Heating method of IF steel in ferrite rolling

Abstract

The invention relates to a heating method of IF steel in ferrite rolling, and belongs to the technical field of hot rolling. By increasing the power loads of the preheating section and the first heating section and controlling the coefficient of excess air to be not less than 1, the plate blank is strongly oxidized once entering the furnace, and the surface ablation amount of the plate blank is increased; after treatment of the preheating section and the first heating section, the temperature of the plate blank is high, at the moment, the power load of the second heating section is low, the temperature difference of the section of the plate blank is further reduced, the strong oxidizing atmosphere is kept, the surface of the plate blank continues to be ablated, and finally after the plate blank enters the soaking section, rapid heating continues to be conducted, so that the surface temperature of the plate blank is increased; oxidized scale on the surface of the plate blank is further thickened and ablated, defects on the surface of the plate blank are effectively ablated, then the blocking rate of slag entrapment and surface warping defects on the surface of a hot coil for ferrite rolling is improved, meanwhile, the temperature difference between the surface and the core of the plate blank can be manufactured in the soaking section heating process, part of heat dissipated by the surface is offset, and the heat dissipation efficiency is improved. And the edge quality of a ferrite rolled coil is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of hot rolling technology, and in particular to a heating method for IF steel during ferrite rolling. Background Art

[0002] IF steel is widely used in the automotive manufacturing industry, especially in automotive outer and inner panels. With the rapid development of the automotive industry, its demand is increasing, and it has great market prospects. At present, most steel mills produce IF steel that is basically rolled in the austenite region, with a tapping temperature of more than 1200°C. The heating furnace fuel consumption and slab burnout rate are at a high level, which also affects the service life of the heating furnace.

[0003] To this end, ferrite rolling, also known as phase change controlled rolling or warm rolling, has been proposed. The strip steel produced by ferrite zone rolling technology can significantly shorten the production process, reduce costs and improve productivity. In addition, the ferrite rolling process requires an extremely low furnace temperature, which reduces energy consumption during the heating process. With the continuous development of the ferrite rolling process, researchers have also found that increasing the coiling temperature during ferrite rolling can achieve the coarsening of the ferrite structure, improve the plasticity of the hot-rolled plate, and effectively reduce the yield strength. Using the hot-rolled plate rolled by ferrite as the cold rolling base material can increase the limit reduction rate of the cold rolling process and produce thinner plate and strip products. Therefore, ferrite rolling is also a cutting-edge green and low-carbon process in the hot rolling field of the steel industry worldwide.

[0004] However, the current blocking rate of slag and warping defects on the surface of ferrite rolled hot coils is as high as over 20%. Summary of the invention

[0005] The present application provides a heating method for IF steel during ferrite rolling, so as to improve the blocking rate of slag and warping defects on the surface of hot coils during ferrite rolling.

[0006] The present application provides a heating method for IF steel during ferrite rolling, the method comprising:

[0007] obtaining a slab;

[0008] The slab is heated in sequence through a preheating section, a first heating section, a second heating section and a soaking section of a heating furnace to obtain a slab to be rolled;

[0009] Wherein, the temperature of the slab at the end of the preheating section is 710°C to 750°C;

[0010] The temperature of the slab at the end of the first heating section is 880°C to 920°C;

[0011] The temperature of the slab at the end of the second heating section is 970°C to 1010°C;

[0012] The temperature of the slab at the end of the soaking section is 1030°C to 1050°C;

[0013] The air excess coefficient of the entire heating process is not less than 1.

[0014] As an optional embodiment, the temperature of the slab at the end of the preheating section is 720° C. to 740° C.; and / or

[0015] The temperature of the slab at the end of the first heating section is 890° C. to 910° C.; and / or

[0016] The temperature of the slab at the end of the second heating section is 980° C. to 1000° C.; and / or

[0017] The temperature of the slab at the end of the soaking section is 1035°C to 1045°C.

[0018] As an optional embodiment, the temperature of the slab at the end of the preheating section is 725° C. to 735° C.; and / or

[0019] The temperature of the slab at the end of the first heating section is 895° C. to 905° C.; and / or

[0020] The temperature of the slab at the end of the second heating section is 985° C. to 995° C.; and / or

[0021] The temperature of the slab at the end of the soaking section is 1037°C to 1043°C.

[0022] As an optional implementation, the excess air coefficient in the preheating section is 1.05-1.10.

[0023] As an optional implementation, the excess air coefficient in the first heating section is 1.10-1.25.

[0024] As an optional implementation, the excess air coefficient in the second heating section is 1.10-1.25.

[0025] As an optional implementation, the excess air coefficient in the soaking section is 1.10 to 1.25.

[0026] As an optional implementation, the total time that the slab passes through the preheating section and the first heating section is not less than 90 minutes.

[0027] As an optional implementation, the time that the slab passes through the soaking section is not less than 25 minutes.

[0028] As an optional implementation, the temperature of the slab when entering the heating furnace is not less than 300°C.

[0029] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0030] The method provided by the embodiment of the present application, during the heating process of the slab, by increasing the power load of the preheating section and the first heating section, and controlling the excess air coefficient to be not less than 1, so that the slab is strongly oxidized as soon as it enters the furnace, thereby increasing the amount of slab surface ablation; after being processed in the preheating section and the first heating section, the slab temperature is already relatively high, and at this time the power load of the second heating section will be relatively low, and the temperature difference of the slab cross section will be further reduced. At this stage, the slab temperature has reached the temperature required by the rolling process, and the strong oxidizing atmosphere is maintained to continue to ablate the slab surface. Finally, after the slab enters the soaking section, it continues to be heated rapidly to increase the surface temperature of the slab, and the oxidized iron scale on the surface of the slab is further thickened and ablated, effectively ablating the surface defects of the slab, thereby improving the surface slag and surface warping defect blocking rate of the ferrite rolled hot coil. At the same time, the heating process in the soaking section can create a temperature difference between the surface and the core of the slab to offset a part of the heat lost on the surface, thereby effectively improving the edge quality of the ferrite rolled coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0033] Figure 1 A schematic diagram of a process for a method provided in an embodiment of the present application;

[0034] Figure 2 A comparison chart of the process provided in the embodiment of the present application and the process provided in the prior art;

[0035] Figure 3 A schematic diagram of the temperature difference variation of the slab heating section provided in the embodiment of the present application;

[0036] Figure 4 A schematic diagram of the surface quality of a ferrite rolled coil provided in Comparative Example 1 of the present application;

[0037] Figure 5 A schematic diagram of the surface quality of a ferrite rolled coil provided in Example 1 of the present application;

[0038] Figure 6 A schematic diagram of the ferrite rolled edge structure provided for Comparative Example 1 of the present application;

[0039] Figure 7 A schematic diagram of the quality of the ferrite rolled edge provided in Comparative Example 1 of the present application;

[0040] Figure 8 A schematic diagram of the ferrite rolled edge structure provided in Example 1 of the present application;

[0041] Fig. 9 This is a schematic diagram of the quality of the ferrite rolled edge provided in Example 1 of the present application. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0043] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0044] Ferrite rolling is also known as phase change controlled rolling or warm rolling. The strip steel produced by ferrite zone rolling technology can significantly shorten the production process, reduce costs and improve productivity. In addition, the ferrite rolling process requires an extremely low furnace temperature, which reduces energy consumption during the heating process. With the continuous development of the ferrite rolling process, researchers have also found that increasing the coiling temperature during ferrite rolling can achieve the coarsening of the ferrite structure, improve the plasticity of the hot-rolled plate, and effectively reduce the yield strength. Using the hot-rolled plate rolled by ferrite as the cold rolling base material can increase the limit reduction rate of the cold rolling process and produce thinner plate and strip products. Therefore, ferrite rolling is also a cutting-edge green and low-carbon process in the hot rolling field of the steel industry worldwide.

[0045] However, the current ferrite rolling process is as follows: the slab is heated in the preheating section at a furnace temperature of 500°C to 800°C, until the temperature of the slab at the outlet of the preheating section is 300°C to 600°C; the slab is heated in the first heating section at a furnace temperature of 800°C to 1100°C, until the temperature of the slab at the outlet of the first heating section is 600°C to 900°C; the slab is heated in the second heating section at a furnace temperature of 1000°C to 1180°C and in an atmosphere with an excess air coefficient of less than 1, until the temperature of the slab at the outlet of the second heating section is 900°C.

[0046] The slab is heated in the atmosphere of 1150℃~1250℃ in the soaking section and the air excess coefficient in the soaking section is less than 1, until the temperature of the slab at the outlet of the soaking section is 1060℃~1160℃. However, the surface slag and warping defects of the hot coil obtained by this method are blocked by more than 20%.

[0047] The applicant believes that this method still uses the heating process of austenite rolling to heat the ferrite rolled slab. Since the heating process temperature required for ferrite rolling itself is extremely low (compared with austenite rolling, the heating process temperature is more than 200°C lower than the latter), this leads to the limited heating capacity of the heating furnace, and also results in less oxidation and burning of the slab, and the surface defects of the slab cannot be effectively burned away, and the surface slag surface warping defects of the final product are high. Due to the low overall heating temperature of the ferrite rolled slab, during the rolling process after leaving the furnace, the heat dissipation of the edge of the strip is fast, resulting in low temperature, and the ferrite fails to complete recrystallization, resulting in elongated structure at the edge during the strip rolling process, and finally causing the ferrite rolled coil to have poor edge quality. If the rolling line has an edge heater, it can be improved by investing in an edge heater, but it will greatly increase the production cost; if there is no edge heater, the existing heating process technology cannot improve the above problems. In addition, the heating atmosphere adjustment of this method is not targeted, and the heating time control of each furnace section is unclear.

[0048] The applicant found that the amount of burnt loss in the heating process is crucial to the elimination of surface defects in the slab. If there is no certain amount of burnt loss, the surface slag and surface peeling defect sealing rate of the final hot-rolled product will remain high. The three factors that affect burnt loss are temperature, time and atmosphere. It is precisely because the heating process temperature required for ferrite rolling itself is extremely low (compared to austenite rolling, the heating process temperature is more than 200°C lower than the latter), which leads to the limited heating capacity of the heating furnace, and the improper control of the original heating time of ferrite rolling and the non-targeted atmosphere adjustment. The above-mentioned unfavorable factors ultimately lead to the surface slag and surface peeling defect sealing rate of ferrite rolled hot coils as high as more than 20%.

[0049] In addition, since the overall heating temperature of the ferrite rolled slab is low, the heat dissipated quickly at the edge of the strip during the rolling process after it comes out of the furnace causes the temperature to be low, and the ferrite fails to complete recrystallization, resulting in elongated structure at the edge during the strip rolling process, which ultimately causes poor edge quality of the ferrite rolled coil.

[0050] To this end, the present application intends to provide a heating method for IF steel during ferrite rolling to improve the surface slag and surface warping defect blocking rate of ferrite rolled hot coils.

[0051] Figure 1 A flow chart of the method provided in the embodiment of the present application is as follows: Figure 1As shown, an embodiment of the present application provides a heating method for IF steel during ferrite rolling, the method comprising:

[0052] S1. Obtain a slab;

[0053] S2. The slab is heated in sequence through the preheating section, the first heating section, the second heating section and the soaking section of the heating furnace to obtain the slab to be rolled; wherein, the temperature of the slab at the end of the preheating section is 710℃~750℃; the temperature of the slab at the end of the first heating section is 880℃~920℃; the temperature of the slab at the end of the second heating section is 970℃~1010℃; the temperature of the slab at the end of the soaking section is 1030℃~1050℃; the excess air coefficient of the entire heating process is not less than 1.

[0054] In the process of heating the slab, the method increases the power load of the preheating section and the first heating section and controls the excess air coefficient to be not less than 1, so that strong oxidation is produced as soon as the slab enters the furnace, thereby increasing the amount of slab surface ablation. After being processed in the preheating section and the first heating section, the slab temperature is already relatively high, and at this time the power load of the second heating section will be relatively low, and the temperature difference of the slab cross section will be further reduced. At this stage, the slab temperature has reached the temperature required by the rolling process, and the strong oxidation atmosphere is maintained to continue to ablate the slab surface. Finally, after the slab enters the soaking section, the temperature continues to rise rapidly, so that the surface temperature of the slab is increased, the iron oxide scale on the surface of the slab is further thickened and ablated, and the surface defects of the slab are effectively ablated, thereby improving the surface slag and surface warping defect blocking rate of the ferrite rolled hot coil. At the same time, the heating process in the soaking section can produce a temperature difference between the surface and the core of the slab to offset a part of the heat lost on the surface, thereby effectively improving the edge quality of the ferrite rolled coil.

[0055] Exemplarily, the temperature of the slab at the end of the preheating section may be 710°C, 715°C, 720°C, 725°C, 730°C, 735°C, 740°C, 745°C, 750°C, etc., and it may also be any value within the range of 710°C to 750°C. The temperature of the slab at the end of the first heating section may be 880°C, 885°C, 890°C, 895°C, 900°C, 905°C, 910°C, 915°C, 920°C, etc., and it may also be any value within the range of 880°C to 920°C. The temperature of the slab at the end of the second heating section may be 970°C, 975°C, 980°C, 985°C, 990°C, 995°C, 1000°C, 1005°C, 1010°C, etc., and it may also be any value within the range of 970°C to 1010°C. The temperature of the slab at the end of the soaking section can be 1030°C, 1035°C, 1040°C, 1045°C, 1050°C, etc., and can also be any value within the range of 1030°C to 1050°C.

[0056] In some embodiments, the temperature of the slab at the end of the preheating section is 720°C to 740°C; the temperature of the slab at the end of the first heating section is 890°C to 910°C; the temperature of the slab at the end of the second heating section is 980°C to 1000°C; the temperature of the slab at the end of the equalizing section is 1035°C to 1045°C.

[0057] Furthermore, the temperature of the slab at the end of the preheating section is 725℃~735℃; the temperature of the slab at the end of the first heating section is 895℃~905℃; the temperature of the slab at the end of the second heating section is 985℃~995℃; the temperature of the slab at the end of the equalizing section is 1037℃~1043℃.

[0058] In some embodiments, the excess air coefficient in the preheating section is 1.05 to 1.10. Exemplarily, the excess air coefficient in the preheating section can be 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, etc., and can also be any value in the range of 1.05 to 1.10.

[0059] In some embodiments, the excess air coefficient in the first heating section is 1.10 to 1.25. For example, the excess air coefficient in the first heating section can be 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25, etc., and can also be any value in the range of 1.10 to 1.25.

[0060] In some embodiments, the excess air coefficient in the second heating section is 1.10 to 1.25. For example, the excess air coefficient in the second heating section can be 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25, etc., and can also be any value in the range of 1.10 to 1.25.

[0061] In some embodiments, the excess air coefficient in the soaking section is 1.10 to 1.25. For example, the excess air coefficient in the soaking section can be 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25, etc., and can also be any value in the range of 1.10 to 1.25.

[0062] In some embodiments, the total time that the slab passes through the preheating section and the first heating section is not less than 90 minutes. Controlling the total time that the slab passes through the preheating section and the first heating section to be not less than 90 minutes can make the slab undergo sufficient ablation, which is beneficial to improve the blocking rate of slag roll and warping defects on the surface of the hot coil of ferrite rolling. Exemplarily, the total time that the slab passes through the preheating section and the first heating section can be 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes, 120 minutes, 125 minutes, 130 minutes, 135 minutes, 140 minutes, 145 minutes, 150 minutes, etc., and it can also be any value within the range of not less than 90 minutes.

[0063] In some embodiments, the time for the slab to pass through the soaking section is not less than 25 minutes. The time for the slab to pass through the soaking section is controlled to be not less than 25 minutes, so that the surface temperature of the slab is well increased, and a temperature difference between the surface and the core of the slab is created to offset a portion of the heat lost from the surface. Exemplarily, the time for the slab to pass through the soaking section can be 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, etc., and it can also be any value within the range of not less than 25 minutes.

[0064] In some embodiments, the temperature of the slab when entering the heating furnace is not less than 300°C.

[0065] Figure 2 A comparison chart of the process provided in the embodiment of the present application and the process provided in the prior art, Figure 3 This is a schematic diagram of the temperature difference change of the slab heating section provided in the embodiment of the present application. Figure 2 and Figure 3As shown, specifically, the entire heating process of this scheme is: the slab enters the furnace, the preheating section and the first heating section burners are turned on, the power load of these two sections is increased, and the air excess coefficient λ in the preheating section is set to 1.05-1.10, and the air excess coefficient λ in the first heating section is set to 1.10-1.25. Thus, the preheating section and the first heating section together constitute the initial heating stage, so that the slab is strongly oxidized as soon as it enters the furnace, ensuring that the heating time of the two sections is ≥90min, and increasing the amount of ablation on the slab surface; after the slab enters the second heating section, since the slab temperature is already high, the power load of the second heating section will be low at this time, and the air excess coefficient λ in the second heating section is set to 1.10-1.25. In this stage, the second heating section is transformed into a soaking stage, and the temperature difference of the slab section will be further reduced. At this stage, the slab temperature has reached the temperature required by the rolling process, and a strong oxidizing atmosphere is maintained to continue to ablate the slab surface; after the slab enters the soaking stage, it continues to heat up rapidly to increase the surface temperature of the slab. This stage is a temperature difference stage, which creates a temperature difference between the surface and the core of the slab (the high temperature of the surface after leaving the furnace can offset part of the heat lost on the surface). The excess air coefficient λ in the soaking stage is set to 1.10-1.25, and the heating time is ≥25min. The oxidized iron scale on the slab surface is further thickened and ablated.

[0066] This method breaks through the traditional heating process methods in the industry. It subversively divides the traditional heating furnace into the initial heating stage, the uniform temperature stage and the differential temperature stage according to the physical furnace section preheating section, the first heating section, the second heating section and the soaking section according to the heating process requirements of the IF steel ferrite rolling slab. Specifically, the heating load of the original preheating section and the first heating section is enhanced, and it is changed into the initial heating stage, so that the surface temperature of the slab rises rapidly, and the surface ablation of the slab is greatly increased under the premise of ensuring sufficient heating time and a strong oxidizing atmosphere; the original second heating section is changed into a uniform temperature section. During this period, under a low-power heating load, the core temperature and the surface temperature of the slab gradually become consistent, and the surface ablation is further enhanced under the action of a strong oxidizing atmosphere; the original soaking section is heated with a medium load, so that the surface temperature of the slab is further increased rapidly, and the temperature difference between the surface and the core of the slab is created. In this way, the higher surface temperature of the slab after it is out of the furnace can make up for the decrease in the temperature of the corners of the slab when it is sent to the rolling line and during the rolling process, and similarly, the surface ablation is further enhanced under the action of a strong oxidizing atmosphere. After finally adopting this process, the IF steel ferrite rolled coil not only improved the edge quality but also reduced the incidence of coil slag and surface warping, greatly improving the surface quality.

[0067] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0068] Example 1

[0069] A heating method for IF steel during ferrite rolling, the method comprising:

[0070] S1. Obtain a slab;

[0071] S2. The slab is sequentially heated through the preheating section, the first heating section, the second heating section and the soaking section of the heating furnace to obtain a slab to be rolled;

[0072] Wherein, the temperature of the slab at the end of the preheating section is 730°C;

[0073] The temperature of the slab at the end of the first heating section is 900°C;

[0074] The temperature of the slab at the end of the second heating section is 990°C;

[0075] The temperature of the slab at the end of the soaking section is 1040°C;

[0076] The excess air coefficient in the preheating section is 1.07.

[0077] The excess air coefficient in the first heating section is 1.18.

[0078] The excess air coefficient in the second heating section is 1.18.

[0079] The excess air coefficient in the soaking section is 1.18.

[0080] Example 1

[0081] A heating method for IF steel during ferrite rolling, the method comprising:

[0082] S1. Obtain a slab;

[0083] S2. The slab is sequentially heated through the preheating section, the first heating section, the second heating section and the soaking section of the heating furnace to obtain a slab to be rolled;

[0084] Wherein, the temperature of the slab at the end of the preheating section is 710°C;

[0085] The temperature of the slab at the end of the first heating section is 880°C;

[0086] The temperature of the slab at the end of the second heating section is 970°C;

[0087] The temperature of the slab at the end of the soaking section is 1030°C;

[0088] The excess air coefficient in the preheating section is 1.05.

[0089] The excess air coefficient in the first heating section is 1.10.

[0090] The excess air coefficient in the second heating section is 1.10.

[0091] The excess air coefficient in the soaking section is 1.10.

[0092] Example 1

[0093] A heating method for IF steel during ferrite rolling, the method comprising:

[0094] S1. Obtain a slab;

[0095] S2. The slab is sequentially heated through the preheating section, the first heating section, the second heating section and the soaking section of the heating furnace to obtain a slab to be rolled;

[0096] Wherein, the temperature of the slab at the end of the preheating section is 750°C;

[0097] The temperature of the slab at the end of the first heating section is 920°C;

[0098] The temperature of the slab at the end of the second heating section is 1010°C;

[0099] The temperature of the slab at the end of the soaking section is 1050°C;

[0100] The excess air coefficient in the preheating section is 1.10.

[0101] The excess air coefficient in the first heating section is 1.25.

[0102] The excess air coefficient in the second heating section is 1.25.

[0103] The excess air coefficient in the soaking section is 1.25.

[0104] Comparative Example 1

[0105] A heating method for IF steel during ferrite rolling, the method comprising:

[0106] The slab is heated in a preheating section at a furnace temperature of 500°C to 800°C, until the temperature of the slab at the outlet of the preheating section is 300°C to 600°C; the slab is heated in a first heating section at a furnace temperature of 800°C to 1100°C, until the temperature of the slab at the outlet of the first heating section is 600°C to 900°C; the slab is heated in a second heating section at a furnace temperature of 1000°C to 1180°C and in an atmosphere with an excess air coefficient of less than 1 in the second heating section, until the temperature of the slab at the outlet of the second heating section is 900°C to 1120°C; the slab is heated in a soaking section at a furnace temperature of 1150°C to 1250°C and in an atmosphere with an excess air coefficient of less than 1 in the soaking section, until the temperature of the slab at the outlet of the soaking section is 1060°C to 1160°C.

[0107] The slabs treated by the heating methods provided in the embodiments and comparative examples were rolled, and the surface quality, edge structure and edge quality of the rolled steel plates were tested. Since the results of the embodiments are similar, only the results of embodiment 1 are specifically described below. The results are as follows: Figures 4 to 9 As shown in the figure, it can be seen that the steel plate obtained by rolling using the method provided in the embodiment of the present application has good surface quality and edge quality.

[0108] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0109] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b and c can be single or multiple.

[0110] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A heating method for IF steel during ferrite rolling, characterized in that: The method comprises: obtaining a slab; The slab is heated in sequence through a preheating section, a first heating section, a second heating section and a soaking section of a heating furnace to obtain a slab to be rolled; Wherein, the temperature of the slab at the end of the preheating section is 710°C to 750°C; The temperature of the slab at the end of the first heating section is 880°C to 920°C; The temperature of the slab at the end of the second heating section is 970°C to 1010°C; The temperature of the slab at the end of the soaking section is 1030°C to 1050°C; The air excess coefficient of the entire heating process is not less than 1.

2. The heating method for IF steel during ferrite rolling according to claim 1, characterized in that: The temperature of the slab at the end of the preheating section is 720° C. to 740° C.; and / or The temperature of the slab at the end of the first heating section is 890° C. to 910° C.; and / or The temperature of the slab at the end of the second heating section is 980° C. to 1000° C.; and / or The temperature of the slab at the end of the soaking section is 1035°C to 1045°C.

3. The heating method for IF steel during ferrite rolling according to claim 2, characterized in that: The temperature of the slab at the end of the preheating section is 725° C. to 735° C.; and / or The temperature of the slab at the end of the first heating section is 895° C. to 905° C.; and / or The temperature of the slab at the end of the second heating section is 985° C. to 995° C.; and / or The temperature of the slab at the end of the soaking section is 1037°C to 1043°C.

4. The heating method for IF steel during ferrite rolling according to claim 1, characterized in that: The excess air coefficient in the preheating section is 1.05 to 1.

10.

5. The heating method for IF steel during ferrite rolling according to claim 1, characterized in that: The air excess coefficient in the first heating section is 1.10-1.

25.

6. The heating method for IF steel during ferrite rolling according to claim 1, characterized in that: The excess air coefficient in the second heating section is 1.10-1.

25.

7. The heating method for IF steel during ferrite rolling according to claim 1, characterized in that: The excess air coefficient in the soaking section is 1.10 to 1.

25.

8. The heating method for IF steel during ferrite rolling according to claim 1, characterized in that: The total time for the slab to pass through the preheating section and the first heating section is not less than 90 minutes.

9. The heating method for IF steel during ferrite rolling according to claim 1, characterized in that: The time for the slab to pass through the soaking section is not less than 25 minutes.

10. The heating method for IF steel during ferrite rolling according to claim 1, characterized in that: The temperature of the slab when entering the heating furnace is not less than 300°C.

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