Hot-rolled double-sided enamel steel based on thin slab continuous casting and rolling and production method thereof

Abstract

The invention relates to the technical field of strip steel production, and discloses hot-rolled double-sided enamel steel based on thin slab continuous casting and rolling, which comprises the following chemical components in percentage by mass: 0.035-0.065% of C, 0.05-0.2% of Si, 0.6-1.2% of Mn, 0.05-0.1% of Ti, less than or equal to 0.004% of S, less than or equal to 0.005% of N, less than or equal to 0.015% of P and the balance of Fe and inevitable impurities. The invention further discloses a production method of the hot-rolled double-sided enamel steel based on thin slab continuous casting and rolling. According to the hot-rolled double-sided enamel steel based on thin slab continuous casting and rolling and the production method of the hot-rolled double-sided enamel steel, the smelting and casting difficulty is low, good manufacturability is achieved, good forming performance and enamel burning resistance are achieved, and the requirement of double-sided enameling for fish scaling resistance is met.

Description

Technical Field

[0001] The invention relates to the technical field of strip steel production, and in particular to a hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling and a production method thereof. Background Art

[0002] Double-sided enameled steel is mainly used for outdoor water storage tank liners, large water treatment facilities, chemical facilities, environmental protection facilities, etc. It must be scale-free on both sides and have a higher pressure-bearing capacity after enameling. Compared with single-sided enameled steel, it has higher requirements for anti-scale performance and strength after enameling.

[0003] The reason why scale explosion defects occur in enameled structural parts is that the excess hydrogen that enters the substrate during the enameling process overflows after enameling and accumulates at the defects where the porcelain layer and the steel plate are combined, generating pressure that exceeds the strength limit of the enamel layer and causes damage to the porcelain layer.

[0004] Compared with hot-rolled steel sheets, cold-rolled steel sheets are more likely to obtain better anti-scale performance, because there are a large number of fine cementite phases with defects in cold-rolled steel sheets, which become irreversible physical hydrogen traps, capturing hydrogen atoms in the steel and inhibiting the escape of hydrogen. However, the thickness specifications of cold-rolled enameled steel sheets are mostly below 3mm, and the yield strength is insufficient, which cannot meet the requirements of large enameled assemblies.

[0005] In order to improve the anti-scale performance, hot-rolled steel plates usually need to add sufficient Ti elements, generally requiring Ti / C ≥ 2.2, to generate a large amount of Ti 4 C 2 S 2 , TiN, TiC and other precipitated phase particles act as irreversible hydrogen storage traps, but too high Ti content will make smelting and casting difficult on the one hand, and on the other hand will cause the hot rolled strength to be too high and the formability to be poor.

[0006] After searching, the patent "A hot-rolled double-sided enameled steel plate and its manufacturing method" (200510047758.1) discloses a hot-rolled double-sided enameled steel plate and its manufacturing method, and its chemical composition (Wt%) is: C: 0.02% to 0.06%, Si: ≤0.50%, Mn: 0.15% to 0.40%, P: ≤0.15%, S: ≤0.006%, N≤0.003%, Ti: 0.08% to 0.20%, Als: 0.005% to 0.055%, Ti / C: 2.2 to 5, the remainder is Fe and unavoidable impurities. The structure in the hot-rolled state is ferrite with a grain diameter of 2μm to 20μm, and TiC particles with a diameter of less than 20nm are evenly distributed in the structure. V: 0.015% to 0.060% and / or Cr: 0.05% to 0.20% can also be added. The manufacturing method of the steel plate is: the slab is produced by continuous casting, the slab is heated to 1180 to 1260°C, the slab is descaled by high-pressure water after being heated, the intermediate slab is roughly rolled, and the target thickness is reached through 5 to 7 passes of finishing rolling, the finishing rolling start temperature is 1100 to 960°C, the final rolling temperature is 920°C to 840°C, and the rolling is continuously cooled to 450 to 630°C within 0 to 7s at a cooling rate of ≥30°C / S for coiling. However, due to the excessively high Ti / C, the product has poor forming performance and an elongation of ≥18%, and is only suitable for bending and simple stamping.

[0007] Patent "A hot-rolled high-strength steel plate for double-sided enamel and its manufacturing method"

[0008] (200710093979.1) discloses a hot-rolled high-strength steel plate for double-sided enameling and a manufacturing method thereof, wherein the chemical composition of the hot-rolled high-strength steel plate for double-sided enameling comprises: C: 0.05-0.15wt%, Si≤1.0wt%, Mn: 0.5-2.0wt%, P≤0.05wt%, S≤0.05wt%, Al: 0.01-0.10wt%, N: 0.008-0.015wt%, Ti≤0.05wt%, V: 0.02-0.2wt%, and the balance is Fe and inevitable impurities. By controlling the hot rolling process and cooling rate, it is ensured that vanadium and titanium generate fine dispersed second phase particles in the steel, thereby improving the strength, scale explosion resistance and adhesion of the steel plate, and the product still maintains a high strength after enameling, which can better meet the pressure resistance requirements of various enameled products, and can be used to manufacture chemical reaction tanks, water treatment tanks, etc. by double-sided enameling process. This patent utilizes vanadium and titanium composite microalloying to generate second phase particles to ensure strength, anti-scale and adhesion. However, the patent composition design has a high carbon content, which easily generates pinholes in the enamel layer after enameling. In addition, the vanadium element has a high solubility, and the precipitated particles are easily coarsened during the enameling process, resulting in a significant decrease in strength after enameling.

[0009] Patent "A high-strength double-sided enameled hot-rolled steel plate and its manufacturing method"

[0010] (201010215739.6) discloses a high-strength hot-rolled steel plate for double-sided enameling and a manufacturing method, wherein the weight percentage of the smelting components is: C: 0.012%~0.03%, Si: ≤0.10%, Mn: 0.55%~1.0%, P: 0.05%~0.11%, S: ≤0.006%, N≤0.005%, Ti: 0.08%~0.20%, Als: 0.005%~0.055%,; Ti / C: 5~15, one or more of V, B, Cu, Cr are selectively added, and the balance is Fe and unavoidable impurities. The slab is produced by continuous casting, heated to 1180℃~1260℃, descaled by high-pressure water after soaking, roughly rolled into intermediate slab, finished rolled to target thickness by 5~7 passes, and coiled by laminar cooling to 570~680℃. The invention has the advantages of no scale explosion, and the yield strength after enameling is more than 280MPa at 800~920℃ and thickness greater than 8mm. It is suitable for rolling forming, bending forming, and simple stamping forming, and is a reliable special steel plate material for double-sided enameled assembly structure. However, due to the excessively high Ti / C, the patent leads to poor product forming performance, elongation ≥18%, and is only suitable for rolling forming, bending forming and simple stamping forming.

[0011] The hot rolled steel sheet described in the patent "Hot rolled steel sheet for double-sided enamel and its production method" (201110052860.6) contains the following components and mass percentages: C: 0.02-0.1%, Si≤0.1%, Mn: 0.2-1.0%, P≤0.02%, S: 0.005-0.035%, Als: 0.01-0.1%, N: 0.002-0.01%, Ti: 0.01-0.1%, Sb: 0.01-0.05%, and the balance is iron and unavoidable impurities. The continuous casting slab heating temperature of the hot rolled steel sheet is controlled to be 1150-1230°C, the finishing rolling inlet temperature is controlled to be 1020±20°C, the finishing rolling end temperature is controlled to be 840-920°C, and the coiling temperature after finishing rolling is controlled to be 550-650°C. The hot-rolled steel plate and its production method make full use of the C, S, and N elements that are the inevitable products of steel production to partially replace the function of the Ti element, which can reduce the amount of Ti element added; at the same time, adding an appropriate amount of Sb element can not only prevent the occurrence of enamel fish scale explosion, but also reduce the steelmaking cost, and can obtain a hot-rolled steel plate with good double-sided enamel processing performance and small change in strength performance after enamel. However, the addition of Sb element in this patent increases the brittleness of the steel. Summary of the invention

[0012] The purpose of the present invention is to address the deficiencies of the above-mentioned technology and to provide a hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling and a production method thereof, which has low difficulty in smelting and casting, good manufacturability, and good forming performance and enameling resistance, meeting the requirements of double-sided enameling for anti-scale explosion performance.

[0013] To achieve the above-mentioned purpose, the hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling designed by the present invention has the following chemical components in percentage by weight: C: 0.035-0.065%, Si: 0.05-0.2%, Mn: 0.6-1.2%, Ti: 0.05-0.1%, S≤0.004%, N≤0.005%, P≤0.015%, and the rest are Fe and unavoidable impurities.

[0014] The role and reasons for control of the main components and processes in the present invention:

[0015] C: Solid solution C will increase the yield strength and tensile strength of steel, and combine with Ti to form TiC as an effective hydrogen trap, which improves the anti-scale explosion performance of enameled steel. However, as the carbon content increases, the plasticity will decrease. At the same time, solid solution C is not good for the enameling performance of enameled steel. On the one hand, the higher the carbon content, the higher the pearlite content. Pearlite is a two-phase structure of ferrite and lamellar cementite. Cementite does not react with the enamel layer, which reduces the bonding force between the matrix and the enamel layer. On the other hand, the higher the solid solution carbon content, the more CO and CO generated during the enameling process will be. 2 The more gases there are, the more they destroy the compactness of the enamel layer, and in severe cases, pinhole defects will be generated. In addition, when the C content exceeds 0.07%, it enters the peritectic steel range, and cracks are likely to occur during the casting process. In severe cases, steel may even leak out. In order to balance the mechanical properties, enameling properties and castability, the present invention controls the C content in the steel to be 0.035-0.065%.

[0016] Si: The main component of enamel powder is SiO 2 During the enameling process, FeO formed by oxidation of the substrate and SiO in the enameling layer 2 Combined to form Fe 2 SiO 4 , forming chemical bonds. This chemical bond is one of the main mechanisms for the adhesion between the substrate and the enamel layer. Si in the steel will form SiO 2 , which slows down the chemical reaction between the substrate and the enamel layer, which is not good for the adhesion between the substrate and the enamel layer. However, Si has a strong solid solution strengthening effect and can improve the enamel resistance. Therefore, the weight percentage of Si is controlled to be 0.05-0.2%.

[0017] Mn: Mn is dissolved in ferrite and austenite, which can improve strength and reduce plasticity. Too low manganese content will cause FeS precipitation and reduce the thermoplasticity of steel. Too high manganese content will make the strength too high and the formability deteriorate. Taking all factors into consideration, the weight percentage of Mn is controlled to be 0.6-1.2%.

[0018] Ti: Ti can combine with C, N, S and other elements in steel to form second phase particles, becoming a good hydrogen storage trap, improving the anti-scale explosion performance of the steel plate. At the same time, Ti precipitates in the process of enameling can hinder the growth of austenite grains and reduce the strength drop during the enameling process. However, too high Ti content will not only increase the strength of the material, reduce the plasticity of the material, and make the material forming and processing performance worse, but also increase the difficulty of smelting and casting. Taking all factors into consideration, the weight percentage of Ti is controlled to be 0.05-0.10%.

[0019] N: Too high nitrogen content will consume Ti element, resulting in a reduction in the amount of TiC precipitation, which is detrimental to the scale-friction performance of the steel plate. At the same time, too high nitrogen content will lead to poor plasticity of the material, so the N content is controlled to ≤0.005%.

[0020] S: S consumes Ti element, which reduces the amount of TiC precipitation and is detrimental to the scale-friction performance of the steel plate. Therefore, S is controlled to be ≤0.004%.

[0021] P: P is a harmful impurity element in steel. P in steel is easy to form segregation in the steel, reducing the toughness and welding performance of the steel. Therefore, the lower the P content, the better. Taking all factors into consideration, the P content is ≤0.015%.

[0022] A production method of hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling, comprising the following steps:

[0023] A) Casting: The thickness of the ingot is 70-85 mm, and the pulling speed is 3.5-4.5 m / min. Under the condition of ensuring the thickness of the finished product, the thickness of the ingot is increased to achieve a large reduction rate rolling in a single pass of finishing rolling, which promotes the precipitation of TiC and Ti(C, N) to become irreversible effective hydrogen traps, so that the product has good anti-scale explosion performance and meets the requirements of double-sided enameling. If the thickness of the ingot is too thin, the single-pass reduction rate is insufficient, and the precipitation of TiC and Ti(C, N) is insufficient, the product has poor anti-scale explosion performance. If the billet thickness is too thick and the single-pass reduction is too large, the finishing rolling load will be too high, which is not conducive to the plate quality and rolling stability. When the billet thickness is 70-85mm, the pulling speed is 3.5-4.5m / min. If the pulling speed is too high, the liquid core length is long and the billet shell thickness is thin, which is prone to bulging defects and steel leakage accidents. If the pulling speed is too low, the casting efficiency is low and it is not conducive to controlling the center segregation. Considering comprehensively, the billet thickness is controlled to be 70-85mm and the pulling speed is 3.5-4.5m / min.

[0024] B) Soaking: The soaking temperature is 1190-1240℃, which promotes the precipitation of coarse TiS and Ti 4 C 2 S 2 The particles fully dissolve back and precipitate in a dispersed and fine form during the rolling deformation process, which can improve the anti-scale performance of the product. When the soaking temperature is too low, the coarse TiS and Ti 4 C 2 S 2 The particles cannot be fully dissolved back, and the soaking temperature is too high, which will endanger the service life of the soaking furnace refractory. After comprehensive consideration, the soaking temperature is controlled to be 1190~1240℃;

[0025] C) Finishing rolling: The finishing rolling equipment is a 6-stand or 7-stand continuous rolling mill. If it is a 7-stand continuous rolling mill, the 3rd stand or the 4th stand is empty, so that the final pressing pass is 6 passes;

[0026] D) Laminar cooling: Laminar cooling is divided into three stages. The first stage is cooled to 750-810℃ at 5-30℃ / s, the second stage is cooled to 1-4s at 5-10℃ / s, and the third stage is cooled to 580-630℃ at 30-100℃ / s. The first stage of cooling rapidly reduces the temperature to the ferrite phase transition temperature, the ferrite phase transition is completed during the second stage of cooling, and the third stage of cooling reduces the temperature to the nose temperature of TiC precipitation in the ferrite. The lower the cooling temperature in the first stage, the finer the ferrite grains, and the worse the plastic deformation performance of the product. The higher the cooling temperature in the first stage, the temperature of the austenite to ferrite phase transition is not reached, and the ferrite phase transition cannot occur. The cooling rate in the first stage will also affect the ferrite phase transition temperature. The faster the cooling rate, the lower the ferrite phase transition temperature and the finer the ferrite grains. Without the use of heating equipment, the cooling rate is difficult to reach below 5℃ / s. Considering the above, the first stage is cooled to 750-810℃ at 5-30℃ / s, the second stage is cooled slowly to transform more than 85% of austenite into ferrite, and the third stage is cooled to 580-630℃ at 30-100℃ / s. This temperature range is the nose temperature of Ti precipitation in ferrite. By coiling at 580-630℃, a small amount of Ti elements that have not been precipitated in the steel continue to precipitate as TiC in ferrite, and more hydrogen traps with hydrogen capture and replenishment are obtained. The higher the coiling temperature, the less kinetic force of TiC precipitation in ferrite, the lower the nucleation rate, the less the amount of TiC precipitation, and the poor anti-scale explosion performance. The lower the coiling temperature, the less kinetic force of TiC precipitation, which also makes TiC precipitation insufficient. The cooling rate of the third stage is controlled to be 30-100℃ / s, which is based on ensuring the cooling rate and temperature of the first two stages, so that the temperature of the steel coil reaches 580-630℃ when coiling.

[0027] E) Coiling: The coiling temperature is 580-630°C.

[0028] Preferably, in step A), the thickness of the ingot is 77-85 mm.

[0029] Preferably, in the step B), the soaking temperature is 1210-1240°C.

[0030] Preferably, in the step C), the reduction rates of the first and second reduction passes are 50-60%, the reduction rates of the third and fourth reduction passes are 30-45%, the reduction rates of the fifth and sixth reduction passes are 20-35%, the final rolling temperature is 830-870°C, and the thickness of the finished product is 2.5-6 mm, ensuring sufficient single-pass reduction rate to promote the dispersion and precipitation of TiC and Ti(C, N). The above reduction rate distribution can promote the full precipitation of Ti elements. The large reduction rate deformation increases the number of defects such as dislocations and vacancies, providing nucleation positions and driving forces for the dispersion and precipitation of TiC and Ti(C, N). However, too high a reduction rate will lead to a large deformation load. It is not conducive to the control of rolling stability and plate shape. Taking into account comprehensively, the reduction rate of the first and second reduction passes is 50-60%, the reduction rate of the third and fourth reduction passes is 30-45%, and the reduction rate of the fifth and sixth reduction passes is 20-35%. The final rolling temperature affects the deformation temperature of each pass to a certain extent. If the final rolling temperature is too high, the deformation temperature is high, the precipitated TiC and Ti (C, N) are coarse in size and small in number, the number of effective hydrogen traps for hydrogen capture is small, and the anti-scale explosion performance is poor. However, if the final rolling temperature is too low, it may cause deformation in the two-phase region, making the structure uneven, and deteriorating the formability and fatigue performance of the product. Taking into account comprehensively, the final rolling temperature is controlled to be 830-870℃. .

[0031] Preferably, the reduction ratios of the first and second reduction passes are 55-60%, the reduction ratios of the third and fourth reduction passes are 37-45%, and the reduction ratios of the fifth and sixth reduction passes are 27-35%.

[0032] Preferably, in the step C), the final rolling temperature is 830-850°C.

[0033] Preferably, in step D), the first stage is cooled to 780-810°C at 5-30°C / s, the second stage is cooled to 5-10°C / s for 3-4s, and the third stage is cooled to 610-630°C at 30-100°C / s.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. It overcomes the disadvantage of the existing technology that the smelting and casting are difficult to control Ti / C ≥ 2.2 in order to meet the double-sided enameling requirements. It has good manufacturability. At the same time, the product has good forming performance and enameling resistance. The product elongation is ≥ 23%, and the yield strength after enameling is ≥ 280MPa, which meets the requirements of double-sided enameling for anti-scale explosion performance;

[0036] 2. The composition design of low Ti, high manganese and high effective Ti is adopted. The large reduction deformation of the thin slab continuous casting and rolling production line is utilized. The TiC and Ti (C, N) particles are fully precipitated during the rolling process through deformation induction. At the same time, the ferrite phase transformation is controlled during the high temperature stage of laminar cooling, so that the product has good forming performance;

[0037] 3. Ti element is fully precipitated in the form of TiC and Ti(C,N) particles, which, on the one hand, improves the anti-scale performance of the product and meets the requirements of double-sided enameling for anti-scale performance. On the other hand, it improves the strength of the product after enameling. Combined with the solid solution strengthening effect of Si and Mn elements, the product has a higher yield strength after enameling, which meets the pressure resistance requirements of enameled products. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] A hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling, the chemical composition of which is as follows by mass percentage: C: 0.035-0.065%, Si: 0.05-0.2%, Mn: 0.6-1.2%, Ti: 0.05-0.1%, S≤0.004%, N≤0.005%, P≤0.015%, and the rest is Fe and unavoidable impurities.

[0040] The above-mentioned production method of hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling comprises the following steps:

[0041] A) Casting: The thickness of the casting is 70-85 mm, and the pulling speed is 3.5-4.5 m / min;

[0042] B) Soaking: Soaking temperature is 1190~1240℃;

[0043] C) Finishing rolling: The finishing rolling equipment is a 6-stand or 7-stand continuous rolling mill. If it is a 7-stand continuous rolling mill, the 3rd stand or the 4th stand is empty, so that the final pressing pass is 6 passes;

[0044] D) Laminar cooling: Laminar cooling is divided into three stages: the first stage is cooled at 5-30℃ / s to 750-810℃, the second stage is cooled at 5-10℃ / s for 1-4s, and the third stage is cooled at 30-100℃ / s to 580-630℃;

[0045] E) Coiling: The coiling temperature is 580-630°C.

[0046] In the above steps, the optimal ingot thickness is 77-85 mm, the optimal soaking temperature is 1210-1240° C., and the optimal final rolling temperature is 830-850° C.

[0047] In step C), the reduction ratio of the first and second reduction passes is 50-60%, the reduction ratio of the third and fourth reduction passes is 30-45%, the reduction ratio of the fifth and sixth reduction passes is 20-35%, the final rolling temperature is 830-870°C, and the thickness of the finished product is 2.5-6 mm. In a more preferred case, the reduction ratio of the first and second reduction passes is 55-60%, the reduction ratio of the third and fourth reduction passes is 37-45%, and the reduction ratio of the fifth and sixth reduction passes is 27-35%.

[0048] In step D), more preferably, the first stage is cooled to 780-810°C at 5-30°C / s, the second stage is cooled to 5-10°C / s for 3-4s, and the third stage is cooled to 610-630°C at 30-100°C / s.

[0049] Ten groups of examples are listed to illustrate the implementation of this process, as shown in Table 1, which is a chemical composition table of the ten examples:

[0050] Table 1 Chemical composition of each example (wt%)

[0051]

[0052] As shown in Table 2, the rolling process parameters of 10 embodiments are as follows:

[0053] Table 2 Rolling process parameters of each embodiment

[0054]

[0055]

[0056] Among them, Examples 1 to 5 are 6-stand continuous rolling, Examples 6 to 10 are 7-stand continuous rolling, and the 3rd stand of Examples 6, 8 and 10 is empty, and the 4th stand of Examples 7 and 9 is empty.

[0057] As shown in Table 3, the cooling process parameters and typical performances of 10 embodiments are shown:

[0058] Table 3 Cooling process parameters and typical performance of each embodiment

[0059]

[0060]

[0061] It can be seen that the hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling overcomes the shortcomings of the prior art that the double-sided enameling requires Ti / C ≥ 2.2, which leads to great difficulty in smelting and casting. The product has good manufacturability, and the product has good forming performance and enameling resistance. The product elongation is ≥ 23%, and the yield strength after enameling is ≥ 280 MPa, which meets the requirements of double-sided enameling for anti-scale explosion performance. The composition design of low Ti, high manganese and high effective Ti is adopted, and the large reduction deformation of the thin slab continuous casting and rolling production line is utilized. The induction effect makes TiC and Ti(C,N) particles fully precipitate during the rolling process, and at the same time controls the ferrite phase transformation to occur during the high temperature stage of laminar cooling, so that the product has good forming performance; the Ti element is fully precipitated in the form of TiC and Ti(C,N) particles, which on the one hand improves the anti-scale performance of the product and meets the requirements of double-sided enameling for anti-scale performance, and on the other hand improves the strength of the product after enameling. Combined with the solid solution strengthening effect of Si and Mn elements, the product has a higher yield strength after enameling, which meets the pressure resistance requirements of enameled products.

[0062] It should be noted that the description of the above technical solutions is exemplary, and this specification can be embodied in different forms and should not be interpreted as being limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are limited only by the scope of the claims.

[0063] The various aspects disclosed for describing the present specification and claims are merely examples, and therefore, the present specification and claims are not limited to the details shown. In the above description, when the detailed description of the related known functions or configurations is determined to be unnecessary to obscure the focus of the present specification and claims, the detailed description will be omitted.

[0064] In the case of using “including”, “having” and “comprising” described in the present specification, unless otherwise used, there may also be another part or other parts, and the terms used may generally be in the singular but may also represent the plural form.

[0065] Finally, it should be pointed out that the above content is a further detailed description of the invention in combination with specific implementation methods. It cannot be considered that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, simple replacements made without departing from the concept of the present invention should be regarded as belonging to the protection scope of the present invention. The above embodiments are only more representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments, and there can be many variations. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention should be considered to belong to the protection scope of the present invention.

[0066] At the same time, it should be noted that the description of the above technical solutions is exemplary, and this specification can be embodied in different forms and should not be construed as being limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are limited only by the scope of the claims. The features of the various embodiments of the present invention may be partially or completely combined or spliced ​​with each other, and may be performed in various different configurations as those skilled in the art may fully understand. The embodiments of the present invention may be performed independently of each other, or may be performed together in a mutually dependent relationship.

[0067] For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and the above structures should be regarded as belonging to the protection scope of the present invention.

Claims

1. A hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling, characterized in that: The mass percentage of its chemical composition is: C: 0.035-0.065%, Si: 0.05-0.2%, Mn: 0.6-1.2%, Ti: 0.05-0.1%, S≤0.004%, N≤0.005%, P≤0.015%, and the rest is Fe and unavoidable impurities.

2. A method for producing hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling as claimed in claim 1, characterized in that: The steps include: A) Casting: The thickness of the casting is 70-85 mm, and the pulling speed is 3.5-4.5 m / min; B) Soaking: Soaking temperature is 1190~1240℃; C) Finishing rolling: The finishing rolling equipment is a 6-stand or 7-stand continuous rolling mill. If it is a 7-stand continuous rolling mill, the 3rd stand or the 4th stand is empty, so that the final pressing pass is 6 passes; D) Laminar cooling: Laminar cooling is divided into three stages: the first stage is cooled at 5-30℃ / s to 750-810℃, the second stage is cooled at 5-10℃ / s for 1-4s, and the third stage is cooled at 30-100℃ / s to 580-630℃; E) Coiling: The coiling temperature is 580-630°C.

3. The method for producing hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling as claimed in claim 2, characterized in that: In the step A), the thickness of the cast slab is 77-85 mm.

4. The method for producing hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling as claimed in claim 2, characterized in that: In the step B), the soaking temperature is 1210-1240°C.

5. The method for producing hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling as claimed in claim 2, characterized in that: In the step C), the reduction ratios of the first and second reduction passes are 50-60%, the reduction ratios of the third and fourth reduction passes are 30-45%, the reduction ratios of the fifth and sixth reduction passes are 20-35%, the final rolling temperature is 830-870°C, and the thickness of the finished product is 2.5-6 mm.

6. The method for producing hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling as claimed in claim 5, characterized in that: The reduction rates of the first and second pressing passes are 55-60%, the reduction rates of the third and fourth pressing passes are 37-45%, and the reduction rates of the fifth and sixth pressing passes are 27-35%.

7. The method for producing hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling as claimed in claim 2, characterized in that: In the step C), the final rolling temperature is 830-850°C.

8. The method for producing hot-rolled double-sided enameled steel based on thin slab continuous casting and rolling as claimed in claim 2, characterized in that: In the step D), the first stage is cooled to 780-810° C. at 5-30° C. / s, the second stage is cooled to 5-10° C. / s for 3-4 seconds, and the third stage is cooled to 610-630° C. at 30-100° C. / s.

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