A steel for enamelling, a high-performance hot-rolled enamelled steel based on it and a method for its production and use

Abstract

The application relates to a kind of enamel steel, high-performance hot-rolled enamel steel based on it and its preparation method and application.The application belongs to the field of hot-rolled enamel steel and its preparation.The application is to solve the technical problem that the mechanical property and anti-scale burst performance of the existing hot-rolled enamel steel are greatly lost before and after enameling.The composition of the enamel steel is as follows: C: 0.02-0.04%, Si<=0.05%, Mn: 0.8-1.2%, P<=0.015%, S<=0.010%, Als<=0.03%, Mo: 0.15-0.25%, Nb: 0.02-0.04%, V: 0.08-0.18%, N<=0.0020%, and the balance is Fe and inevitable impurities.The application significantly reduces the loss of mechanical property and anti-scale burst performance before and after high-temperature enameling by reasonably controlling the mass content and ratio of C, N, Nb and V of the enamel steel, and optimizing the process parameters such as hot rolling, laminar cooling and coiling.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of hot-rolled enamel steel and its preparation, and particularly relates to an enamel steel, a high-performance hot-rolled enamel steel based on the same, and a preparation method and application thereof. BACKGROUND

[0002] Enamel products have the advantages of acid and alkali resistance, high temperature resistance, easy cleaning, beautiful surface, long service life, etc. of the enamel layer, and the characteristics of high strength and easy forming of the metal substrate. In recent years, they have been widely used in various industries of the national economy. Steel material is a commonly used substrate material for enamel products, and the steel grade used for enamel products is called enamel steel. According to the different rolling methods, the enamel steel can be divided into cold-rolled enamel steel and hot-rolled enamel steel. The cold-rolled enamel steel is mainly used for producing enamel products with high forming requirements, such as bathtubs, electric kettles, oven liners, etc.; the hot-rolled enamel steel is mainly used for producing large-scale water treatment facilities, chemical facilities, and enamel assembled tanks for environmental protection facilities, at which time the strength requirement of the hot-rolled enamel steel is higher.

[0003] Scale explosion is a common and fatal defect of enamel products, which refers to the phenomenon of half-moon-shaped fish scale-shaped peeling of different sizes and depths on the surface of the enamel layer. Once scale explosion occurs, it means that the enamel product is scrapped, which is an unacceptable defect. The free-diffusion hydrogen existing in the steel is the main cause of scale explosion of enamel products. During the enameling process, the hydrogen produced by the reaction of the crystal water contained in the clay with the metal will diffuse into the steel plate. The solubility of hydrogen in the steel is higher at high temperature, and gradually decreases in the subsequent cooling process. The free-diffusion hydrogen that is supersaturated at room temperature will gradually accumulate at the interface between the steel and the enamel layer, and when the pressure generated by the accumulation exceeds the bonding strength of the enamel layer and the steel, the enamel layer will peel off, i.e. scale explosion phenomenon occurs. The anti-scale explosion sensitivity (TH value) is usually used to evaluate the anti-scale explosion performance of enamel steel. The larger the TH value, the better the anti-scale explosion performance of the enamel steel, i.e. the less likely to occur scale explosion phenomenon. It is generally believed that when the TH value is ≥ 6.7 min / mm 2

[0004] When hot-rolled enamel steel is used to produce enamel assembled tanks, processes such as bending, surface shot blasting, and twice enameling are required. The first enameling is the enameling of the bottom glaze, and the second enameling is the enameling of the face glaze, both of which are at a temperature of 800-900℃. After twice enameling, the strength and anti-scale explosion sensitivity of the hot-rolled enamel steel will inevitably decrease, thereby adversely affecting the service of the enamel assembled tank.

[0005] ​At present, in order to improve the strength and anti-scaling performance of hot-rolled enamel steel at the same time, most patents about hot-rolled enamel steel adopt the composition design idea of Ti micro-alloying, using nano-sized TiC as hydrogen trap to improve the anti-scaling performance, and TiC can also play the effect of precipitation strengthening to improve the strength of hot-rolled enamel steel. Or adding a small amount of Nb and V as well as Ti as the main micro-alloying element to form a second phase precipitation particle group mainly composed of Ti precipitates and supplemented by Nb and V precipitates to improve the strength and anti-scaling performance of hot-rolled enamel steel. In order to ensure the strength of hot-rolled enamel steel, the microstructure of most patents about hot-rolled enamel steel is ferrite + pearlite / bainite, and the existence of pearlite and bainite will reduce the formability of hot-rolled enamel steel. For example, in the patent with publication number CN1966753A and the name of "a hot-rolled double-sided enamel steel plate and its manufacturing method", the Ti content in the hot-rolled enamel steel is 0.08-0.20%, the Ti / C is controlled at 2.2-5, the V content is 0.015-0.060%, and the microstructure is ferrite. The yield strength and tensile strength after enameling decrease by 100-260 MPa. In the patent with publication number 106834920A and the name of "a hot-rolled enamel steel plate and its preparation method", the Ti content in the hot-rolled enamel steel is 0.1-0.2%, the Ti / C is controlled at 1.1-3.3, and the microstructure is ferrite and pearlite. The yield strength and tensile strength after enameling decrease by about 200 MPa. In the patent with publication number CN109423576A and the name of "a hot-rolled enamel steel plate and its manufacturing method", the hot-rolled enamel steel is added with 0.02-0.08% of Ti, 0.02-0.055% of V and 0.01-0.05% of Nb. The microstructure is ferrite plus a small amount of pearlite. The yield strength and tensile strength after enameling have a loss of 100-200 MPa. In the patent with publication number CN108950423A and the name of "a hot-rolled double-sided enamel steel, a double-sided enamel steel and its manufacturing method", the hot-rolled enamel steel is added with 0.01-0.06% of Ti, 0.02-0.10% of V and 0.01-0.10% of Nb. The microstructure before and after enameling is ferrite + pearlite and granular bainite respectively. The yield strength after enameling decreases by 100-200 MPa. As can be seen from the above, in the existing patents about hot-rolled enamel steel, the yield strength and tensile strength of the enamel steel after high-temperature enameling decrease significantly, because the TiC precipitation particles coarsen during enameling, resulting in the decrease of precipitation strengthening effect and strength. In addition, since the trap position of hydrogen captured by TiC is the interface between TiC and ferrite matrix, the coarsening of TiC will lead to the reduction of the interface area between TiC and ferrite matrix, i.e. the reduction of the number of hydrogen traps, thus leading to the significant decrease of the anti-scaling performance of hot-rolled enamel steel. The decrease of strength and anti-scaling performance is obviously not conducive to the performance of hot-rolled enamel steel. SUMMARY

[0006] The present application is to overcome the above technical defects, the present application provides a kind of enamel steel by reasonably controlling the mass content and proportion of C, N, Nb and V for enamel, simultaneously combining the optimization of process parameters such as hot rolling, laminar cooling and coiling, and the yield strength, tensile strength and anti-scale burst performance after high temperature enamel are not obviously decreased, even almost not decreased, and the method and application of the enamel steel based on the preparation of hot-rolled enamel steel with high mechanical properties and excellent anti-scale burst performance.

[0007] The purpose of the present application is realized by the following technical scheme:

[0008] One of the purposes of the present application is to provide a kind of enamel steel, the chemical composition of the enamel steel is as follows: C: 0.02-0.04%, Si≤0.05%, Mn: 0.8-1.2%, P≤0.015%, S≤0.010%, Als≤0.03%, Mo: 0.15-0.25%, Nb: 0.02-0.04%, V: 0.08-0.18%, N≤0.0020%, the balance is Fe and inevitable impurities.

[0009] The design principle of each chemical element in the enamel steel of the present application is as follows:

[0010] C and N: the component design idea of the present application is to use Nb and V to fix N, so that most of C in the steel is combined with V to produce VC, and there is no solid solution C and N in the steel. In order to ensure that the content of Nb and V combined with N in the steel is as low as possible, the content of N is controlled to be less than or equal to 0.0020%. In order to form a sufficient number of VC precipitates, the content of C is controlled to be 0.02-0.04%. If the content of C is too low, the number of VC precipitates formed is insufficient, and the hot-rolled enamel steel is prone to scale burst phenomenon. If the content of C is too high, it is necessary to add a higher content of V, which significantly increases the production cost.

[0011] Nb: Nb is a strong carbon and nitride forming element. Compared with NbC, the solid solubility of NbN is smaller and the precipitation temperature is higher, so NbN is more likely to precipitate than NbC. In the technical scheme described in the present application, the main role of Nb is to fix N, and to generate large size composite precipitates (Nb, V) (C, N) together with V and C. Large size (Nb, V) (C, N) can capture part of hydrogen during high temperature enamel, and reduce the scale burst tendency of hot-rolled enamel steel. According to the content range of N and the atomic weight ratio of Nb and N, the content of Nb can be determined to be between 0.02-0.04%.

[0012] V: V is also a strong carbon, nitride forming element. In the present application, the role of V is to combine with C to produce a large number of VC of nanometer size, which can not only play the role of precipitation strengthening, but also can capture hydrogen as hydrogen traps to improve the anti-scaling performance of the hot-rolled enamel steel. According to the contents of C, N and Nb and their atomic weights, the content of V can be determined in the range of 0.08-0.18%.

[0013] Si: When the content of Si exceeds 0.05%, the enamel adhesion performance of the hot-rolled enamel steel decreases, therefore the content of Si is controlled to be less than or equal to 0.05% in the present application.

[0014] Mn: Mn is a strengthening element in steel, in order to make the hot-rolled enamel steel of the present application have high strength, the content of Mn is controlled to be 0.8-1.2%.

[0015] Mo: Mo is a carbide forming element, which can refine the grain of the steel and improve the strength of the steel. The content of Mo in the hot-rolled enamel steel of the present application is limited to 0.15-0.25%.

[0016] Al: In the present application, Al is used as the main deoxidizer. However, Al2O3 has poor plasticity, which will affect the forming performance of the hot-rolled enamel steel. In addition, high Al content is also not conducive to the surface quality of the enamel layer after enameling. Therefore, the content of Al is controlled to be less than 0.03%.

[0017] P: P will increase the cold brittleness of the steel and reduce the plasticity, the content of P is controlled to be ≤0.015% in the present application.

[0018] S: S will react with Mn to form MnS, which will reduce the ductility and plasticity of the hot-rolled enamel steel, the content of S is controlled to be ≤0.010% in the present application.

[0019] As a further preferred embodiment of the enamel steel of the present application, the contents of the elements in the enamel steel should also satisfy the following formula:

[0020] V≥4.24×[C-(Nb-6.64N) / 7.74]

[0021] wherein C, N, Nb and V represent the numerical values of the mass percentage of the corresponding elements. For example, when the mass percentage of C is 0.03%, the numerical value in the formula is 0.03.

[0022] When the enamel steel of the present application satisfies this formula, it can be ensured that most of the C in the steel combines with V to form VC and all the N exists in (Nb, V)(C, N), so that the expected type of nano precipitates is obtained.

[0023] The second object of the present application is to provide the use of the above-mentioned enamel steel in the preparation of high-performance hot-rolled enamel steel.

[0024] The third object of the present application is to provide a preparation method of high-performance hot-rolled enamel steel, which is carried out according to the following steps:

[0025] S1, smelting: the chemical components of the above-mentioned enamel steel are weighed and smelted;

[0026] S2, continuous casting;

[0027] S3, hot rolling: the heating temperature during hot rolling is 1200-1250 DEG C, and after the end of the holding, the rolling is carried out, and the final rolling temperature is controlled at 850-950 DEG C;

[0028] S4, laminar cooling: the cooling rate during laminar cooling is 10-20 DEG C / s;

[0029] S5, coiling.

[0030] As a further preferred embodiment of the preparation method of high-performance hot-rolled enamel steel of the present application, the holding time in S3 is 2h.

[0031] As a further preferred embodiment of the preparation method of high-performance hot-rolled enamel steel of the present application, the coiling temperature in S5 is 600-700 DEG C.

[0032] The fourth object of the present application is to provide a high-performance hot-rolled enamel steel prepared by the above-mentioned method, and the microstructure of the high-performance hot-rolled enamel steel is ferrite and nano-second phase precipitates (Nb, V) (C, N) and VC.

[0033] As a further preferred embodiment of the high-performance hot-rolled enamel steel of the present application, the size of (Nb, V) (C, N) is 100-300 nm, and the size of VC is 5-25 nm.

[0034] As a further preferred embodiment of the high-performance hot-rolled enamel steel of the present application, the yield strength of the high-performance hot-rolled enamel steel is greater than or equal to 300 MPa, the tensile strength is greater than or equal to 520 MPa, and the anti-scaling sensitivity (TH value) before and after enameling is greater than or equal to 20 min / mm 2 .

[0035] The fifth object of the present application is to provide an application of the high-performance hot-rolled enamel steel prepared by the above-mentioned method in the preparation of large-scale facility enamel assembled tanks.

[0036] As a further preferred embodiment of the application of the high-performance hot-rolled enamel steel of the present application, the large-scale facility includes water treatment facilities, chemical facilities, and environmental protection facilities.

[0037] Compared with the prior art, the present application has the following advantages:

[0038] The present application provides a kind of enamel steel for high temperature enameled after yield strength, tensile strength and anti scale explosion performance are not obviously decreased, even almost not decreased, and the method and application of preparing high mechanical property and excellent anti scale explosion performance of hot-rolled enamel steel based on the enamel steel, specific advantages are as follows:

[0039] (1) the present application by reasonable control C, N, Nb and V mass fraction and hot rolling, laminar cooling and coiling process parameters, so that the microstructure of the hot-rolled enamel steel of the present application is ferrite and nanometer size (Nb, V) (C, N) and VC distributed therein. In the process of enameled, large size (Nb, V) (C, N) almost does not occur coarsening, and VC can be completely dissolved during enameled due to its low solid solution temperature, and during subsequent cooling process, VC is precipitated again in the form of dispersion due to the sharp decrease of solid solubility, so the precipitation strengthening effect is almost unchanged. The strength loss during enameled is mainly caused by grain coarsening, so the strength decreases less. Since the size of VC before and after enameled almost does not change, the anti scale explosion performance (anti scale explosion sensitivity TH value) of the hot-rolled enamel steel also almost does not decrease.

[0040] (2) in the preparation method of the high performance hot-rolled enamel steel of the present application, the second phase precipitate of nanometer size is fully dissolved in austenite at 1200-1250 DEG C for a certain time before hot rolling, and fully precipitates during subsequent rolling and coiling process, to ensure the precipitation strengthening effect and anti scale explosion performance. The final rolling temperature is controlled at 850-950 DEG C, because too low final rolling temperature will result in poor plasticity of the hot-rolled enamel steel, and too high final rolling temperature will result in ferrite grain coarsening and decrease the strength of the hot-rolled enamel steel.

[0041] (3) in the preparation method of the high performance hot-rolled enamel steel of the present application, the cooling rate of laminar cooling is controlled at 10-20 DEG C / s, because in this cooling rate range, the strength of the hot-rolled enamel steel can be improved, and its anti scale explosion performance can also be improved.

[0042] (4) in the preparation method of the high performance hot-rolled enamel steel of the present application, the coiling temperature is controlled at 600-700 DEG C. Because when coiling at this temperature range, most of the VC precipitates can be precipitated, and the size of the precipitates can be controlled, which is beneficial to improve the strength and anti scale explosion performance. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 The microstructure of the high performance hot-rolled enamel steel prepared in example 1 of the present application;

[0044] Figure 2Transmission electron micrograph of VC and (Nb, V)(C, N) mixed precipitates in a high performance hot-rolled enamel steel produced according to Example 1 of the present application. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to examples. It should be understood that the specific examples described herein are intended to explain the present application, and are not intended to limit the present application.

[0046] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are conventional materials, reagents, methods, and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0047] The terms "comprising", "including", "containing", "have" or "including" or any other variant thereof in the following examples are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0048] When a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values for an equivalent, concentration, or other value or parameter is expressed, it should be understood that all ranges formed by any pairings of an upper limit or preferred value with a lower limit or preferred value of any range, whether or not the range is expressly disclosed, are specifically disclosed. For example, when a range "1 to 5" is disclosed, the described range should be interpreted to include ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include the end values and all integers and fractions within that range. In the specification and claims of this application, range limitations can be combined and / or interchanged, unless otherwise stated, and these ranges include all sub-ranges contained therein.

[0049] The indefinite articles "a" and "an" preceding an element or component of the present application are intended to be non-limiting regarding the number of elements or components. Thus, "a" or "an" should be interpreted to mean one or at least one, and the singular form "the" includes the plural unless the number is clearly specified in the context

[0050] Specific embodiment one: the chemical composition of the enamel steel in this embodiment is as follows in terms of mass percentage: C: 0.02-0.04%, Si≤0.05%, Mn: 0.8-1.2%, P≤0.015%, S≤0.010%, Als≤0.03%, Mo: 0.15-0.25%, Nb: 0.02-0.04%, V: 0.08-0.18%, N≤0.0020%, and the balance is Fe and inevitable impurities, and the elements in the enamel steel should also satisfy the following formulas:

[0051] V≥4.24×[C-(Nb-6.64N) / 7.74]

[0052] wherein C, N, Nb and V represent the numerical values of the mass percentage of the corresponding elements. For example, when the mass percentage of C is 0.03%, the numerical value in the formula is 0.03.

[0053] The design principle of each chemical element in the enamel steel in this embodiment is as follows:

[0054] C and N: the design idea of the composition of the present application is to use Nb and V to fix N, so that most of the C in the steel is combined with V to produce VC, and there is no solid solution of C and N in the steel. In order to ensure that the content of Nb and V combined with N in the steel is as low as possible, the content of N is controlled to be less than or equal to 0.0020%. In order to form a sufficient amount of VC precipitates, the content of C is controlled to be 0.02-0.04%. If the content of C is too low, the amount of VC precipitates formed is insufficient, and the hot-rolled enamel steel is prone to scale explosion. If the content of C is too high, a higher content of V needs to be added, which significantly increases the production cost.

[0055] Nb: Nb is a strong carbon and nitride forming element. Compared with NbC, NbN has a smaller solid solubility and a higher precipitation temperature, so NbN is more likely to precipitate than NbC. In the technical solution described in the present application, the main role of Nb is to fix N and generate large-size composite precipitates (Nb, V)(C, N) together with V and C. The large-size (Nb, V)(C, N) can capture part of the hydrogen during high-temperature enameling, reducing the scale explosion tendency of the hot-rolled enamel steel. According to the content range of N and the atomic weight ratio of Nb and N, the content of Nb can be determined to be between 0.02-0.04%.

[0056] V: V is also a strong carbon and nitride forming element. In the present application, the role of V is to combine with C to produce a large amount of nanoscale VC, which can not only play a precipitation strengthening role, but also act as a hydrogen trap to capture hydrogen and improve the scale explosion resistance of the hot-rolled enamel steel. According to the contents of C, N and Nb and their atomic weights, the content of V can be determined to be in the range of 0.08-0.18%.

[0057] Si: When the Si content exceeds 0.05%, the enamel adhesion performance of the hot-rolled enamel steel decreases, and therefore the Si content is controlled to be less than or equal to 0.05% in the present application.

[0058] Mn: Mn is a strengthening element in the steel, and in order to make the hot-rolled enamel steel of the present application have high strength, the Mn content is controlled to be 0.8-1.2%.

[0059] Mo: Mo is a carbide-forming element, which can refine the grain of the steel and improve the strength of the steel. In the hot-rolled enamel steel of the present application, the Mo content is limited to 0.15-0.25%.

[0060] Al: In the present application, Al is used as the main deoxidizer. However, Al2O3 has poor plasticity, which will affect the formability of the hot-rolled enamel steel. In addition, a high Al content is also not conducive to the surface quality of the enamel layer after enameling. Therefore, the Al content is controlled to be less than or equal to 0.03%.

[0061] P: P will increase the cold brittleness of the steel and reduce the plasticity, and in the present application, the P content is controlled to be less than or equal to 0.015%.

[0062] S: S will react with Mn to form MnS, which will reduce the ductility and plasticity of the hot-rolled enamel steel, and in the present application, the S content is controlled to be less than or equal to 0.010%.

[0063] When the enamel steel of the present application satisfies the formula, it can be ensured that most of the C in the steel is combined with V to form VC and all of the N exists in (Nb, V)(C, N), so that the expected type of nano precipitates is obtained.

[0064] Specific embodiment two: the present embodiment aims to provide an application of the above-mentioned enamel steel in the preparation of high-performance hot-rolled enamel steel.

[0065] Specific embodiment three: the present embodiment aims to provide a preparation method of high-performance hot-rolled enamel steel, which is specifically carried out according to the following steps:

[0066] S1, smelting: the chemical components of the above-mentioned enamel steel are weighed and smelted according to the above-mentioned steps;

[0067] S2, continuous casting;

[0068] S3, hot rolling: the heating temperature during hot rolling is 1200-1250°C, and the temperature is kept for 2h. After the temperature keeping is finished, the steel is discharged and rolled, and the final rolling temperature is controlled to be 850-950°C;

[0069] The heating temperature of 1200-1250℃ can ensure that the nanometer-sized second phase precipitates are fully dissolved in austenite and fully precipitate during subsequent rolling and coiling, thereby ensuring the precipitation strengthening effect and the anti-scaling performance. The finish rolling temperature that is too low will result in poor plasticity of the hot-rolled enamel steel, and the finish rolling temperature that is too high will result in coarse ferrite grains and reduced strength of the hot-rolled enamel steel, and therefore the finish rolling temperature is controlled at 850-950℃.

[0070] The cooling rate during the laminar cooling is 10-20℃ / s.

[0071] The cooling rate during the laminar cooling is 10-20℃ / s, because within this cooling rate range, the strength of the hot-rolled enamel steel can be improved, and the anti-scaling performance can also be improved.

[0072] S5, coiling: the coiling temperature is 600-700℃.

[0073] The coiling temperature is controlled at 600-700℃. This is because when coiling at this temperature range, most of the VC precipitates can be precipitated, and the size of the precipitates can be controlled, which is beneficial to improving the strength and the anti-scaling performance.

[0074] Specific embodiment four: the embodiment is intended to provide a high-performance hot-rolled enamel steel prepared by the above method, the microstructure of the high-performance hot-rolled enamel steel is ferrite and nanometer second phase precipitates (Nb, V) (C, N) and VC, the size of the (Nb, V) (C, N) is 100-300nm, the size of the VC is 5-25nm, the yield strength of the high-performance hot-rolled enamel steel is ≥300MPa, the tensile strength is ≥520MPa, and the anti-scaling sensitivity (TH value) before and after enameling is ≥20min / mm 2 .

[0075] Specific embodiment five: the embodiment is intended to provide an application of the high-performance hot-rolled enamel steel prepared by the above method in the preparation of an enamel assembled tank for large facilities, the large facilities including water treatment facilities, chemical facilities, and environmental protection facilities.

[0076] Example 1:

[0077] The preparation method of a high-performance hot-rolled enamel steel of the embodiment is carried out according to the following steps:

[0078] S1, smelting:

[0079] The materials were weighed according to the following chemical composition by mass percentage: C: 0.02%, Si: 0.04%, Mn: 1%, P: 0.012%, S: 0.008%, Als: 0.02%, Mo: 0.2%, Nb: 0.02%, V: 0.1%, N: 0.0020%, with the balance being Fe and unavoidable impurities.

[0080] The smelting process is as follows: (1) Smelting is carried out in a converter at a temperature of 1550-1580℃ for 30 minutes, and then the steel is tapped and subjected to initial alloying treatment; (2) Refining is carried out in an LF furnace using a high-basicity slag deoxidation process to adjust the composition of the molten steel to the target range; (3) Vacuum treatment is carried out in an RH furnace, with the vacuum pressure controlled at 100Pa and the vacuum treatment time at 10 minutes to obtain molten steel.

[0081] S2, Continuous Casting:

[0082] The molten steel obtained from S1 is continuously cast into a continuous casting billet with a cross-sectional size of 160mm×160mm;

[0083] S3, Hot Rolled:

[0084] The continuously cast billet obtained from S2 was heated to 1200℃ and held for 2 hours. Then it was hot rolled after being taken out of the furnace. The final rolling temperature during hot rolling was set to 950℃ to obtain a hot-rolled plate with a thickness of 5mm.

[0085] S4, Laminar flow cooling:

[0086] The hot-rolled plate obtained from S3 was subjected to laminar flow cooling at a cooling rate of 15℃ / s.

[0087] S5, winding:

[0088] The steel sheet cooled by S4 laminar flow is coiled at 700℃ to obtain high-performance hot-rolled enamel steel.

[0089] The microstructure of the high-performance hot-rolled enamel steel obtained in Example 1 was observed using a metallographic microscope, and the results are as follows: Figure 1 The image shows ferrite. Figure 2 The image shows a transmission electron microscope (TEM) image of the mixed VC and (Nb,V)(C,N) precipitates in the hot-rolled enamel steel obtained in Example 1.

[0090] The high-performance hot-rolled enamel steel obtained in Example 1 was enameled at 850℃ for 10 min, followed by air cooling to room temperature. Tensile tests were conducted at room temperature on the enamel steel before and after enameling according to GB / T 228.1-2021. Anti-scaling performance was tested according to GB / T29515-2013, and the anti-scaling sensitivity (TH value) of the enamel steel before and after enameling was determined. The tensile properties and anti-scaling performance test results of the high-performance hot-rolled enamel steel obtained in Example 1 are shown in Table 1.

[0091] Example 2

[0092] The preparation method of the high-performance hot-rolled enamel steel in this embodiment is carried out in the following steps:

[0093] S1, smelting:

[0094] According to the chemical composition, the mass percentage is: C: 0.04%, Si: 0.04%, Mn: 0.8%, P: 0.010%, S: 0.009%, Als: 0.02%, Mo: 0.2%, Nb: 0.02%, V: 0.18%, N: 0.0020%, and the balance is Fe and inevitable impurities;

[0095] and smelting, the steps during smelting are as follows: (1) smelting in the converter, the smelting temperature is 1550-1580℃, and the holding time is 30min, then tapping and initial alloying treatment; (2) LF furnace refining, using high basicity slag deoxidization process for smelting, adjusting the composition of the molten steel to the target range; (3) RH furnace vacuum treatment, controlling the vacuum pressure to be 100Pa, the vacuum treatment time is 10min, and the molten steel is obtained.

[0096] S2, continuous casting:

[0097] The molten steel obtained in S1 is continuously cast into a continuous casting billet with a cross-sectional size of 160mmx160mm;

[0098] S3, hot rolling:

[0099] The continuous casting billet obtained in S2 is heated, the heating temperature is 1200℃, the holding time is 2h, then hot rolling after furnace tapping, the final rolling temperature during hot rolling is set to 950℃, and a hot-rolled plate with a thickness of 5mm is obtained;

[0100] S4, laminar cooling:

[0101] The hot-rolled plate obtained in S3 is subjected to laminar cooling under the condition that the cooling rate is 15℃ / s;

[0102] S5, coiling:

[0103] The steel plate after laminar cooling in S4 is coiled at 700℃, and a high-performance hot-rolled enamel steel is obtained.

[0104] The high-performance hot-rolled enamel steel obtained in Example 2 was enameled at 850℃ for 10min, and then air-cooled to room temperature. The enamel steel before and after enameled was subjected to room temperature tensile test according to GB / T 228.1-2021. The anti-scaling performance test was carried out according to GB / T29515-2013 to determine the anti-scaling sensitivity (TH value) of the enamel steel before and after enameled. The tensile properties and anti-scaling performance test results of the high-performance hot-rolled enamel steel obtained in Example 2 are shown in Table 1.

[0105] Example 3:

[0106] The preparation method of a high-performance hot-rolled enamel steel in this embodiment is carried out in the following steps:

[0107] S1, smelting:

[0108] The chemical composition is as follows: C: 0.02%, Si: 0.04%, Mn: 1%, P: 0.012%, S: 0.008%, Als: 0.02%, Mo: 0.2%, Nb: 0.02%, V: 0.1%, N: 0.0020%, and the balance is Fe and inevitable impurities;

[0109] and smelting. The steps during smelting are as follows: (1) smelting in a converter, the smelting temperature is 1550-1580℃, and the holding time is 30min, then tapping and initial alloying treatment; (2) LF furnace refining, using high basicity slag deoxidization process for smelting, adjusting the composition of the molten steel to the target range; (3) RH furnace vacuum treatment, controlling the vacuum pressure to be 100Pa, and the vacuum treatment time is 10min, obtaining the molten steel.

[0110] S2, continuous casting:

[0111] The molten steel obtained in S1 is continuously cast into a continuous casting billet with a cross-sectional size of 160mmx160mm;

[0112] S3, hot rolling:

[0113] The continuous casting billet obtained in S2 is heated, the heating temperature is 1250℃, and the holding time is 2h, then hot rolling after tapping, the finish rolling temperature during hot rolling is set to 900℃, obtaining a hot-rolled plate with a thickness of 5mm;

[0114] S4, laminar cooling:

[0115] The hot-rolled plate obtained in S3 is subjected to laminar cooling at a cooling rate of 15℃ / s;

[0116] S5, coiling:

[0117] The steel plate after laminar cooling in S4 is coiled at 700℃, obtaining a high-performance hot-rolled enamel steel.

[0118] The high-performance hot-rolled enamel steel obtained in Example 3 was enameled at 850℃ for 10min, and then air-cooled to room temperature. The enamel steel before and after enameled was subjected to room temperature tensile test according to GB / T 228.1-2021. The anti-scaling performance test was carried out according to GB / T 29515-2013 to determine the anti-scaling sensitivity (TH value) of the enamel steel before and after enameled. The tensile properties and anti-scaling performance test results of the high-performance hot-rolled enamel steel obtained in Example 3 are shown in Table 1.

[0119] Example 4:

[0120] The preparation method of a high-performance hot-rolled enamel steel of the present embodiment is carried out in the following steps:

[0121] S1, smelting:

[0122] The chemical composition is as follows: C: 0.04%, Si: 0.04%, Mn: 0.8%, P: 0.010%, S: 0.009%, Als: 0.02%, Mo: 0.2%, Nb: 0.02%, V: 0.18%, N: 0.0020%, and the balance is Fe and inevitable impurities;

[0123] and smelting. The steps during smelting are as follows: (1) smelting in a converter, the smelting temperature is 1550-1580℃, and the holding time is 30min, then tapping and initial alloying treatment; (2) LF furnace refining, using high basicity slag deoxidization process for smelting, adjusting the composition of the molten steel to the target range; (3) RH furnace vacuum treatment, controlling the vacuum pressure to be 100Pa, and the vacuum treatment time is 10min, obtaining the molten steel.

[0124] S2, continuous casting:

[0125] The molten steel obtained in S1 is continuously cast into a continuous casting billet with a cross-sectional size of 160mmx160mm;

[0126] S3, hot rolling:

[0127] The continuous casting billet obtained in S2 is heated, the heating temperature is 1200℃, and the holding time is 2h, then hot rolling after furnace tapping, the finish rolling temperature during hot rolling is set to 950℃, obtaining a hot-rolled plate with a thickness of 5mm;

[0128] S4, laminar cooling:

[0129] The hot-rolled plate obtained in S3 is subjected to laminar cooling under the condition of cooling rate of 15℃ / s;

[0130] S5, coiling:

[0131] The steel plate after laminar cooling in S4 is coiled at 650℃ to obtain a high-performance hot-rolled enamel steel.

[0132] The high-performance hot-rolled enamel steel obtained in Example 4 was enameled at 850℃ for 10min, and then air-cooled to room temperature. The tensile test of the enamel steel before and after enameled was carried out according to GB / T 228.1-2021. The anti-scaling performance test was carried out according to GB / T 29515-2013 to determine the anti-scaling sensitivity (TH value) of the enamel steel before and after enameled. The tensile properties and anti-scaling performance test results of the high-performance hot-rolled enamel steel obtained in Example 4 are shown in Table 1.

[0133] Table 1 Tensile properties and anti-scaling performance of Examples 1-4

[0134]

[0135] As can be seen from Table 1, the yield strength of the hot-rolled enamel steel of the four examples is all ≥300MPa, the tensile strength is all ≥520MPa, and the anti-scaling sensitivity TH value before and after enameled is all ≥20min / mm 2 It can also be seen that after enameled at 850℃ for 10min, the yield strength, tensile strength and anti-scaling sensitivity (TH value) of the four examples all decrease very little, which can be applied to the production of enamel assembled tanks.

[0136] The above description is only the preferred specific embodiments of the present application, these specific embodiments are different implementations based on the overall concept of the present application, and the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high-performance hot-rolled enamel steel, characterized in that, The high-performance hot-rolled enamel steel is prepared from enamel steel with the following chemical composition by mass percentage: C: 0.02~0.04%, Si≤0.05%, Mn: 0.8~1.2%, P≤0.015%, S≤0.010%, Als≤0.03%, Mo: 0.15~0.25%, Nb: 0.02~0.04%, V: 0.08~0.18%, N≤0.0020%, with the balance being Fe and unavoidable impurities. Each element also satisfies the following formula: V≥4.24×[C-(Nb-6.64N) / 7.74]; The microstructure of the high-performance hot-rolled enamel steel consists of ferrite and nano-second-phase precipitates (Nb, V)(C, N) and VC. The size of (Nb, V)(C, N) is 100~300 nm, and the size of VC is 5~25 nm. Its yield strength is ≥300 MPa, tensile strength is ≥520 MPa, and TH value before and after enameling is ≥20 min / mm. 2 .

2. The method for preparing high-performance hot-rolled enamel steel according to claim 1, characterized in that, Follow these steps: S1. Smelting: Weigh and smelt the steel according to its chemical composition. S2, continuous casting; S3. Hot rolling: The heating temperature during hot rolling is 1200~1250℃. After heat preservation, the product is rolled out of the furnace, and the final rolling temperature is controlled at 850~950℃. S4. Laminar flow cooling: The cooling rate during laminar flow cooling is 10~20℃ / s; S5, winding.

3. The method according to claim 2, characterized in that, The temperature is maintained at 2 h in S3, and the winding temperature in S5 is 600~700℃.

4. The application of the high-performance hot-rolled enamel steel according to claim 1 in the preparation of enamel-lined assembly tanks for large facilities.

5. The application according to claim 4, characterized in that, Large-scale facilities include water treatment facilities, chemical facilities, and environmental protection facilities.

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