Stainless steel composite panel having excellent interface bonding and preparation method therefor

Abstract

Disclosed in the present invention are a stainless steel composite panel having excellent interface bonding and a preparation method therefor. In a rolling process of the method, longitudinal rolling is performed after n passes of transverse rolling, a reduction rate of a first pass is greater than or equal to 25 mm, the temperature is greater than or equal to 1060°C in the first pass, a target width is achieved in an nth pass, and the temperature is greater than or equal to 1030°C in the nth pass; after the nth pass and an (n+2)-th pass, reciprocating water cooling is performed once in six sets of headers, the cooling water amount of upper headers and the cooling water amount of lower headers are respectively 120-180 m3 / h and 160-220 m3 / h, and the roller way speed is 0.8-1.2 m / s; the reduction rate of the (n+1)-th to (n+3)-th passes is greater than or equal to 40 mm, and the temperature is greater than or equal to 950°C in the (n+1)-th pass; when reaching an mth pass, the temperature is greater than or equal to 900°C, and a blank thickness is 2.5-3.5 times of a target thickness of a large composite panel; then watering and cooling are performed until the surface temperature of a blank is reduced to 840°C or below; and then second-stage rolling is performed, the temperature of the first pass of the second-stage rolling is 810-840°C, and the temperature of the last pass of the second-stage rolling is 780-810°C.

Description

Stainless steel composite plate with excellent interface bonding and preparation method thereof Technical Field

[0001] The invention belongs to the technical field of steel material preparation, and relates to a stainless steel composite plate with excellent interface bonding and a preparation method thereof. Background Art

[0002] Stainless steel clad panels are composite materials composed of a stainless steel cladding layer and a carbon steel or low-alloy steel base layer, bonded together through specific processing methods. Stainless steel clad panels combine the corrosion resistance of the stainless steel cladding layer with the outstanding mechanical properties and price advantages of the carbon steel base layer, representing a key development direction for steel materials. Furthermore, during the use of stainless steel clad panels, requirements are placed on the interface bonding performance (shear strength and bonding ratio) between the base layer and the cladding layer. The quality of this interface bonding performance significantly impacts the quality of the project in which the stainless steel clad panels are used.

[0003] However, the currently known production technologies for stainless steel composite plates, such as the patented technologies with Chinese publication numbers CN105945067A and CN111530927A, disclose basic preparation methods for composite plates but do not focus on interface bonding performance. Furthermore, the process for improving interface bonding performance is not disclosed in the prior art.

[0004] Summary of the Invention

[0005] The object of the present invention is to provide a stainless steel composite plate with excellent interface bonding and a preparation method thereof.

[0006] To achieve the above-mentioned object of the invention, one embodiment of the present invention provides a method for preparing a stainless steel composite plate with excellent interface bonding, the method comprising the following steps:

[0007] A composite blank with a thickness of t is prepared by preparing a steel blank, applying a release agent, assembling the blank, sealing, vacuuming, and sealing; the composite blank includes an upper substrate, a lower substrate, a middle composite material, and four frames for sealing the middle composite material between the upper substrate and the lower substrate;

[0008] The composite blank is heated in a heating furnace according to a five-stage method of a preheating section, a first heating section, a second heating section, a third heating section, and a soaking section, wherein the temperature of the preheating section is ≤850°C, the temperature of the first heating section is 1080±30°C, the temperature of the second heating section is 1160±30°C, the temperature of the third heating section is 1220±20°C, the temperature of the soaking section is 1190±20°C, the residence time of the third heating section is (0.25-0.35)×t min / mm, and the residence time of the soaking section is 15 min to 30 min;

[0009] The composite billet coming out of the heating furnace is rolled to produce a large composite plate; during the entire rolling process, the first n passes are transverse rolling, and the n+1 pass and thereafter are longitudinal rolling, and the rolling reduction of the first pass is ≥25mm and the rolling temperature is ≥1060℃, the width of the billet obtained by the nth pass is Wt+0~40mm, Wt is the target width of the large composite plate, and the rolling temperature of the nth pass is ≥1030℃; between the nth pass and the n+1 pass and between the n+2 pass and the n+3 pass, the billet is water-cooled once in 6 groups of headers, and the cooling water volume of the upper header of each group of headers is 120~180m 3 / h, cooling water volume of lower header: 160~220m 3 / h, and the roller speed is 0.8-1.2m / s; the rolling reduction from the n+1th to the n+3th pass is ≥40mm, and the rolling temperature of the n+1th pass is ≥950℃; by the mth pass, the rolling temperature is ≥900℃, and the billet is rolled to a thickness of 2.5-3.5 times the target thickness of the composite plate; then water cooling is carried out until the surface temperature of the billet drops below 840℃; then the second stage rolling is carried out until the billet thickness reaches the target thickness of the composite plate, completing the entire rolling process. The rolling temperature of the first pass of the second stage rolling is 810℃-840℃, and the rolling temperature of the last pass is 780-810℃;

[0010] The obtained composite plate is cooled, split and straightened to obtain a stainless steel composite plate product.

[0011] To achieve the above-mentioned object, one embodiment of the present invention provides a stainless steel composite plate with excellent interface bonding, wherein the shear strength of the bonding interface of the stainless steel composite plate is ≥360 MPa. During the preparation process of the stainless steel composite plate, a composite blank consisting of an upper substrate, a lower substrate, and a middle composite material is heated and then rolled into a large composite plate;

[0012] During the rolling process, the first n passes are rolled in the transverse direction, and the n+1 pass and thereafter are rolled in the longitudinal direction. Furthermore, the first pass rolling reduction is ≥25mm and the rolling temperature is ≥1060℃. The width of the billet obtained by the n-th pass rolling is Wt+0~40mm, Wt is the target width of the composite plate, and the rolling temperature of the n-th pass is ≥1030℃. Between the n-th pass and the n+1 pass, and between the n+2 pass and the n+3 pass, the billet is water-cooled once in 6 sets of headers, and the cooling water volume of the upper header of each set of headers is 120~180m 3 / h, cooling water volume of lower header: 160~220m 3 / h, and the roller speed is 0.8~1.2m / s; the rolling reduction from the n+1th to the n+3th pass is ≥40mm, and the rolling temperature of the n+1th pass is ≥950℃; when it comes to the mth pass, the rolling temperature is ≥900℃, and the billet is rolled to a thickness of 2.5~3.5 times the target thickness of the composite plate; then water cooling is carried out until the surface temperature of the billet drops below 840℃; then the second stage rolling is carried out until the billet thickness reaches the target thickness of the composite plate, completing the entire rolling process, the rolling temperature of the first pass of the second stage rolling is 810℃~840℃, and the rolling temperature of the last pass is 780~810℃.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: by preparing the composite blank and improving the heating and rolling technology of the composite blank, on the one hand, the temperature uniformity of the composite blank is ensured, and on the other hand, the core of the composite blank is ensured to be effectively penetrated. Furthermore, it can not only ensure that the inherent advantages of the substrate and the composite material can be brought into play, but more importantly, it can also ensure the excellent bonding strength of the bonding interface between the substrate and the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For the sake of clarity in presentation and description, in the various drawings of the present invention, certain dimensions of structures or parts are exaggerated relative to other structures or parts. Therefore, these drawings are only used to illustrate the basic structure of the subject matter of the present invention.

[0015] FIG1 is a schematic cross-sectional view of a steel billet used in a preparation method according to one embodiment of the present invention;

[0016] FIG2 is a schematic cross-sectional view of a composite blank according to a preparation method of an embodiment of the present invention; the cross section is perpendicular to the length direction of the composite blank;

[0017] FIG3 is another schematic cross-sectional view of a composite blank of a preparation method according to an embodiment of the present invention; the cross section is perpendicular to the thickness direction of the composite blank;

[0018] FIG4 is a schematic cross-sectional view of a composite plate obtained by the preparation method according to one embodiment of the present invention. DETAILED DESCRIPTION

[0019] One embodiment of the present invention provides a method for preparing a stainless steel composite plate, which is used to prepare a single-sided stainless steel composite plate composed of a carbon steel base layer and a stainless steel composite layer, so that the obtained stainless steel composite plate has excellent interface bonding performance, that is, the strength of the bonding interface between the base layer and the composite layer is excellent.

[0020] The preparation method includes the following steps: preparing steel billets, applying a release agent, assembling billets, sealing and welding, vacuuming, sealing, heating, rolling, cooling, separating plates, and straightening. Specifically:

[0021] A composite blank with a thickness of t is prepared by preparing a steel blank, applying a release agent, assembling the blank, sealing, vacuuming, and sealing; the composite blank includes an upper substrate, a lower substrate, a middle composite material, and four frames for sealing the middle composite material between the upper substrate and the lower substrate;

[0022] The composite blank is heated in a heating furnace according to a five-stage method of a preheating section, a first heating section, a second heating section, a third heating section, and a soaking section, wherein the temperature of the preheating section is ≤850°C, the temperature of the first heating section is 1080±30°C, the temperature of the second heating section is 1160±30°C, the temperature of the third heating section is 1220±20°C, the temperature of the soaking section is 1190±20°C, the residence time of the third heating section is (0.25-0.35)×t min / mm, and the residence time of the soaking section is 15 min to 30 min;

[0023] The composite billet coming out of the heating furnace is rolled to produce a large composite plate; during the entire rolling process, the first n passes are transverse rolling, and the n+1 pass and thereafter are longitudinal rolling, and the rolling reduction of the first pass is ≥25mm and the rolling temperature is ≥1060℃, the width of the billet obtained by the nth pass is Wt+0~40mm, Wt is the target width of the large composite plate, and the rolling temperature of the nth pass is ≥1030℃; between the nth pass and the n+1 pass and between the n+2 pass and the n+3 pass, the billet is water-cooled once in 6 groups of headers, and the cooling water volume of the upper header of each group of headers is 120~180m 3 / h, cooling water volume of lower header: 160~220m 3 / h, and the roller speed is 0.8~1.2m / s; the rolling reduction from the n+1th to the n+3th pass is ≥40mm, and the rolling temperature of the n+1th pass is ≥950℃; when it comes to the mth pass, the rolling temperature is ≥900℃, and the billet is rolled to a thickness of 2.5~3.5 times the target thickness of the composite plate; then water cooling is carried out until the surface temperature of the billet drops below 840℃; then the second stage rolling is carried out until the billet thickness reaches the target thickness of the composite plate, completing the entire rolling process, the rolling temperature of the first pass of the second stage rolling is 810℃~840℃, and the rolling temperature of the last pass is 780~810℃;

[0024] The obtained composite plate is cooled, split and straightened to obtain a stainless steel composite plate product.

[0025] Thus, in one embodiment of the present invention, by preparing the composite blank, the composite blank is subjected to the above-mentioned heating and rolling technology, especially the whole process of the rolling process, which ensures the temperature uniformity of the composite blank on the one hand, and ensures the effective penetration of the core of the composite blank on the other hand. Furthermore, it can not only ensure that the advantages of the substrate and the composite material themselves can be brought into play, but more importantly, it can also ensure the excellent bonding strength of the bonding interface between the substrate and the composite material.

[0026] As a preferred embodiment, the rolling reduction in the n+2th pass is ≥42 mm.

[0027] More preferably, the cooling water volume of the upper header of each group of headers is 150m 3 / h, cooling water volume of lower header 200m 3 / h, and the roller speed is 1m / s.

[0028] As a preferred embodiment, in the composite billet obtained in the step of "preparing a steel billet, applying a release agent, assembling billets, sealing, welding, vacuuming, and sealing to prepare a composite billet having a thickness of t":

[0029] The middle layer composite material includes two laminated composite materials, that is, a base material, a composite material, another composite material, and another base material are laminated in sequence from top to bottom;

[0030] The four frames include sealing strips surrounding the four sides of the middle substrate, and a surfacing welding filling layer located in a groove surrounded by the upper substrate, the lower substrate and the sealing strips.

[0031] The following is a detailed description of the composite blank preparation process according to a preferred embodiment of the present invention.

[0032] The steel slab preparation step includes preparing two carbon steel slabs of length L1 and width W1 as two substrates, such as substrate 11 and substrate 12 in Figure 1. Substrates 11 and 12 have the same length L1 and width W1. Furthermore, substrates 11 and 12 can have the same or different thicknesses. If different thicknesses are used, stainless steel clad plates of varying thicknesses can be produced.

[0033] The steel billet preparation step further includes preparing two stainless steel billets of length L2 and width W2, as two composite materials, such as composite material 21 and composite material 22 in FIG1 . Composite materials 21 and 22 have the same length L2 and width W2. Furthermore, composite materials 21 and 22 can have the same or different thicknesses. If different thicknesses are set, stainless steel composite plates of different thicknesses can be produced accordingly.

[0034] Further preferably, the length and width of the substrate 11 and the substrate 12 are both larger than the length and width of the composite material 21 and the composite material 22 , that is, L1>L2, W1>W2.

[0035] A more optimal ratio is L1 = L2 + 90-150mm, and W1 = W2 + 90-150mm. In other words, the length of each substrate is 90-150mm greater than the length of each composite, and the width of each substrate is 90-150mm greater than the width of each composite. This ensures the dimensions of the four sides of the composite blank, ensuring the sealing of the composite blank and improving the interface bonding quality.

[0036] It is understood that the composite material and substrate prepared in the steel slab preparation process are ultimately converted into the cladding layer and base layer of the resulting stainless steel clad plate after undergoing the aforementioned preparation method. Therefore, the same reference numerals are used in the accompanying drawings for the composite material and cladding layer, and for the base layer and base layer.

[0037] Preferably, the steel slab preparation step further includes grinding and polishing the surfaces to be bonded of each substrate and each composite material to remove surface oxide scale and reveal a metallic luster. After grinding and polishing, the surface roughness Ra of the bonded surfaces is less than 5 μm. In this manner, these polished surfaces serve as contact surfaces to be bonded during subsequent assembly, thereby enhancing the interfacial bonding strength of the resulting stainless steel clad plate.

[0038] In the present application, the "surface to be composited" refers to the surface where the substrate and the composite material need to be interfaced when forming a composite board.

[0039] Specifically, referring to FIG. 2 , for example, for substrate 11, substrate 12, composite material 21, and composite material 22, any one of the two surfaces in the thickness direction can be selected as the “surface to be composited” for grinding and polishing, such as surface p1 of substrate 11 and surface p2 of substrate 12, which can be specifically ground and polished using a grinding wheel machine, a sanding belt machine, or a milling machine, and surface p3 of substrate 21 and surface p4 of substrate 22, which can be specifically ground and polished using a wire wheel.

[0040] It can be understood that after the surface grinding process, each base material and each composite material are blanks of uniform thickness.

[0041] Here, only the grinding and polishing treatment of the surface to be composited of each substrate and each composite is described. However, it should be noted that other surfaces of each substrate and composite can be further ground and polished. Although such additional grinding and polishing of other surfaces is not necessary to achieve the technical effect of the present invention, it may be more preferable.

[0042] As a preferred embodiment, the two composite materials are preferably austenitic stainless steel. Its chemical composition, by mass percentage, is as follows: C ≤ 0.15%, Si ≤ 1.00%, Mn ≤ 2.00%, P ≤ 0.045%, S ≤ 0.030%, Ni: 6.0-22.0%, Cr: 16.0-26.0%, Mo ≤ 3.0%, with the balance being Fe and unavoidable impurities. Using a stainless steel billet with this chemical composition can further enhance the performance of the composite plate, particularly the corrosion resistance of the composite layer, while maintaining the aforementioned technical effects. For example, the composite layer of the composite plate (i.e., obtained by rolling the composite material) exhibits no intergranular corrosion cracking after being boiled in a sulfuric acid-copper sulfate solution for 20 hours and then bent 180°.

[0043] It should be noted that the chemical compositions of the two composite materials may be the same or different, and only one of them may adopt the chemical composition provided by the above preferred solution, or both of them may adopt the chemical composition provided by the above preferred solution, or neither of them may adopt the chemical composition provided by the above preferred solution.

[0044] As a preferred solution, the two substrates are preferably carbon steel for bridge structures, and their chemical composition is as follows in mass percentage: C: 0.03~0.16%, Si: 0.11~0.29%, Mn: 1.31~1.54%, P≤0.018%, S≤0.0030%, Cr: 0.06~0.29%, Nb: 0.011~0.034%, Ti: 0.011~0.019%, Al: 0.030~0.040%, and the rest is Fe and unavoidable impurities.

[0045] More preferably, the chemical composition of the substrate may further include one, two, or all of the following: Ni: 0.06-0.14%, Mo: 0.11-0.19%, and Cu: 0.16-0.24%, in terms of mass percentage.

[0046] Here, the chemical compositions of the two substrates may be the same or different. Only one of the two substrates may adopt the chemical composition provided by the above preferred solution, or both substrates may adopt the chemical composition provided by the above preferred solution, or neither substrate may adopt the chemical composition provided by the above preferred solution.

[0047] In a further preferred embodiment, the release agent application step specifically includes applying a release agent to a surface of at least one composite material not to be laminated. In this application, "surface not to be laminated" refers to a surface that does not require interfacial bonding when forming the composite panel. For example, surface p5 of composite material 21 and surface p6 of composite material 22 are both considered "surfaces not to be laminated."

[0048] Specifically, the release agent can be applied to the non-combined surface of each composite material, or to one of the two composite materials. In this way, the release agent can prevent the contact surfaces of the two composite materials (i.e., the non-combined surfaces) from bonding during the subsequent composite billet rolling step, making it difficult to separate them.

[0049] A first embodiment of the release agent is a coating solution comprising silicon oxide and magnesium oxide, wherein the mass ratio of silicon oxide to magnesium oxide is 3:1.

[0050] The isolating agent of this embodiment can achieve a good isolation effect and ensure the subsequent separation of the two composite board panels. The total amount of the isolating agent 30 (see Figure 2) between the two composite materials is 18 to 22 mg / m 2 , preferably 20 μg / m 2 y is the ratio of the total thickness of the composite blank obtained in the sealing process to the thickness of the rolled composite plate. This ratio is also known as the composite blank rolling reduction ratio. In a preferred embodiment in which the composite blank comprises substrate 11, composite material 21, composite material 22, and substrate 12 stacked sequentially, the total thickness of the composite blank is the sum of the thicknesses of the two substrates and the two composite materials. After applying the release agent and before the subsequent assembly process, the composite material coated with the release agent is placed in a trolley furnace for heating and drying at a temperature of 340-360°C for 35-45 minutes.

[0051] A second embodiment of the release agent comprises a composition, by weight, of 25-35% silicon nitride, 5-10% thermosetting amino resin, and 55-70% water. Compared to existing release agents, and even compared to the first embodiment of the release agent, this release agent not only achieves excellent isolation, ensuring the subsequent separation of the two composite board panels, but also boasts strong chemical stability and high-temperature and thermal shock resistance from the active ingredient, silicon nitride. The thermosetting amino resin, serving as a binder, cures at low temperatures, is non-toxic, and achieves strong adhesion with minimal usage. Consequently, it offers low cost, ease of operation, and superior isolation and adhesion properties.

[0052] Here, a preferred preparation method of the release agent of the second embodiment is provided, comprising: first placing 5-10% silicon nitride (by weight percentage) in a container such as a beaker, and then pouring in 15-25% water and stirring; after the silicon nitride has no granularity and no bubbles, pouring in 2-3% thermosetting amino resin and continuing to stir; when it becomes viscous, continue to pour in the remaining silicon nitride and water, stir for 3-5 minutes, and then pour in the remaining thermosetting amino resin; when it is stirred until it becomes viscous, the release agent is prepared.

[0053] For the release agent of the second embodiment, the release agent 30 (see Figure 2) between the two composite materials is applied according to a total thickness of 0.2 to 0.5 mm; after the release agent is applied and before the subsequent assembly process, the composite material coated with the release agent is heated and dried at a temperature of 100 to 250°C for 20 to 40 minutes.

[0054] As described above, for the first and second embodiments of the release agent, if the release agent is applied to both surface p5 and surface p6, the amount of release agent applied to each of surface p5 and surface p6 can be half of the total amount / total thickness. If the release agent is applied to only one of surface p5 and surface p6, it shall be applied according to the total amount / total thickness.

[0055] In a further preferred embodiment, the blank assembly process includes: assembling the blank in a manner such that the composite material 21 and the composite material 22 are in the middle, the substrate 11 is stacked on top, the substrate 12 is stacked on the bottom, and the seal surrounds the four sides of the composite material 21 and the composite material 22, and welding the upper edge of the seal (see reference numeral 40 in FIG. 2 ) and the substrate 11, and the lower edge of the seal 40 and the substrate 12 to form a composite blank base blank.

[0056] Further preferably, the substrate 11, the composite material 21, the composite material 22, the substrate 12, and the seal 40 are arranged as a whole as follows:

[0057] 1 and 2 , a substrate 11, a composite material 21, a composite material 22, and a substrate 12 are stacked in sequence from top to bottom; wherein the surfaces of the substrates and the composite materials that are in contact with each other are surfaces to be composited that have undergone the grinding and polishing treatment described above, for example, surface p2 of the substrate 12 and surface p4 of the composite material 22 are in contact with each other, and surface p1 of the substrate 11 and surface p3 of the composite material 21 are in contact with each other; and the surface of the composite material coated with the release agent faces the other composite material, and one of the surface p6 of the composite material 22 and the surface p5 of the composite material 21 is coated with a release agent 30; it should be noted that, for ease of understanding and explanation, the thickness of the release agent 30 between the two composite materials is exaggerated in FIG2 , that is, the ratio of the release agent thickness to the substrate thickness, the composite thickness, and the seal width mentioned later is exaggerated.

[0058] In addition, referring to FIG. 3 , a seal 40 is wrapped around four sides of the composite material 21 and the composite material 22 .

[0059] In a specific implementation, the substrate 11, composite material 21, composite material 22, and substrate 12 can be stacked first, and then the seal 40 can be wrapped around the four sides of the composite materials 21 and 22. Finally, the upper edge of the seal 40 can be welded to the surface p1 of the substrate 11, and the lower edge of the seal 40 can be welded to the surface p2 of the substrate 12. Of course, in a variant embodiment, the lower edge of the seal 40 can also be welded to the surface p2 of the substrate 12 first, so that the seal 40 forms a quadrilateral frame on the surface p2 of the substrate 12. Then, the composite materials 22 and 21 can be placed in the frame, and the composite material 21 and the frame can be covered with the substrate 11. Finally, the upper edge of the seal 40 can be welded to the surface p1 of the substrate 11. In yet another alternative embodiment, the upper edge of the seal 40 may be welded to the surface p1 of the substrate 11, and then the substrate 12, composite material 22, and composite material 21 are stacked in sequence from bottom to top. The combined seal 40 and substrate 11 is then placed over and around the composite materials 21 and 22, and finally, the lower edge of the seal 40 is welded to the surface p2 of the substrate 12. These embodiments do not depart from the technical spirit of the present invention.

[0060] Preferably, gas shielded welding is used to weld the upper edge of the seal 40 to the substrate 11 and the lower edge of the seal 40 to the substrate 12. The welding current during gas shielded welding is 220-240A, the welding voltage is 28-32V, the welding speed is 300-360mm / min, and the interpass temperature is controlled at 140-160°C.

[0061] In addition, before performing gas shielded welding, it is preferred to preheat and bake the base materials 11 and 12 using a flame gun, and the baking temperature is 150-250°C.

[0062] Furthermore, after the upper substrate, the lower substrate, and the middle composite material are stacked, a four-column hydraulic machine is used to pressurize the opposite surfaces of the two substrates, with a pressure of ≥500 tons.

[0063] Furthermore, regarding the dimensions of the seal 40, the width W3 of the seal 40 is equal to or slightly less than the sum of the thicknesses of the composite materials 21 and 22, within 2 mm, and the thickness T3 is between 12 and 15 mm. Preferably, the width W3 and thickness T3 of the seal 40 are the same on all four sides of the composite preform. Furthermore, at the long sides of the composite preform, the length L31 of the seal 40 is L2 minus 0 to 2 mm, preferably L2 minus 1 to 2 mm; while at the short sides of the composite preform, the length L32 of the seal 40 is W2 minus 0 to 2 mm, preferably W2 minus 1 to 2 mm. Of course, this is not limiting.

[0064] Preferably, during the assembly process, the composite is centered relative to the substrate. For example, as previously described, the length and width dimensions of the composite and substrate satisfy L1 = L2 + 90-150 mm, and W1 = W2 + 90-150 mm. During assembly, the distance W01 from the two lateral sides (i.e., long sides) of the composite to the corresponding two lateral sides (i.e., long sides) of the substrate is equal, and this distance W01 is half of W1-W2. The distance W02 from the two longitudinal sides (i.e., short sides) of the composite to the corresponding two lateral sides (i.e., short sides) of the substrate is also equal, and this distance W02 is half of L1-L2.

[0065] Furthermore, the four sides of the resulting composite blank have grooves of depth D, defined by the substrate 11, the seal 40, and the substrate 12. It will be appreciated that the depth D depends on the length and width differences between the composite material and the substrate (e.g., distances W01 and W02), as well as the thickness T3 of the seal 40. Controlling this depth D not only effectively prevents weld cracking during composite blank rolling, but also prevents the formation of weld thermal cracks due to deep penetration during subsequent sealing, which could affect the sealing quality of the composite blank.

[0066] Furthermore, a circular through-hole is formed in the seal 40 on one side of the composite blank base. During the blank assembly process, a round tube is welded into the through-hole. The through-hole can be machined before the gas shielded welding of the seal 40 and the substrates 11 and 12, or it can be machined after the gas shielded welding is completed. All of these remain within the technical scope of this application.

[0067] Preferably, the through hole is opened on the seal 40 on the short side of the composite blank base blank.

[0068] Preferably, the diameter of the through hole is consistent with the outer diameter of the circular tube, which is 8 to 12 mm; and the wall thickness of the circular tube is 1.2 to 2 mm, and the length is 200 to 400 mm.

[0069] In a preferred embodiment, the sealing process includes performing buildup welding on the grooves on the four sides of the composite blank, specifically employing submerged arc buildup welding. As will be appreciated, the sealing process forms a four-sided weld filler layer 50 outside the frame formed by the seal 40, as shown in Figures 2 and 3. The weld filler layer 50 and the seal 40 together form the four sides of the composite blank, which seal the composite material between the two substrates.

[0070] Preferably, the penetration depth of the surfacing filler layer 50 is D, that is, the same as the depth of the groove on the side of the composite blank.

[0071] As a preferred method, before welding, the flux is baked at 350°C for 2 hours and then held at 150°C for 1 hour. During welding, the interpass temperature is controlled between 135°C and 165°C, the welding current is between 570A and 630A, the welding voltage is between 28V and 32V, and the welding speed is between 420mm / min and 480mm / min. This submerged arc cladding technology, combined with the previous sealing and gas shielded welding, achieves a stable connection between the four billets, ensuring joint strength and preventing cracking during subsequent rolling processes, further enhancing the interface bonding effect.

[0072] In addition, during the surfacing process, before each welding operation, the weld attachments need to be cleaned to keep the weld clean; after welding, the weld is covered with thermal insulation cotton for insulation.

[0073] As a preferred embodiment, the vacuuming process includes: vacuuming the inner space of the composite blank three times and breaking the vacuum twice, and finally maintaining the inner space of the composite blank with a vacuum degree of ≤10 -2 Pa.

[0074] Here, the internal space of the composite blank includes the surface gap between the composite material and the base material, the surface gap between the composite materials, the end surface gap between the composite material and the seal, etc. Specifically, the circular tube is connected to the internal space of the composite blank, and the vacuum is pumped three times and the vacuum is broken twice through the circular tube.

[0075] Furthermore, the vacuuming process more specifically includes:

[0076] First, connect the vacuum pump to the round tube to evacuate the inner space of the composite blank for the first time, and the vacuum degree is ≤10 -2 Pa, and then maintain the pressure for more than 4 hours; next, switch the round tube to connect the nitrogen device, break the composite blank and fill it with nitrogen;

[0077] Afterwards, the vacuum pump is connected to the round tube again to evacuate the composite blank for the second time, with a vacuum degree of ≤10 -1 Pa, no pressure maintenance; next, the round tube is switched to connect to the nitrogen device again, the composite blank is broken for the second time and filled with nitrogen;

[0078] Finally, the vacuum pump is connected to the round tube again, and the composite blank is vacuumed for the third time, with a vacuum degree of ≤10 -2 Pa.

[0079] In this way, the air in the space can be prevented from causing surface oxidation at the composite interface during subsequent heating and rolling processes, thereby ensuring the bonding quality of the composite interface.

[0080] Furthermore, the sealing process is to seal the outlet of the composite blank. In a preferred embodiment of the present invention, the outlet is composed of the round tube, which can be implemented in an existing feasible way in the steel field, such as heating and flattening the round tube with a flame gun to achieve sealing and obtain a completed composite blank.

[0081] Next, in one embodiment of the present invention, the heating process, as described above, includes: heating the composite blank in a heating furnace according to a five-stage process of preheating, first heating, second heating, third heating, and soaking, wherein the preheating temperature is ≤850°C, the first heating temperature is 1080±30°C, the second heating temperature is 1160±30°C, the third heating temperature is 1220±20°C, the soaking temperature is 1190±20°C, the dwell time of the third heating is (0.25-0.35)×t min / mm, and the dwell time of the soaking is 15min-30min. In this way, the middle layer of the composite blank is a stainless steel composite material, and the upper and lower layers are carbon steel substrates. The thermal conductivity and expansion coefficient of the two materials are quite different, and there will be large stress during the heating process. The heating process of this embodiment can better control the heating rate of the composite blank in each section, ensure uniform heating, and thus avoid the risks of cracking and air leakage, thereby laying the foundation for obtaining an excellent bonding interface.

[0082] In one embodiment of the present invention, the rolling step, as described above, includes:

[0083] The composite billet coming out of the heating furnace is rolled to produce a large composite plate;

[0084] During the entire rolling process, the first n passes are rolled in the transverse direction, and the n+1th pass and thereafter are rolled in the longitudinal direction. Furthermore, the first pass rolling reduction is ≥25 mm and the rolling temperature is ≥1060°C. The width of the billet obtained by the nth pass rolling is Wt+0~40 mm, where Wt is the target width of the composite plate. The rolling temperature of the nth pass is ≥1030°C.

[0085] Between the nth pass and the n+1th pass and between the n+2th pass and the n+3th pass, the billet is water-cooled once in 6 sets of headers. The cooling water volume of the upper header of each set of headers is 120 to 180 m3. 3 / h, cooling water volume of lower header: 160~220m 3 / h, and the roller speed is 0.8 ~ 1.2m / s; preferably, more preferably, the cooling water volume of the upper header of each group of headers is 150m 3 / h, cooling water volume of lower header 200m 3 / h, and the roller speed is 1m / s;

[0086] The rolling reduction of the n+1th to n+3th passes is ≥40mm, and the rolling temperature of the n+1th pass is ≥950°C; preferably, the rolling reduction of the n+2th pass is ≥42mm;

[0087] At the mth pass, the rolling temperature is ≥900°C, and the billet is rolled to a thickness of 2.5 to 3.5 times the target thickness of the composite plate;

[0088] Then water cooling is carried out until the surface temperature of the blank drops below 840℃;

[0089] Then the second stage of rolling is carried out until the billet thickness reaches the target thickness of the composite plate, completing the entire rolling process. The rolling temperature of the first pass of the second stage of rolling is 810℃~840℃, and the rolling temperature of the last pass is 780℃~810℃.

[0090] In this way, the rolling process of this embodiment can, on the one hand, ensure the deformation penetration effect of the core, facilitate the bonding of the composite material and the substrate, and improve the interface bonding rate and bonding strength of the base layer and the composite layer of the final composite plate; on the other hand, ensure the relevant mechanical properties, corrosion resistance and low-temperature impact toughness of the large composite plate, and avoid performance degradation due to the composite of the substrate and the composite material.

[0091] Furthermore, as a preferred first embodiment, the cooling process includes:

[0092] The rolled composite plate enters the ultra-fast cooling system for cooling, with the starting cooling temperature ≥ 730°C, the cooling rate 6-20°C / s, and the final cooling temperature 480-590°C;

[0093] After leaving the ultra-fast cooling system, the composite panels are air-cooled on a cooling bed until they reach room temperature.

[0094] As a more preferred second embodiment, the cooling process includes:

[0095] The rolled composite plate enters an ultra-rapid cooling system for cooling: the ultra-rapid cooling system has 24 groups of cooling manifolds arranged at intervals of 1 meter along the roller table, and the cooling distance of each group of cooling manifolds is 1 meter. When the composite plate passes through the ultra-rapid cooling system, the opening and closing states of all 24 groups of cooling manifolds are controlled by opening N groups of cooling manifolds and then closing M groups of cooling manifolds. The cooling water pressure is 0.15-0.30 MPa, the cooling rate is 3-15°C / s, and the final cooling temperature is 380-590°C. Wherein N is 2, 3 or 4, and M is 2, 3 or 4.

[0096] After leaving the ultra-fast cooling system, the composite panels are air-cooled on a cooling bed until they reach room temperature.

[0097] In this second embodiment, the clad plate passes through the ultra-rapid cooling system, alternating between opening and closing the cooling manifolds. This way, every part of the clad plate cools, then returns to a red state, cools, returns to a red state, and repeats this cycle until the clad plate leaves the ultra-rapid cooling system. During this cooling and red state cycle, the carbon steel substrate undergoes a continuous phase transformation and auto-tempering effect, with the phase transformation reaction gradually permeating the core until the entire carbon steel substrate has undergone the phase transformation. This intermittent cooling process differs from conventional reciprocating cooling. In reciprocating cooling, the annealing and self-tempering occur after the surface or near-surface phase transition has completed, resulting in significant temperature differences or cooling rates between the surface and core, and consequently, significant differences in microstructure and mechanical properties. In contrast, the intermittent cooling process of this embodiment allows for simultaneous cooling of some areas of the composite panel and annealing / self-tempering of others. Furthermore, each area of ​​the composite panel alternates between cooling and annealing over time, minimizing differences in temperature, cooling rate, microstructure, and mechanical properties between the surface and core. For example, the resulting composite panel exhibits a Vickers hardness difference of ≤10 across the thickness of the base layer, a head-to-tail strength difference of ≤40 MPa, and a strength difference of ≤40 MPa across the entire panel. Furthermore, intermittent cooling further improves the composite panel's shape, resulting in reduced unevenness. Even after cooling, excellent panel shape can be achieved by direct cooling on a cooling bed without straightening.

[0098] Further preferably, in the cooling process, when the thickness of the composite plate slab is less than 54 mm, for example, when the thickness is 10 to 54 mm, the roller speed of the ultra-rapid cooling system is 0.4 to 0.8 m / s, and the composite plate slab passes through the ultra-rapid cooling system once before exiting the ultra-rapid cooling system. Furthermore, the 24 cooling manifold groups can be controlled in the following manner: cooling manifold groups 1 to 4 are enabled, cooling manifold groups 5 to 6 are disabled, cooling manifold groups 7 to 8 are enabled, cooling manifold groups 9 to 10 are disabled, cooling manifold groups 11 to 12 are enabled, cooling manifold groups 13 to 14 are disabled, cooling manifold groups 15 to 16 are enabled, cooling manifold groups 17 to 18 are disabled, cooling manifold groups 19 to 20 are enabled, cooling manifold groups 21 to 22 are disabled, and cooling manifold groups 23 to 24 are enabled.

[0099] In the cooling process, when the thickness of the composite plate is greater than 54 mm, for example, when the thickness is greater than 54 mm and less than 70 mm, the roller speed of the ultra-fast cooling system is greater than 0.2 m / s and less than 0.6 m / s, and the composite plate passes through the ultra-fast cooling system once and then leaves the ultra-fast cooling system. In this way, the shape control and uniformity control of the thick stainless steel composite plate are achieved, overcoming the production difficulties of the existing thick stainless steel composite plate. In addition, the control mode of the 24 groups of cooling manifolds can be: the 1st to 4th groups of cooling manifolds are turned on, the 5th to 8th groups of cooling manifolds are not turned on, the 9th to 12th groups of cooling manifolds are turned on, the 13th to 16th groups of cooling manifolds are not turned on, the 17th to 20th groups of cooling manifolds are turned on, the 21st to 22nd groups of cooling manifolds are not turned on, and the 23rd to 24th groups of cooling manifolds are turned on.

[0100] In the cooling process, when the thickness of the composite plate slab is ≥70 mm, for example, when the thickness is between 70 mm and 110 mm, the roller speed of the ultra-rapid cooling system is 0.4 to 0.9 m / s. The composite plate slab first enters the ultra-rapid cooling system entrance in the forward direction. When its head reaches the 24th group of cooling manifolds, the rollers reverse direction, and the composite plate slab passes through the ultra-rapid cooling system in the reverse direction and exits the ultra-rapid cooling system entrance. In this way, the plate shape and uniformity control of the extra-thick stainless steel composite plate are achieved, overcoming the production difficulties of existing extra-thick stainless steel composite plates. In addition, the control mode of the 24 groups of cooling manifolds can be: cooling manifolds of groups 1 to 4 are open, cooling manifolds of groups 5 to 8 are closed, cooling manifolds of groups 9 to 12 are open, cooling manifolds of groups 13 to 16 are closed, cooling manifolds of groups 17 to 20 are open, cooling manifolds of groups 21 to 22 are closed, and cooling manifolds of groups 23 to 24 are open.

[0101] As a preferred embodiment, the panel separation process includes: cutting the four sides of the large composite board to remove the portion other than the seal, and separating the large composite board into two upper and lower composite board small boards.

[0102] The "portion outside the seal" refers to the edge of the composite plate, which is formed from the seal 40 and the weld filler layer 50 in the composite billet mentioned above after the previous rolling process. This portion is removed to expose the stainless steel cladding. Without the connecting function of these edge portions, the composite plate automatically separates into two small composite plates, one above the other.

[0103] As a preferred embodiment, the straightening process includes: sizing, flattening and cold straightening the composite plate small plate to obtain two single-sided stainless steel composite plate finished products.

[0104] Refer to Figure 4, which shows two corresponding finished single-sided stainless steel clad plates. Each stainless steel clad plate consists of a cladding layer and a base layer. The cladding layer is rolled from the original cladding material, and the base layer is rolled from the original base material. Therefore, in Figure 4, the cladding layer is still labeled with the original cladding material number, and the base layer is still labeled with the original base material number.

[0105] Next, an embodiment of the present invention further provides a stainless steel composite plate, which is prepared by the preparation method described in any of the above embodiments. The base layer of the stainless steel composite plate is carbon steel, and the cladding layer is stainless steel.

[0106] The total thickness of the stainless steel composite plate is 15-39 mm, the thickness of the base layer is 12-36 mm, and the thickness of the composite layer is 1-5 mm.

[0107] Specifically, the single-sided stainless steel composite plate according to one embodiment of the present invention was sampled in accordance with GB / T 2975-Steel and Steel Products-"Sampling Location and Sample Preparation for Mechanical Properties Tests", and:

[0108] In terms of interface bonding quality, the composite plate was subjected to a tensile test in accordance with GB / T 6396-Test Methods for Mechanical and Process Properties of Composite Steel Plates. The composite plate showed a composite interface bonding rate of 100% and a shear strength of ≥360MPa, which is much higher than that of existing composite plates.

[0109] In terms of plate shape, the test is carried out in accordance with GB / T 709- "Dimensions, shape, weight and allowable deviations of hot-rolled steel plates and steel strips". The unevenness of the composite plate is ≤3mm / m, and even ≤2mm / m.

[0110] In terms of uniformity, tensile tests were conducted in accordance with GB / T 6396- "Test methods for mechanical and process properties of composite steel plates" and GB / T 228.1- "Tension tests on metallic materials - Part 1: Test methods at room temperature". The Vickers hardness difference in the thickness direction of the base layer of the composite plate was ≤10, the head-middle-tail strength difference was ≤40MPa, and the strength difference across the entire plate was ≤40MPa.

[0111] In terms of low-temperature impact toughness, the test was carried out in accordance with GB / T 6396-"Test methods for mechanical and process properties of composite steel plates" and GB / T 229-"Charpy pendulum impact test method for metallic materials". The impact energy of the composite plate at 0°C is ≥240J, the impact energy at -20°C is ≥200J, and the impact energy at -40°C is ≥150J.

[0112] The detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0113] The beneficial effects of the present invention are further illustrated below through a plurality of embodiments. Of course, these embodiments are only a part of the many variations of the present invention, but not all of them.

[0114] Examples 1 to 4 each provide a single-sided stainless steel composite plate, comprising a carbon steel base layer and a stainless steel cladding layer. The thickness, base layer thickness and material, and cladding layer thickness and material of the composite plates of these examples are shown in Table 1. The specific chemical composition of each material in Table 1 is disclosed in the appendix to Table 1.

[0115] Table 1

[0116] Furthermore, composite panels from various examples were sampled and tested. All examples demonstrated a 100% interfacial bonding rate, a passing 180° inward bend (no cracks), and a passing 180° outward bend (no cracks). Furthermore, after being boiled in a sulfuric acid-copper sulfate solution for 20 hours and then bent 180°, the composite layer showed no intergranular corrosion cracks. Other performance test results are shown in Table 2.

[0117] Table 2

[0118] The preparation methods of the above embodiments are introduced below according to the process.

[0119] <Steel Billet Preparation Process>

[0120] Two substrates and two composites of the same size were prepared. The materials of the substrates and composites were consistent with the materials of the base layer and the composite layer of the composite board, respectively, as shown in Table 1. The sizes of the substrates and composites of various embodiments are shown in Table 3.

[0121] Table 3

[0122] The surfaces of each substrate and each composite material to be composited are subjected to grinding and polishing treatment; after the grinding and polishing treatment, the surfaces to be composited are free of oxide scale, revealing metallic luster, and the surface roughness Ra is less than 5 μm.

[0123] <Coating release agent>

[0124] For one of the two substrates, a release agent is applied to the surface not to be composited.

[0125] The release agent used in Examples 1 and 3 is a coating liquid containing silicon oxide and magnesium oxide, wherein the mass ratio of silicon oxide to magnesium oxide is 3:1. The total amount of the release agent applied is 140 mg / m 2After the release agent is applied, the composite material coated with the release agent is placed in a trolley furnace for heating and drying. The drying temperature is 350°C and the drying time is 40 minutes.

[0126] The release agent used in Examples 2 and 4 consisted of a weight ratio of 25-35% silicon nitride, 5-10% thermosetting amino resin, and 55-70% water. The release agent was applied to a thickness of 0.35 mm. After application, the composite was heated and dried at a temperature of 100-250°C for 20-40 minutes.

[0127] <Assembly process>

[0128] In each embodiment, the substrate A, composite A, composite B, and substrate B are stacked in order from bottom to top; wherein the surface of substrate A to be composited is in contact with the surface of composite A to be composited, the surface of substrate B to be composited is in contact with the surface of composite B to be composited, the release agent is located between composite A and composite B, and the two composites are centered relative to the two substrates (i.e., W01 is 60 mm and W02 is 60 mm as described above).

[0129] After the base material A, composite material A, composite material B, and base material B are stacked, a four-column hydraulic machine is used to pressurize the opposite surfaces of the two base materials with a pressure of ≥500 tons.

[0130] In each example, two long and two short seals were prepared. The dimensions of the two long and two short seals are shown in Table 3 above. The four seals were used to surround the two composite materials, with the upper edges of the seals welded to substrate B and the lower edges welded to substrate A. Furthermore, a through-hole with a diameter of 10 mm was machined in the center of one of the short seals. A circular tube with an outer diameter matching the through-hole diameter, a wall thickness of 1.2 to 2 mm, and a length of 200 to 400 mm was welded into the through-hole.

[0131] <Sealing process - Vacuuming process - Sealing process>

[0132] For the composite billet base prepared in the previous billet assembly process, submerged arc surfacing is used to fill the grooves on the four sides of the composite billet base, that is, the surfacing penetration depth is the same as the depth of the groove.

[0133] Then, the internal space of the composite blank is vacuumed three times and broken twice, and finally the internal space of the composite blank is kept at a vacuum degree of ≤10 -2 Pa.

[0134] Afterwards, the round tube is sealed to obtain a composite blank.

[0135] <Heating process>

[0136] In each embodiment, the composite blank is heated in a heating furnace according to a five-stage process of a preheating stage, a first heating stage, a second heating stage, a third heating stage, and a soaking stage. The specific temperatures and times are shown in Table 4.

[0137] Table 4

[0138] <Rolling process>

[0139] The composite billet coming out of the heating furnace is rolled to produce a composite plate. During the entire rolling process, the first n passes are rolled transversely, and the n+1 pass and thereafter are rolled longitudinally. The width of the billet obtained by rolling the nth pass is Wt+0~40mm, where Wt is the target width of the composite plate. Between the nth pass and the n+1th pass, and between the n+2nd pass and the n+3rd pass, the billet is water-cooled once in 6 groups of headers, and the cooling water volume of the upper header of each group of headers is 120~180m 3 / h, cooling water volume of lower header: 160~220m 3 / h, and the roller speed is 0.8~1.2m / s; the rolling reduction from the n+1th pass to the n+3th pass is ≥40mm; at the mth pass, the billet is rolled to a thickness of 2.5~3.5 times the target thickness of the composite plate; then water cooling is carried out until the surface temperature of the billet drops below 840℃; then the second stage rolling is carried out until the billet thickness reaches the target thickness of the composite plate, completing the entire rolling process; other parameters are shown in Table 5.

[0140] Table 5

[0141] <Cooling process>

[0142] An ultra-fast cooling system is used, which has 24 groups of cooling headers arranged at intervals of 1m along the roller table, and the cooling distance of each group of cooling headers is 1m.

[0143] The composite panels of Examples 1 and 2 were cooled in an ultra-rapid cooling system with a starting temperature of 770°C, a cooling rate of 12°C / s, and a final cooling temperature of 550°C. After leaving the ultra-rapid cooling system, the composite panels were air-cooled on a cooling bed until they reached room temperature.

[0144] The composite panel slabs of Examples 3 and 4 were cooled in an ultra-rapid cooling system. As the composite panel slabs passed through the ultra-rapid cooling system, the opening and closing states of all 24 cooling manifolds were controlled by opening N sets of cooling manifolds and then closing M sets of cooling manifolds. The cooling water pressure was 0.15-0.30 MPa, the cooling rate was 3-15°C / s, and the final cooling temperature was 380-590°C. N was 2, 3, or 4, and M was 2, 3, or 4. After leaving the ultra-rapid cooling system, the composite panel slabs were air-cooled on a cooling bed until they reached room temperature. For specific parameters in each example, such as the composite panel thickness, cooling water pressure, cooling rate, final cooling temperature, roller speed, number of passes through the ultra-rapid cooling system (referred to as water passes), and cooling manifold opening and closing methods, please refer to Table 6.

[0145] Table 6

[0146] <Plate separation process-straightening process>

[0147] Cut the four sides of the large composite board to remove the parts other than the seal, and separate the large composite board into two small composite boards, one above the other.

[0148] Afterwards, the composite plate was sized, flattened, and cold-straightened to obtain the stainless steel composite plates of various embodiments (such as the composite plates mentioned in Table 1 and Table 2).

[0149] From the above, it can be seen that the preparation method provided by the preferred embodiment of the present invention, through technical improvements in the heating process and the rolling process, the stainless steel composite plate obtained, compared with the existing technology, not only ensures excellent mechanical properties and corrosion resistance, but also improves the interface bonding performance, thereby greatly increasing the interface bonding strength; and further, through other further preferred schemes such as the cooling process, the assembly process, and the vacuum process, the composite plate can also have excellent plate shape, uniformity and impact toughness.

Claims

1. A method for preparing a stainless steel composite plate, characterized in that: The method comprises the following steps: A composite blank with a thickness of t is prepared by preparing a steel blank, coating a release agent, assembling the blank, sealing and welding, vacuuming, and sealing; the composite blank comprises an upper substrate, a lower substrate, a middle composite material, and four frames for sealing the middle composite material between the upper substrate and the lower substrate; The composite blank is heated in a heating furnace according to a five-stage method of a preheating stage, a first heating stage, a second heating stage, a third heating stage and a soaking stage, wherein the temperature of the preheating stage is ≤850°C, the temperature of the first heating stage is 1080±30°C, the temperature of the second heating stage is 1160±30°C, the temperature of the third heating stage is 1220±20°C, the temperature of the soaking stage is 1190±20°C, the residence time of the third heating stage is (0.25-0.35)×t min / mm, and the residence time of the soaking stage is 15min-30min; The composite billet coming out of the heating furnace is rolled to obtain a large composite plate; during the entire rolling process, the first n passes are rolled transversely, and the n+1 pass and thereafter are rolled longitudinally, and the first pass rolling reduction is ≥25mm and the rolling temperature is ≥1060°C, the width of the billet obtained by the nth pass rolling is Wt+0~40mm, Wt is the target width of the large composite plate, and the rolling temperature of the nth pass is ≥1030°C; between the nth pass and the n+1th pass and between the n+2nd pass and the n+3rd pass, the billet is water-cooled once in 6 groups of headers, and the cooling water volume of the upper header of each group of headers is 120~180m 3 / h, cooling water volume of lower header 160~220m 3 / h, and the roller speed is 0.8~1.2m / s; the rolling reduction from the n+1th pass to the n+3th pass is ≥40mm, and the rolling temperature of the n+1th pass is ≥950℃; when it comes to the mth pass, the rolling temperature is ≥900℃, and the billet is rolled to a thickness of 2.5~3.5 times the target thickness of the composite plate; then water cooling is carried out until the surface temperature of the billet drops below 840℃; then the second stage of rolling is carried out until the billet thickness is the target thickness of the composite plate, and the whole rolling process is completed. The rolling temperature of the first pass of the second stage rolling is 810℃~840℃, and the rolling temperature of the last pass is 780~810℃; The obtained composite plate is cooled, split and straightened to obtain a stainless steel composite plate product.

2. The method for preparing a stainless steel composite plate according to claim 1, characterized in that: The rolling reduction of the n+2th pass is ≥42mm.

3. The method for preparing a stainless steel composite plate according to claim 1, characterized in that: The cooling process of the step "cooling, splitting and straightening the obtained composite plate to obtain a stainless steel composite plate product" includes: The rolled composite plate enters the ultra-fast cooling system for cooling, with the start cooling temperature ≥730°C, the cooling rate 6-20°C / s, and the final cooling temperature 480-590°C; After leaving the ultra-fast cooling system, the composite board is air-cooled on a cooling bed to room temperature.

4. The method for preparing a stainless steel composite plate according to claim 1, characterized in that: The cooling process of the step "cooling, splitting and straightening the obtained composite plate to obtain a stainless steel composite plate product" includes: The large composite plate obtained by rolling enters the ultra-fast cooling system for cooling: the ultra-fast cooling system has 24 groups of cooling manifolds arranged at intervals of 1m along the roller table, and the cooling distance of each group of cooling manifolds is 1m. When the large composite plate passes through the ultra-fast cooling system, the opening and closing states of all 24 groups of cooling manifolds are controlled in a manner of opening N groups of cooling manifolds and then not opening M groups of cooling manifolds. The cooling water pressure is 0.15-0.30MPa, the cooling rate is 3-15℃ / s, and the final cooling temperature is 380-590℃; wherein N is 2, 3 or 4, and M is 2, 3 or 4.

5. The method for preparing a stainless steel composite plate according to claim 4, characterized in that: The cooling process of the step "cooling, splitting and straightening the obtained composite plate to obtain a stainless steel composite plate product" includes: After leaving the ultra-fast cooling system, the composite board is air-cooled on a cooling bed to room temperature.

6. The method for preparing a stainless steel composite plate according to claim 4, characterized in that: The thickness of the large composite board is below 54 mm, the roller speed of the ultra-fast cooling system is 0.4-0.8 m / s, and the large composite board passes through the ultra-fast cooling system once and then leaves the ultra-fast cooling system.

7. The method for preparing a stainless steel composite plate according to claim 4, characterized in that: The thickness of the large composite plate is greater than 54 mm, the roller speed of the ultra-fast cooling system is greater than 0.2 m / s and less than 0.6 m / s, and the large composite plate passes through the ultra-fast cooling system once and then leaves the ultra-fast cooling system.

8. The method for preparing a stainless steel composite plate according to claim 4, characterized in that: When the thickness of the large composite plate is ≥70mm, the roller speed of the ultra-fast cooling system is 0.4-0.9m / s. The large composite plate first enters the ultra-fast cooling system in the forward direction. When its head reaches the 24th group of cooling manifolds, the roller reverses, and the large composite plate passes through the ultra-fast cooling system in the reverse direction and leaves the ultra-fast cooling system inlet.

9. The method for preparing a stainless steel composite plate according to claim 1, characterized in that: The vacuuming process in the step of "preparing a composite billet with a thickness of t by preparing a steel billet, coating a release agent, assembling billets, sealing, vacuuming, and sealing" includes: The internal space of the composite blank is vacuumed three times and broken twice, and finally the internal space of the composite blank is kept at a vacuum degree of ≤10 -2 Pa.

10. The method for preparing a stainless steel composite plate according to claim 9, characterized in that: Step "Evacuate the inner space of the composite blank three times and break the vacuum twice, and finally keep the inner space of the composite blank at a vacuum degree of ≤10 -2 "Pa" includes: First, vacuum the internal space of the composite blank to a vacuum degree of ≤10 -2 Pa, and then maintain the pressure for more than 4 hours; then the composite blank is vented and filled with nitrogen; After that, the composite blank is vacuumed to a vacuum degree of ≤10 -1 Pa, without pressure maintenance; next, the composite blank is emptied and filled with nitrogen; Finally, the composite blank is vacuumed for the third time, and the vacuum degree is ≤10 -2 Pa.

11. The method for preparing a stainless steel composite plate according to claim 1, characterized in that: In the composite blank obtained in the step of "preparing a steel blank, applying a release agent, assembling the blanks, sealing and welding, evacuating, and sealing to prepare a composite blank having a thickness of t": The middle layer composite material includes two composite materials arranged in a stacked manner; The four frames include sealing strips surrounding the four sides of the middle substrate, and a surfacing filling layer located in a groove surrounded by the upper substrate, the lower substrate and the sealing strips.

12. The method for preparing a stainless steel composite plate according to claim 11, characterized in that: The upper edge of the seal strip and the upper substrate, and the lower edge and the lower substrate are welded together by gas shielded welding.

13. The method for preparing a stainless steel composite plate according to claim 11, characterized in that: The process of coating the release agent in the step of "preparing a steel billet, coating the release agent, assembling the billets, sealing and welding, vacuuming, and sealing to prepare a composite billet having a thickness of t" includes: A release agent is applied on at least one of the contacting surfaces of the two composite materials.

14. The method for preparing a stainless steel composite plate according to claim 13, characterized in that: The release agent used is a coating liquid containing silicon oxide and magnesium oxide, wherein the mass ratio of silicon oxide to magnesium oxide is 3:

1.

15. The method for preparing a stainless steel composite plate according to claim 14, characterized in that: The total amount of the release agent applied between the two composite materials is 18-22 mg / m 2 , y is the ratio of the sum of the thickness of the two composite materials and the two base materials to the thickness of the composite board.

16. The method for preparing a stainless steel composite plate according to claim 13, characterized in that: The components of the isolation agent used are as follows by weight: 25-35% of silicon nitride, 5-10% of thermosetting amino resin, and 55-70% of water.

17. The method for preparing a stainless steel composite plate according to claim 16, characterized in that: The total thickness of the isolation agent applied between the two composite materials is 0.2 to 0.5 mm.

18. The method for preparing a stainless steel composite plate according to claim 1, characterized in that: In the assembly process of the step "preparing a composite billet with a thickness of t by preparing a steel billet, coating an isolation agent, assembling the billets, sealing and welding, vacuuming, and sealing", the upper substrate, the lower substrate, and the middle composite material are stacked and placed, and then a four-column hydraulic machine is used to pressurize the opposite surfaces of the two substrates, and the pressure is ≥500 tons.

19. A stainless steel composite plate, characterized in that: The shear strength of the bonding interface of the stainless steel composite plate is ≥360MPa. During the preparation of the stainless steel composite plate, the composite blank consisting of the upper substrate, the lower substrate and the middle composite material is heated and then rolled into a large composite plate. During the rolling process, the first n passes are rolled transversely, and the n+1 pass and thereafter are rolled longitudinally, and the first pass rolling reduction is ≥25mm and the rolling temperature is ≥1060℃, the width of the billet obtained by the nth pass rolling is Wt+0~40mm, Wt is the target width of the composite plate, and the rolling temperature of the nth pass is ≥1030℃; between the nth pass and the n+1th pass and between the n+2nd pass and the n+3rd pass, the billet is water-cooled once in 6 sets of headers, and the cooling water volume of the upper header of each set of headers is 120~180m 3 / h, cooling water volume of lower header 160~220m 3 / h, and the roller speed is 0.8~1.2m / s; the rolling reduction from the n+1th to the n+3th pass is ≥40mm, and the rolling temperature of the n+1th pass is ≥950℃; when it comes to the mth pass, the rolling temperature is ≥900℃, and the billet is rolled to a thickness of 2.5~3.5 times the target thickness of the composite plate; then water cooling is carried out until the surface temperature of the billet drops below 840℃; then the second stage of rolling is carried out until the billet thickness is the target thickness of the composite plate, completing the entire rolling process, the first rolling temperature of the second stage rolling is 810℃~840℃, and the rolling temperature of the last pass is 780~810℃.

20. The stainless steel composite plate according to claim 19, characterized in that: The base layer of the composite plate is carbon steel, and the composite layer is stainless steel.

Images