Heating method for reducing iron oxide warping defect of hot rolled plate strip

Abstract

The invention relates to a heating method for reducing iron oxide warping defects of a hot rolled plate strip, and belongs to the technical field of hot rolling processes. The method comprises the following steps: obtaining a plate blank; the plate blank is heated, the oxygen enrichment degree of heating is controlled according to the charging temperature and the tapping rhythm of the plate blank, and a plate blank to be rolled is obtained; wherein heating comprises a preheating section, a first heating section, a second heating section and a soaking section; in the heating process, the oxidation rate of the plate blank is 12 [mu] m / min to 16 [mu] m / min. Oxygen-enriched combustion is put into different furnace sections (a preheating section, a heating section and a soaking section), equivalently, the in-furnace time is prolonged, the surface temperature of the plate blank can be remarkably increased, and the oxidation burning loss process is accelerated. The setting of the oxygen enrichment degree is adjusted according to the slab charging temperature and the tapping rhythm, insufficient heating time caused by rapid production can be compensated, it is ensured that the total burning loss reaches the threshold value for removing microcracks, the occurrence rate of the surface warping defect of the hot-rolled strip is effectively reduced, and the surface quality of the hot-rolled strip is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hot rolling process, in particular to a heating method for reducing hot-rolled strip oxide scale skin defects. BACKGROUND

[0002] Hot-rolled strip is an important product in the steel industry, widely used in automobile manufacturing, container manufacturing and other fields. However, the hot-rolled strip surface skin defect has always been a common problem that plagues high-quality steel strip production. This defect not only affects the appearance quality of the product, but also can cause increased roll wear, thereby affecting production efficiency and cost. The causes of hot-rolled strip surface skin defects are complex and diverse, and can run through the whole process of steel production, including smelting, continuous casting, hot rolling and cold rolling. According to its morphology and organizational characteristics, the causes of skin defects can be divided into five categories: subcutaneous inclusion, surface crack, subcutaneous bubble, scale pressure and intermediate blank edge. These defects can further deteriorate during hot rolling, leading to hot-rolled strip degradation or rejection, seriously affecting the yield and market competitiveness of the product.

[0003] In particular, hot-rolled strip oxide scale skin defects are a common type of defect in the hot rolling process. This defect mainly manifests as the oxide scale on the surface of the steel plate being raised or falling off during rolling, which not only affects the appearance of the product, but also can cause adverse effects on subsequent processing and use. According to statistics, the incidence of hot-rolled strip oxide scale skin defects accounts for more than 50% of the total skin defects, becoming one of the key factors restricting high-quality steel strip production.

[0004] In order to reduce the incidence of hot-rolled strip oxide scale skin defects, the burn loss can be increased by increasing the slab heating temperature and increasing the furnace time, but since the variety heating process temperature is determined, it is not possible to arbitrarily increase the heating temperature to control the burn loss, and the heating time is directly related to the rolling rhythm and capacity of the production line, so it is not possible to arbitrarily extend the furnace time to control the burn loss, therefore, there is an urgent need for a new heating method that can effectively reduce the incidence of hot-rolled strip oxide scale skin defects while ensuring production rhythm and capacity, improve the surface quality and yield of the product. SUMMARY

[0005] The present application provides a heating method for reducing hot-rolled strip oxide scale skin defects, to solve the technical problem of how to effectively reduce the incidence of hot-rolled strip surface skin defects.

[0006] The present application provides a heating method for reducing hot-rolled strip oxide scale skin defects, the method comprising:

[0007] obtaining a slab;

[0008] The slab is heated, and the oxygen enrichment degree of the heating is controlled according to the charging temperature and the tapping rhythm of the slab, so as to obtain a slab to be rolled; wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section.

[0009] During the heating process, the oxidation rate of the slab is 12-16 μm / min.

[0010] Optionally, the controlling of the oxygen enrichment degree of the heating according to the charging temperature and the tapping rhythm of the slab comprises:

[0011] controlling the oxygen enrichment degree of the preheating section of the heating according to the charging temperature and the tapping rhythm of the slab.

[0012] Optionally, the controlling of the oxygen enrichment degree of the preheating section of the heating according to the charging temperature and the tapping rhythm of the slab comprises:

[0013] if the charging temperature is ≥600℃ and the tapping rhythm is ≥115s, the oxygen enrichment degree of the preheating section is 21-23%;

[0014] if 400℃≤the charging temperature<600℃ and 110s≤the tapping rhythm<115s, the oxygen enrichment degree of the preheating section is 23-35%;

[0015] if the charging temperature<400℃ and the tapping rhythm<110s, the oxygen enrichment degree of the preheating section is 35-40%.

[0016] Optionally, the single-side flame length of the preheating section is 5-6.5 m.

[0017] Optionally, the controlling of the oxygen enrichment degree of the heating according to the tapping rhythm of the slab comprises:

[0018] controlling the oxygen enrichment degree of the first heating section and the second heating section of the heating according to the tapping rhythm of the slab.

[0019] Optionally, the controlling of the oxygen enrichment degree of the first heating section and the second heating section of the heating according to the tapping rhythm of the slab comprises:

[0020] if the tapping rhythm is ≥115s, the oxygen enrichment degree of the first heating section and the second heating section is both 23-25%;

[0021] if 110s≤the tapping rhythm<115s, the oxygen enrichment degree of the first heating section and the second heating section is both 23-30%;

[0022] if the tapping rhythm<110s, the oxygen enrichment degree of the first heating section and the second heating section is both 28-38%.

[0023] Optionally, the oxygen enrichment of the heating is controlled according to the tapping rhythm of the slab, including:

[0024] The oxygen enrichment of the soaking section of the heating is controlled according to the tapping rhythm of the slab.

[0025] Optionally, the oxygen enrichment of the soaking section of the heating is controlled according to the tapping rhythm of the slab, including:

[0026] If the tapping rhythm is greater than or equal to 115s, the oxygen enrichment of the soaking section is 21% to 25%;

[0027] If 110s is less than the tapping rhythm and less than 115s, the oxygen enrichment of the soaking section is 23% to 26%;

[0028] If the tapping rhythm is less than 110s, the oxygen enrichment of the soaking section is 25% to 30%.

[0029] Optionally, the single-side flame length of the soaking section is 4.5m to 6.0m.

[0030] Optionally, the air excess coefficient of the preheating section is 1.00 to 1.05, the air excess coefficients of the first heating section and the second heating section are both 0.95 to 1.05, and the air excess coefficient of the soaking section is 1.15 to 1.30.

[0031] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0032] The embodiments of the present application provide a heating method for reducing iron oxide skin defects of hot-rolled strip, including: obtaining a slab; heating the slab, and controlling the oxygen enrichment of the heating according to the furnace entry temperature and the tapping rhythm of the slab to obtain a slab to be rolled; wherein the heating includes a preheating section, a first heating section, a second heating section, and a soaking section; and during the heating process, the oxidation rate of the slab is 12μm / min to 16μm / min. By injecting oxygen-enriched combustion in different furnace sections (preheating section, heating section, and soaking section), the equivalent of extending the furnace time can significantly improve the slab surface temperature and accelerate the oxidation loss process. The setting of the oxygen enrichment is adjusted according to the furnace entry temperature and the tapping rhythm of the slab, which can compensate for the insufficient heating time caused by fast production, ensure that the total loss amount reaches the threshold for removing micro-cracks, effectively reduce the occurrence rate of hot-rolled strip surface skin defects, and improve the surface quality of the hot-rolled strip. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0035] Figure 1 A flowchart of a heating method for reducing iron oxide type skin defects of hot-rolled strip provided by the embodiment of the present application is shown in the figure.

[0036] Figure 2 A hot coil cross-section microscopic detection figure (left) and a hot coil pittsburgh table detection figure (right) provided by the embodiment 1 of the present application are shown in the figure.

[0037] Figure 3 A hot coil cross-section microscopic detection figure (left) and a hot coil pittsburgh table detection figure (right) provided by the comparative example 1 of the present application are shown in the figure. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0039] The range descriptions described herein, such as numerical range, ratio range, etc., all include all possible sub-ranges and single values within the range, for example, the range description of "1 to 6" or "1-6" covers all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "include", "contain" and the like used herein mean "include but not limited to"; the relationship terms "first", "second" and the like are only used to distinguish different entities or operations, and do not imply actual sequence or relationship; "and / or" means that multiple cases can exist independently or simultaneously; "at least one", "multiple", "at least one" and the like refer to any combination of the corresponding objects, including single or multiple combinations of objects. The ratio relationship involved herein, such as mass ratio, molar ratio, etc., should be understood as the corresponding relationship between the front and the rear in the ratio. The raw materials, reagents, instruments and equipment used herein can be purchased or prepared by existing methods.

[0040] Figure 1 A flowchart of a heating method for reducing iron oxide type skin defects of hot-rolled strip provided by the embodiment of the present application is shown in the figure.

[0041] See Figure 1 The embodiment of the present application provides a heating method for reducing iron oxide skin defects of hot-rolled strip, and the method comprises the following steps:

[0042] S1, obtaining a slab;

[0043] S2, heating the slab, and controlling oxygen enrichment degree of the heating according to the furnace temperature and the tapping rhythm of the slab, to obtain a slab to be rolled; wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section;

[0044] The oxygen enrichment degree refers to the proportion of oxygen content in the combustion-supporting gas in the heating furnace, and the core function is to improve the combustion intensity and thermal efficiency. The oxygen enrichment degree is formed by supplementing oxygen (more than 21% of the oxygen content in natural air) to the combustion-supporting air to form an oxygen-enriched combustion environment. This process can increase the flame temperature and accelerate the oxidation reaction on the surface of the slab, thereby enhancing the ablation ability to the micro-cracks on the surface layer of the slab. In the embodiment of the present application, the preheating section, the heating section and the soaking section of the heating process have different oxygen enrichment degrees. In the embodiment of the present application, the slab to be rolled is suitable for IF steel and welding bottle steel.

[0045] In some embodiments, the oxygen enrichment degree of the heating is controlled according to the furnace temperature and the tapping rhythm of the slab, comprising:

[0046] According to the furnace temperature and the tapping rhythm of the slab, the oxygen enrichment degree of the preheating section of the heating is controlled.

[0047] In some embodiments, the oxygen enrichment degree of the preheating section of the heating is controlled according to the furnace temperature and the tapping rhythm of the slab, comprising:

[0048] If the furnace temperature is greater than or equal to 600 DEG C, and the tapping rhythm is greater than or equal to 115 s, the oxygen enrichment degree of the preheating section is 21% to 23%;

[0049] If the furnace temperature is 400 DEG C to less than 600 DEG C, and the tapping rhythm is 110 s to less than 115 s, the oxygen enrichment degree of the preheating section is 23% to 35%;

[0050] If the furnace temperature is less than 400 DEG C, and the tapping rhythm is less than 110 s, the oxygen enrichment degree of the preheating section is 35% to 40%.

[0051] The entry temperature refers to the initial temperature of the slab when it starts entering the heating furnace. The entry temperature is a starting parameter for the heating process and directly affects the temperature control logic of each subsequent furnace section. Experimental data show that for every 100°C increase in the entry temperature, the equivalent in-furnace time is extended by 8.9 minutes. Through oxygen-enriched combustion, the insufficient heating time caused by rapid production can be compensated for to ensure that the total burning loss reaches the threshold for removing micro-cracks. These conclusions provide a quantitative basis for process optimization.

[0052] The embodiments of the present application achieve precise regulation of the intensity of oxygen-enriched combustion by establishing a coupling relationship between the entry temperature and the tapping rhythm. When the entry temperature is low (<400°C) and the production rhythm is fast (tapping <110s), a high oxygen enrichment degree of 35%-40% is used to quickly increase the slab surface temperature and effectively increase the temperature of the slab entering the heating section, which is equivalent to extending the in-furnace time. This non-linear compensation mechanism breaks through the limitations of traditional fixed parameter control.

[0053] In the embodiments of the present application, the difference between the slab surface temperature with and without oxygen-enriched combustion in the preheating section can reach 105°C-296°C.

[0054] In some embodiments, the single-side flame length of the preheating section is 5m-6.5m.

[0055] In the embodiments of the present application, the preheating section can adjust the included angle between the center line of the oxygen lance and the center line of the side burner to 0°-5° to ensure that the single-side flame length reaches 5m-6.5m. The oxygen lance is a device used to inject oxygen or oxygen-rich gas into the furnace, while the side burner is a burner installed on the side of the furnace. The included angle refers to the angle between the center lines of the two, which affects the direction and coverage of the flame. The smaller the included angle, the closer the direction of the oxygen lance and the side burner flame, which makes the flame more concentrated and the coverage more uniform. Long flame also increases the contact area and time with the slab, improving the heating efficiency. By adjusting the included angle between the center line of the oxygen lance and the center line of the side burner to 0°-5° in the preheating section, the embodiments of the present application ensure that the single-side flame length reaches 5m-6.5m, which can ensure that the slab fully contacts the high-temperature area in the preheating section, improve the heat transfer efficiency, and reduce the temperature gradient.

[0056] The use of oxygen-enriched combustion increases the temperature of the preheating section, and in combination with the control of the flame length, it can effectively increase the temperature of the slab entering the heating section, thereby enhancing the oxidation burning capacity and removing surface defects.

[0057] In some embodiments, the control of the oxygen enrichment degree of the heating according to the tapping rhythm of the slab includes:

[0058] The oxygen enrichment degree of the first heating section and the second heating section is controlled according to the tapping rhythm of the slab.

[0059] In some embodiments, the controlling the oxygen enrichment degree of the first heating section and the second heating section according to the tapping rhythm of the slab comprises:

[0060] If the tapping rhythm is ≥ 115 s, the oxygen enrichment degree of the first heating section and the second heating section is 23% to 25%;

[0061] If 110 s ≤ the tapping rhythm < 115 s, the oxygen enrichment degree of the first heating section and the second heating section is 23% to 30%;

[0062] If the tapping rhythm < 110 s, the oxygen enrichment degree of the first heating section and the second heating section is 28% to 38%.

[0063] The embodiments of the present application set specific ranges of oxygen enrichment degree for the first heating section and the second heating section according to different ranges of tapping rhythm, which can effectively improve the heating rate of the slab in the heating section (equivalent to increasing the heating temperature of the slab), ensure the uniformity of the heating temperature, and effectively ablate the micro-cracks on the surface of the slab.

[0064] When the tapping rhythm is ≥ 115 s, the positive effect of the oxygen enrichment degree of 23% to 25% in the first heating section and the second heating section is that the tapping rhythm ≥ 115 s corresponds to a slower production rhythm, which allows the oxygen enrichment degree to be appropriately reduced, the time of the slab in the first heating section and the second heating section is prolonged to achieve the oxidation and ablation target, and at this time, the oxygen enrichment combustion mainly ensures the temperature uniformity rather than rapid heating.

[0065] When 110 s ≤ the tapping rhythm < 115 s, the positive effect of the oxygen enrichment degree of 23% to 30% in the first heating section and the second heating section is that under the medium rhythm, the oxidation rate and the production rhythm need to be balanced, the oxygen enrichment degree of 23% to 30% can increase the temperature difference on the surface of the slab, accelerate the oxidation and ablation of the shallow surface cracks, and at the same time, avoid the too large temperature difference in the core caused by too fast heating.

[0066] When the tapping rhythm < 110 s, the positive effect of the oxygen enrichment degree of 28% to 38% in the first heating section and the second heating section is that under the fast production rhythm, the heating rate needs to be significantly increased through high oxygen enrichment degree (28% to 38%), at this time, the temperature difference between the surface of the slab and the core increases, but through the optimization of the oxygen lance angle and the flame length, the temperature uniformity can still be ensured.

[0067] This measure enhances the adaptability of the heating process, different tapping rhythms correspond to different oxygen enrichment degrees, so that the heating process can flexibly respond to changes in the production rhythm, and ensure that high heating quality and efficiency can be maintained under different production conditions. Finally, through the optimization of the oxygen enrichment degree setting, the product quality can be guaranteed while reducing energy consumption and production cost, and a more efficient heating process means less energy waste, which is of great significance to improve the economic benefit of the hot rolling production line.

[0068] In the embodiments of the present application, the difference between the slab surface temperature corresponding to the oxygen-enriched combustion and the slab surface temperature corresponding to the non-oxygen-enriched combustion can reach 75-186 ℃ in the first adding section and 23-78 ℃ in the second adding section.

[0069] In some embodiments, the oxygen enrichment of the heating is controlled according to the tapping rhythm of the slab, including:

[0070] The oxygen enrichment of the soaking section of the heating is controlled according to the tapping rhythm of the slab.

[0071] In some embodiments, the oxygen enrichment of the soaking section is controlled according to the tapping rhythm of the slab, including:

[0072] If the tapping rhythm is ≥115 s, the oxygen enrichment of the soaking section is 21-25%;

[0073] If 110 s≤the tapping rhythm<115 s, the oxygen enrichment of the soaking section is 23-26%;

[0074] If the tapping rhythm<110 s, the oxygen enrichment of the soaking section is 25-30%.

[0075] The embodiments of the present application set specific ranges of the oxygen enrichment of the soaking section for different ranges of the tapping rhythm, which can effectively improve the surface heat flux density of the slab in the soaking process, ensure the uniformity of the heating temperature, and effectively ablate the surface layer micro-cracks of the slab.

[0076] When the tapping rhythm is ≥115 s (slow rhythm), the oxygen enrichment of 21-25% is adopted, which can ensure the effective ablation of the iron oxide scale on the slab surface and avoid the waste of energy caused by too high oxygen enrichment. When the tapping rhythm is <110 s (fast rhythm), the oxygen enrichment of 25-30% is adopted, which can compensate for the shortened heating time by enhancing the oxidation rate and ensure the ablation amount per unit time, and this gradient setting realizes the dynamic coupling of the process parameters and the production rhythm.

[0077] In the embodiments of the present application, the difference between the slab surface temperature corresponding to the oxygen-enriched combustion and the slab surface temperature corresponding to the non-oxygen-enriched combustion can reach 12-35 ℃ in the soaking section.

[0078] In some embodiments, the single-side flame length of the soaking section is 4.5-6.0 m.

[0079] In the embodiments of the present application, the angle between the center line of the oxygen lance and the center line of the side burner in the soaking section is adjusted to 5-15°, so as to ensure that the single-side flame length reaches 4.5-6.0 m.

[0080] In some embodiments, the air excess coefficient of the preheating section is 1.00-1.05, the air excess coefficients of the first and second adding sections are both 0.95-1.05, and the air excess coefficient of the soaking section is 1.15-1.30.

[0081] The air excess coefficient refers to the ratio of the actual air supply for combustion to the air amount required for complete combustion, and is a core parameter for controlling the combustion atmosphere of an industrial heating furnace. When the air excess coefficient α = 1, it indicates that the fuel and oxygen are completely reacted; when α > 1, it is oxygen-rich combustion (oxidizing atmosphere); and when α < 1, it is oxygen-poor combustion (reducing atmosphere). In the hot rolling heating process, the coefficient directly affects the generation rate of iron oxide scale and the ablation effect of surface defects of the cast slab. The larger the α value, the stronger the oxidizing atmosphere, and the faster the generation rate of the surface iron oxide scale of the slab. The preheating section α = 1.00-1.10 can establish a moderate oxidation environment to eliminate open cracks in the surface layer of the cast slab, and the soaking section α is set to 1.15-1.20 to increase the surface heat flux density and promote the oxidation of micro-cracks. By adjusting the α value in sections (preheating section 1.00-1.10, heating section 0.95-1.15), the oxidation ablation depth of the surface layer can be ensured, and excessive oxidation to cause scale indentation defects can be avoided.

[0082] In some embodiments, the oxidation rate of the slab during the heating process is 12 μm / min-16 μm / min.

[0083] The oxidation rate of 12 μm / min-16 μm / min is achieved by the synergistic regulation of the entry temperature and oxygen-rich combustion, so that the thickening of the surface iron oxide scale of the slab and the ablation of micro-cracks are balanced.

[0084] The present application is further described below in conjunction with specific examples. The experimental methods in the following examples, for which no specific conditions are indicated, are generally determined according to national standards / industry standards; if there is no corresponding national standard / industry standard, the methods are determined according to the general international standards, conventional conditions, or the conditions recommended by the manufacturers.

[0085] Example 1

[0086] The entry temperature of the slab is 100°C, the tapping rhythm is 100 s, the oxygen enrichment degree of the preheating section is 40%, the air excess coefficient is 1.10, the angle between the center line of the oxygen lance and the center line of the side burner is 5°, the single-side flame length reaches 6.5 m, and the surface temperature of the slab in the preheating section reaches 780°C.

[0087] After the slab enters the heating section (first and second adding sections), the oxygen enrichment degree is set to 38%, and the air excess coefficient is 1.15. The surface temperature of the slab in the first adding section reaches 1050°C, and the surface temperature of the slab in the second adding section reaches 1250°C.

[0088] After the slab enters the soaking section, the oxygen enrichment degree is set to 26%, the excess air coefficient is 1.20, the angle between the center line of the oxygen lance and the center line of the side burner is 10°, the single-side flame length reaches 6.0 m, and the surface temperature of the slab in the soaking section reaches 1240℃. The hot coil obtained is detected, and the surface scale defect occurrence rate is 1.25%.

[0089] Example 2

[0090] The furnace temperature is 500℃, the tapping rhythm is 113s, the oxygen enrichment degree in the preheating section is 30%, the excess air coefficient is 1.10, the angle between the center line of the oxygen lance and the center line of the side burner is 5°, the single-side flame length reaches 6.0 m, and the surface temperature of the slab in the preheating section reaches 850℃.

[0091] After the slab enters the heating section (one plus and two plus), the oxygen enrichment degree is set to 28%, the excess air coefficient is 1.10, the surface temperature of the slab in the one plus section reaches 1050℃, and the surface temperature of the slab in the two plus section reaches 1250℃.

[0092] After the slab enters the soaking section, the oxygen enrichment degree is set to 23%, the excess air coefficient is 1.15, the angle between the center line of the oxygen lance and the center line of the side burner is 10°, the single-side flame length reaches 5.0 m, and the surface temperature of the slab in the soaking section reaches 1240℃. The hot coil obtained is detected, and the surface scale defect occurrence rate is 1.17%.

[0093] Example 3

[0094] The furnace temperature of the slab is 700℃, the tapping rhythm is 120s, the oxygen enrichment degree in the preheating section is 21%, the excess air coefficient is 1.05, the angle between the center line of the oxygen lance and the center line of the side burner is 0°, the single-side flame length reaches 5 m, and the surface temperature of the slab in the preheating section reaches 900℃.

[0095] After the slab enters the heating section (one plus and two plus), the oxygen enrichment degree is set to 23%, the excess air coefficient is 1.05, the surface temperature of the slab in the one plus section reaches 1100℃, and the surface temperature of the slab in the two plus section reaches 1250℃.

[0096] After the slab enters the soaking section, the oxygen enrichment degree is set to 21%, the excess air coefficient is 1.15, the angle between the center line of the oxygen lance and the center line of the side burner is 5°, the single-side flame length reaches 4.5 m, and the surface temperature of the slab in the soaking section reaches 1240℃. The hot coil obtained is detected, and the surface scale defect occurrence rate is 1.06%.

[0097] Comparative Example 1

[0098] The furnace temperature of the slab is 100℃, the tapping rhythm is 100s, the oxygen enrichment degree in the preheating section is 0%, the excess air coefficient is 1.10, the single-side flame length reaches 6.0 m, and the surface temperature of the slab in the preheating section reaches 580℃.

[0099] After the slab enters the heating section (first and second additions), the oxygen enrichment degree is set to 0%, and the excess air coefficient is -1.10, the slab surface temperature reaches 900 DEG C in the first addition section, and the surface temperature reaches 1220 DEG C in the second addition section.

[0100] After the slab enters the soaking section, the oxygen enrichment degree is set to 0%, the excess air coefficient is 1.05, the single-sided flame length reaches 6.0m, and the slab surface temperature reaches 1240 DEG C in the soaking section. The obtained hot coil is detected, and the surface scale defect occurrence rate is 3.02%.

[0101] The detailed description of the drawings is as follows: Figures 2-3 The detailed description of the drawings is as follows:

[0102] Figure 2 The hot coil cross-section microscopic detection figure (left) and the hot coil Baitai surface detection figure (right) provided by the embodiment 1 of the application; Figure 3 The hot coil cross-section microscopic detection figure (left) and the hot coil Baitai surface detection figure (right) provided by the comparative example 1 of the application; it can be known from the comparison that the surface scale defect of the hot coil is greatly reduced by using the heating method provided by the application.

[0103] In addition, one or more technical solutions in the embodiment of the application have at least the following technical effects or advantages:

[0104] The method provided by the embodiment of the application greatly reduces the occurrence rate of the iron oxide scale defect on the surface of the hot-rolled plate strip, which not only improves the appearance quality of the product, but also reduces the degradation and rejection caused by the defect.

[0105] The embodiment of the application realizes precise regulation and control of the oxidation loss amount under the premise of ensuring the rolling capacity through the linkage control of the oxygen enrichment degree and the tapping rhythm.

[0106] The above is only a specific embodiment of the application, which enables those skilled in the art to understand or implement the application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined in the application can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the application will not be limited to these embodiments shown in the application, but will conform to the widest scope consistent with the principles and novel features of the application claimed.

Claims

1. A heating method for reducing iron oxide scale buckling defects of hot-rolled strip, the method comprising: obtaining a slab; heating the slab and controlling oxygen enrichment of the heating according to an entry temperature of the slab and a tapping rhythm to obtain a slab to be rolled; wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section; during the heating, an oxidation rate of the slab is 12 μm / min to 16 μm / min.

2. The method of claim 1, wherein, the controlling of the oxygen enrichment of the heating according to the entry temperature of the slab and the tapping rhythm comprises: controlling the oxygen enrichment of the preheating section of the heating according to the entry temperature of the slab and the tapping rhythm.

3. The method of claim 2, wherein, the controlling of the oxygen enrichment of the preheating section of the heating according to the entry temperature of the slab and the tapping rhythm comprises: if the entry temperature is ≥600 ℃ and the tapping rhythm is ≥115 s, the oxygen enrichment of the preheating section is 21% to 23%; if 400 ℃≤the entry temperature <600 ℃ and 110 s≤the tapping rhythm <115 s, the oxygen enrichment of the preheating section is 23% to 35%; if the entry temperature <400 ℃ and the tapping rhythm <110 s, the oxygen enrichment of the preheating section is 35% to 40%.

4. The method of claim 3, wherein, a single-side flame length of the preheating section is 5 m to 6.5 m.

5. The method of claim 1, wherein, the controlling of the oxygen enrichment of the heating according to the tapping rhythm of the slab comprises: controlling the oxygen enrichment of the first heating section and the second heating section of the heating according to the tapping rhythm of the slab.

6. The method of claim 4, wherein, the controlling of the oxygen enrichment of the first heating section and the second heating section of the heating according to the tapping rhythm of the slab comprises: if the tapping rhythm is ≥115 s, the oxygen enrichment of the first heating section and the second heating section is 23% to 25%; if 110 s≤the tapping rhythm <115 s, the oxygen enrichment of the first heating section and the second heating section is 23% to 30%; if the tapping rhythm <110 s, the oxygen enrichment of the first heating section and the second heating section is 28% to 38%.

7. The method of claim 1, wherein, the controlling of the oxygen enrichment of the heating according to the tapping rhythm of the slab comprises: controlling the oxygen enrichment of the soaking section of the heating according to the tapping rhythm of the slab.

8. The method of claim 6, wherein, the controlling of the oxygen enrichment of the soaking section according to the tapping rhythm of the slab comprises: if the tapping rhythm is ≥115 s, the oxygen enrichment of the soaking section is 21% to 25%; if 110 s≤the tapping rhythm <115 s, the oxygen enrichment of the soaking section is 23% to 26%; if the tapping rhythm <110 s, the oxygen enrichment of the soaking section is 25% to 30%.

9. The method of claim 8, wherein, a single-side flame length of the soaking section is 4.5 m to 6.0 m.

10. The method of claim 1, wherein, an air excess ratio of the preheating section is 1.00 to 1.05, an air excess ratio of the first heating section and the second heating section is 0.95 to 1.05, and an air excess ratio of the soaking section is 1.15 to 1.30.

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