Enamel steel plate and method for manufacturing the same, enamel steel, and enamel assembled tank

Abstract

The application provides a steel plate for enamel, a preparation method of the steel plate, an enamel steel plate and an enamel assembled tank. The chemical components of the steel plate for enamel include C, Si, Mn, P, S, Alt, Ti, Nb, N and Fe; the content of C is 0.16-0.22% by mass fraction, the content of Si is 0.3-0.5% by mass fraction, the content of Mn is 2.4-3% by mass fraction, the content of P is less than 0.015% by mass fraction, the content of S is less than 0.005% by mass fraction, the content of Alt is 0.02-0.08% by mass fraction, the content of Ti is 0.13-0.25% by mass fraction, the content of Nb is 0.02-0.07% by mass fraction, and the content of N is less than 0.005% by mass fraction; wherein the mass fraction of the Ti and the S satisfies the following relationship: [Ti] / [S] >= 26, wherein [Ti] represents the mass fraction of Ti, and [S] represents the mass fraction of S. By reasonably designing the chemical components and rolling process, a bainite structure is formed, TiC and NbC precipitated phases are dispersedly distributed in the matrix, and the steel plate for enamel has high strength. The yield strength of the steel plate for enamel provided in the application is greater than or equal to 660 MPa, the steel plate can be high-temperature enamelized, and a 25000m 3 The above large-scale enamel assembled tank.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel production, and particularly relates to a steel plate for enamel, a preparation method thereof, an enamel steel and an enamel assembled tank. BACKGROUND

[0002] Large enamel assembled tanks are applied to facilities such as water treatment, chemical industry environmental protection and biological energy engineering. With the development of economy and society, the global environmental problems are becoming increasingly serious, and the capacity of sewage treatment tanks and water storage tanks required is becoming larger and larger. The larger the capacity of the enamel assembled tank is, the greater the thickness of the steel plate required is, and the higher the strength is.

[0003] Compared with thin gauge steel plates, it is more difficult to obtain high strength of thick gauge steel plates. Firstly, it is more difficult to obtain high hot-rolled strength of thick gauge steel plates because of small reduction during hot rolling. Secondly, the enamel burning time of thick gauge steel plates is longer than that of thin gauge steel plates, and the strength of thick gauge steel plates decreases more after enamel burning. At present, the thickness of steel plates for large enamel assembled tanks in China is generally below 15 mm, and they are mostly suitable for manufacturing water storage tanks with a capacity of 20000 m 3 The following tank bodies lack the manufacturing of water storage tanks with a capacity of 25000 m 3 The above steel plates for extra-large enamel assembled tanks. At present, there is no enamel steel with a thickness of 16 mm to 20 mm, therefore, it is urgent to develop a thick gauge steel plate with high strength level for manufacturing water storage tanks with a capacity of 25000 m 3 The above extra-large enamel assembled tanks. SUMMARY

[0004] The present application provides a steel plate for enamel, a preparation method thereof, an enamel steel and an enamel assembled tank, so as to realize the preparation of a thick gauge (thickness of 16 mm to 20 mm) steel plate with high strength level (yield strength of 660 MPa or more) for the above extra-large tank. 3 The above extra-large tank.

[0005] In a first aspect, the present application provides a steel plate for enamel, the microstructure of the steel plate for enamel is bainite, and the chemical composition of the steel plate for enamel comprises C, Si, Mn, P, S, Alt, Ti, Nb, N and Fe; the content of C is 0.16% to 0.22% by mass fraction, the content of Si is 0.3% to 0.5% by mass fraction, the content of Mn is 2.4% to 3% by mass fraction, the content of P is less than 0.015% by mass fraction, the content of S is less than 0.0050% by mass fraction, the content of Alt is 0.02% to 0.08% by mass fraction, the content of Ti is 0.13% to 0.25% by mass fraction, the content of Nb is 0.02% to 0.07% by mass fraction, and the content of N is less than 0.005% by mass fraction.

[0006] The mass fraction of the Ti and the S satisfies the following relationship: [Ti] / [S]≥26,

[0007] In the formula, [Ti] represents the mass fraction of Ti, and [S] represents the mass fraction of S.

[0008] Optionally, the base of the steel plate for enamel has precipitates of TiC and NbC dispersedly distributed therein, and the size of the precipitates is less than or equal to 50 nm.

[0009] Optionally, the thickness of the steel plate for enamel is 16 mm to 20 mm, and the steel plate for enamel satisfies the following performances: the yield strength is 660 MPa to 750 MPa, the tensile strength is 710 MPa to 880 MPa, the elongation A50mm after fracture is 20% to 35%, and the steel plate for enamel is resistant to high temperature enameling at 800 ℃ to 900 ℃.

[0010] In a second aspect, the application provides a preparation method of the steel plate for enamel in any one of the embodiments of the first aspect, and the method comprises the following steps:

[0011] obtaining a cast blank with the chemical composition;

[0012] heating, two-stage rolling and stage cooling the cast blank to obtain the steel plate for enamel.

[0013] Optionally, the stage cooling comprises first-stage cooling, second-stage cooling and third-stage cooling, the cooling speed of the first-stage cooling is 30 ℃ / s to 40 ℃ / s, the cooling speed of the second-stage cooling is less than or equal to 20 ℃ / s, the final cooling temperature of the second-stage cooling is 470 ℃ to 540 ℃, and the third-stage cooling is air cooling to room temperature.

[0014] Optionally, the heating temperature is 1190 ℃ to 1260 ℃, the two-stage rolling comprises rough rolling and finish rolling, the rough rolling is 5 passes to 7 passes, the finish rolling is 5 passes to 7 passes, and the finish rolling temperature is 800 ℃ to 900 ℃.

[0015] In a third aspect, the application provides an enamel steel, which comprises the steel plate for enamel in any one of the embodiments of the first aspect and an enamel layer, and the enamel layer is arranged on at least one plate surface of the steel plate for enamel.

[0016] Optionally, the microstructure of the enamel steel comprises pearlite and ferrite, the grain size of the enamel steel is less than 5 μm, and new precipitates of TiC and NbC are dispersedly distributed in the base of the enamel steel, and the size of the new precipitates is less than 20 nm.

[0017] Optionally, the enamel steel satisfies the following performances: the yield strength is 380 MPa to 450 MPa, the tensile strength is 520 MPa to 750 MPa, and the elongation A50mm after fracture is 28% to 47%.

[0018] Fourthly, this application provides an enamel-lined assembled tank with a water storage capacity of ≥25000m³. 3 The enamel-lined assembled tank includes metal structural components made of enamel steel as described in any embodiment of the third aspect.

[0019] The technical solutions provided in this application have the following advantages compared with the prior art:

[0020] The enamel steel plate provided in this application, through the rational design of chemical composition and rolling process, forms a bainitic structure with TiC and NbC precipitates dispersed in the matrix, ensuring high strength. Simultaneously, by using the relationship [Ti] / [S]≥26, a high-Ti, low-S composition is adopted to avoid excessive S combining with Ti to form Ti4C2S2, thus reducing the formation of fine TiC and preventing a decrease in steel plate strength.

[0021] Furthermore, the enamel-enameled steel plate provided in this application has a yield strength ≥660MPa and is resistant to high-temperature enameling, making it suitable for manufacturing water storage capacities of 25,000 m³. 3 The above are extra-large enamel-coated assembled tanks. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic flowchart illustrating a method for preparing an enamel-coated steel plate according to an embodiment of this application;

[0025] Figure 2 Metallographic image of the enamel steel plate provided in Embodiment 1 of this application;

[0026] Figure 3 Transmission electron microscope image of the precipitates of the enamel steel plate provided in Embodiment 1 of this application. Detailed Implementation

[0027] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0028] Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single values in the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers in the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated in the present application, it refers to any cited number (fraction or integer) in the indicated range.

[0029] In addition, in the description of the present application, the terms "include", "contain" and the like mean "include but not limited to". In the present application, the relationship terms such as "first" and "second" are merely 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 the entities or operations. In the present application, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Wherein A, B can be singular or plural. In the present application, "one or more" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of the items, including single item or any combination of multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, c can be single or multiple.

[0030] Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0031] In a first aspect, the present application provides a steel plate for enamel, the microstructure of the steel plate for enamel is bainite, and the chemical composition of the steel plate for enamel comprises C, Si, Mn, P, S, Alt, Ti, Nb, N and Fe; in terms of mass fraction, the content of C is 0.16% to 0.22%, the content of Si is 0.3% to 0.5%, the content of Mn is 2.4% to 3%, the content of P is less than 0.015%, the content of S is less than 0.0050%, the content of Alt is 0.02% to 0.08%, the content of Ti is 0.13% to 0.25%, the content of Nb is 0.02% to 0.07%, and the content of N is less than 0.005%.

[0032] wherein the mass fraction of the Ti and the S satisfies the following relationship: [Ti] / [S]≥26,

[0033] In the formula, [Ti] represents the mass fraction of Ti, and [S] represents the mass fraction of S.

[0034] In some embodiments, the content of C is controlled to be 0.16% to 0.22%: both the solid-solution carbon and the precipitated carbide provide strength for the steel plate, the precipitated TiC and NbC have the effect of precipitation strengthening, the dispersedly precipitated TiC and NbC particles can inhibit grain growth, thereby ensuring that the steel plate has fine grains, the fine grains ensure that the steel plate has high strength before and after enameling, especially the TiC and NbC precipitated during the enameling process, which ensures that the steel plate still has high strength after enameling, and the TiC and NbC can act as hydrogen traps to improve the anti-scaling performance of the steel plate. If the content of C is too low, the strength of the steel cannot be ensured, and if the content of C is too high, the enameling process is adversely affected, resulting in bubble defects in the enameling process. The content of C can be 0.16%, 0.17%, 0.18%, 0.20% or 0.22%.

[0035] The content of Si is controlled to be 0.3% to 0.5%: Si is used as a deoxidizer to remove oxygen in the molten steel, and a too high content of Si will reduce the enamel adhesion and damage the surface quality. The content of Si can be 0.3%, 0.4% or 0.5%.

[0036] The content of Mn is controlled to be 2.4% to 3%: Mn can refine the structure and reduce the size and average distance of precipitated particles. Mn is a solid-solution strengthening element, which can reduce the phase transition temperature of austenite to ferrite, expand the hot working temperature range, refine the grain size, and improve the yield strength and tensile strength of the steel. If the content of Mn is too high, the strength is too high, which is not conducive to the punching and bending processes of the steel plate. The content of Mn can be 2.4%, 2.5%, 2.6%, 2.8% or 3%.

[0037] The positive effects of controlling phosphorus content to <0.015%: Phosphorus is an impurity element that easily segregates at grain boundaries, increasing the brittleness of steel plates and impairing their formability. Therefore, phosphorus content should be controlled below 0.015%. This phosphorus content can be 0.003%, 0.006%, 0.009%, 0.012%, etc.

[0038] The positive effects of controlling the sulfur content to <0.005% are as follows: When the sulfur content is high, it easily combines with titanium (Ti) to form Ti₄C₂S₂. The size of Ti₄C₂S₂ is generally between 100 and 400 nm. The formation of Ti₄C₂S₂ consumes Ti, reduces the formation of fine TiC, weakens precipitation strengthening, reduces the strength of the steel plate, and also reduces the steel plate's resistance to blistering. The sulfur content can be 0.001%, 0.002%, 0.004%, etc.

[0039] The positive effects of controlling the Alt content to 0.02%–0.08% are as follows: Aluminum is a strong deoxidizer that can inhibit the formation of other oxides. Aluminum reacts with oxygen to form alumina, which has poor plasticity. Large amounts of alumina inclusions can impair the workability of steel plates. Therefore, a certain amount of aluminum is selected for deoxidation. The Alt content can be 0.02%, 0.04%, 0.06%, 0.08%, etc.

[0040] The positive effects of controlling the Ti content to 0.13%–0.25% include: Ti reacts with C to form TiC, which has precipitation strengthening properties. The dispersed TiC particles inhibit grain growth, ensuring fine grains in the steel plate and improving its strength. Simultaneously, TiC acts as a good hydrogen trap, enhancing the steel plate's resistance to spalling. Excessive titanium content increases costs. The Ti content can be 0.13%, 0.16%, 0.19%, 0.22%, 0.25%, etc.

[0041] The positive effects of controlling the Nb content to 0.02%–0.07% include: Niobium is the most effective microalloying element for refining grain size; additionally, Nb combines with C to form NbC, which has precipitation strengthening properties, increasing the strength of the steel plate; and NbC is also a good hydrogen trap, improving the steel plate's resistance to blistering. Excessive niobium content will increase costs. The Nb content can be 0.02%, 0.03%, 0.04%, 0.06%, 0.07%, etc.

[0042] The positive effects of controlling the N content to <0.005% are: N readily combines with Ti to form TiN, and Ti preferentially combines with N to form TiN, then with C to form TiC. TiN has a size in the micrometer range, while TiC has a size in the nanometer range. TiC contributes significantly more to strength and has a much higher hydrogen storage capacity than TiN. Therefore, it is desirable for Ti to form as much TiC as possible, rather than TiN, hence the need to control the N content as low as possible. This N content can be 0.001%, 0.003%, 0.004%, etc.

[0043] The mass fraction of Ti and S elements satisfies the following relationship: [Ti] / [S]≥26. The positive effect of using high-Ti and low-S components is that the excessive S is avoided from combining with Ti to generate Ti4C2S2, the generation of fine TiC is reduced, the precipitation strengthening is weakened, and thus the reduction of the strength of the steel plate is avoided. The value of [Ti] / [S] can be 26, 27, 28, 29, 30, etc.

[0044] Meanwhile, the enamel steel plate provided in the application does not add elements such as Cr, Cu, Mo, V, and B, and has relatively low cost.

[0045] In some embodiments, the base body of the enamel steel plate has a dispersion distribution of TiC and NbC precipitates, and the size of the precipitates is ≤50 nm.

[0046] In the application, the base body of the enamel steel plate has fine TiC and NbC particles, has the effect of precipitation strengthening, and can inhibit grain growth, so as to ensure that the enamel steel plate has fine grains, thereby ensuring that the enamel steel plate has high strength. The size of the precipitates can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0047] In some embodiments, the enamel steel plate satisfies the following performances: the yield strength is 660 MPa-750 MPa, the tensile strength is 710 MPa-880 MPa, the elongation A 50mm is 20%-35%, and the enamel can withstand high temperature of 800-900℃.

[0048] The enamel steel plate provided in the application is a high-strength thick-gauge steel plate and can withstand high-temperature enameling, and the yield strength of the enamel steel obtained after high-temperature enameling decreases less. The yield strength can be 660 MPa, 680 MPa, 700 MPa, 720 MPa, 740 MPa, 750 MPa, etc.; the tensile strength can be 710 MPa, 740 MPa, 780 MPa, 820 MPa, 860 MPa, 880 MPa, etc.; and the elongation A 50mm can be 20%, 25%, 30%, 35%, etc.; and the enamel can withstand high temperature of 800℃, 830℃, 860℃, 880℃, 890℃, 900℃, etc.

[0049] In some embodiments, the thickness of the enamel steel plate is 16-20 mm.

[0050] The enamel steel plate in the application is a high-strength thick-gauge steel plate, and is used to manufacture a water storage tank with a capacity of 25000m 3The above extra-large enamel assembled tank. The thickness of the enamel steel plate can be 16mm, 17mm, 18mm, 19mm, 20mm, etc.

[0051] In a second aspect, the application provides a preparation method of the enamel steel plate described in any one of the embodiments of the first aspect, see Figure 1 , the method comprises:

[0052] S1, obtaining a casting blank with the chemical composition.

[0053] In some embodiments, the above S1 step further comprises molten iron pretreatment, converter smelting, and refining.

[0054] S2, heating the casting blank, two-stage rolling, and stage cooling to obtain an enamel steel plate.

[0055] In some embodiments, the heating temperature is 1190-1260℃; the two-stage rolling includes rough rolling and finish rolling, the rough rolling is 5-7 passes, the finish rolling is 5-7 passes, and the finish rolling temperature is 800-900℃.

[0056] The heating temperature is controlled to be 1190-1260℃, which aims to obtain uniform austenite microstructure on the one hand, and to promote the dissolution of TiC, NbC and other precipitates in the slab as much as possible on the other hand, so as to facilitate the re-precipitation and formation of fine and dispersed precipitates in the subsequent process steps. The heating temperature can be 1190℃, 1210℃, 1230℃, 1245℃, 1260℃, etc.

[0057] The rough rolling is controlled to be 5-7 passes, the finish rolling is controlled to be 5-7 passes, and the finish rolling temperature is controlled to be 800-900℃, so that the steel plate obtains appropriate thickness and mechanical properties. The rough rolling can be 5 passes, 6 passes, 7 passes, the finish rolling can be 5 passes, 6 passes, 7 passes, and the finish rolling temperature can be 800℃, 820℃, 850℃, 870℃, 900℃, etc.

[0058] In some embodiments, the stage cooling includes first stage cooling, second stage cooling, and third stage cooling, the first stage cooling is ultra-fast cooling, the cooling speed of the first stage cooling is 30-40℃ / s; the second stage cooling is laminar cooling, the cooling speed of the second stage cooling is ≤20℃ / s, and the final cooling temperature of the second stage cooling is 470-540℃; the third stage cooling is air cooling to room temperature.

[0059] The cooling speed of the first stage cooling is controlled to be 30-40℃ / s, the cooling speed of the second stage cooling is controlled to be ≤20℃ / s, and the final cooling temperature of the second stage cooling is controlled to be 470-540℃, so as to obtain a bainite structure and suitable mechanical properties. The cooling speed of the first stage cooling can be 30℃ / s, 32℃ / s, 34℃ / s, 36℃ / s, 38℃ / s, 40℃ / s, etc. The cooling speed of the second stage cooling can be 5℃ / s, 7℃ / s, 10℃ / s, 12℃ / s, 15℃ / s, 20℃ / s, etc. The final cooling temperature of the second stage cooling can be 470℃, 490℃, 500℃, 520℃, 540℃, etc.

[0060] In a third aspect, the present application provides a enamel steel, which comprises the enamel steel plate according to any one of the embodiments of the first aspect and an enamel layer arranged on at least one plate surface of the enamel steel plate.

[0061] In some embodiments, the enamel layer is arranged on both plate surfaces of the enamel steel plate.

[0062] In some embodiments, the microstructure of the enamel steel comprises pearlite and ferrite, the grain size of the enamel steel is <5μm, and new precipitated phases of TiC and NbC are dispersedly distributed in the matrix of the enamel steel, and the size of the new precipitated phases is <20nm.

[0063] The newly precipitated TiC and NbC in the enameling process ensure that the steel plate still has high strength after enameling, and the TiC and NbC can act as hydrogen traps to improve the anti-scaling performance of the steel plate. The grain size can be 3μm, 4μm, 4.5μm, etc. The size of the new precipitated phases can be 5nm, 10nm, 15nm, 19nm, etc.

[0064] In some embodiments, the enamel steel satisfies the following performances: the yield strength is 380-450MPa, the tensile strength is 520-750MPa, and the elongation A 50mm is 28-47%.

[0065] The enamel steel provided by the present application has high strength level and can be used to manufacture large-scale enamel tanks with a storage capacity of 25000m 3 The above large-scale enamel assembled tanks. The yield strength can be 380MPa, 400MPa, 420MPa, 435MPa, 450MPa, etc. The tensile strength can be 520MPa, 600MPa, 620MPa, 700MPa, 750MPa, etc. The elongation A 50mm can be 28%, 35%, 40%, 45%, 47%, etc.

[0066] In a fourth aspect, the present application provides a enamel assembled tank, the water storage capacity of the enamel assembled tank is > 25000m 3 The enamel assembled tank comprises the metal structural part prepared from the enamel steel plate according to any one of the third aspect.

[0067] The preparation method of the enamel steel plate is based on the chemical composition and the hot rolling process of the above-mentioned enamel steel plate. The chemical composition of the enamel steel plate can refer to the above-mentioned embodiments. Since the preparation method of the enamel steel plate adopts part or all of the technical solutions of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

[0068] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods not specified in the following examples are generally determined according to the national standards. If there is no corresponding national standard, the international standard, the conventional condition or the condition suggested by the manufacturer is used.

[0069] The steel liquid of examples 1-5 and comparative examples 1-3 is prepared and cast into a casting blank, and the chemical composition of the casting blank is shown in table 1.

[0070] Table 1: Chemical composition of each example and comparative example (wt%)

[0071] Group C Si Mn P S Alt Ti Nb N [Ti] / [S] Example 1 0.16 0.45 2.4 0.010 0.0030 0.035 0.14 0.03 0.0048 46.67 Example 2 0.22 0.3 3 0.010 0.0034 0.030 0.21 0.07 0.0042 61.76 Example 3 0.17 0.5 2.5 0.009 0.0040 0.060 0.15 0.04 0.0026 37.50 Example 4 0.20 0.4 2.8 0.080 0.0045 0.033 0.19 0.06 0.0040 42.22 Example 5 0.18 0.35 2.6 0.011 0.0025 0.025 0.17 0.05 0.0033 68.00 Comparative Example 1 0.16 0.45 2.4 0.010 0.0200 0.035 0.14 0.03 0.0048 7 Comparative Example 2 0.17 0.5 2.5 0.009 0.0040 0.060 0.15 0.04 0.0026 37.50 Comparative Example 3 0.16 0.45 2.4 0.010 0.0200 0.035 0.14 0.03 0.0048 7

[0072] Based on the chemical composition of the above-mentioned enamel steel plate, the present application provides a preparation method of the enamel steel plate, which comprises:

[0073] S11, obtaining a casting blank with the chemical composition;

[0074] S21, heating, two-stage rolling and stage cooling the casting blank to obtain an enamel steel plate, and the main process parameters are shown in table 2.

[0075] Table 2: Preparation process parameters of the enamel steel plate

[0076]

[0077] Based on the above-mentioned enamel steel plate, the present application provides a preparation method of the enamel steel plate, which comprises: coating and baking the enamel steel plate three times, and the baking temperature is 870℃, and the total baking time is 2.5h.

[0078] The mechanical properties of the enamel steel plate and the enamel steel are tested, and the results are shown in table 3.

[0079] Table 3 Mechanical property results of the enamel steel plate and the enamel steel

[0080]

[0081]

[0082] attached Figure 2 , 3 Detailed description:

[0083] Figure 2 The metallographic structure photo of the enamel steel plate provided in Embodiment 1 of the present application can be seen from the figure that the microstructure of the steel plate is bainite.

[0084] Figure 3 The precipitate transmission electron microscope photo of the enamel steel plate provided in Embodiment 1 of the present application can be seen from the figure that the titanium carbide and niobium carbide precipitate phase particles distributed in the steel are ≤50nm in size.

[0085] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0086] (1) In the embodiments of the present application, the thick-gauge enamel steel plate has high strength level, is resistant to high-temperature enameling, and has a yield strength of 380MPa-450MPa and a tensile strength of 520MPa-750MPa after enameling at 870℃ for 2.5h.

[0087] (2) In the embodiments of the present application, the enamel steel plate has good enameling performance and anti-scaling performance. The can has large volume and can be used to make a large-scale water storage tank with a storage capacity of 25000m 3 The above large-scale enamel assembled tank.

[0088] (3) In the embodiments of the present application, the enamel steel plate does not add elements such as Cr, Cu, Mo, V and B, and has relatively low cost.

[0089] The above is only the specific embodiments of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features sought to be applied herein.

Claims

1. A method for preparing a steel plate for enamel enamel, characterized in that, The method for preparing the enamel steel plate includes: obtaining a cast billet with a specific chemical composition; heating, two-stage rolling, and staged cooling of the cast billet to obtain the enamel steel plate; the two-stage rolling includes rough rolling and finish rolling, with the finish rolling final temperature being 800℃~900℃; the staged cooling includes a first-stage cooling, a second-stage cooling, and a third-stage cooling; the cooling rate of the first-stage cooling is 30℃ / s~40℃ / s; the cooling rate of the second-stage cooling is ≤20℃ / s; the final cooling temperature of the second-stage cooling is 470℃~540℃; and the third-stage cooling is air cooling to... Room temperature; the microstructure of the enamel-coated steel plate is bainitic, and the chemical composition includes: C, Si, Mn, P, S, Alt, Ti, Nb, N and the balance Fe; by mass fraction, the content of C is 0.16%~0.22%, the content of Si is 0.3%~0.5%, the content of Mn is 2.4%~3%, the content of P is <0.015%, the content of S is <0.005%, the content of Alt is 0.02%~0.08%, the content of Ti is 0.13%~0.25%, the content of Nb is 0.02%~0.07%, and the content of N is <0.005%; The mass fractions of Ti and S satisfy the following relationship: [Ti] / [S]≥26, In the formula, [Ti] represents the mass fraction of Ti, and [S] represents the mass fraction of S.

2. The method according to claim 1, characterized in that, The heating temperature is 1190℃~1260℃; the rough rolling is performed in 5 to 7 passes, and the finish rolling is performed in 5 to 7 passes.

3. The enamel steel plate prepared by the preparation method according to any one of claims 1-2, characterized in that, The matrix of the enamel steel plate contains dispersed TiC and NbC precipitates with a size ≤50nm.

4. The enamel steel plate according to claim 3, characterized in that, The thickness of the enamel-enameled steel plate is 16mm~20mm, and the enamel-enameled steel plate meets the following properties: yield strength of 660MPa~750MPa, tensile strength of 710MPa~880MPa, and elongation after fracture A. 50mm It has a content of 20%~35% and can withstand high-temperature enamel firing at 800℃~900℃.

5. A type of enamel steel, characterized in that, The enamel steel includes the enamel steel plate and the enamel layer as described in any one of claims 3-4, wherein the enamel layer is disposed on at least one surface of the enamel steel plate.

6. The enamel steel according to claim 5, characterized in that, The microstructure of the enamel steel includes pearlite and ferrite, the grain size of the enamel steel is <5μm, and new precipitates of TiC and NbC are dispersed in the matrix of the enamel steel, the size of the new precipitates is <20nm.

7. The enamel steel according to claim 5, characterized in that, The enamel steel meets the following properties: yield strength of 380MPa~450MPa, tensile strength of 520MPa~750MPa, and elongation after fracture A. 50mm The percentage is 28% to 47%.

8. An enamel-coated assembled can, characterized in that, The enameled assembly tank has a water storage capacity of ≥25000m³. 3 The enamel-lined assembled tank includes metal structural components made of enamel steel as described in any one of claims 5-7.

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