A method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation

Abstract

The present invention provides a method for solving the oil spot defect on the surface of IF steel continuous annealing plate after shipping by sea, which belongs to the technical field of IF steel surface quality control. The method comprises: smelting molten steel, then continuously casting, and obtaining a slab; heating and hot rolling the slab to obtain a hot-rolled plate; pickling, cold rolling, continuous annealing, coiling, leveling and oiling the hot-rolled plate to obtain an IF steel continuous annealing plate finished product; the molten steel comprises the following chemical components by mass fraction: C: 0.015-0.02%, Al: 0.02-0.05%, Mn: 0.1-0.2%, Si: 0.05-0.07%, Ti: 0.06-0.08%, Sb: 0.005-0.01%. The method can improve the corrosion resistance of the existing IF steel continuous annealing plate by controlling the composition of the smelted molten steel, thereby solving the problem of the oil spot defect on the surface of the existing IF steel continuous annealing plate after shipping by sea.

Description

Technical Field

[0001] The present application relates to the technical field of IF steel surface quality control, and in particular to a method for solving the surface oil spot defect of IF steel continuous withdrawal plate after sea transportation. Background Art

[0002] When the metal surface comes into contact with the air, a very thin oxide layer will be generated. This oxide layer film usually has a high porosity and mechanical strength, and cannot effectively protect the metal material from corrosion. Anti-rust oil is a short-term protective measure for steel plates during storage and transportation, and is currently widely used in the anti-corrosion of steel materials. Anti-rust oil adheres to the metal surface to form a firm film, isolating the metal from the corrosive medium (moisture, air, carbon dioxide, acid, alkali, salt, etc.), thereby preventing the metal from rusting. However, during the production process, it was found that on the metal surface coated with lubricating oil and anti-rust oil, a discoloration phenomenon from brown to dark brown was often found. This discoloration is different from on-site rust and corrosion, and is generally referred to as oil spots or oil stains (collectively referred to as surface oil spot defects). Not only does it exist as a pre-rust substance, causing product quality problems, but it cannot be completely removed by general degreasing processes, resulting in a decline in product quality and an increase in production costs. Summary of the invention

[0003] The embodiment of the present application provides a method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation, so as to solve the technical problem that the existing IF steel continuous withdrawal plate has the oil spot defect on the surface after sea transportation.

[0004] In a first aspect, the present application provides a method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation, the method comprising:

[0005] The molten steel is smelted and then continuously cast to obtain slabs;

[0006] Heating and hot rolling the slab to obtain a hot-rolled plate;

[0007] The hot-rolled sheet is pickled, cold-rolled, continuously annealed, coiled, leveled and oiled to obtain a finished IF steel continuously annealed sheet;

[0008] Calculated by mass fraction, the molten steel includes the following chemical components: C: 0.015-0.02%, Al: 0.02-0.05%, Mn: 0.1-0.2%, Si: 0.05-0.07%, Ti: 0.06-0.08%, Sb: 0.005-0.01%.

[0009] Furthermore, the molten steel includes the following chemical components by mass fraction: C: 0.018%, Al: 0.035%, Mn: 0.15%, Si: 0.06%, Ti: 0.07%, and Sb: 0.008%.

[0010] Furthermore, the flattening process parameters include: the rolling force within 100 meters of the head and tail of the IF steel continuously undressed plate is 800-1000KN, and the rolling force in the middle of the IF steel continuously undressed plate is 2000-2500KN.

[0011] Furthermore, the flattening process parameters include: the rolling force within 100 meters of the head and tail of the IF steel continuously withdrawn plate is 900KN, and the rolling force in the middle of the IF steel continuously withdrawn plate is 2250KN.

[0012] Furthermore, the process parameters of oiling include: the oiling amount within 100 meters of the head and tail of the IF steel continuous retreat plate is: the thickness of the IF steel continuous retreat plate is ≤1.0mm, and the oiling amount is 550-650g / m 2 IF steel continuous annealing plate thickness> 1.0mm, oiling amount 750 ~ 850g / m 2 IF steel continuous retreat plate middle part oil coating amount is 1150 ~ 1250g / m 2 .

[0013] Furthermore, the oiling process parameters include: the oiling amount within 100 meters of the head and tail of the IF steel continuous retreat plate is: the thickness of the IF steel continuous retreat plate is ≤1.0mm, the oiling amount is 600g / m 2 IF steel continuous retreat plate thickness> 1.0mm, oil coating amount 800g / m 2 IF steel continuous retreat plate middle part oil coating amount is 1200g / m 2 .

[0014] Furthermore, the pickling process parameters include: the residual chloride ion on the surface of the strip after pickling is less than 2 mg / m 2 The chloride ion content in the condensed water / desalted water in the rinsing section is less than 0.1 mg / L.

[0015] Furthermore, the surface roughness of the finished IF steel continuously annealed plate is between 0.8 and 1.0 um.

[0016] Furthermore, the surface roughness of the finished IF steel continuously annealed plate is 0.9 um.

[0017] Furthermore, the coiling process parameters include: the coiling tension within 100 meters of the tail of the IF steel continuously unreeled plate is 30-35MPa; the coiling tension at the head and middle of the IF steel continuously unreeled plate is 27-32MPa.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The embodiment of the present application provides a method for solving the oil spot defect on the surface of IF steel continuously withdrawn plate after sea transportation. The method can improve the corrosion resistance of the existing IF steel continuously withdrawn plate by controlling the composition of the smelted molten steel (in terms of mass fraction, the molten steel includes the following chemical components: C: 0.015-0.02%, Al: 0.02-0.05%, Mn: 0.1-0.2%, Si: 0.05-0.07%, Ti: 0.06-0.08%, Sb: 0.005-0.01%). For example, the Sb element has a certain effect of inhibiting corrosion, and the surface layer is concentrated to protect the matrix, but the amount added cannot be too high, otherwise brittle cracking will occur. It can prevent a large number of tiny corrosion pits from forming on the surface of the existing IF steel continuously withdrawn plate matrix, thereby solving the problem of the oil spot defect on the surface of the existing IF steel continuously withdrawn plate after sea transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] In order to more clearly illustrate the embodiments of the present invention 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.

[0022] Figure 1 A flow chart of a method for solving the oil spot defect on the surface of IF steel continuous-retracted plates after sea transportation provided in an embodiment of the present application;

[0023] Figure 2 This is the macroscopic morphological characteristic diagram of the oil spot defect on the surface of the IF steel continuous annealing plate;

[0024] Figure 3 This is the morphology of the internal corrosion pits of the oil spot defect on the surface of the IF steel continuous retreat plate;

[0025] Figure 4 This is a diagram of the steel plate surface condition after implementing a method provided in an embodiment of the present application for solving the oil spot defect on the surface of IF steel continuously withdrawn plates after sea transportation. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are for illustrating the present invention, rather than limiting the present invention.

[0027] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0028] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0029] When the metal surface comes into contact with the air, a very thin oxide layer will be generated. This oxide layer film usually has a high porosity and mechanical strength, and cannot effectively protect the metal material from corrosion. Anti-rust oil is a short-term protective measure for steel plates during storage and transportation, and is currently widely used in the anti-corrosion of steel materials. Anti-rust oil adheres to the metal surface to form a firm film, isolating the metal from the corrosive medium (moisture, air, carbon dioxide, acid, alkali, salt, etc.), thereby preventing the metal from rusting. However, during the production process, it was found that on the metal surface coated with lubricating oil and anti-rust oil, a discoloration phenomenon from brown to dark brown was often found. This discoloration is different from on-site rust and corrosion, and is generally referred to as oil spots or oil stains (collectively referred to as surface oil spot defects). Not only does it exist as a pre-rust substance, causing product quality problems, but it cannot be completely removed by general degreasing processes, resulting in a decline in product quality and an increase in production costs.

[0030] The actual IF steel production process on site generally adopts the wet leveling process, which means that lubricating liquid is sprayed on the surface of the cold-rolled strip during the leveling process to reduce the rolling friction. However, if the purging is not thorough, a large amount of leveling liquid will remain on the surface of the steel plate, which will accelerate the occurrence of oil spot defects on the steel plate surface.

[0031] The technical solution provided by the embodiment of the present invention is to solve the above technical problems, and the overall idea is as follows:

[0032] In the first aspect, the embodiments of the present application provide a method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation, such as Figure 1 As shown, the method includes:

[0033] The molten steel is smelted and then continuously cast to obtain slabs;

[0034] Heating and hot rolling the slab to obtain a hot-rolled plate;

[0035] The hot-rolled sheet is pickled, cold-rolled, continuously annealed, coiled, leveled and oiled to obtain a finished IF steel continuously annealed sheet;

[0036] Calculated by mass fraction, the molten steel includes the following chemical components: C: 0.015-0.02%, Al: 0.02-0.05%, Mn: 0.1-0.2%, Si: 0.05-0.07%, Ti: 0.06-0.08%, Sb: 0.005-0.01%.

[0037] The embodiment of the present application provides a method for solving the oil spot defect on the surface of IF steel continuously withdrawn plate after sea transportation. The method can improve the corrosion resistance of the existing IF steel continuously withdrawn plate by controlling the composition of the smelted molten steel (in terms of mass fraction, the molten steel includes the following chemical components: C: 0.015-0.02%, Al: 0.02-0.05%, Mn: 0.1-0.2%, Si: 0.05-0.07%, Ti: 0.06-0.08%, Sb: 0.005-0.01%). For example, the Sb element has a certain effect of inhibiting corrosion, and the surface layer is concentrated to protect the matrix, but the amount added cannot be too high, otherwise brittle cracking will occur. It can prevent a large number of tiny corrosion pits from forming on the surface of the existing IF steel continuously withdrawn plate matrix, thereby solving the problem of the oil spot defect on the surface of the existing IF steel continuously withdrawn plate after sea transportation.

[0038] As an implementation method of an embodiment of the present application, the molten steel includes the following chemical components by mass fraction: C: 0.018%, Al: 0.035%, Mn: 0.15%, Si: 0.06%, Ti: 0.07%.

[0039] The essence of the oil spot defect is weak corrosion on the substrate surface, forming a large number of tiny corrosion pits, which appear as "stains" on a macro scale. The main reason for the weak corrosion is that the oil film on the surface of the steel plate fails during shipping at the defect location and storage at high temperature and humidity, and adsorbs Cl ions in the environment, causing weak electrochemical corrosion of the steel plate substrate. The present application can improve the corrosion resistance of the existing IF steel continuous withdrawal plate by controlling the smelting molten steel to the above-mentioned components, and can prevent the formation of a large number of tiny corrosion pits on the substrate surface of the existing IF steel continuous withdrawal plate, thereby solving the problem of oil spot defects on the surface of the existing IF steel continuous withdrawal plate after sea transportation.

[0040] As an implementation method of an embodiment of the present application, the flattening process parameters include: the rolling force within 100 meters of the head and tail of the IF steel continuously withdrawn plate is 800-1000KN, and the rolling force in the middle of the IF steel continuously withdrawn plate is 2000-2500KN.

[0041] In this application, low rolling force during the leveling process may lead to the problem of residual leveling liquid. During the production process, the rolling force of the first and last 100 meters of the strip must be controlled at 800-1000KN, and the rolling force in the middle must be controlled at 2000-2500KN. The nozzles on the spray beam of the support roller are blocked outside the width of 1700mm to reduce the residual leveling liquid at the edge of the strip.

[0042] As an implementation method of an embodiment of the present application, the flattening process parameters include: the rolling force within 100 meters of the head and tail of the IF steel continuously withdrawn plate is 900KN, and the rolling force in the middle of the IF steel continuously withdrawn plate is 2250KN.

[0043] As an implementation method of the present application, the process parameters of the oiling include: the oiling amount within 100 meters of the head and tail of the IF steel continuous retreat plate is: the thickness of the IF steel continuous retreat plate is ≤1.0mm, the oiling amount is 550~650g / m 2 IF steel continuous annealing plate thickness> 1.0mm, oiling amount 750 ~ 850g / m 2 IF steel continuous retreat plate middle part oil coating amount is 1150 ~ 1250g / m 2 .

[0044] In this application, from the perspective of economy and avoiding slipping problems, the oiling amount of the continuous steel plate at the head and tail of 100 meters is appropriately increased, and the oiling amount of the steel plate with a thickness of less than 1.0 mm is 550-650 g / m 2 , the oil coating amount for thickness above 1.0mm is 750~850g / m 2 , the oil coating amount in the middle should be kept at 1150~1250g / m 2 In some specific embodiments, the performance of the rust-proof oil requires that the viscosity of the oil be controlled at 28-32 mm at room temperature (40°C). 2 / s, moisture content is less than 0.01%, which improves the oil storage performance of the strip surface.

[0045] As an implementation method of the present application, the process parameters of the oiling include: the oiling amount within 100 meters of the head and tail of the IF steel continuous retreat plate is: the thickness of the IF steel continuous retreat plate is ≤1.0mm, the oiling amount is 600g / m 2 IF steel continuous retreat plate thickness> 1.0mm, oil coating amount 800g / m 2 IF steel continuous retreat plate middle part oil coating amount is 1200g / m 2 .

[0046] As an implementation method of the present application, the pickling process parameters include: the residual chloride ion on the surface of the strip after pickling is less than 2 mg / m 2 The chloride ion content in the condensed water / desalted water in the rinsing section is less than 0.1 mg / L.

[0047] In this application, the pickling process ensures that the residual chloride ion on the surface of the strip after rinsing is less than 2 mg / m 2 The chloride ion content of the condensed water / desalted water in the rinsing section is required to be less than 0.1 mg / l to avoid the presence of chloride ion surface residues in the pickling process.

[0048] As an implementation method of the embodiment of the present application, the surface roughness of the finished IF steel continuously annealed plate is 0.8 to 1.0 um.

[0049] In the present application, for the surface of the steel plate, the surface roughness is an important factor affecting the surface quality of the steel plate. If the surface roughness of the steel plate is large and the surface is uneven, it means that its contact area with the external environment is larger, which will not only cause impurities to adhere to the surface of the steel plate more easily, causing uneven distribution of the potential difference on the surface of the steel plate, but also a larger contact area means a larger mass transfer area between the steel plate and the outside world, which will affect the overall corrosion resistance of the steel plate. The surface roughness of the steel plate is controlled at 0.8-1.0um.

[0050] As an implementation method of the embodiment of the present application, the surface roughness of the finished IF steel continuous annealing plate is 0.9um.

[0051] As an implementation method of an embodiment of the present application, the coiling process parameters include: the coiling tension within 100 meters of the tail of the IF steel continuously unreeled plate is 30-35MPa; the coiling tension in the head and middle of the IF steel continuously unreeled plate is 27-32MPa.

[0052] In this application, the coiling tension system is optimized to appropriately increase the coiling tension of the tail 100 meters to 30-35MPa, and the coiling tension of the main body is controlled at 27-32MPa, which is beneficial to improve the compactness of the steel coil after coiling.

[0053] In summary, a method for solving the surface oil spot defect of IF steel continuous withdrawal plate after sea transportation is

[0054] 1. Macroscopic morphological characteristics of chromatic aberration defects, such as Figure 2 As shown,

[0055] All of them occur at the head and tail, with more in the outer circle than in the inner circle; mostly on one side of the upper surface. There are many round light yellow and light gray spot-like defects on the surface, which exist evenly on the defective board surface, and the size of the spots is 1-5mm.

[0056] 2. Microscopic morphological characteristics of chromatic aberration defects, such as Figure 3 As shown,

[0057] There are many small corrosion pits clustered inside the defect, but there is no such morphology outside the defect.

[0058] 3. Causes and key factors of oil spot defects

[0059] The essence of oil spot defect is weak corrosion on the substrate surface, forming a large number of tiny corrosion pits, which appear as "spots" on a macro scale. The main reason for weak corrosion is that the oil film on the surface of the steel plate fails during shipping and storage at high temperature and humidity at the defect location, and absorbs Cl ions in the environment, causing weak electrochemical corrosion of the steel plate substrate.

[0060] Oiling is a low-cost anti-corrosion method to isolate steel from water and air. However, due to the unstable rolling of the head and tail during the production process, it is easy to slip. Generally, the amount of oiling is reduced, which is prone to uneven oiling or insufficient integrity of the oil film, which can easily cause shallow surface corrosion on the steel plate, that is, the formation of oil spot defects. Therefore, to suppress the surface oil spot defect, it is necessary to ensure the uniformity of the oil film.

[0061] On the other hand, the IF steel cold rolling annealing line has no yield platform, and the flattening process is uniquely designed to ensure the required plate shape and surface roughness. Generally, the flattening machine uses a flattening liquid for wet flattening. During the production of IF steel, due to the low flattening elongation, the number and angle of the purge nozzles are unreasonable, and the local purge is not thorough, resulting in residual flattening liquid on the edge of the steel plate. These water films are difficult to detect with the naked eye, thus creating conditions for rust to occur.

[0062] 4. Avoid residual Cl ions on the surface during pickling

[0063] The pickling process ensures that the residual chloride ion on the strip surface after rinsing is less than 2 mg / m2, and the chloride ion content of the condensed water / desalted water in the rinsing section is required to be less than 0.1 mg / l to avoid the presence of chloride ion surface residues in the pickling process.

[0064] 5. Head and tail oil film integrity control measures

[0065] The finished strip convexity is inherited from the hot coil convexity to the cold rolling. Since the strip adopts the principle of equal proportion convexity during the cold rolling process, the finished cold rolling convexity will be greatly affected by the hot coil convexity. The target convexity of the hot rolled coil is adjusted to 40-50um to ensure the uniformity of the transverse secondary oil film after cold rolling.

[0066] For the surface of steel plates, surface roughness is an important factor affecting the surface quality of steel plates. If the surface roughness of the steel plate is large and the surface is uneven, it means that its contact area with the external environment is larger, which will not only cause impurities to adhere to the surface of the steel plate more easily, causing uneven distribution of potential difference on the surface of the steel plate, but also a larger contact area means a larger mass transfer area between the steel plate and the outside world, which will affect the overall corrosion resistance of the steel plate. The surface roughness of the steel plate is controlled at 0.8-1.0 (um).

[0067] From the perspective of economy and avoiding slipping, the amount of oil applied to the first and last 100 meters of the continuously retreated steel plate should be appropriately increased, of which 600g / m2 should be applied for thickness below 1.0mm, 800g / m2 for thickness above 1.0mm, and 1200g / m2 should be maintained in the middle.

[0068] The oil performance requirements of anti-rust oil are that the viscosity at room temperature (40°C) is controlled at 28-32mm2 / s, the water content is less than 0.01%, and the oil storage performance of the strip surface is improved.

[0069] 6. Prevent the problem of residual leveling fluid during the leveling process

[0070] Low rolling force during the leveling process may lead to the problem of residual leveling liquid. During the production process, the rolling force of the first and last 100 meters of the strip must be controlled at 800-1000KN, and the rolling force in the middle must be controlled at 2000-2500KN. The nozzles on the spray beam of the support roller are blocked outside the width of 1700mm to reduce the residual leveling liquid at the edge of the strip.

[0071] 6. Winding tension control

[0072] During the coiling process of the oiled strip, if the coiling tension fluctuates greatly, the strip steel between the coiled layers will no longer be in close contact, and there may be looseness or even gaps between the layers. When gaps appear between the layers, under the action of gravity, the anti-rust oil originally attached to the surface of the strip will flow down along the gaps, and will continue to precipitate and gather in the relevant area at the bottom of the steel coil during the placement of the steel coil. During transportation and hoisting, the entire steel coil will continue to move, causing mutual extrusion and friction between the strip steel with loose gaps, causing the accumulation and deterioration of anti-rust oil and other substances to produce oil spots. From the optimization of the coiling tension system, the coiling tension of the tail 100 meters of the strip is appropriately increased to 30-35MPa, and the coiling tension of the main body is controlled at 27-32MPa, which is conducive to improving the compactness of the steel coil after coiling.

[0073] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then proceed according to general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0074] Example 1

[0075] This example provides a method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation, and the method comprises:

[0076] The molten steel is smelted and then continuously cast to obtain slabs;

[0077] Heating and hot rolling the slab to obtain a hot-rolled plate;

[0078] The hot-rolled sheet is pickled, cold-rolled, continuously annealed, coiled, leveled and oiled to obtain a finished IF steel continuously annealed sheet;

[0079] The molten steel comprises the following chemical components by mass fraction: C: 0.018%, Al: 0.035%, Mn: 0.15%, Si: 0.06%, Ti: 0.07%, Sb: 0.006%;

[0080] The flattening process parameters include: the flattening process parameters include: the rolling force within 100 meters of the head and tail of the IF steel continuous annealing plate is 900KN, and the rolling force in the middle of the IF steel continuous annealing plate is 2250KN;

[0081] The oiling process parameters include: the oiling amount within 100 meters of the head and tail of the IF steel continuous retreat plate is: the thickness of the IF steel continuous retreat plate is ≤1.0mm, the oiling amount is 600g / m 2 IF steel continuous retreat plate thickness> 1.0mm, oil coating amount 800g / m 2 IF steel continuous retreat plate middle part oil coating amount is 1200g / m 2 ;

[0082] The pickling process parameters include: the residual chloride ion on the surface of the strip after pickling is less than 2 mg / m 2 , the chloride ion content in the condensed water / desalted water in the rinsing section is less than 0.1 mg / L;

[0083] The surface roughness of the finished IF steel continuous annealing plate is 0.8-1.0um;

[0084] The coiling process parameters include: the coiling tension within 100 meters of the tail of the IF steel continuously unreeled plate is 33MPa; the coiling tension in the head and middle of the IF steel continuously unreeled plate is 30MPa.

[0085] After the method provided in this example is implemented to solve the surface oil spot defect of IF steel continuous withdrawal plate after sea transportation, the surface condition of the steel plate is as follows Figure 4 As shown, the surface quality is good, without surface oil spots and other defects.

[0086] Example 2

[0087] This example provides a method for solving the oil spot defect on the surface of IF steel continuously withdrawn plate after sea transportation. The only difference from Example 1 is that: the flattening process parameters include: the rolling force within 100 meters of the head and tail of the IF steel continuously withdrawn plate is 850KN, and the rolling force in the middle of the IF steel continuously withdrawn plate is 2050KN; the coiling process parameters include: the coiling tension within 100 meters of the tail of the IF steel continuously withdrawn plate is 35MPa; the coiling tension in the head and middle of the IF steel continuously withdrawn plate is 32MPa; the remaining steps and parameters are the same.

[0088] After the method provided in this example for solving the surface oil spot defect of IF steel continuous withdrawal plate after sea transportation is implemented, the surface quality of the steel plate is good, without problems such as surface oil spot defect.

[0089] It should be understood that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0090] It should be noted that, 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 any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, the term "and / or" appearing in this article is only a kind of association relationship describing associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone.

[0091] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation, characterized in that: The method comprises: The molten steel is smelted and then continuously cast to obtain slabs; Heating and hot rolling the slab to obtain a hot-rolled plate; The hot-rolled sheet is pickled, cold-rolled, continuously annealed, coiled, leveled and oiled to obtain a finished IF steel continuously annealed sheet; The molten steel comprises the following chemical components by mass fraction: C: 0.015-0.02%, Al: 0.02-0.05%, Mn: 0.1-0.2%, Si: 0.05-0.07%, Ti: 0.06-0.08%, Sb: 0.005-0.01%; The flattening process parameters include: the rolling force within 100 meters of the head and tail of the IF steel continuously annealed plate is 800-1000 KN, and the rolling force in the middle of the IF steel continuously annealed plate is 2000-2500 KN.

2. The method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation according to claim 1 is characterized in that: Calculated by mass fraction, the molten steel includes the following chemical components: C: 0.018%, Al: 0.035%, Mn: 0.15%, Si: 0.06%, Ti: 0.07%, and Sb: 0.008%.

3. The method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation according to claim 1 is characterized in that: The flattening process parameters include: the rolling force within 100 meters of the head and tail of the IF steel continuously annealed plate is 900 KN, and the rolling force in the middle of the IF steel continuously annealed plate is 2250 KN.

4. The method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation according to claim 1 is characterized in that: The oiling process parameters include: the oiling amount within 100 meters of the head and tail of the IF steel continuous retreat plate is: the thickness of the IF steel continuous retreat plate is ≤1.0 mm, and the oiling amount is 550~650 g / m 2 IF steel continuous annealing plate thickness> 1.0 mm, oiling amount 750~850 g / m 2 IF steel continuous retreat plate middle part oil coating amount is 1150~1250 g / m 2 .

5. The method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation according to claim 4 is characterized in that: The oiling process parameters include: the oiling amount within 100 meters of the head and tail of the IF steel continuous retreat plate is: the thickness of the IF steel continuous retreat plate is ≤1.0 mm, the oiling amount is 600 g / m 2 IF steel continuous annealing plate thickness >1.0 mm, oiling amount 800 g / m 2 IF steel continuous retreat plate middle part oil coating amount is 1200 g / m 2 .

6. The method for solving the oil spot defect on the surface of IF steel continuous withdrawal plate after sea transportation according to claim 1 is characterized in that: The pickling process parameters include: the residual chloride ion on the surface of the strip after pickling is less than 2 mg / m 2 , the chloride ion content in the condensed water / desalted water in the rinsing section is less than 0.1 mg / L.

7. The method for solving the oil spot defect on the surface of IF steel continuous-retracted plate after sea transportation according to claim 1 is characterized in that: The surface roughness of the finished IF steel continuously annealed plate is between 0.8 and 1.0 um.

8. The method for solving the oil spot defect on the surface of IF steel continuous-retracted plate after sea transportation according to claim 7 is characterized in that: The surface roughness of the finished IF steel continuously annealed plate is 0.9 um.

9. The method for solving the oil spot defect on the surface of IF steel continuous-retracted plate after sea transportation according to claim 1 is characterized in that: The coiling process parameters include: the coiling tension within 100 meters of the tail of the IF steel continuous unwinding plate is 30-35 MPa; the coiling tension in the head and middle of the IF steel continuous unwinding plate is 27-32 MPa.

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