Method for controlling scale structure uniformity of hot-rolled steel

Abstract

The application is suitable for the technical field of steel production, and particularly relates to a method for controlling the uniformity of the oxide scale structure of hot-rolled steel, which comprises the following steps: arranging at least one conditioning cavity; injecting working gas containing oxygen into the conditioning cavity at positive pressure; arranging a temperature detection unit in each conditioning cavity to obtain the surface temperature of the hot-rolled steel in real time, dynamically adjusting the parameters of the working gas in the corresponding conditioning cavity according to the obtained temperature value; measuring the thickness of the final oxide scale layer, comparing the measured thickness value with a preset target thickness range, and correcting the target setting value of the subsequent process parameters according to the comparison result. By injecting positive pressure gas, the application reduces the equipment cost and maintenance difficulty, dynamically adjusts the composition and flow of the working gas through temperature monitoring, actively controls the oxidation reaction process, and based on the detection and feedback correction of the thickness of the final product oxide layer, can continuously optimize the process parameter setting value of the subsequent production.

Description

Technical Field

[0001] This invention belongs to the field of steel production technology, and in particular relates to a method for controlling the uniformity of iron oxide scale structure in hot-rolled steel. Background Technology

[0002] During the high-temperature rolling process, hot-rolled steel reacts with oxygen in the air to form a layer of iron oxide scale, mainly composed of FeO, Fe3O4, and Fe2O3. The structure of this iron oxide scale (the thickness ratio, density, and uniformity of each layer) directly affects the subsequent processing performance and surface quality of the steel. For hot-rolled products with complex cross-sections, such as structural steel and rails, the significant differences in heat dissipation conditions and oxygen supply environment at different parts (such as flanges, webs, and radius corners) during the cooling process after rolling make it easy to form an iron oxide scale layer with uneven thickness and inconsistent structure. This leads to problems such as difficulties in subsequent pickling, surface color differences, and even affecting coating adhesion.

[0003] Existing methods for controlling iron oxide scale in hot-rolled steel mainly focus on adjusting rolling temperature and cooling rate, as well as physical removal methods such as high-pressure water descaling, or reducing oxidation by controlling the furnace atmosphere in a completely sealed heating furnace. However, these methods are difficult to implement low-cost online atmosphere control for continuous hot-rolling production lines in open environments, especially for steel sections with asymmetrical and complex cross-sections. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling the uniformity of iron oxide scale structure in hot-rolled steel, aiming to solve the problem that existing methods are difficult to achieve low-cost online atmosphere control in continuous hot rolling production lines in open environments, especially for steel sections with asymmetrical and complex cross-sections.

[0005] This invention is implemented as follows: a method for controlling the uniformity of iron oxide scale structure in hot-rolled steel, the method comprising: At least one quenching and tempering chamber is provided, which is set along the rolling direction of the steel section. The inlet and outlet of the quenching and tempering chamber are matched with the cross-sectional shape of the hot-rolled steel section and a predetermined gap is left. A working gas containing oxygen is injected into the conditioning chamber under positive pressure, and a positive pressure air curtain is used to maintain the required atmosphere environment inside the conditioning chamber. A temperature detection unit is set in each tempering chamber to acquire the surface temperature of the hot-rolled steel in real time. Based on the acquired temperature value, the parameters of the working gas in the corresponding tempering chamber are dynamically adjusted to control the oxidation reaction process. After all the tempering and heat treatment chambers are completed and completely cooled, the final iron oxide scale thickness is measured. The measured thickness value is compared with the preset target thickness range, and the target setting values ​​of subsequent process parameters are corrected based on the comparison results.

[0006] Preferably, the conditioning chamber is provided with an adjustable exhaust port, the opening of which is linked to the positive pressure value inside the conditioning chamber. When the positive pressure value increases, the opening of the exhaust port increases.

[0007] Preferably, the step of injecting a working gas containing oxygen into the conditioning chamber under positive pressure and maintaining the required atmosphere environment within the conditioning chamber using a positive pressure gas curtain includes: Based on the preset target oxide layer thickness and the real-time detected surface temperature of the steel profile, calculate the required oxygen concentration, injection flow rate, and injection pressure of the working gas. Working gas is injected into the quenching and tempering chamber through multiple injection holes arranged on the inner wall of the chamber, forming a continuous positive pressure air curtain in the gap between the steel surface and the inner wall of the chamber. The pressure fluctuations inside the conditioning chamber are monitored in real time, and the injection flow rate of the working gas and the opening of the exhaust port are dynamically adjusted based on the monitoring results.

[0008] Preferably, the step of setting a temperature detection unit in each tempering chamber to acquire the surface temperature of the hot-rolled steel section in real time, and dynamically adjusting the parameters of the working gas in the corresponding tempering chamber according to the acquired temperature value to control the oxidation reaction process includes: Non-contact temperature sensors are arranged at multiple locations within the tempering chamber to collect surface temperature data of different parts of the hot-rolled steel in real time. The collected temperature data is compared with the preset optimal temperature for oxidation reaction. When the temperature deviates, the adjustment amount of the working gas in the conditioning chamber is calculated according to the degree of deviation. The adjustment amount includes at least one of oxygen concentration adjustment amount, gas injection flow rate adjustment amount, or gas flow rate adjustment amount. By adjusting the supply parameters of the working gas in the corresponding conditioning chamber, the temperature of that part can be restored to the optimal temperature.

[0009] Preferably, the step of measuring the final iron oxide scale thickness after completing the treatment of all tempering chambers and achieving complete cooling, comparing the measured thickness value with a preset target thickness range, and correcting the target settings of subsequent process parameters based on the comparison result includes: After the hot-rolled steel treated in the tempering chamber is naturally cooled to room temperature, the thickness of the final iron oxide scale layer at multiple different locations on the surface of the steel is measured using an offline detection method, and its average value and uniformity deviation are calculated. The measured average thickness is compared with the preset target thickness range, and the uniformity deviation is compared with the preset allowable deviation range to determine whether the control effect of the current batch of iron oxide scale is qualified. If it is not qualified, the correction amount of the process parameters is output based on the thickness deviation value and the uniformity deviation value. The correction amount is applied to the target setpoints of subsequent production process parameters, including correcting at least one of the following: oxygen concentration of the working gas, injection flow rate, positive pressure value, temperature control window, or steel profile travel speed.

[0010] Preferably, the number of tempering cavities is 2 to 6, and they are arranged in series along the rolling direction of the steel section.

[0011] Preferably, the working gas is one or more of air, oxygen-enriched air, nitrogen, or a nitrogen-hydrogen mixture.

[0012] The method for controlling the uniformity of iron oxide scale structure in hot-rolled steel provided by this invention reduces equipment costs and maintenance difficulty by setting a tempering chamber that matches the cross-section of the steel section and leaves a gap, and by introducing positive pressure gas. Through temperature monitoring, the composition and flow rate of the working gas are dynamically adjusted to achieve active control of the oxidation reaction process. Based on the detection and feedback correction of the oxide layer thickness of the final product, the process parameter settings for subsequent production can be continuously optimized. Attached Figure Description

[0013] Figure 1 A flowchart illustrating the method for controlling the uniformity of iron oxide scale structure in hot-rolled steel according to an embodiment of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0015] like Figure 1 The diagram shows a flowchart of a method for controlling the uniformity of iron oxide scale structure in hot-rolled steel according to an embodiment of the present invention. The method includes: S100, at least one quenching and tempering chamber is provided, the quenching and tempering chamber is provided along the rolling direction of the section steel, the inlet and outlet of the quenching and tempering chamber are matched with the cross-sectional shape of the hot-rolled section steel, and a predetermined gap is left.

[0016] In this step, multiple tempering chambers are sequentially set along the moving path of the steel section in the rolling exit direction of the hot-rolled steel section production line, such as 2 to 6 arranged in series. The inlet and outlet shapes of each tempering chamber are designed according to the cross-sectional profile of the steel section being processed. For example, for H-beams, the inlet and outlet shapes are H-shaped, and a predetermined gap of 0.5 to 5 mm is maintained between them and the surface of the steel section to ensure that the steel section passes through smoothly.

[0017] S200 injects working gas containing oxygen into the conditioning chamber under positive pressure, and uses a positive pressure air curtain to maintain the required atmosphere environment inside the conditioning chamber.

[0018] In this step, after the steel profile enters the tempering chamber, working gas is continuously injected into the chamber through multiple injection holes arranged on the inner wall of the chamber at a positive pressure higher than the external ambient pressure. The working gas can be one or more of air, oxygen-enriched air, nitrogen, or a nitrogen-hydrogen mixture, with air being preferred. The injected gas forms a positive pressure air curtain in the gap between the surface of the steel profile and the inner wall of the chamber, effectively preventing the intrusion of external air without the need for sealing. The chamber is equipped with an adjustable exhaust port, the opening of which is linked to the positive pressure value inside the chamber. When the positive pressure increases, the exhaust port automatically opens wider to ensure smooth gas flow.

[0019] The S300 is equipped with a temperature detection unit in each tempering chamber to acquire the surface temperature of the hot-rolled steel in real time. Based on the acquired temperature value, the parameters of the working gas in the corresponding tempering chamber are dynamically adjusted to control the oxidation reaction process.

[0020] In this step, an infrared thermometer is installed inside each tempering chamber to acquire the surface temperature data of the steel profile in real time. The acquired temperature is compared with the preset optimal temperature for the oxidation reaction. When the temperature of a certain part deviates from the window, the working gas parameters are adjusted according to the degree of deviation, including changing the oxygen concentration, increasing or decreasing the gas injection flow rate, and adjusting the gas flow rate. For example, when the local temperature is detected to be too high, the heat can be removed and the oxidation rate reduced by increasing the proportion of nitrogen or increasing the gas flow rate; when the temperature is too low, the injection volume of oxygen-enriched air is increased to promote the oxidation reaction.

[0021] S400: After completing the treatment of all tempering chambers and achieving complete cooling, the final iron oxide scale layer thickness is measured. The measured thickness value is compared with the preset target thickness range, and the target setting value of subsequent process parameters is corrected based on the comparison result.

[0022] In this step, after the steel profiles have undergone complete heat treatment in the tempering chamber and have cooled completely to room temperature, an offline testing method, such as ultrasonic thickness measurement, is used to measure the final iron oxide scale thickness at multiple locations on their surface. The average thickness and uniformity deviation are calculated, and the measurement results are compared with the preset target thickness range and allowable uniformity deviation. If the requirements are not met, the correction amount for relevant process parameters in subsequent production is calculated based on the thickness deviation value and uniformity deviation value through a pre-established process correction model. The process parameters include the oxygen concentration of the working gas, injection flow rate, positive pressure value, temperature control window, or steel profile travel speed, etc. The correction amount is applied to the target setting values ​​of the production process parameters for the next batch of steel profiles.

[0023] As a preferred embodiment of the present invention, the step of injecting a working gas containing oxygen into the conditioning chamber under positive pressure and maintaining the required atmosphere environment within the conditioning chamber using a positive pressure gas curtain includes: S201, based on the preset oxide layer thickness target and the real-time detected steel surface temperature, calculates the required working gas oxygen concentration, injection flow rate and injection pressure.

[0024] In this step, just before the steel section enters the tempering chamber, based on the preset target thickness of the iron oxide scale (e.g., 8–12 μm) and the current surface temperature of the steel section detected in real time by a temperature sensor, the required oxygen concentration, injection flow rate, and injection pressure of the working gas are calculated using a built-in oxidation kinetic model. For example, if the target thickness is too thin and the temperature is too high, the oxygen concentration needs to be reduced to suppress oxidation; conversely, if the temperature is too low and the target thickness is too thick, the injection volume of oxygen-enriched air is increased. Taking the production of H400×200 steel section as an example, when the web temperature is 30°C higher than the flange temperature, it is calculated that the oxygen concentration in the corresponding area of ​​the injection hole needs to be reduced from 21% (air) to 15%, and the gas injection flow rate should be increased from 10 m³ / s. 3 / h increased to 15m 3 / h, and set the positive pressure value to 30Pa to balance the different oxidation trends on both sides.

[0025] S202 injects working gas into the tempering chamber through multiple injection holes arranged on the inner wall of the tempering chamber, forming a continuous positive pressure air curtain in the gap between the steel surface and the inner wall of the chamber.

[0026] In this step, multiple injection holes are distributed on the inner wall of the tempering chamber according to the cross-sectional shape of the steel profile. The injection holes face the surface of the steel profile and correspond to key parts such as the flanges, webs, and radius (R-angle) of the steel profile. During operation, working gas is continuously injected into the chamber through the pipeline at a preset positive pressure value. After the gas flows out of the injection holes at high speed, a continuous and stable positive pressure air curtain is formed in the narrow gap of only a few millimeters between the surface of the steel profile and the inner wall of the chamber. The air curtain has two functions: first, it flows outward from both ends of the gap, blocking the intrusion of external air; second, it acts directly on the surface of the steel profile, and the oxidation reaction rate in this area is controlled by changing the gas composition and flow rate. For example, in actual production, air is injected near the inlet of the tempering chamber to form a basic oxide layer, while a nitrogen-hydrogen mixture is injected near the outlet. The air curtain is used to drive away residual oxygen, thereby achieving segmented control of oxidation followed by inhibition along the length of the steel profile.

[0027] S203 monitors the pressure fluctuations inside the conditioning chamber in real time and dynamically adjusts the injection flow rate of the working gas and the opening of the exhaust port based on the monitoring results.

[0028] In this step, a pressure sensor is installed inside the tempering chamber to monitor pressure fluctuations in the chamber in real time. When the sensor detects that the pressure deviates from the preset stable range, it automatically adjusts according to the degree of deviation: on the one hand, the injection flow rate of the working gas is adjusted through the proportional regulating valve; on the other hand, the opening of the exhaust port installed on the chamber is adjusted in conjunction with the control. For example, when the steel profile passes through at high speed, its surface drives the gas to generate additional dynamic pressure, causing the pressure inside the chamber to rise to 45Pa. At this time, the control system first appropriately reduces the injection flow rate of the working gas, and at the same time increases the opening of the exhaust port to allow the excess gas to be discharged quickly until the pressure returns to about 30Pa.

[0029] In a preferred embodiment of the present invention, the step of setting a temperature detection unit in each tempering chamber to acquire the surface temperature of the hot-rolled steel section in real time, and dynamically adjusting the parameters of the working gas in the corresponding tempering chamber according to the acquired temperature value to control the oxidation reaction process includes: S301 uses non-contact temperature sensors arranged at multiple locations within the tempering chamber to collect surface temperature data of different parts of the hot-rolled steel in real time.

[0030] In this step, multiple infrared thermometers are arranged inside each tempering chamber according to the cross-sectional shape of the steel section. The installation positions of the sensors need to cover all key parts of the steel section, including the flange tip, flange middle, web center, and inner and outer R-angle transition areas. Taking H-section steel as an example, sensors are set above, on both sides and below the tempering chamber, corresponding to the upper flange, web, lower flange and R-angle areas, respectively. The sensors collect the surface temperature of the steel section in real time at a sampling frequency of milliseconds.

[0031] S302, compare the collected temperature data with the preset optimal temperature for oxidation reaction. When the temperature deviates, calculate the adjustment amount of the working gas in the conditioning chamber according to the degree of deviation. The adjustment amount includes at least one of oxygen concentration adjustment amount, gas injection flow rate adjustment amount, or gas flow rate adjustment amount.

[0032] In this step, the real-time temperatures of each location are compared with a pre-stored optimal temperature window for the oxidation reaction. This optimal window is typically determined based on the steel grade and the target oxide layer structure, such as being set to 820–840℃. When the measured temperature of a certain location deviates from this window, the adjustment amount of the working gas in the corresponding tempering chamber is calculated based on the magnitude of the temperature difference and the preset oxidation kinetic model. The adjustment amount can be the oxygen concentration adjustment amount or the gas injection flow rate adjustment amount (m). 3 At least one of the following: gas flow rate adjustment (m / s) or gas flow rate adjustment (h). For example, when the web temperature is detected to be 870°C, which is 30°C higher than the upper limit of the optimal window, in order to suppress the excessively rapid oxidation reaction in this part, it is calculated that the oxygen concentration in the corresponding injection area needs to be reduced from 21% to 12%, and the gas flow rate should be reduced from 10 m³ / h to 12%. 3 / h increased to 18m 3 / h, to accelerate convective cooling; while for the lower temperature wing edge (810℃), the system calculates that the oxygen concentration needs to be increased to 25% to promote oxidation, or the flow rate needs to be appropriately reduced to reduce the cooling effect.

[0033] S303 adjusts the supply parameters of the working gas in the corresponding conditioning chamber according to the adjustment amount, so that the temperature of that part is restored to the optimal temperature.

[0034] In this step, the calculated adjustment amount is converted into control commands. Through actuators such as proportional valves, mass flow controllers, and variable frequency fans, the supply parameters of the working gas in the corresponding tempering chamber are changed. For example, for the overheated area of ​​the web, some oxygen valves are closed, while the nitrogen branch is opened, and the working gas injected near the web is switched from oxygen-enriched air to low-oxygen mixture, and the injection velocity is increased. For the undercooled area of ​​the flange, the supply ratio of oxygen-enriched air is increased. After adjustment, the temperature of each part of the steel surface gradually becomes uniform and returns to the optimal temperature window.

[0035] In a preferred embodiment of the present invention, the step of measuring the final iron oxide scale thickness after completing the treatment and complete cooling of all tempering chambers, comparing the measured thickness value with a preset target thickness range, and correcting the target settings of subsequent process parameters based on the comparison result includes: S401 involves naturally cooling hot-rolled steel, which has undergone tempering treatment, to room temperature. Then, using an offline testing method, the final iron oxide scale thickness at multiple different locations on the steel surface is measured, and its average value and uniformity deviation are calculated.

[0036] In this step, the hot-rolled steel sections that have undergone complete tempering are naturally cooled to room temperature and then enter the offline testing station. The thickness of the iron oxide scale layer is measured at multiple different locations on the surface of the steel section using ultrasonic thickness measurement. These multiple locations include at least the outer side of the flange, the end face of the flange, the center of the web, and the transition area between the inner and outer radius corners. At least 3 to 5 measurement points are selected for each location. For example, for a batch of H400×200 hot-rolled steel sections, one section is taken from each of the head, middle, and tail sections. Eight points are measured at each section, including the upper flange, web, lower flange, and four radius corners, for a total of 24 data points. The arithmetic mean of these data is calculated as the representative thickness value for this batch. At the same time, the standard deviation or range of the thickness at each point from the average value is calculated as the uniformity deviation. For example, if the measured average thickness is 11.5 μm, the uniformity deviation (standard deviation) is 2.8 μm.

[0037] In S402, the measured average thickness is compared with the preset target thickness range, and the uniformity deviation is compared with the preset allowable deviation range, so as to judge whether the control effect of scale of the current batch is qualified. If it is unqualified, the correction amount of process parameters is output according to the thickness deviation value and the uniformity deviation value.

[0038] In this step, the average thickness is compared with the preset target thickness range, and the uniformity deviation is compared with the preset allowable deviation range at the same time. Only when the average thickness falls within the target range and the uniformity deviation does not exceed the allowable range, the control effect of this batch is judged to be qualified; otherwise, it is judged to be unqualified. For example, the average thickness of 11.5μm is still within the range of 8 to 12μm, but the uniformity deviation of 2.8μm exceeds 2.0μm, so correction is required. According to the thickness deviation (+1.5μm, relative to the optimal value of 10μm) and the uniformity deviation (+0.8μm), the correction amount of each process parameter is calculated through the preset process correction model, and the calculation results show that: the oxygen concentration in the working gas needs to be reduced by 3% (from 21% to 18%), and the flow rate of the injection hole corresponding to the flange needs to be increased by 5m 3 / h, and the flow rate of the injection hole corresponding to the web needs to be reduced by 2m 3 / h, the positive pressure value needs to be increased by 5Pa, and the traveling speed of the section steel needs to be reduced by 0.2m / s.

[0039] In S403, the correction amount is applied to the target set values of subsequent production process parameters, including correcting at least one of the oxygen concentration of the working gas, the injection flow rate, the positive pressure value, the temperature control window or the traveling speed of the section steel.

[0040] In this step, the correction amount is updated to the target set values of process parameters for subsequent production of section steel of the same steel grade and the same specification. The correction items include the oxygen concentration of the working gas, the gas injection flow rate, the positive pressure value in the conditioning cavity, the temperature control window or the traveling speed of the section steel. After correction, when the next batch of section steel enters the conditioning cavity, the control system will perform regulation based on the new target set values.

[0041] The foregoing descriptions are merely preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall all be included in the protection scope of the present invention.

Claims

1. A method for controlling the uniformity of iron oxide scale structure in hot-rolled steel, characterized in that, The method includes: At least one quenching and tempering chamber is provided, which is set along the rolling direction of the steel section. The inlet and outlet of the quenching and tempering chamber are matched with the cross-sectional shape of the hot-rolled steel section and a predetermined gap is left. A working gas containing oxygen is injected into the conditioning chamber under positive pressure, and a positive pressure air curtain is used to maintain the required atmosphere environment inside the conditioning chamber. A temperature detection unit is set in each tempering chamber to acquire the surface temperature of the hot-rolled steel in real time. Based on the acquired temperature value, the parameters of the working gas in the corresponding tempering chamber are dynamically adjusted to control the oxidation reaction process. After all the tempering and heat treatment chambers are completed and completely cooled, the final iron oxide scale thickness is measured. The measured thickness value is compared with the preset target thickness range, and the target setting values ​​of subsequent process parameters are corrected based on the comparison results.

2. The method for controlling the uniformity of iron oxide scale structure in hot-rolled steel according to claim 1, characterized in that, The conditioning chamber is equipped with an adjustable exhaust port. The opening of the exhaust port is linked to the positive pressure value inside the conditioning chamber. When the positive pressure value increases, the opening of the exhaust port increases.

3. The method for controlling the uniformity of iron oxide scale structure in hot-rolled steel according to claim 1, characterized in that, The step of injecting oxygen-containing working gas into the conditioning chamber under positive pressure and maintaining the required atmosphere environment within the conditioning chamber using a positive pressure gas curtain includes: Based on the preset target oxide layer thickness and the real-time detected surface temperature of the steel profile, calculate the required oxygen concentration, injection flow rate, and injection pressure of the working gas. Working gas is injected into the quenching and tempering chamber through multiple injection holes arranged on the inner wall of the chamber, forming a continuous positive pressure air curtain in the gap between the steel surface and the inner wall of the chamber. The pressure fluctuations inside the conditioning chamber are monitored in real time, and the injection flow rate of the working gas and the opening of the exhaust port are dynamically adjusted based on the monitoring results.

4. The method for controlling the uniformity of iron oxide scale structure in hot-rolled steel according to claim 1, characterized in that, The step of setting a temperature detection unit in each tempering chamber to acquire the surface temperature of the hot-rolled steel section in real time, and dynamically adjusting the parameters of the working gas in the corresponding tempering chamber according to the acquired temperature value to control the oxidation reaction process includes: Non-contact temperature sensors are arranged at multiple locations within the tempering chamber to collect surface temperature data of different parts of the hot-rolled steel in real time. The collected temperature data is compared with the preset optimal temperature for oxidation reaction. When the temperature deviates, the adjustment amount of the working gas in the conditioning chamber is calculated according to the degree of deviation. The adjustment amount includes at least one of oxygen concentration adjustment amount, gas injection flow rate adjustment amount, or gas flow rate adjustment amount. By adjusting the supply parameters of the working gas in the corresponding conditioning chamber, the temperature of that part can be restored to the optimal temperature.

5. The method for controlling the uniformity of iron oxide scale structure in hot-rolled steel according to claim 1, characterized in that, The step of measuring the final iron oxide scale thickness after completing the treatment and complete cooling of all tempering chambers, comparing the measured thickness value with the preset target thickness range, and correcting the target settings of subsequent process parameters based on the comparison result includes: After the hot-rolled steel treated in the tempering chamber is naturally cooled to room temperature, the final iron oxide scale thickness at multiple different locations on the surface of the steel is measured using an offline detection method, and its average value and uniformity deviation are calculated. The measured average thickness is compared with the preset target thickness range, and the uniformity deviation is compared with the preset allowable deviation range to determine whether the control effect of the current batch of iron oxide scale is qualified. If it is not qualified, the correction amount of the process parameters is output based on the thickness deviation value and the uniformity deviation value. The correction amount is applied to the target setpoints of subsequent production process parameters, including correcting at least one of the following: oxygen concentration of the working gas, injection flow rate, positive pressure value, temperature control window, or steel profile travel speed.

6. The method for controlling the uniformity of iron oxide scale structure in hot-rolled steel according to claim 1, characterized in that, The number of tempering cavities is 2 to 6, and they are arranged in series along the rolling direction of the steel section.

7. The method for controlling the uniformity of iron oxide scale structure in hot-rolled steel according to claim 1, characterized in that, The working gas is one or more of air, oxygen-enriched air, nitrogen, or a nitrogen-hydrogen mixture.

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