directly influences the original austenite grain size before hot rolling plastic deformation, and uniform slab heating and soaking are the basic guarantee for obtaining good and proper original austenite grains and are the basic requirements of a steel rolling process on a heating process. The slab heating process comprises the steps of firstly heating the slab in a furnace for 250 +/-10 min, and ensuring that the slab is not over-heated and not over-fired.
Because the slab heating time in the heating furnace is too short or the heating temperature is too low, the second phase particles precipitated in the casting process cannot be dissolved, and the quality problem can occur in the rolling process.
However, if the slab is in the heating furnace for too long time, the slab is over-burnt, the corners of the casting blank are over-oxidized, the grains of the slab grow abnormally, and the performance and the surface quality of the steel plate are deteriorated. Meanwhile, the excessive heating time of the plate blank increases the oxidation burning loss of the surface layer of the casting blank, the thickness of the iron scale is increased, the impurities enriched and captured on the surface layer of the casting blank are easier to remove in the rough descaling process, and finally the occurrence rate of the surface quality defects of the rolled product is reduced.
It should be noted that the heating time in the heating furnace is basically the same (250 ± 10 min) regardless of the slab charged at high temperature or low temperature, which is a requirement for ensuring the rolling rhythm of the subsequent slab and ensures the uniform rolling of the subsequent slab. However, the initial temperature of the slab entering the heating furnace is different between the high-temperature charging and the low-temperature charging, the initial temperature of the slab entering the heating furnace is high, the initial temperature of the low-temperature charging is low, so that the heating rates of the slab entering the heating furnace and the low-temperature charging in the heating furnace are different, and the slab heating process model calculates the heating rate of the slab through vibration according to the difference between the initial temperature of the slab entering the heating furnace and the target temperature of the slab leaving the heating furnace and the given heating time. The heating rate of the plate blank with high initial temperature of high-temperature charging is slower, and the heating rate of the plate blank with low initial temperature of low-temperature charging is faster.
3. Optimizing a heating process: when the plate blank is heated, the heat load of the heating furnace moves forward, the heating section heats up quickly, and the heating temperature of the first heating section is controlled to be 1060 +/-30 ℃; the heating temperature of the second adding section is 1160 +/-10 ℃; slowly heating in the soaking section and making the tapping temperature less than 1210 +/-10 ℃.
The slab is taken out of the heating furnace and enters a primary rolling procedure, and the reverse pass descaling of the primary rolling R2 is started at the moment, so that the high-temperature iron scale generated in the heating furnace can be effectively removed under the striking of a high-pressure water dephosphorization device after being taken out of the furnace, and the defect of slag inclusion of the iron scale on the surface of the steel plate is reduced.
Temperature fluctuation and uneven heating of the slab in the heating process of the heating furnace can cause a mixed crystal structure with different sizes of austenite grains, and the performance and the surface quality of the steel plate are deteriorated. In the slab heating process, the temperatures of the heating section and the soaking section of the heating furnace in industrial production are generally within the range of 1120-. The heating load and the soaking load are properly adjusted, so that the very refined and uniform grain size can be achieved, and the surface crack defects and the steel plate performance of the steel plate are controlled.
Since the precipitation of carbonitride particles such as AlN and Nb (CN) inevitably occurs in the slab during continuous casting from the viewpoint of the dissolution of the second phase particles, the carbonitride particles such as AlN should be sufficiently dissolved in the matrix during heating in order to avoid the occurrence of cracks during rolling. If the early heating is insufficient, the carbonitride is not sufficiently dissolved, the thermoplasticity difference of the steel is large, and the hot rolling crack tendency of the steel plate is large. If the later heating is too fast and the heating temperature is too high, the rolling temperature enters the I high-temperature brittle zone (1300-.
Compared with the prior art, the invention has the following beneficial effects because the technology is adopted:
the invention provides the continuous casting billet hot-feeding hot-charging and heating process which can realize hot-feeding hot-charging and effectively avoid cracks on the surface of a rolled steel plate, can achieve good energy-saving effect and can effectively avoid surface defects such as cracks, slag inclusion and the like after the steel plate is rolled.
The invention discloses a heating process for avoiding surface defects of a steel plate, which not only realizes hot feeding and hot charging of a plate blank, but also fully utilizes the residual heat of a continuous casting billet to achieve a good energy-saving effect on the premise of not increasing any equipment and production cost. The iron scale on the surface of the steel plate is easier to remove, the carbonitride is fully dissolved in the heating process, the high-temperature plasticity of the steel is improved, and the surface defects of slag inclusion, cracks and the like of the rolled steel plate are avoided;
the invention emphasizes the temperature control process before the plate blank enters the heating furnace and the change of the heating process of the plate blank in the heating furnace to achieve the purpose of controlling the surface cracks of the steel plate. The method avoids the traditional methods of smelting, ladle refining, hot rolling process, recrystallization, heat engine rolling, deformation compression optimization, cold rolling process and the like which are mostly concentrated on the control research of the surface crack defect of the steel plate at present, develops a new way, overcomes the technical bias inherent in the technology, improves the thermodynamic and kinetic conditions in the heating and soaking processes by innovatively controlling the temperature before the plate blank is arranged into the heating furnace and optimizing the heating process of the plate blank in the heating furnace, controls the austenite grain size and uniformity in the full length and thickness direction of the plate blank, reduces the surface crack defect of the steel plate, and improves the performance of the steel plate.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a schematic diagram of slab solidification structure transition at different hot charging temperatures;
FIG. 3 is a schematic diagram of the austenite structure of a plate blank under different heating temperatures;
FIG. 4 is a comparison of the surface structure of the materials before and after different processes are applied to examples 5 and 6.
Detailed Description
The invention is further elucidated with reference to the drawings and the detailed description.
Example 1
The hot-feeding, heating and loading of the plate blank and the heating process are adopted by a certain steel mill for 230mm x 1300mm ultralow-carbon interstitial free steel, namely IF steel, the surface temperature of the continuous casting blank of the IF steel is more than or equal to 300 ℃ but less than the Ar1 temperature of the IF steel and 600 ℃, the heating time of the plate blank in a heating furnace is controlled to be 240 minutes, when the heating furnace is used for heating, the temperature of a first heating section is quickly raised, the temperature of a second heating section and a soaking section are slowly raised, the tail temperature of the first heating section is controlled to be more than 1060 ℃, the tail temperature of the second heating section is controlled to. The thickness of the rolled steel plate is 0.2-0.4mm, and the surface of the steel plate has no surface defects such as slag inclusion, cracks and the like. Compared with a cold charging continuous casting billet, the process can save energy by 40 percent and improve the qualification rate of the steel plate by 0.24 percent.
Example 2
The plate blank hot-feeding, hot-charging and heating process is adopted by a certain steel mill for 230mm x 950mm low-carbon tinned plate steel, the surface temperature of the tinned plate steel continuous casting blank is more than or equal to 200 ℃ but is 550 ℃ lower than the tinned plate steel Ar1 temperature, the plate blank is charged into a heating furnace, the heating time of the plate blank in the heating furnace is controlled within 245 minutes, when the heating furnace is used for heating, the temperature of a first heating section is rapidly increased, the temperature of a second heating section and a soaking section are slowly increased, the end temperature of the first heating section is controlled to be more than 1030 ℃, the end temperature of the. The thickness of the rolled steel plate is 0.3-0.6mm, and the surface of the steel plate has no surface defects such as slag inclusion, cracks and the like. Compared with a cold charging continuous casting billet, the process can save energy by 38 percent and improve the qualification rate of the steel plate by 0.21 percent.
Example 3
A certain steel mill adopts the hot-feeding, heating and loading process of the plate blank of the invention for the high-carbon tool steel 65Mn of 230mm multiplied by 1200mm, the continuous casting and secondary cooling process of the 65Mn steel adopts the weak cooling process, a heat preservation cover is added for heat preservation in the transportation process, the plate blank is transferred into a heating furnace after being cut for 3 hours, the surface temperature of the plate blank before being loaded into the heating furnace is more than or equal to 750 ℃ (Ar 3 temperature), the heating time of the plate blank in the heating furnace is controlled to be 260 minutes, when the heating furnace is used for relieving heat, the temperature of the first heating section is rapidly increased, the temperature of the second heating section and the uniform heating section is slowly increased, the end temperature of the first heating section. The thickness of the rolled steel plate is 6.0mm, and the surface of the steel plate has no surface defects such as slag inclusion, cracks and the like. Compared with a cold charging continuous casting billet, the process can save energy by 56 percent and improve the qualification rate of the steel plate by 0.85 percent.
Example 4
The hot-feeding, heating and heating process of the plate blank is adopted by a certain steel mill for 230mm x 1150mm high-carbon fine blanking steel C45E, the C45E plate blank enters a plate blank storehouse heat-preserving cover for slow cooling for 24-48 hours after being cut, the surface temperature of the plate blank is controlled to be lower than 550 ℃ (Ar 1 temperature) and is not lower than 200 ℃, the plate blank is loaded into a heating furnace, the heating time of the plate blank in the heating furnace is controlled to be 250 minutes, when the heating furnace is used for heating, the temperature of a first heating section is rapidly increased, the temperature of a second heating section is slowly increased, the end temperature of the first heating section is controlled to be higher than 1060 ℃, the end temperature of the second heating section is controlled to be higher. The thickness of the rolled steel plate is 3.0mm, and the surface of the steel plate has no surface defects such as slag inclusion, cracks and the like. Compared with a cold charging continuous casting billet, the process can save 45% of energy and improve the qualification rate of the steel plate by 0.76%.
Example 5
The traditional production process comprises the following steps: when a certain steel factory produces the 230mm multiplied by 1250mm medium carbon tool steel 20CrMnTi, the traditional slab hot-feeding hot-charging process is adopted, the surface temperature of the actually measured slab before being charged into the heating furnace is between 600 ℃ and 680 ℃, the heating time of the heating furnace is 300 minutes, the heating section and the soaking section are uniformly heated and heated, and the temperature of the heating furnace is 1250 ℃. The Ar1 temperature of the 20CrMnTi steel grade is 585 ℃, the Ar3 temperature is 750 ℃, the hot charging temperature of the plate blank just falls into the Ar1-Ar3 temperature range of the 20CrMnTi steel grade, a large amount of crackle warping defects are generated on the surface of the steel plate after rolling, and the performance index of the steel plate is poor, which is shown in figure 4 (a).
Example 6
The hot-feeding hot-charging and heating process is adopted, the 20CrMnTi continuous casting secondary cooling process adopts a weak cooling process, the plate blank enters a heat-preserving cover of a plate blank storehouse for slow cooling for 24-36 hours after being cut, the surface temperature of the plate blank is lower than 600 ℃ (Ar 1), the surface temperature of the plate blank is more than or equal to 250 ℃, the plate blank is charged into a heating furnace, the heating time of the plate blank in the heating furnace is controlled to be 255 minutes, the first heating section is rapidly heated up, the second heating section and the uniform heating section are slowly heated up, the end temperature of the first heating section is controlled to be less than 1090 ℃, the end temperature of the second heating section is controlled to be. As a result of rolling, no crackling defects were generated on the surface of the steel sheet, as shown in FIG. 4 (b).
The performance indexes of tensile strength, elongation, reduction of area and the like of 20CrMnTi produced in example 5 and example 6 under different processes are detected, and the comparison result is shown in the following table 1.
TABLE 1 COMPARATIVE TABLE OF PERFORMANCE OF STEEL SHEETS PRODUCED IN EXAMPLE 5 AND EXAMPLE 6
Therefore, the invention provides the continuous casting billet hot-feeding hot-charging and heating process which can realize hot-feeding hot-charging and effectively avoid cracks on the surface of a rolled steel plate, can achieve good energy-saving effect and can effectively avoid surface defects such as cracks, slag inclusion and the like after the steel plate is rolled. On the premise of not increasing any equipment and production cost, hot feeding and hot charging of the plate blank are realized, the waste heat of the continuous casting blank is fully utilized, and a good energy-saving effect is achieved. And the iron scale on the surface of the steel plate is easier to remove, the carbonitride is fully dissolved in the heating process, the high-temperature plasticity of the steel is improved, and the surface defects of slag inclusion, cracks and the like of the rolled steel plate are avoided.
The above-mentioned embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and the scope of the present invention should be defined by the claims, and equivalents including technical features of the claims, i.e., equivalent modifications within the scope of the present invention.
Claims (10)
1. A heating process for avoiding surface defects of a steel plate is characterized by comprising the following specific process flows: producing a plate blank by a continuous casting machine, cutting the plate blank into a spray mark, heating the plate blank in a heating furnace, primarily rolling the plate blank, finely rolling the plate blank, coiling and baling and cutting a finished product; before the plate blank is heated in a heating furnace, the temperature of the plate blank is controlled, and the specific reaction conditions are as follows: controlling the surface temperature of the slab to be higher than the Ar3 temperature or controlling the surface temperature of the slab to be lower than the Ar1 temperature and higher than 200 ℃.
2. The heating process for avoiding the surface defects of the steel plate as claimed in claim 1, wherein the method for controlling the surface temperature of the plate blank to be higher than the Ar3 temperature comprises the following specific steps: the secondary cooling of the slab in the continuous casting machine is controlled by weak cooling, the transportation process of the slab adopts heat preservation measures, and the slab is placed into a heating furnace 5 hours after being cut.
3. A heating process for avoiding surface defects of a steel sheet according to claim 2, wherein: the weak cold control comprises the following specific steps: and the secondary cooling process of the slab adopts a weak cooling process, and the surface temperature of the slab leaving the continuous casting machine is controlled to be higher than the Ar3 temperature.
4. A heating process for avoiding surface defects of a steel sheet according to claim 2, wherein: the concrete steps of the heat preservation measures adopted in the slab transportation process are that a heat preservation cover is covered or the slab enters the heat preservation box in the slab transportation process, and the surface temperature of the slab entering the heating furnace is controlled to be higher than the Ar3 temperature.
5. A heating process for avoiding surface defects of a steel sheet according to claim 1, wherein: the method comprises the following steps of controlling the surface temperature of the plate blank to be lower than Ar1 and higher than 200 ℃, and comprises the following specific steps: (1) forcibly cooling the hot-charged plate blank which is loaded into the heating furnace 5 hours after the plate blank is cut; (2) and (4) carrying out heat preservation and slow cooling on the cold-charged plate blank which is not required to be loaded into the heating furnace within 5 hours after the plate blank is cut.
6. A heating process for avoiding surface defects of a steel sheet according to claim 5, wherein: the forced cooling steps are as follows: and carrying out water spraying and cooling on the slab from the horizontal section to the position before cutting for three times.
7. A heating process for avoiding surface defects of a steel sheet according to claim 5, wherein: the heat preservation and slow cooling steps are as follows: and (4) placing the slab into a heat preservation pit or a heat preservation cover for slow cooling.
8. A heating process for avoiding surface defects of a steel sheet according to claim 1, wherein: and heating the plate blank in a heating furnace, and controlling the heating time of the plate blank in the heating furnace to be 250 +/-10 min.
9. A heating process for avoiding surface defects of a steel sheet according to claim 1, wherein: the slab is heated in a heating furnace, when the slab is heated, the heat load of the heating furnace moves forward, the heating section heats up quickly, and the heating temperature of the first heating section is controlled to be 1060 +/-30 ℃; the heating temperature of the second adding section is 1160 +/-10 ℃; slowly heating in the soaking section and making the tapping temperature less than 1210 +/-10 ℃.
10. A heating process for avoiding surface defects of a steel sheet according to claim 1, wherein: and when the slab leaves the heating furnace and enters the primary rolling procedure, the outlet of the primary rolling R2 is opened for reverse descaling.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113210423A (en) * | 2021-04-21 | 2021-08-06 | 鞍钢联众(广州)不锈钢有限公司 | Manufacturing method of invar alloy hot-rolled steel coil |
| CN114669606A (en) * | 2020-12-24 | 2022-06-28 | 宝山钢铁股份有限公司 | Internally cooled steel plate interruption prevention control method and rolling line |
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| CN114669606A (en) * | 2020-12-24 | 2022-06-28 | 宝山钢铁股份有限公司 | Internally cooled steel plate interruption prevention control method and rolling line |
| CN114669606B (en) * | 2020-12-24 | 2024-03-08 | 宝山钢铁股份有限公司 | Method for preventing interruption of intermediate cooling steel plate and rolling line |
| CN113210423A (en) * | 2021-04-21 | 2021-08-06 | 鞍钢联众(广州)不锈钢有限公司 | Manufacturing method of invar alloy hot-rolled steel coil |
| CN113210423B (en) * | 2021-04-21 | 2022-02-22 | 鞍钢联众(广州)不锈钢有限公司 | Manufacturing method of invar alloy hot-rolled steel coil |
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