Highly corrosion-resistant strip steel and its manufacturing method

Abstract

The present invention discloses a highly corrosion-resistant strip steel including a carbon steel base layer and a corrosion-resistant layer rolled and combined with the carbon steel base layer, wherein the corrosion-resistant layer is made of austenitic stainless steel or pure titanium, and the thickness of the corrosion-resistant layer is 0.5-5% of the total thickness of the strip steel. The present invention also discloses a method for producing the highly corrosion-resistant strip steel, which includes the following steps: (1) obtaining base layer material and coating layer material; (2) assembling a billet; (3) preheating: preheating the billet to a temperature of 1150-1250°C to allow diffusion of elements in the corrosion-resistant layer and the carbon steel base layer at the interface to form a stable transition layer, followed by slow cooling to room temperature; (4) secondary heating and rolling; and (5) water cooling followed by coiling. It is expected that, through rational component design, thickness design, and process design, it will ultimately be possible to obtain highly corrosion-resistant strip steel that satisfies the requirements of having a highly corrosion-resistant surface, excellent interlayer bonding, excellent mechanical properties, and excellent workability.

Description

[Technical Field]

[0001] The present invention relates to a steel grade and a method for manufacturing the same, and more particularly to a corrosion-resistant strip steel and a method for manufacturing the same. [Background technology]

[0002] In addition to coating steel surfaces with zinc or zinc alloys to improve corrosion resistance, other prior art methods for improving the corrosion resistance of carbon steel include forming a highly corrosion-resistant layer on the surface of the carbon steel sheet through a rolling process. This method eliminates the need for post-rolling coating and plating processes and provides significantly higher corrosion resistance than that achieved by galvanizing. This is because the rolled highly corrosion-resistant layer and the carbon steel are metallurgically bonded together, ensuring the strength and formability of the steel sheet while also providing excellent corrosion resistance, thereby upgrading the product. However, in the prior art, the rolled highly corrosion-resistant layer is limited in thickness. Further thinning the highly corrosion-resistant layer significantly increases the difficulty of billet assembly, heating, and rolling, and there are currently no successful examples in the industry.

[0003] In the case of steel plates or strips where the thickness of the highly corrosion-resistant layer is less than 5% of the total thickness, the difficulties are extremely high, and the difficulties are particularly as follows: (1) The ratio of the highly corrosion-resistant layer to the matrix metal (carbon steel sheet) is usually significantly different, at 1:50 or more, resulting in significant differences in material properties and making it difficult to control the heating, rolling, or heat treatment processes. Specifically, these difficulties include, for example, deformation and swelling caused by temperature non-uniformity during the heating process, which can prevent the highly corrosion-resistant layer from bonding to the matrix metal, and the tendency for the highly corrosion-resistant layer to separate from the matrix metal and crack during the rolling process, making it difficult to ensure uniform thickness of the final steel sheet.

[0004] (2) For hot- or cold-rolled strip steel with a total thickness of 0.2-2 mm, the thickness of its high corrosion-resistant layer is only 20-100 μm. If the initial compounding is not completed, the bonding quality will be poor, and the continuity and uniformity of the corrosion-resistant layer of the finished product will not be ensured after subsequent processing such as pickling and forming, which will cause serious problems in subsequent use.

[0005] (3) In some steel plates, when the carbon content of the carbon steel layer is high and the stabilizing elements are insufficient, an obvious decarburized layer will form on the carbon steel side at the interface between the high corrosion-resistant layer and the carbon steel layer, resulting in an uneven matrix structure in the carbon steel layer, which is prone to surface defects after processing and makes it difficult to satisfy the mechanical properties of the final product.

[0006] Based on this, it is expected that, through rational component design, thickness design, and process design, it will be possible to finally obtain a highly corrosion-resistant strip steel in which the resulting steel plate or steel strip has a highly corrosion-resistant surface, excellent interlayer bonding, excellent mechanical properties, and excellent workability. Summary of the Invention [Problem to be solved by the invention]

[0007] One of the objects of the present invention is to provide a highly corrosion-resistant strip steel that is ultimately obtained by rationally designing the components, thickness, and process, such that the resulting steel plate or strip has a highly corrosion-resistant surface, excellent interlayer bonding, excellent mechanical properties, and excellent workability. [Means for solving the problem]

[0008] To achieve the above object, the present invention proposes a highly corrosion-resistant strip steel including a carbon steel base layer and a corrosion-resistant layer rolled and combined with the carbon steel base layer, wherein the corrosion-resistant layer is made of austenitic stainless steel or pure titanium, and the thickness of the corrosion-resistant layer is 0.5-5% of the total thickness of the strip steel.

[0009] In the highly corrosion-resistant steel strip described in the present invention, the thickness of the corrosion-resistant layer has a decisive effect on the performance of the final steel strip product. If the corrosion-resistant layer is too thick, the mechanical performance of the steel strip product will be affected and the cost will increase. If the corrosion-resistant layer is too thin, the corrosion resistance and service life of the highly corrosion-resistant steel strip will be reduced. Based on this, in the technical solution described in the present invention, the thickness of the corrosion-resistant layer is controlled to 0.5-5% of the total thickness of the steel strip.

[0010] It should be noted that the corrosion-resistant layer of the present invention is an extremely thin corrosion-resistant layer, with a thickness of 0.5 to 5% of the total thickness of the strip steel, which is much thinner than the general coating layers of the prior art.

[0011] Furthermore, the austenitic stainless steel or pure titanium used in the corrosion-resistant layer only needs to meet domestic or international standards, and austenitic stainless steel or pure titanium with different corrosion resistance can be selected depending on the conditions of use. For example, it is important to note that 304, 304L, 316, or 316L can be used as austenitic stainless steel, and TA2 can be used as pure titanium.

[0012] Furthermore, in consideration of the high mechanical performance of the final strip steel product, a carbon steel base layer that ensures high strength and good workability may be used as the carbon steel base layer.

[0013] Furthermore, in the highly corrosion resistant strip steel described in the present invention, the mass percentages of the chemical elements in the base layer of carbon steel are: C: 0.01~0.20%; Si: 0.10~0.5%; Mn: 0.5~2.0%; Al: 0.02~0.04%; Ti: 0.005~0.018%; Nb: 0.005~0.020%; The balance is Fe and other unavoidable impurities.

[0014] Furthermore, in the highly corrosion resistant strip steel described in the present invention, the contents of C, Si, Mn, Al, Ti and Nb satisfy at least one of the following: C: 0.01~0.18%; Si: 0.10~0.3%; Mn: 0.5-1.5%; Al: 0.02~0.03%; Ti: 0.005~0.015%; Nb: 0.005~0.015%.

[0015] In the above technical proposal, the design principles of each chemical element of the carbon steel base layer are as follows: C: In the technical solution described in the present invention, C is an austenite stabilizer and acts as a solid-solution strengthening element in steel, significantly improving the strength of the steel. However, if the mass percentage of C is too high, weldability and toughness are impaired, and hard phase structures such as pearlite and martensite tend to increase, adversely affecting the corrosion resistance of the steel. Therefore, considering the matching of strength and toughness of steel sheets and the requirements for corrosion resistance of carbon steel materials, controlling the mass percentage of C in the present invention within the range of 0.01 to 0.20% can contribute to ensuring a certain level of hardness and strength in the highly corrosion-resistant strip steel of the present invention during air cooling after rolling. However, if the mass percentage of C is too high, the weldability of the base layer of the carbon steel will be impaired. In particular, since the thickness of the corrosion-resistant layer of the present invention is 0.5 to 5% of the total thickness of the strip steel, it is even more important to maintain the mass percentage of C in this range to avoid adverse effects on weldability. In some preferred embodiments, the mass percentage of C may be further controlled to 0.01 to 0.18%, In some preferred embodiments, the mass percentage of C may be further controlled to 0.10 to 0.20%, more preferably 0.10 to 0.18%.

[0016] Si: In the technical solution described in the present invention, adding Si to steel increases the purity of the steel and achieves deoxidation. Si acts as a solid solution strengthening element in steel, but a high mass percentage of Si is detrimental to weldability. Therefore, in the high corrosion-resistant strip steel described in the present invention, the mass percentage of Si is controlled to 0.10-0.5%, which does not adversely affect the corrosion resistance of the corrosion-resistant layer and ensures good weldability of the carbon steel base layer. In some preferred embodiments, the mass percentage of Si may be further controlled to 0.10-0.3%. In one preferred embodiment, the mass percentage of Si is controlled to 0.15-0.35%.

[0017] Mn: In the highly corrosion-resistant strip steel described in the present invention, Mn can delay the pearlite transformation, reduce the critical cooling rate, and improve the hardenability of the steel. At the same time, Mn also has a solid-solution strengthening effect on the steel, making it the main solid-solution strengthening element in steel. However, if the mass percentage of Mn is too high, segregation zones and martensite structures are likely to occur, adversely affecting the toughness of the steel. Furthermore, the presence of segregation zones reduces the corrosion resistance of the steel. Based on this, the mass percentage of Mn in the technical solution described in the present invention may be controlled to 0.5-2.0%. In some preferred embodiments, the mass percentage of Mn may further be controlled to 0.5-1.5%.

[0018] Al: For the highly corrosion-resistant strip steel described in the present invention, Al is a strong deoxidizing element. To ensure that the oxygen content in the steel is as low as possible, the mass percentage of Al is controlled to 0.02-0.04% in the technical solution described in the present invention. Excess Al and nitrogen in the steel after deoxidation can form AlN precipitates, which can improve the strength of the final strip steel product and refine the elemental austenite grain size of the steel during heat treatment. In some preferred embodiments, the mass percentage of Al may be further controlled to 0.02-0.03%.

[0019] Ti: For the high corrosion-resistant strip steel described in the present invention, Ti is an element that forms strong carbides. Adding a small amount of Ti to the steel promotes the fixation of N in the steel, and the formed TiN prevents the matrix austenite grains inherited from the billet from growing excessively, and refines the original austenite grain size. In addition, Ti reacts with carbon and sulfur in the steel to generate TiC, TiS, and Ti4C2S2, which exist as inclusions and second-phase particles. The above carbonitride precipitates of Ti can suppress the grain growth in the heat-affected zone during welding and improve the weldability. Therefore, in the technical solution described in the present invention, the mass percentage of Ti is controlled to be 0.005 - 0.018%. In some preferred embodiments, the mass percentage of Ti may be further controlled to be 0.005 - 0.015%.

[0020] Nb: For the high corrosion-resistant strip steel described in the present invention, Nb is an element that forms strong carbides. Adding a small amount of Nb to the base layer of carbon steel mainly raises the recrystallization temperature. Combined with a relatively high final rolling temperature, the high corrosion-resistant strip steel of the present application refines the grains in the recrystallized and non-recrystallized regions at the end of rolling, contributing to the improvement of the low-temperature impact toughness of the base layer of carbon steel. Therefore, in the technical solution described in the present invention, the mass percentage of Nb is controlled to be 0.005 - 0.020%. In some preferred embodiments, the mass percentage of Nb may be further controlled to be 0.005 - 0.015%.

[0021] Furthermore, the high corrosion-resistant strip steel described in the present invention further contains at least one of the following chemical elements: 0 < B ≤ 0.0003%; 0 < N ≤ 0.006%; 0 < Ni ≤ 0.20%; 0 < Cr ≤ 0.20%; 0 < Mo ≤ 0.10%; 0 < Sb ≤ 0.30%; 0 < V ≤ 0.30%; 0 < W ≤ 0.30%; 0 < Cu ≤ 0.30%; 0 < Sn ≤ 0.30%; 0 < Bi ≤ 0.30%; 0 < Se ≤ 0.30%; 0 < Te ≤ 0.30%; 0 < Ge ≤ 0.30%; 0 < As ≤ 0.30%; 0 < Ca ≤ 0.30%; 0 < Mg ≤ 0.30%; 0 < Zr ≤ 0.30%; 0 < Hf ≤ 0.30%; 0 < rare earth elements ≤ 0.50%.

[0022] Among the above elements, for example, B can play the following roles: B can significantly improve the hardenability of steel; in order to obtain a better microstructure, such as all ferrite + pearlite, and suppress the formation of bainite, when the corrosion-resistant layer thickness of the high corrosion-resistant strip steel of the present application is in the range of 0.5% - 5% of the total thickness, in the present application, the mass percentage of added B may be limited to 0 < B ≤ 0.0003%.

[0023] Regarding Ni, Ni is an element that stabilizes austenite and has the role of improving strength. When Ni is added to steel, especially quenched and tempered steel, the low-temperature impact toughness of the steel can be significantly improved. Therefore, in the technical solution described in the present invention, the added Ni may be limited to a mass percentage of 0 < Ni ≤ 0.20%. In some embodiments, the mass percentage of added Ni is 0 < Ni ≤ 0.10%.

[0024] Regarding Cr, compared with Mn, the segregation tendency of Cr is smaller. When the mass percentage of Mn in the base layer of carbon steel is high and obvious segregation areas or banded structures are generated in the steel, the mass percentage of Mn can be appropriately reduced and Cr can be added. In addition, the addition of Cr to the base layer of carbon steel also has the effect of suppressing the diffusion of Cr from the corrosion-resistant layer to the base layer of carbon steel. Therefore, in the technical solution described in the present invention, the mass percentage of added Cr may be limited to 0 < Cr ≤ 0.20%.

[0025] Regarding Mo, Mo can significantly refine the crystal grains and improve the strength and toughness; Mo can reduce the temper brittleness of steel and at the same time precipitate very fine carbides during tempering, significantly strengthening the matrix of the steel; the addition of Mo helps to suppress the self-tempering brittleness that is likely to occur during the air-cooling process of the steel plate. Therefore, in the technical solution described in the present invention, the mass percentage of added Mo may be limited to 0 < Mo ≤ 0.10%.

[0026] Furthermore, in the high corrosion-resistant strip steel described in the present invention, for other inevitable impurities, P ≤ 0.015%; and / or S ≤ 0.010%.

[0027] In the technical solution described in the present invention, S reacts with Mn in steel to form plastic inclusion MnS, which impairs the transverse plasticity and toughness of the steel. Therefore, the mass percentage of S should be as low as possible. P is also a harmful element in steel, which significantly impairs the plastic deformation and toughness of the steel plate. Therefore, considering the actual steel production level in the steelworks, the mass percentages of P and S are limited to P≤0.015% and / or S≤0.010%.

[0028] In some embodiments of the present invention, in the high corrosion-resistant strip steel described in the present invention, the mass percentages of chemical elements in the base layer of carbon steel are: C: 0.01 - 0.20%, preferably 0.01 - 0.18%, more preferably 0.10 - 0.18%; Si: 0.10 - 0.5%, preferably 0.10 - 0.3% or 0.15 - 0.35%; Mn: 0.5 - 2.0%, preferably 0.5 - 1.5%; Al: 0.02 - 0.04%, preferably 0.02 - 0.03%; Ti: 0.005 - 0.018%, preferably 0.005 - 0.015%; Nb: 0.005 - 0.020%, preferably 0.005 - 0.015%; 0 < N ≤ 0.006%, preferably 0.0035 - 0.0055%; Mo: ≤ 0.10%; Cr: ≤ 0.20%; Ni: ≤ 0.20%, preferably ≤ 0.10%; the balance is Fe and other inevitable impurities. Further, in the high corrosion-resistant strip steel described in the present invention, the microstructure of the base layer of carbon steel is ferrite and pearlite, the microstructure of the corrosion-resistant layer of austenitic stainless steel is austenite, and the transition layer between the base layer of carbon steel and the corrosion-resistant layer is pearlite and ferrite.

[0029] Furthermore, in the high corrosion-resistant strip steel described in the present invention, its tensile strength ≥ 500 MPa, preferably ≥ 530 MPa, the yield strength is 370 - 510 MPa, and the elongation ≥ 30%.

[0030] Furthermore, the highly corrosion-resistant strip steel described in the present invention has a tensile strength of 600 MPa or more, a yield strength of 470-510 MPa, and an elongation of 35% or more. In some embodiments, the highly corrosion-resistant strip steel described in the present invention has a tensile strength of 600-650 MPa, a yield strength of 470-510 MPa, and an elongation of 35-40%.

[0031] Furthermore, the highly corrosion resistant strip steel of the present invention is a hot rolled strip steel or a cold rolled strip steel.

[0032] Correspondingly, another object of the present invention is to provide a method for producing a highly corrosion resistant strip steel, by which a highly corrosion resistant strip steel can be obtained.

[0033] To achieve the above object, the present invention proposes a method for producing highly corrosion-resistant strip steel, comprising the following steps: (1) Obtain a carbon steel base layer as the base layer material and a corrosion-resistant layer as the coating layer material; (2) Billet assembly; (3) Preheating: The billet is preheated to a temperature of 1150-1250°C, and the elements in the corrosion-resistant layer and the carbon steel base layer diffuse at the interface to form a stable transition layer, after which it is slowly cooled to room temperature; (4) Secondary heating and rolling: Secondary heating at a temperature of 1100-1200°C, multiple-pass rolling, and final rolling temperature controlled at 900°C or higher; (5) After water cooling, winding is carried out.

[0034] In the technical solution described in the present invention, the corrosion-resistant layer on the surface of the billet is preheated to form a uniform austenitic structure, and any carbides that may have originally been present are completely dissolved, and the compounds of the alloying elements in the carbon steel base layer are dissolved in whole or in part. The elements in the corrosion-resistant layer and the carbon steel base layer diffuse at the interface to form a stable transition layer, and then the billet is slowly cooled to room temperature.

[0035] Furthermore, in the manufacturing method described in the present invention, in step (1), the thickness of each layer of the coating layer material is 5 to 20 mm, preferably 8 to 15 mm.

[0036] Furthermore, in the manufacturing method of the present invention, in step (1), the thickness of the base layer material is 300 to 370 mm.

[0037] Furthermore, in the manufacturing method of the present invention, in step (4), the total rolling reduction is controlled to 70% or more. In some embodiments, the total rolling reduction is controlled to 90% or more.

[0038] Furthermore, in the manufacturing method of the present invention, the final rolling temperature is controlled to 920 to 1000°C in step (4).

[0039] Furthermore, in the production method of the present invention, the coiling temperature is controlled to 500 to 650°C, preferably 550 to 650°C in step (5).

[0040] Furthermore, the manufacturing method described in the present invention may further include a surface treatment step or a cold rolling step after step (5).

[0041] The surface treatment step may be pickling or machine Includes mechanical descaling. Furthermore, in the cold rolling step, the cold rolling annealing temperature is controlled to 600 to 750°C. [Effects of the Invention]

[0042] Compared with the prior art, the highly corrosion-resistant strip steel and its manufacturing method described in the present invention have the following advantages and beneficial effects: By providing a corrosion-resistant layer and a carbon steel base layer with appropriate thickness, the highly corrosion-resistant strip steel described in the present invention can obtain a steel plate / strip with high corrosion resistance and good mechanical properties.

[0043] In some embodiments, the corrosion-resistant layer and the carbon steel base layer form a transition layer structure of a certain thickness, achieving a complete metallurgical bond between the corrosion-resistant layer and the carbon steel base layer, maintaining corrosion resistance and mechanical performance, while improving the applicability and economic efficiency of the material, resolving the essential pain points of current carbon steel materials, and providing corrosion resistance, bonding strength, and durability that cannot be achieved by current galvanized sheet products, while also being energy-saving, environmentally friendly, and maintenance-free, which has great significance and broad future prospects.

[0044] The present invention further includes a highly corrosion-resistant strip steel obtained by the method described in any one of the embodiments of the present invention. The corrosion resistance of the highly corrosion-resistant strip steel of the present invention can reach the corrosion resistance of the material used for the coating layer material.

[0045] The manufacturing method of the present invention also has the above-mentioned advantages and beneficial effects. [Brief explanation of the drawings]

[0046] [Figure 1] 1 shows, in schematic form, the structure of the highly corrosion resistant strip steel according to the invention in several embodiments. [Figure 2] 2 shows, in a schematic form, the structure of a highly corrosion resistant strip steel according to another embodiment of the present invention. [Figure 3] 1 is a typical microstructure photograph of the upper surface of the highly corrosion-resistant strip steel of Example 1. [Figure 4] 1 is a typical microstructure photograph of the lower surface of the highly corrosion-resistant strip steel of Example 1. [Figure 5] 1 is a typical microstructure photograph of the highly corrosion-resistant strip steel of Example 2. [Figure 6] 1 is a typical microstructure photograph of the highly corrosion-resistant strip steel of Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0047] The highly corrosion-resistant strip steel and its manufacturing method described in the present invention will be further explained below based on the description of the drawings and specific examples, but the explanations and interpretations should not be construed as unduly limiting the technical solutions of the present invention.

[0048] Examples 1 to 6 The highly corrosion resistant strip steels of Examples 1-6 were produced by the following steps: (1) Obtain the base layer material and the covering layer material, but refer to Table 1 for the proportions of each chemical component of the matrix layer and covering layer material.

[0049] (2) Billet assembly: The billet is assembled so that the thickness of the highly corrosion-resistant strip steel is 0.5% to 5% of the total billet thickness. In some embodiments, before the billet is assembled, the matrix layer and the coating layer material are pre-treated, and then the bonding surfaces between the matrix layer and the coating layer material are welded and sealed all around, and the welded and sealed bonding surfaces are treated with vacuum suction.

[0050] (3) Preheating: The billet is preheated to a temperature of 1150 to 1250°C, and the elements in the corrosion-resistant layer and the carbon steel base layer diffuse at the interface to form a stable transition layer, after which it is slowly cooled to room temperature.

[0051] (4) Secondary heating and rolling: Secondary heating is performed at a temperature of 1100 to 1200°C, and multiple passes of rolling are performed, with the final rolling temperature controlled at 900°C or higher.

[0052] (5) After water cooling, winding is carried out. In some embodiments, in step (4), the total rolling reduction is controlled to 70% or more.

[0053] In some preferred embodiments, in step (4), the final rolling temperature may be controlled to 920 to 1000°C.

[0054] In some other embodiments, the coiling temperature may be controlled to 500 to 650°C in step (5).

[0055] In some embodiments, after step (5), the hot rolled highly corrosion resistant strip steel coil is pickled or machine Surface treatments including mechanical descaling may also be performed.

[0056] In some other embodiments, step (5) may be followed by cold rolling annealing to obtain cold rolled highly corrosion resistant strip steel coil.

[0057] The mass percentage composition ratios of the chemical elements in the highly corrosion-resistant strip steels of Examples 1 to 6 are shown in Table 1.

[0058] [Table 1]

[0059] Table 2 shows the specific process parameters for the highly corrosion resistant strip steels of Examples 1-6.

[0060] [Table 2]

[0061] In order to verify the practical effect of the present invention and prove its superior effect in comparison with the prior art, the highly corrosion-resistant strip steels of Examples 1 to 6 were tested, and the test results are shown in Table 3.

[0062] [Table 3]

[0063] FIG. 1 shows, in a schematic form, the structure of the highly corrosion-resistant strip steel according to the invention in several embodiments.

[0064] As shown in FIG. 1, in this embodiment, the highly corrosion-resistant strip steel includes a carbon steel base layer 1 and a corrosion-resistant layer 2 rolled and combined with the upper and lower surfaces of the carbon steel base layer 1. The corrosion-resistant layer 2 may be austenitic stainless steel or pure titanium, and the thickness of the corrosion-resistant layer is 0.5-5% of the total thickness of the strip steel.

[0065] FIG. 2 shows, in a schematic form, the structure of the highly corrosion resistant strip steel according to another embodiment of the present invention.

[0066] As shown in FIG. 2, in this embodiment, the highly corrosion-resistant strip steel includes a carbon steel base layer 1 and a corrosion-resistant layer 2 rolled and combined with the upper surface of the carbon steel base layer 1 (of course, in some other embodiments, the corrosion-resistant layer 2 may be rolled and combined with the lower surface of the carbon steel base layer 1), and the corrosion-resistant layer 2 may be austenitic stainless steel or pure titanium, and the thickness of the corrosion-resistant layer is 0.5-5% of the total thickness of the strip steel.

[0067] 3 is a typical structural photograph of the upper surface of the highly corrosion-resistant strip steel of Example 1. FIG. 4 is a typical structural photograph of the lower surface of the highly corrosion-resistant strip steel of Example 1.

[0068] 3 and 4, it can be seen that in the highly corrosion-resistant strip steel of Example 1, the microstructure of the carbon steel base layer 1 is ferrite and pearlite, the corrosion-resistant layer 2 is an austenitic stainless steel corrosion-resistant layer, the microstructure of the corrosion-resistant layer 2 is austenite, and the transition layer between the carbon steel base layer 1 and the corrosion-resistant layer 2 is ferrite and pearlite.

[0069] FIG. 5 is a typical photograph of the structure of the highly corrosion-resistant strip steel of Example 2. As shown in Figure 5, in the highly corrosion-resistant strip steel of Example 2, the microstructure of the carbon steel base layer 1 is ferrite and pearlite, and the corrosion-resistant layer 2 is an austenitic stainless steel corrosion-resistant layer. The microstructure of the corrosion-resistant layer 2 is austenite, and the transition layer between the carbon steel base layer 1 and the corrosion-resistant layer 2 is ferrite and pearlite. Figure 5 shows that the thickness of the highly corrosion-resistant strip steel of Example 2 is 3.5 mm, and the thickness of the corrosion-resistant layer 2 is 40 µm.

[0070] FIG. 6 is a typical photograph of the structure of the highly corrosion-resistant strip steel of Example 6. As shown in Figure 6, in the highly corrosion-resistant strip steel of Example 6, the microstructure of the carbon steel base layer 1 is ferrite and pearlite, the corrosion-resistant layer 2 is a pure titanium corrosion-resistant layer with an α-Ti microstructure, and the transition layer between the carbon steel base layer 1 and the corrosion-resistant layer 2 is ferrite and pearlite. The thickness of the highly corrosion-resistant strip steel of Example 6 is 0.5 mm, and the thickness of each layer of the corrosion-resistant layer 2 is 20 µm.

[0071] In other words, by providing a corrosion-resistant layer and a carbon steel base layer with appropriate thickness, the highly corrosion-resistant strip steel described in the present invention can obtain a steel plate / strip with high corrosion resistance and good mechanical properties.

[0072] In some embodiments, the corrosion-resistant layer and the carbon steel base layer form a transition layer structure of a certain thickness, achieving a complete metallurgical bond between the corrosion-resistant layer and the carbon steel base layer, maintaining corrosion resistance and mechanical properties, while improving the applicability and economic efficiency of the material, resolving the essential pain points of current carbon steel materials, and providing corrosion resistance, bonding strength, and durability that cannot be achieved by current plated sheet products, while also being energy-saving, environmentally friendly, and maintenance-free, which has great significance and broad future prospects.

[0073] The manufacturing method of the present invention also has the above-mentioned advantages and beneficial effects. It should be noted that the prior art portion within the scope of protection of the present invention is not limited to the examples described in this application document, and all prior art that is not inconsistent with the solution of the present invention (including, but not limited to, prior patent documents, prior public publications, prior public use, etc.) is incorporated into the scope of protection of the present invention.

[0074] Furthermore, the combinations of the technical features in this application are not limited to the combinations described in the claims of this application or the combinations described in the specific examples, and as long as there are no contradictions, all technical features described in this application can be freely combined or combined in any form.

[0075] Furthermore, it should be noted that the above-mentioned embodiments are merely specific embodiments of the present invention, and the present invention is not limited to the above-mentioned embodiments, and it is clear that any similar changes or modifications that can be directly derived or easily conceived by those skilled in the art from the disclosure of the present invention are included in the protection scope of the present invention.

Claims

1. A corrosion-resistant strip steel, comprising a carbon steel base layer, a corrosion-resistant layer rolled and combined with the carbon steel base layer, and a transition layer between the carbon steel base layer and the corrosion-resistant layer, wherein the corrosion-resistant layer is an austenitic stainless steel or pure titanium, and the thickness of the corrosion-resistant layer is 0.5-5% of the total thickness of the strip steel; The mass percentage of chemical elements in the carbon steel base layer is characterized in that: C: 0.01-0.20%; Si: 0.10-0.5%; Mn: 0.5-2.0%; Al: 0.02-0.04%; Ti: 0.005-0.018%; Nb: 0.005-0.020%; The balance is Fe and other unavoidable impurities; and, Corrosion-resistant strip steel characterized in that the microstructure of the base layer of the carbon steel is ferrite and pearlite, the microstructure of the corrosion-resistant layer of the austenitic stainless steel is austenite, and the microstructure of the transition layer between the base layer of the carbon steel and the corrosion-resistant layer is pearlite and ferrite.

2. 2. The corrosion-resistant strip steel according to claim 1, wherein the contents of C, Si, Mn, Al, Ti and Nb satisfy at least one of the following: C: 0.01-0.18%; Si: 0.10-0.3%; Mn: 0.5-1.5%; Al: 0.02-0.03%; Ti: 0.005-0.015%; Nb: 0.005-0.015%.

3. The corrosion-resistant strip steel according to claim 1, wherein the carbon steel base layer further contains at least one of the following chemical elements: 0<B≦0.0003%; 0<N≦0.006%; 0<Ni≦0.20%; 0<Cr≦0.20%; 0<Mo≦0.10%; 0<Sb≦0.30%; 0<V≦0.30%; 0<W≦0.30%; 0<Cu≦0.30%; 0<Sn≦0.30%; 0<Bi≦0.30%; 0<Se≦0.30%; 0<Te≦0.30%; 0<Ge≦0.30%; 0<As≦0.30%; 0<Ca≦0.30%; 0<Mg≦0.30%; 0<Zr≦0.30%; 0<Hf≦0.30%; 0<rare earth elements≦0.50%.

4. 2. Corrosion-resistant strip steel according to claim 1, characterized in that among other unavoidable impurities: P≦0.015%; and / or S≦0.010%.

5. 2. The corrosion-resistant strip steel according to claim 1, characterized in that the mass percentages of chemical elements in the base layer of the carbon steel are: C: 0.01-0.20%; Si: 0.10-0.5%; Mn: 0.5-2.0%; Al: 0.02-0.04%; Ti: 0.005-0.018%; Nb: 0.005-0.020%; N: 0<N≦0.006%; Mo: ≦0.10%; Cr: ≦0.20%; Ni: ≦0.20%; the balance being Fe and other unavoidable impurities.

6. 6. Corrosion-resistant strip steel according to claim 5, characterized in that the Ni content is Ni: ≦0.10%.

7. 2. Corrosion-resistant strip steel according to claim 1, characterized in that it has a tensile strength ≥ 500 MPa, a yield strength of 370-510 MPa and an elongation ≥ 30%.

8. A method for producing a corrosion resistant strip steel according to any one of claims 1 to 7, characterized in that it comprises the following steps: (1) A carbon steel base layer is used as the base layer material, and a corrosion-resistant layer is used as the coating layer material; (2) Billet assembly; (3) Preheating: The billet is preheated to a temperature of 1150-1250°C, and the elements in the corrosion-resistant layer and the carbon steel base layer diffuse at the interface to form a stable transition layer, and then slowly cooled to room temperature; (4) Secondary heating and rolling: Secondary heating is performed at a temperature of 1100-1200°C, and multiple rolling passes are performed, with the final rolling temperature controlled to 900°C or higher; (5) After water cooling, winding is carried out.

9. 9. The manufacturing method according to claim 8, wherein in step (4), the total rolling reduction is 70% or more.

10. 9. The method according to claim 8, wherein in step (4), the final rolling temperature is controlled to 920 to 1000°C.

11. 9. The manufacturing method according to claim 8, wherein in step (5), the coiling temperature is controlled to 500 to 650°C.

12. 9. The method according to claim 8, further comprising a surface treatment step or a cold rolling step after step (5).

13. 13. The method according to claim 12, wherein the surface treatment step includes pickling or mechanical descaling, and the cold rolling annealing temperature in the cold rolling step is controlled to 600 to 750°C.

14. 9. The method of claim 8, wherein in step (1), the thickness of each layer of the covering layer material is 5-20 mm, and the thickness of each layer of the base layer material is 300-370 mm.

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