Method and device for controlling foreign matter indentation and indentation defects on the surface of short-process pickled steel

Abstract

The present application relates to the technical field of steel metallurgical production, and discloses a kind of short process pickling steel surface foreign matter press-in and indentation defect control method, based on thin slab continuous casting and rolling pickling steel manufacturing process, process includes molten steel smelting, thin slab continuous casting, slab edge pre-heating, slab descaling before furnace, slab soaking furnace heating, descaling before finishing, seven rack finishing, laminar cooling and coiling, finally through leveling, pickling oil forming hot-rolled pickling steel.The present application also discloses a kind of device for short process pickling steel surface foreign matter press-in and indentation defect control method.The short process pickling steel surface foreign matter press-in and indentation defect control method and device of the present application can effectively reduce the quality degradation rate of foreign matter press-in and indentation defect during short process hot-rolled pickling steel production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgical production, in particular to a method and device for controlling foreign matter pressing and indentation defects on the surface of short-process pickled steel. BACKGROUND

[0002] Under the background of realizing green manufacturing in the steel industry, thin slab continuous casting and rolling process (short process) is developed to produce thin gauge hot-rolled strip steel, which covers low carbon steel, medium and high carbon steel, low alloy high strength steel, advanced high strength steel, etc., and can be widely used in automobile and parts manufacturing, container, logistics, power engineering, agricultural machinery and mechanical manufacturing, hardware and electrical appliances, tools, etc.

[0003] The mechanical properties and application performance of thin gauge hot-rolled pickled steel produced by short process production line are equivalent to those of cold-rolled products of the same thickness, which can realize "hot instead of cold". Although the short process thin gauge hot-rolled pickled steel has the above advantages, there is still a certain gap in surface quality compared with traditional hot-rolled products and cold-rolled products. For example, the thin gauge hot-rolled pickled steel produced by short process production line often has surface foreign matter pressing and indentation defects, which causes defect reclassification and significantly affects the competitiveness of related products in the market and user end.

[0004] Chinese patent CN201820603831.1 discloses a device for reducing the indentation of steel coil head winding and a strip steel winding equipment, which reduces the indentation during the winding process of strip steel. Chinese patent CN201610085325.3 discloses a method for eliminating the indentation of hot-rolled strip steel head, in which a computer automatically adjusts the jump-off value of the coiling roller according to different hardness and thickness and gives control of the coiling roller pressure. The above technology mainly solves the indentation formed during the winding process.

[0005] Chinese patent CN201721124671.4 provides a strip steel edge burr processing device, which can roll the edge of the strip formed by cutting the edge of the plate, effectively eliminating the burr of the edge of the strip, and at the same time avoiding indentation of the edge of the strip. Chinese patent CN201120059865.7 provides a side guide plate for preventing damage to the edge of the strip, which is composed of a body and a lining plate, the edge of the lining plate is provided with a plurality of arc surfaces matched with the shape of the roller, and a guide groove is opened on the lining plate near the tangent position of the arc surface in the axial direction, which reduces the possibility of indentation defects caused by debris falling on the surface of the steel plate. Chinese patent CN201610912673.3 discloses a rolling mill device for preventing foreign matter from pressing, in which a nozzle is added, which can flush away the foreign matter flowing down from the surface of the steel plate by water, improve the surface quality, has simple structure, low cost and obvious effect of cleaning foreign matter.

[0006] However, the above disclosed technologies do not essentially solve the problem of the source of burrs and foreign matter. SUMMARY

[0007] The present application aims at the above technical deficiencies, and provides a short-process pickling steel surface foreign matter pressing and indentation defect control method and device, which can effectively reduce the quality degradation rate of foreign matter pressing and indentation defects in short-process hot-rolled pickling steel production.

[0008] To achieve the above-mentioned purpose, the short-process pickling steel surface foreign matter pressing and indentation defect control method designed by the present application is based on a thin slab continuous casting and rolling pickling steel manufacturing process, and the process includes molten steel smelting, thin slab continuous casting, slab edge pre-heating, slab descaling before the furnace, slab soaking furnace heating, descaling before finish rolling, seven-stand finish rolling, laminar cooling and coiling, and finally forming hot-rolled pickling steel through leveling, pickling and oiling;

[0009] In the slab edge pre-heating, the edge and corner of the cast slab is pre-heated at the outlet stage of the thin slab continuous casting, to compensate for the heat loss of the edge and corner of the cast slab due to fast cooling and subsequent slab descaling before the furnace, reduce the precipitation of fine AlN at the austenite grain boundary, and avoid the explosive precipitation of intergranular ferrite and AlN in the ferrite when the austenite cools to the two-phase region;

[0010] The heating temperature and time are controlled in the slab soaking furnace heating stage, to promote the dissolution of the precipitated AlN into the austenite, improve the high-temperature thermal plasticity of the slab, and reduce the formation of strip edge burrs during hot rolling;

[0011] The side guide plate pressure control is used in the pre-coiling stage to reduce the shedding of strip edge burrs caused by pressure, and the bidirectional side water spray adjustment is used to reduce the adhesion of the shedded burrs to the plate surface to form foreign matter pressing.

[0012] Preferably, in the slab edge pre-heating stage, the edge and corner of the cast slab is pre-heated by an edge heater after the cast slab exits the continuous casting machine, and the pre-heating temperature is controlled according to the Ar3 temperature calculated based on the measured chemical composition of the current heat, the full solid solution temperature T free of Al and free nitrogen N AS in the steel austenite, and the measured temperature of the edge and corner of the slab before entering the soaking furnace, when the minimum value min(T ds , T os ) of the measured temperatures T ds , T os of the two edge and corner of the slab before entering the soaking furnace is lower than the Ar3 temperature, the edge heater heating temperature ΔT is controlled as ΔT = Ar3 - min(T ds , T os ) + dT, when T AS ≤ 1150℃, dT = 50℃, when T AS > 1150℃, dT = 50℃ + (T AS-1150) / 2, Ar3 is calculated by an empirical formula with steel chemical composition mass percentage as variable, the calculation formula is Ar3=901-325xC%+33xSi%+287xP%+40xAl%-92xMn%, T AS calculated by austenite solid solubility formula: T AS =6770 / (1.03-lg(Als% x N free

[0013] Preferably, the edge heater adopts electromagnetic induction heating or gas burner heating.

[0014] Preferably, the slab edge corner heating width is 50-100mm.

[0015] Preferably, in the slab reheating furnace heating stage, the reheated and descaled slab is heated and reheated by the tunnel reheating furnace, and the slab discharge temperature T=T AS +0-100℃, and the heating time is 35-50min.

[0016] Preferably, in the pre-coiling stage, the pre-coiling side guide pressure is ≤2KN, and the side spray water pressure is 12-15bar.

[0017] Preferably, the chemical composition mass percentage of the short-process pickling steel is C: 0.01-0.08%, Si: 0.01-0.20%, Mn: 0.10-1.50%, S: ≤0.010%, P: ≤0.010%, N: 0.002-0.008%, Als: 0.02-0.07%; and the residual Ti in the steel is 0.0010-0.0020%.

[0018] A device for controlling the short-process pickling steel surface foreign matter pressing and indentation defect control method, comprising a slab continuous casting machine, an edge heater, a descaling machine, a shearing machine, a tunnel reheating furnace, a finishing descaling machine, a finishing mill, a laminar cooling device and a coiler, the end of the descaling machine is provided with an edge corner temperature gauge, the uncut continuous casting slab produced by the slab continuous casting machine is sequentially subjected to the edge heater, the descaling machine and the shearing machine to obtain a cut slab, the cut slab is subjected to the tunnel reheating furnace, the finishing descaling machine and the finishing mill to obtain a strip, and the strip is subjected to the laminar cooling device and then enters the coiler.

[0019] Preferably, the coiler is provided with a coiling pinch roll, coiling side guides on both sides of the strip and a pre-pinch roll side spray.

[0020] ​Compared with the prior art, the present application has the following advantages: the quality degradation rate caused by the foreign matter pressing into the surface of pickled steel and the indentation defect is reduced to below 0.2% through the heat supplement at the continuous casting outlet stage, the process control at the heating stage, the guide plate at the coiling stage and the optimization of the side spraying process. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a schematic diagram of the device for the control method of the foreign matter pressing into the surface of the short-process pickled steel and the indentation defect of the present application;

[0022] Figure 2 The figure is a schematic diagram of the plate surface foreign matter flushing before the pinch roll;

[0023] Figure 3 The figure is a metallographic analysis result of the burr defect (a) and the foreign matter pressing into defect (b) of the short-process pickled steel strip;

[0024] Figure 4 The figure is a schematic diagram of the foreign matter pressing into and indentation defect formation mechanism of the short-process pickled steel, (a) is the strip edge burr defect peeling under the action of the side guide plate, (b) is the peeled burr pressed into the plate surface under the rolling action of the pinch roll;

[0025] Figure 5 The figure is a schematic diagram of the phase transition and AlN precipitation behavior of the edge corner of the casting blank under different thermal histories.

[0026] The labels of the components in the figure are as follows:

[0027] Slab continuous casting machine 1, uncut continuous casting blank 2, edge heater 3, descaling machine before furnace 4, edge corner temperature gauge 5, swing shear 6, cut slab 7, tunnel soaking furnace 8, descaling machine after finishing rolling 9, finishing rolling mill 10, strip 11, laminar cooling device 12, coiling side guide plate 13a, pinch roll front side spraying 13b, coiling pinch roll 14, coiling machine 15. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0029] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] As shown in Figure 1 A device for controlling the method of short process pickling steel surface foreign matter pressing and indentation defect, comprising a slab continuous casting machine 1, a side heater 3, a descaling machine before the furnace 4, a swing shear 6, a tunnel type soaking furnace 8, a descaling machine before the furnace 9, a finishing mill 10, a laminar cooling device 12 and a coiler 15, and a corner temperature gauge 5 is arranged at the end of the descaling machine before the furnace 4. The uncut continuous casting billet 2 produced by the slab continuous casting machine 1 passes through the side heater 3, the descaling machine before the furnace 4 and the swing shear 6 in sequence to obtain the cut-off slab 7. The cut-off slab 7 passes through the tunnel type soaking furnace 8, the descaling machine before the furnace 9 and the finishing mill 10 to obtain the strip steel 11. The strip steel 11 passes through the laminar cooling device 12 and enters the coiler 15.

[0032] In addition, as shown in Figure 2 The coiler 15 is provided with a coiling pinch roll 14 and coiling side guide plates 13a located on both sides of the strip steel 11 and a pinch roll front side spray 13b.

[0033] A method for controlling the pressing of foreign matter on the surface of short process pickling steel and indentation defects, based on the thin slab continuous casting and rolling pickling steel manufacturing process, the process includes molten steel smelting, thin slab continuous casting, slab edge pre-heating, slab descaling before the furnace, slab soaking furnace heating, descaling before finishing, seven-stand finishing, laminar cooling and coiling, and finally forming hot-rolled pickling steel through leveling, pickling and oiling;

[0034] Wherein, the slab edge pre-heating is to pre-heat the edge corner of the cast slab at the outlet stage of the thin slab continuous casting, to compensate the heat loss of the edge corner of the cast slab due to fast cooling and subsequent slab descaling, to reduce the fine AlN precipitation at the austenite grain boundary, to avoid the explosive precipitation of the intergranular ferrite and AlN in the ferrite when the austenite is cooled to the two-phase region, at the slab edge pre-heating stage, the edge heater is used to pre-heat the edge corner of the cast slab after the cast slab is discharged from the caster, the pre-heating temperature is controlled according to the Ar3 temperature calculated based on the measured chemical composition of the current heat, the AlS and free nitrogen N free in the austenite, the full solid solution temperature T AS of the AlS and N ds , and the measured temperature of the slab edge corner before entering the soaking furnace (measured by the edge corner temperature gauge 5), when the minimum value min(T os , T ds ) of the measured temperatures T os of the two edge corners before the slab enters the soaking furnace is lower than the Ar3 temperature, the edge heater heating temperature ΔT = Ar3 - min(T ds , T os ) + dT is controlled, when T AS ≤ 1150℃, dT = 50℃, when T AS > 1150℃, dT = 50℃ + (T AS - 1150) / 2, the Ar3 is calculated by using the empirical formula with the mass percentage of the steel chemical composition as the variable, the calculation formula is Ar3 = 901 - 325×C% + 33×Si% + 287×P% + 40×Al% - 92×Mn%, the T AS is calculated by using the solid solubility formula in the austenite: T AS = 6770 / (1.03-lg(Als%×N free %))-273;

[0035] The heating temperature and heating time are controlled at the slab soaking furnace heating stage, to promote the AlN that has been precipitated to dissolve back into the austenite, to improve the high temperature thermal plasticity of the slab, and to reduce the edge burr formation of the strip during hot rolling, at the slab soaking furnace heating stage, the slab that has been pre-heated and descaled before the furnace is heated and soaked by the tunnel-type soaking furnace, the slab discharge temperature T = T AS + 0-100℃ is controlled, and the heating time is 35-50min;

[0036] The side guide pressure is controlled at the stage before coiling to reduce the shedding of the edge burr of the strip caused by the pressure, and the double-side water spray is adjusted to reduce the foreign matter formed by the adhered burr shedding on the plate surface, at the stage before coiling, the side guide pressure before coiling is ≤2KN, and the double-side water spray is used to flush the foreign matter on the plate surface before the pinch roll, and the side water spray pressure is 12-15bar.

[0037] Specifically, the edge heater adopts electromagnetic induction heating or gas burner heating, and the slab edge corner heating width is 50-100mm.

[0038] In addition, the short-process pickling steel has the following chemical composition: C: 0.01-0.08%, Si: 0.01-0.20%, Mn: 0.10-1.50%, S: ≤0.010%, P: ≤0.010%, N: 0.002-0.008%, and Als: 0.02-0.07%.

[0039] In the present application, the surface indentation defect of the short-process low-alloy steel is distributed on the edge of the strip steel, the defect site is separated from the steel base, and presents the state of foreign matter being pressed in, the foreign matter site has no obvious difference with the composition of the steel base, and the indentation is formed if the foreign matter falls off. It is found that the steel coil with indentation defect also has burrs on the edge of the strip steel, and the burrs and the indentation have obvious correlation. No inclusions and high-temperature oxidation dots are found in the metallographic structure of the burr site, and no obvious abnormality is found in the microstructure near the defect, which indicates that the defect is not derived from the casting slab crack defect. Figure 3 The metallographic analysis results of the burrs on the edge of the short-process pickling steel strip and the indentation defect caused by foreign matter being pressed in are attached Figure 4 The indentation defect caused by foreign matter being pressed in and the formation mechanism of the indentation defect of the short-process pickling steel are shown in the schematic diagram, the burrs on the edge of the strip steel are peeled off under the action of the side guide plate and fall onto the plate, and are pressed into the plate under the rolling action of the coiling pinch roll, and part of the burrs that are not pressed in fall off, thus leaving the indentation. The indentation and the foreign matter being pressed in both cause the quality of the strip steel to degrade. The continuous casting slab is analyzed, and no transverse corner crack defect is found on the edge of the slab, so the burrs on the edge of the strip steel are generated in the finishing rolling stage, which is related to the low high-temperature plasticity of the strip steel on the edge during rolling.

[0040] Based on the process history characteristics of the short-process production line, the surface of the short-process pickling steel is easily affected by the inheritance of the surface defects of the casting slab (sintering of the mold powder film, mold powder carbonization, vibration marks), in order to obtain good surface quality, the pickling steel with high surface requirements must use a larger descaling pressure to descale the surface of the continuous casting slab before entering the soaking furnace, remove the mold powder film and accelerate the removal of the carbonization and vibration mark defect layer. However, due to the fast heat dissipation of the edge and corner of the casting slab, the temperature drops greatly, and under the action of the descaling water, the edge and corner of the casting slab is easily reduced to below the Ar3 temperature and enters the austenite γ + ferrite α two-phase region. The grain size of the short-process casting slab is large (800-1000 μm), so a thin film of ferrite is precipitated at the coarse austenite grain boundary, and according to the solubility product formula of AlN in austenite and ferrite γ =1.03-6770 / T and lg([Al][N]) α= 2.05 - 8790 / T, a large amount of fine dispersed AlN will precipitate at the austenite grain boundary and the grain boundary ferrite, especially explosive nucleation and precipitation of AlN will occur in the ferrite. Although slab soaking can promote the grain boundary ferrite and the dissolution of AlN, the short process slab heating time is short, and it is difficult to dissolve all the AlN into austenite, and a large amount of AlN still exists in the coarse austenite grain boundary, resulting in the reduction of hot plasticity of the slab corner part during hot rolling, as shown in ①→ ②→ ④→ ⑤ of the attached drawing. During hot rolling, the hot plasticity of the corner part of the casting slab is the most critical reason for the formation of the edge burr of the strip. Figure 5

[0041] Therefore, the key of the method for controlling the foreign matter pressing and indentation defects on the surface of the pickling steel is to control the hot plasticity of the corner part of the continuous casting slab, and to assist with the process control of the coiling side guide and the front side spray of the pinch roll.

[0042] The following will be further described in combination with specific examples. Table 1 is the smelting chemical composition (mass percentage) and Ar3, T AS Table 2 is the edge heat supplement and heating process comparison of each example and the comparative example, and Table 3 is the coiling front side guide and front side spray of the pinch roll process of each example and the comparative example.

[0043] Table 1 is the smelting chemical composition (mass percentage) and Ar3, T AS Table 2 is the edge heat supplement and heating process comparison of each example and the comparative example, and Table 3 is the coiling front side guide and front side spray of the pinch roll process of each example and the comparative example.

[0044]

[0045] Table 2 is the edge heat supplement and heating process comparison of each example and the comparative example, and Table 3 is the coiling front side guide and front side spray of the pinch roll process of each example and the comparative example.

[0046]

[0047] Table 3 is the coiling front side guide and front side spray of the pinch roll process of each example and the comparative example.

[0048]

[0049] The edge burr, foreign matter pressing and indentation defect inspection results of the strip under different processes of each example and the comparative example are shown in Table 4. It can be seen that the occurrence rates of the edge burr, foreign matter pressing and indentation defects of the strip under the process of the examples are significantly reduced compared with the comparative example. Through the comprehensive optimization of the processes such as the continuous casting outlet stage, the slab heating stage and the coiling front stage, the present application realizes the control of the precipitates based on the smelting composition and the regulation of the high temperature plasticity of the slab. The degradation rate caused by the foreign matter pressing and indentation defects on the surface of the pickling steel with high surface requirement is reduced to less than 0.2%.

[0050] Table 4 is the edge burr, foreign matter pressing and indentation defect results of the strip under different processes of each example and the comparative example.​

[0051] Strip edge burr, place / roll Foreign object indentation and marking, place / roll Example 1 0 0 Example 2 8 2 Example 3 3 0 Example 4 4 0 Example 5 2 0 Comparative Example 1 66 21 Comparative Example 2 220 52 Comparative Example 3 54 13 Comparative Example 4 29 8 Comparative Example 5 25 6

[0052] Here, it should be noted that the above-described technical solutions are exemplary, and the present specification can be embodied in different forms, and should not be interpreted as being limited to the technical solutions set forth herein. Rather, providing these descriptions will make the present disclosure thorough and complete, and will fully convey the scope disclosed by the present specification to those skilled in the art. In addition, the technical solutions of the present application are limited only by the scope of the claims.

[0053] The aspects disclosed for describing the present specification and claims are merely examples, and thus the present specification and claims are not limited to the shown details. In the above description, when detailed descriptions of related known functions or configurations are determined to unnecessarily obscure the points of the present specification and claims, detailed descriptions will be omitted.

[0054] In the case of using "include", "have", and "contain" described in the present specification, unless otherwise used, another part or other parts can also be present, and the terms used can be singular but can also indicate a plural form.

[0055] Finally, it should be noted that the above is a further detailed description of the application in conjunction with the specific embodiments, and the specific embodiments of the present application should not be considered as being limited to these descriptions. For those skilled in the art, simple substitutions made without departing from the concept of the present application should be considered as falling within the scope of protection of the present application. The above examples are only more representative examples of the present application. Obviously, the present application is not limited to the above examples, and there can be many variations. Any simple modification, equivalent change, and modification made according to the technical essence of the present application to the above examples should be considered as falling within the scope of protection of the present application.

[0056] At the same time, it should be noted that the above-described technical solutions are exemplary, and the present specification can be embodied in different forms, and should not be interpreted as being limited to the technical solutions set forth herein. Rather, providing these descriptions will make the present disclosure thorough and complete, and will fully convey the scope disclosed by the present specification to those skilled in the art. In addition, the technical solutions of the present application are limited only by the scope of the claims. The features of various embodiments of the present application can be partially or entirely combined with each other or spliced, and can be executed in various different configurations as can be fully understood by those skilled in the art. Embodiments of the present application can be executed independently of each other, or can be executed together in a mutually dependent relationship.

[0057] For those skilled in the art to which this application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, and the above structures should be considered as belonging to the protection scope of the present application.

Claims

1. A method for controlling foreign matter indentation and indentation defects on the surface of pickled steel in a short-process process, based on the thin slab continuous casting and rolling pickled steel manufacturing process, characterized in that: The process includes steelmaking, thin slab continuous casting, slab edge preheating, slab descaling in front of the furnace, slab heating in the soaking furnace, descaling before finishing rolling, seven-stand finishing rolling, laminar flow cooling and coiling, and finally forming hot-rolled pickled steel through leveling, pickling and oiling. Among them, the preheating of the slab edge is to preheat the corners of the cast slab at the exit stage of thin slab continuous casting to compensate for the heat loss caused by the rapid cooling of the corners of the continuous casting slab and the subsequent descaling of the slab in front of the furnace, reduce the precipitation of fine AlN at the austenite grain boundaries, and avoid the precipitation of grain boundary ferrite and explosive precipitation of AlN in the ferrite as the austenite cools down to the two-phase region. Controlling the heating temperature and time during the slab soaking furnace heating stage promotes the redissolution of precipitated AlN into austenite, improves the high-temperature thermoplasticity of the slab, and reduces the formation of burrs on the strip edge during hot rolling. Before coiling, pressure control of the side guide plate reduces the burrs on the strip edge from falling off due to pressure, and bidirectional side water spraying reduces the burrs from adhering to the plate surface and forming foreign objects pressed in. During the preheating stage of the slab edge, after the continuously cast slab exits the continuous casting machine, an edge heater is used to preheat the edges and corners of the slab. The preheating temperature is calculated based on the Ar3 temperature, Als content, and free nitrogen content in the austenite of the steel, based on the measured chemical composition of this heat. free The total solution temperature T AS The measured temperature of the slab's edges and corners before entering the soaking furnace is controlled. The measured temperature T of the two edges and corners of the slab before entering the soaking furnace is... ds T os The minimum value min(T) ds ,T os When the temperature is below Ar3, control the supplementary heating temperature of the edge heater ∆T = Ar3 - min(T) ds ,T os )+dT, when T AS When ≤1150℃, dT=50℃, when T AS When the temperature is greater than 1150℃, dT = 50℃ + (T AS Ar3 is calculated using an empirical formula with the mass percentage of the steel's chemical composition as the variable. The formula is: Ar3 = 901 - 325 × C% + 33 × Si% + 287 × P% + 40 × Al% - 92 × Mn%, T AS Calculated using the formula for solid solubility in austenite: T AS =6770 / (1.03-lg(Als%×N free %))-273.

2. The method for controlling foreign matter indentation and indentation defects on the surface of short-process pickled steel according to claim 1, characterized in that: The side heaters are heated by electromagnetic induction or by gas burners.

3. The method for controlling foreign matter indentation and indentation defects on the surface of steel in short-process pickling according to claim 2, characterized in that: The heating width at the edges and corners of the slab is 50~100mm.

4. The method for controlling foreign matter indentation and indentation defects on the surface of short-process pickled steel according to claim 1, characterized in that: During the slab soaking furnace heating stage, the slabs that have undergone supplementary heating and descaling at the furnace front are heated and soaked in a tunnel-type soaking furnace to control the slab exit temperature T=T AS +0~100℃, heating time is 35~50min.

5. The method for controlling foreign matter indentation and indentation defects on the surface of steel subjected to short-process pickling according to claim 1, characterized in that: Before winding, the pressure of the guide plate before winding is ≤2KN. Bidirectional side water spray is used to flush foreign objects on the plate surface in front of the pinch roller, and the side water spray pressure is 12~15bar.

6. The method for controlling foreign matter indentation and indentation defects on the surface of steel subjected to short-process pickling according to claim 1, characterized in that: The chemical composition (mass percentage) of the short-process pickling steel is as follows: C: 0.01~0.08%, Si: 0.01~0.20%, Mn: 0.10~1.50%, S: ≤0.010%, P: ≤0.010%, N: 0.002~0.008%, Als: 0.02~0.07%; the residual Ti in the steel is 0.0010~0.0020%.

Images