Stainless steel clad sheet with excellent interfacial bonding properties and method for manufacturing the same

Abstract

This invention discloses a stainless clad steel sheet with excellent interfacial bonding properties and a method for manufacturing the same. In the rolling process of the above method, after n widthwise rolling, longitudinal rolling is performed, with the first reduction amount ≥ 25 mm and temperature ≥ 1060 °C, the target width being reached in the nth roll, and the temperature in the nth roll ≥ 1030 °C. After the nth and (n+2)th rolls, the sheet is water-cooled once in a reciprocating cycle using six sets of headers, with the cooling water volume in the upper and lower headers being 120 to 180 ml, respectively. 3 / h, 160~220m 3 The rolling speed is 0.8 to 1.2 m / s per hour. The reduction amount from the (n+1)th to the (n+3)th pass is ≥ 40 mm, and the temperature of the (n+1)th pass is ≥ 950°C. In the mth pass, the temperature reaches ≥ 900°C, and the clad steel sheet reaches 2.5 to 3.5 times the target thickness. After that, it is cooled by water spraying until the surface temperature of the material is 840°C or lower. Then the second stage of rolling is performed, with the temperature of the first pass of this stage being 810°C to 840°C and the temperature of the final pass being 780°C to 810°C.

Description

[Technical Field]

[0001] This invention belongs to the field of steel material manufacturing technology and relates to stainless clad steel sheets with excellent interfacial bonding properties and a method for manufacturing the same. [Background technology]

[0002] Stainless steel clad sheets are composite materials in which stainless steel is used as the clad layer and carbon steel or low-alloy steel is used as the base material, and these materials are integrally bonded together using a specific process. Stainless steel clad sheets not only possess the corrosion resistance of the stainless steel clad layer, but also the excellent mechanical properties and cost advantages of the carbon steel base material, making them one of the important development directions for steel materials. Furthermore, in the process of using stainless steel clad sheets, there are requirements for the bonding performance (shear strength, bonding ratio) of the bonding interface between the base material and the clad layer, and the quality of the interface bonding performance has a significant impact on the quality of construction work using stainless steel clad sheets.

[0003] However, in the currently known production technologies for stainless steel clad sheets, while basic manufacturing methods for clad sheets are disclosed, such as in the patent technologies with Chinese publication numbers CN105945067A and CN111530927A, attention is not paid to interfacial bonding performance, and no process means to improve interfacial bonding performance are further disclosed in the prior art. [Overview of the project]

[0004] The object of the present invention is to provide a stainless steel clad sheet with excellent interfacial bonding properties and a method for manufacturing the same.

[0005] To achieve the object of the above invention, one embodiment of the present invention provides a method for manufacturing a stainless clad steel sheet with excellent interfacial bonding properties. The method is A process for manufacturing a composite material of thickness t, comprising the steps of preparing steel materials, applying a release agent, lamination, seal welding, vacuuming, and sealing, wherein the composite material includes an upper base material, a lower base material, an intermediate cladding material, and a quadrilateral frame that seals the intermediate cladding material between the upper and lower base materials. A process of heating the composite material in a heating furnace in five stages: a preheating zone, a first heating zone, a second heating zone, a third heating zone, and a uniform zone, wherein the preheating zone temperature is ≤850°C, the first heating zone temperature is 1080±30°C, the second heating zone temperature is 1160±30°C, the third heating zone temperature is 1220±20°C, the uniform zone temperature is 1190±20°C, the residence time in the third heating zone is (0.25~0.35)×t min / mm, and the residence time in the uniform zone is 15 min~30 min. The process involves rolling a composite material removed from a heating furnace to produce a large sheet of clad steel, wherein the first n rolls in the entire rolling process are widthwise, and the (n+1)th rolls onward are longitudinal. The reduction amount of the first roll is ≥ 25 mm and the rolling temperature is ≥ 1060°C. The width of the material obtained from the nth roll is Wt + (0~40) mm, where Wt is the target width of the large sheet of clad steel. The rolling temperature for the nth roll is ≥ 1030°C. Between the nth and (n+1)th rolls, and between the (n+2)th and (n+3)th rolls, the material is water-cooled once in a reciprocating motion using six sets of headers, with a cooling water volume of 120~180 m³ in the upper header of each set of headers. 3 / h, the cooling water volume in the lower header is 160-220m 3 The process involves a roll table speed of 0.8-1.2 m / s, a reduction in rolling volume from the (n+1)th to the (n+3)th roll all being ≥40 mm, a rolling temperature of ≥950°C in the (n+1)th roll, a rolling temperature of ≥900°C in the mth roll, rolling until the material thickness is 2.5-3.5 times the target thickness of the clad steel sheet, then water cooling until the surface temperature of the material is 840°C or lower, followed by a second stage of rolling, where the material thickness is rolled until the material thickness is the target thickness of the clad steel sheet to complete the entire rolling process, with the first rolling temperature of the second stage being 810°C-840°C and the final rolling temperature being 780-810°C. The process includes the steps of cooling, dividing, and straightening the resulting large sheet of clad steel to obtain stainless steel clad steel product.

[0006] To achieve the objective of the above invention, one embodiment of the present invention provides a stainless steel clad sheet with excellent interfacial bonding properties. The shear strength of the bonding interface of the stainless steel clad sheet is ≥ 360 MPa, and in the manufacturing process of the stainless steel clad sheet, a composite material consisting of an upper base material, a lower base material, and an intermediate clad material is heated and then rolled to form a large sheet of clad steel.

[0007] The first n rolls in the entire rolling process are widthwise rolling, and from the (n+1)th roll onwards, longitudinal rolling is used. The reduction amount of the first roll is ≥25 mm and the rolling temperature is ≥1060°C. The width of the material obtained from the nth roll is Wt + (0~40) mm, where Wt is the target width of the large clad steel sheet. The rolling temperature for the nth roll is ≥1030°C. Between the nth and (n+1)th rolls, and between the (n+2)th and (n+3)th rolls, the material is water-cooled once in a reciprocating motion using six sets of headers, with a cooling water volume of 120~180 m³ in the upper header of each set of headers. 3 / h, the cooling water volume in the lower header is 160-220m 3 The rolling speed is 0.8 to 1.2 m / s, the reduction amount for the (n+1)th to (n+3)th rolling passes is all ≥ 40 mm, the rolling temperature for the (n+1)th pass is ≥ 950°C, the rolling temperature for the mth pass is ≥ 900°C, the material is rolled until its thickness is 2.5 to 3.5 times the target thickness of the clad steel sheet, then water cooling is performed until the surface temperature of the material is 840°C or lower, then the second stage of rolling is performed, the material is rolled until its thickness is the target thickness of the clad steel sheet, completing the entire rolling process, the rolling temperature for the first pass of the second stage is 810°C to 840°C, and the rolling temperature for the last pass is 780°C to 810°C.

[0008] Compared to conventional technology, the advantageous effect of the present invention is that, by manufacturing the composite material and improving the heating and rolling techniques applied to the composite material, temperature uniformity of the composite material is ensured on the one hand, and effective diffusion and penetration into the center of the composite material is guaranteed on the other hand. This not only allows the advantages of each material, the base material and the cladding material, to be realized, but more importantly, it ensures excellent bonding strength at the bonding interface between the base material and the cladding material. [Brief explanation of the drawing]

[0009] For clear representation and explanation, in each drawing of the present invention, the dimensions of some structures or parts are enlarged relative to other structures or parts, and are used solely to illustrate the basic structure of the subject matter of the present invention. [Figure 1] Figure 1 is a schematic cross-sectional view of a steel material used in a manufacturing method of one embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view of a composite material in a manufacturing method of one embodiment of the present invention. The cross-section is perpendicular to the longitudinal direction of the composite material. [Figure 3] Figure 3 is a schematic cross-sectional view of another composite material in a manufacturing method of one embodiment of the present invention. The cross-section is perpendicular to the thickness direction of the composite material. [Figure 4] Figure 4 is a schematic cross-sectional view of a clad steel sheet obtained by a manufacturing method according to one embodiment of the present invention. [Modes for carrying out the invention]

[0010] One embodiment of the present invention provides a method for manufacturing a stainless steel clad sheet for producing a single-sided stainless steel clad sheet consisting of a carbon steel base material and a stainless steel clad layer, wherein the resulting stainless steel clad sheet has excellent interfacial bonding performance, that is, the strength of the bonding interface between the base material and the clad layer is excellent.

[0011] The aforementioned manufacturing method includes processes such as preparing the steel material, applying a release agent, lamination, seal welding, vacuuming, sealing, heating, rolling, cooling, splitting, and straightening. Specifically, A process for manufacturing a composite material of thickness t, comprising the steps of preparing steel materials, applying a release agent, lamination, seal welding, vacuuming, and sealing, wherein the composite material includes an upper base material, a lower base material, an intermediate cladding material, and a quadrilateral frame that seals the intermediate cladding material between the upper and lower base materials. A process of heating the composite material in a heating furnace in five stages: a preheating zone, a first heating zone, a second heating zone, a third heating zone, and a uniform zone, wherein the preheating zone temperature is ≤850°C, the first heating zone temperature is 1080±30°C, the second heating zone temperature is 1160±30°C, the third heating zone temperature is 1220±20°C, the uniform zone temperature is 1190±20°C, the residence time in the third heating zone is (0.25~0.35)×t min / mm, and the residence time in the uniform zone is 15 min~30 min. The process involves rolling a composite material removed from a heating furnace to produce a large sheet of clad steel, wherein the first n rolls in the entire rolling process are widthwise, and the (n+1)th rolls onward are longitudinal. The reduction amount of the first roll is ≥ 25 mm and the rolling temperature is ≥ 1060°C. The width of the material obtained from the nth roll is Wt + (0~40) mm, where Wt is the target width of the large sheet of clad steel. The rolling temperature for the nth roll is ≥ 1030°C. Between the nth and (n+1)th rolls, and between the (n+2)th and (n+3)th rolls, the material is water-cooled once in a reciprocating motion using six sets of headers, with a cooling water volume of 120~180 m³ in the upper header of each set of headers. 3 / h, the cooling water volume in the lower header is 160-220m 3 The process involves a roll table speed of 0.8-1.2 m / s, a reduction in rolling volume from the (n+1)th to the (n+3)th roll all being ≥40 mm, a rolling temperature of ≥950°C in the (n+1)th roll, a rolling temperature of ≥900°C in the mth roll, rolling until the material thickness is 2.5-3.5 times the target thickness of the clad steel sheet, then water cooling until the surface temperature of the material is 840°C or lower, followed by a second stage of rolling, where the material thickness is rolled until the material thickness is the target thickness of the clad steel sheet to complete the entire rolling process, with the first rolling temperature of the second stage being 810°C-840°C and the final rolling temperature being 780-810°C. The process includes the steps of cooling, dividing, and straightening the resulting large sheet of clad steel to obtain stainless steel clad steel product.

[0012] Thus, in one embodiment of the present invention, by manufacturing the composite material and implementing the above-described heating and rolling techniques, particularly the overall scheme of the rolling process, for the composite material, on the one hand, the temperature uniformity of the composite material is ensured, and on the other hand, effective diffusion penetration into the central portion of the composite material is guaranteed. Thereby, not only can the advantages of each of the base material and the clad material be exerted, but more importantly, excellent bonding strength of the bonding interface between the base material and the clad material can be ensured.

[0013] As a preferred embodiment, the reduction in thickness during the (n + 2)-th rolling is ≧ 42 mm.

[0014] More preferably, the cooling water volume of the upper header of each set of headers is 150 m 3 / h, the cooling water volume of the lower header is 200 m 3 / h, and the roll table speed is 1 m / s.

[0015] As a preferred embodiment, in the composite material obtained by the process of "preparing the steel material, applying the release agent, laminating, seal welding, evacuating, and sealing to manufacture a composite material with a thickness t", The intermediate layer clad material includes two laminated clad materials. That is, one base material, one clad material, another clad material, and another base material are sequentially laminated from top to bottom. The four-sided frame includes a seal surrounding the four sides of the intermediate layer base material, and a molten metal filling layer located in a concave groove surrounded by the upper layer base material or the lower layer base material and the seal.

[0016] Hereinafter, the manufacturing process of the composite material in the preferred embodiment of the present invention will be described in detail.

[0017] Here, in the step of preparing the steel material, two carbon steel plates with a length L1 and a width W1 are prepared and used as the two base materials. That is, the base material 11 and the base material 12 shown in FIG. 1. The lengths L1 of the base material 11 and the base material 12 are the same, and the widths W1 are also the same. Also, the thicknesses of the base material 11 and the base material 12 may be the same or different. When setting different thicknesses, stainless clad steel plates with different thickness specifications can be manufactured accordingly.

[0018] In the steel material preparation process described above, two stainless steel plates with length L2 and width W2 are further prepared and used as two clad materials. These are clad material 21 and clad material 22 as shown in Figure 1. Clad material 21 and clad material 22 have the same length L2 and the same width W2. Furthermore, the thicknesses of clad material 21 and clad material 22 may be the same or different, and if they are set to different thicknesses, stainless steel clad plates of different thickness specifications can be manufactured accordingly.

[0019] More preferably, the length and width dimensions of the base material 11 and base material 12 are both larger than the length and width dimensions of the clad material 21 and clad material 22. That is, L1 > L2 and W1 > W2.

[0020] More preferably, L1 = L2 + (90~150) mm and W1 = W2 + (90~150) mm. In other words, the length of each base material is 90~150 mm greater than the length of each cladding material, and the width of each base material is 90~150 mm greater than the width of each cladding material. By doing so, the dimensions of the four-sided frame in the manufactured composite material can be ensured, the airtightness of the composite material can be guaranteed, and thereby the quality of the interfacial bonding can be improved.

[0021] To make it easier to understand, the clad material and base material prepared in the steel material preparation process transform into the clad layer and base material of the stainless steel clad sheet obtained after going through the manufacturing method described above. Therefore, the same drawing reference numerals are used for the clad material and clad layer in the drawings, and the same drawing reference numerals are also used for the base material and base layer.

[0022] More preferably, the preparation step for the steel material further includes polishing the surfaces to be joined between each base material and each cladding material to remove surface oxide scale and expose the metallic luster. After polishing, the surface roughness of the surfaces to be joined is Ra < 5 μm. In this way, polishing allows these polished surfaces to come into contact as the surfaces to be joined in the subsequent lamination process, thereby improving the interfacial bonding strength of the final stainless cladding sheet.

[0023] In this application, the term "surface to be joined" refers to the surface on which the base material and the cladding material require interfacial joining when forming a cladding steel sheet.

[0024] Specifically, as shown in Figure 2, for example, for the base material 11, base material 12, clad material 21, and clad material 22, one of two surfaces in the thickness direction can be selected as the "planned joining surface" and polished. For example, for surface p1 of base material 11 and surface p2 of base material 12, polishing can be specifically performed using a grinder, belt sander, or milling machine, and for surface p3 of clad material 21 and surface p4 of clad material 22, polishing can specifically be performed using a wire brush.

[0025] To make it easier to understand, after the surface polishing treatment, each base material and each cladding material will be of equal thickness.

[0026] Here, we have only described the polishing treatment of the joining surfaces of each base material and each cladding material. However, it is necessary to explain that other surfaces of each base material and cladding material can also be polished. While such additional polishing of other surfaces is not essential to realizing the technical effects of the present invention, it may be preferable in some cases.

[0027] As a preferred option, the two cladding materials are preferably austenitic stainless steel. Its chemical composition, by mass percentage, is: 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 remainder being Fe and unavoidable impurities. By using stainless steel material with this chemical composition, the performance of the cladding sheet, particularly the corrosion resistance of the cladding layer, can be further guaranteed under the aforementioned technical effects. For example, the cladding layer of the resulting cladding sheet (i.e., obtained by rolling the cladding material) does not exhibit intergranular corrosion cracking even after being boiled in a sulfuric acid-copper sulfate solution for 20 hours and then subjected to a 180° bending test.

[0028] What needs to be explained here is that the chemical compositions of the two cladding materials may be the same or different, only one of them may adopt the chemical composition provided in the preferred solution described above, or both may adopt it or neither may adopt it.

[0029] A preferred solution is for the two base materials to be carbon steel for bridge structures, with a chemical composition by mass percentage of: 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%, with the remainder being Fe and unavoidable impurities.

[0030] More preferably, the chemical composition of the base material may further include one, two, or all of the following by mass percentage: Ni: 0.06-0.14%, Mo: 0.11-0.19%, and Cu: 0.16-0.24%.

[0031] Here, the chemical compositions of the two base materials may be the same or different, only one of the two base materials may adopt the chemical composition provided in the above preferred solution, or both may adopt it or neither.

[0032] In a more preferred embodiment, the mold release agent application step specifically includes applying the mold release agent to the non-joined surface of at least one clad material. In this application, the "non-joined surface" refers to a surface that does not require interfacial joining when forming the clad steel sheet. For example, the surface p5 of clad material 21 and the surface p6 of clad material 22 are both the "non-joined surface".

[0033] Specifically, the release agent may be applied to all non-joining surfaces of each clad material, or it may be applied to one of the two clad materials. In this way, the release agent is used to prevent the contact surfaces of the two clad materials (i.e., non-joining surfaces) from joining during the subsequent composite material rolling process, which would ultimately make separation difficult.

[0034] The first embodiment of the release agent is a coating solution containing silicon dioxide and magnesium oxide, and the mass ratio of silicon dioxide to magnesium oxide is 3:1.

[0035] The release agent of this embodiment can achieve an excellent release effect and ensure the separation of the subsequent two small clad steel plates. When using the release agent, the total amount of the release agent 30 (see Figure 2) between the two clad materials is 18 - 22y mg / m 2 , preferably 20y mg / m 2 where y is the ratio of the thickness of the large plate of the clad steel plate formed by rolling the total thickness of the composite material obtained by the sealing process to the thickness of the large plate of the clad steel plate, and this ratio is also called the composite material rolling compression ratio. In a preferred embodiment where the base material 11, clad material 21, clad material 22, and base material 12 are sequentially laminated in the composite material, the total thickness of the composite material is the sum of the thicknesses of the two base materials and the two clad materials. After the application of the release agent and before the subsequent lamination process, the clad material coated with the release agent is heated and dried in a trolley furnace, and the drying temperature is 340 - 360 °C and the drying time is 35 - 45 min.

[0036] In the second embodiment of the release agent, the components are silicon nitride 25 - 35% + thermosetting amino resin 5 - 10% + water 55 - 70% by weight ratio. Compared with the conventional release agent and even compared with the first embodiment of the release agent described above, the release agent of this embodiment can achieve an excellent release effect and ensure the separation of the subsequent two small clad steel plates. Moreover, the active ingredient silicon nitride has high chemical stability, excellent high-temperature resistance and thermal shock resistance, and the thermosetting amino resin used as an adhesive can be cured even at low temperatures, is non-toxic, and can obtain a strong adhesive effect with a small amount of use. Therefore, overall, it has a low price, is easy to operate, and has good release and adhesion effects.

[0037] Herein, we provide an example of a preferred method for producing the release agent according to the second embodiment. This method includes the following: First, 5-10% (by weight) of silicon nitride is placed in a container such as a beaker, and then 15-25% of water is poured in and stirred. Once the silicon nitride is free of particles and there are no more bubbles, 2-3% of thermosetting amino resin is poured in and stirring continues. When it becomes viscous, the remaining silicon nitride and water are added and stirred for 3-5 minutes, after which the remaining thermosetting amino resin is added. Once it has been stirred and become viscous, the production of the release agent is complete.

[0038] In the second embodiment described above, the release agent 30 (see Figure 2) between the two clad materials is applied to a total thickness of 0.2 to 0.5 mm. After the application of the release agent is complete and before the subsequent lamination process, the clad materials coated with the release agent are heated and dried at a drying temperature of 100 to 250°C and a drying time of 20 to 40 minutes.

[0039] In the above, for the first and second embodiments of the release agent, when the release agent is applied to both surface p5 and surface p6, the amount of release agent applied to each surface p5 and surface p6 can be half of the total amount / total thickness, and when the release agent is applied to only one of surface p5 or surface p6, it is applied in the total amount / total thickness.

[0040] In a more preferred embodiment, the lamination process involves laminating the clad material 21 and clad material 22 in the center, the base material 11 above it, the base material 12 below it, arranging the seal strips to surround the four sides of the clad material 21 and clad material 22, and further welding the upper end of the seal strip (see reference numeral 40 in Figure 2) between the base material 11 and the lower end of the seal strip 40 between the base material 12 to form the base material of the composite material.

[0041] More preferably, the base material 11, clad material 21, clad material 22, base material 12, and seal 40 are arranged as follows overall. Referring to Figures 1 and 2, the base material 11, clad material 21, clad material 22, and base material 12 are sequentially stacked from top to bottom. Here, the surfaces of the base material and clad material that come into contact with each other are the joining surfaces that have undergone the aforementioned polishing treatment. For example, the surface p2 of the base material 12 and the surface p4 of the clad material 22 come into contact with each other, and the surface p1 of the base material 11 and the surface p3 of the clad material 21 come into contact with each other. Also, the surface of the clad material to which the release agent has been applied is facing the other clad material, and the release agent 30 is applied to either the surface p6 of the clad material 22 or the surface p5 of the clad material 21. What needs to be explained here is that, in order to facilitate understanding and explanation, Figure 2 shows an enlarged view of the thickness dimension of the release agent 30 between the two clad materials, that is, the ratio of the thickness of the release agent shown in the figure to the thickness of the base material, the thickness of the clad material, and the width of the seal, which will be described later, is shown in an enlarged view.

[0042] Also, referring to Figure 3, the seal 40 surrounds all four sides of the clad material 21 and clad material 22.

[0043] In a concrete implementation, the base material 11, clad material 21, clad material 22, and base material 12 can be laminated first, then the seal 40 can be wrapped around the four sides of the clad material 21 and clad material 22, and finally the upper end of the seal 40 can be welded to the surface p1 of the base material 11, and the lower end of the seal 40 can be welded to the surface p2 of the base material 12. Of course, in another embodiment, the lower end of the seal 40 can be welded to the surface p2 of the base material 12 first, so that the seal 40 forms a rectangular frame on the surface p2 of the base material 12, then the clad material 22 and clad material 21 can be sequentially placed in the frame, and the clad material 21 and the frame can be covered with the base material 11, and finally the upper end of the seal 40 can be welded to the surface p1 of the base material 11. In yet another embodiment, the upper end of the seal 40 can be welded to the surface p1 of the base material 11, then the base material 12, clad material 22, and clad material 21 can be sequentially laminated from bottom to top, the integrated seal 40 and base material 11 can be placed over and around the clad material 21 and clad material 22, and finally the lower end of the seal 40 can be welded to the surface p2 of the base material 12. None of these embodiments deviate from the technical spirit of the present invention.

[0044] Preferably, the upper end of the seal 40 and the base material 11, and the lower end of the seal 40 and the base material 12 are welded by gas shield welding. During gas shield welding, the welding current is controlled to 220-240A, the welding voltage to 28-32V, the welding speed to 300-360mm / min, and the interpass temperature to 140-160°C.

[0045] Furthermore, before performing gas shielded welding, it is preferable to preheat and bake the base material 11 and base material 12 with a torch, with a baking temperature of 150 to 250°C.

[0046] Furthermore, after stacking the upper base material, lower base material, and intermediate cladding material, a four-column hydraulic press is used to apply pressure to the surfaces of the two base materials facing away from each other, to a pressure of ≥ 500 tons.

[0047] Furthermore, regarding the dimensions of the seal 40, the width W3 of the seal 40 is within 2 mm less than the sum of the thicknesses of the cladding material 21 and the cladding material 22, or the sum of the thicknesses of the two, and the thickness T3 is 12 to 15 mm. Preferably, the width W3 of the seal 40 on all four sides of the base material of the composite material is the same, and the thickness T3 is also the same. Also, on the long side of the base material of the composite material, the length L31 of the seal 40 is L2 - (0 to 2) mm, preferably L2 - (1 to 2) mm, and on the short side, the length L32 of the seal 40 is W2 - (0 to 2) mm, preferably W2 - (1 to 2) mm. Of course, it is not limited to this.

[0048] Preferably, in the lamination process, the clad material is positioned centered relative to the base material. For example, as mentioned above, the length and width dimensions of the clad material and base material satisfy L1 = L2 + (90~150) mm and W1 = W2 + (90~150) mm, and during lamination, the distance W01 from both sides (i.e., the long sides) of the clad material in the lateral direction to the corresponding sides (i.e., the long sides) of the base material is equal, and this distance W01 is half of W1-W2. Similarly, the distance W02 from both sides (i.e., the short sides) of the clad material in the longitudinal direction to the corresponding sides (i.e., the short sides) of the base material is equal, and this distance W02 is half of L1-L2.

[0049] Furthermore, grooves with a depth D are formed on all four sides of the base material of the resulting composite material, surrounded by the base material 11, the seal 40, and the base material 12. As can be understood, this depth D depends on the dimensional difference in length and width between the clad material and the base material (e.g., distance W01, distance W02), and the thickness T3 of the seal 40. By controlling this depth D, it is possible not only to effectively prevent cracking of the weld during the rolling of the composite material, but also to prevent the formation of thermal cracks due to deep penetration during subsequent seal welding, thereby preventing an impact on the seal welding quality of the composite material.

[0050] Furthermore, a circular through-hole is provided in the seal 40 on one side of the base material of the composite material, and a circular pipe is welded into the through-hole during the lamination process. Here, the through-hole may be processed before the gas shield welding of the seal 40 and the base materials 11 and 12, or it may be processed after the gas shield welding is completed. Neither of these methods deviates from the technical concept of this application.

[0051] Preferably, the through-hole is provided in the seal 40 on the short side of the base material of the composite material.

[0052] Preferably, the diameter of the through hole is the same as the outer diameter of the circular pipe, being 8 to 12 mm, the wall thickness of the circular pipe is 1.2 to 2 mm, and the length is 200 to 400 mm.

[0053] In a preferred embodiment, the seal welding process involves overlay welding on the grooves on the four sides of the base material of the composite material, specifically employing submerged arc overlay welding. As can be understood, a four-sided frame-shaped overlay layer 50 is formed on the outside of the frame formed by the seal strip 40 by the seal welding process (see Figures 2 and 3). The overlay layer 50 and the seal strip 40 together constitute the four-sided frame of the composite material, and this four-sided frame can seal the clad material between the two base materials.

[0054] Preferably, the penetration depth of the metal filler layer 50 is D, which is the same as the groove depth on the side of the base material of the composite material.

[0055] A preferred method involves baking the flux at 350°C for 2 hours before welding, followed by holding it at 150°C for 1 hour. During the welding process, the interpass temperature is controlled to 135-165°C, the welding current to 570-630A, the welding voltage to 28-32V, and the welding speed to 420-480 mm / min. In this way, the submerged arc overlay welding technique, when combined with the aforementioned sealing and gas shielding welding, can achieve stable joining of four steel plates, guarantee joint strength, prevent cracking abnormalities in the subsequent rolling process, and further improve the interfacial joining effect.

[0056] Furthermore, during the overlay welding process, it is necessary to clean any deposits from the weld bead before each welding operation to maintain the cleanliness of the weld bead. After welding is complete, the weld should be covered with insulating material to retain heat.

[0057] In a preferred embodiment, the vacuuming process involves vacuuming the internal space of the composite material three times and breaking the vacuum twice, ultimately reducing the vacuum level of the internal space of the composite material to ≤10 -2 Hold it in Pa.

[0058] Here, the internal space of the composite material includes the inter-plane gap between the clad material and the base material, the inter-plane gap between the clad materials themselves, and the end-face gap between the clad material and the seal. Specifically, the circular tube communicates with the internal space of the composite material, and three vacuum pumping and two vacuum breaking are performed through the circular tube.

[0059] Furthermore, the vacuuming process more specifically includes the following: First, connect the vacuum pump to the aforementioned cylindrical tube and perform the first vacuuming of the internal space of the composite material, so that the vacuum level is ≤ 10. -2 The pressure is set to Pa, and then maintained for 4 hours or more. Next, the cylindrical tube is switched to and connected to a nitrogen gas device, the vacuum is broken against the composite material, and nitrogen gas is filled in.

[0060] Subsequently, the vacuum pump is reconnected to the aforementioned cylindrical pipe, and a second vacuum is performed on the composite material, resulting in a vacuum level of ≤ 10. -1The pressure is set to Pa, and no holding pressure is applied. Next, the cylindrical tube is switched back to the nitrogen gas device and connected, a second vacuum breaking is performed on the composite material, and nitrogen gas is filled in.

[0061] Finally, the vacuum pump is reconnected to the circular pipe, and a third vacuum is performed on the composite material, with a vacuum level of ≤ 10. -2 Let's call it Pa.

[0062] In this way, the air in the space prevents surface oxidation at the composite interface during subsequent heating and rolling processes, thereby ensuring the bonding quality of the composite interface.

[0063] Furthermore, regarding the sealing process, i.e., sealing the outlet of the composite material, in a preferred embodiment of the present invention, the outlet is made up of the circular tube and can be carried out by existing feasible methods in the steel industry, for example, by heating the circular tube with a torch and flattening it to achieve sealing and obtain the completed composite material.

[0064] Next, in one embodiment of the present invention, the heating step is a process of heating the composite material in a heating furnace in five stages: a preheating zone, a first heating zone, a second heating zone, a third heating zone, and a uniform heating zone, as described above. The preheating zone temperature is ≤850°C, the first heating zone temperature is 1080±30°C, the second heating zone temperature is 1160±30°C, the third heating zone temperature is 1220±20°C, and the uniform heating zone temperature is 1190±20°C. The residence time in the third heating zone is (0.25~0.35)×t min / mm, and the residence time in the uniform heating zone is 15 min~30 min. Thus, the intermediate layer of the composite material is stainless steel clad material, and the upper and lower two layers are carbon steel base material. There is a large difference in thermal conductivity, coefficient of expansion, etc. between the two types of materials, and there is a possibility that large stress will occur during the heating process. However, the heating step of this embodiment can effectively control the heating rate of the composite material at each stage, ensure uniform heating, thereby preventing risks such as cracking and gas leakage, and laying the foundation for obtaining an excellent bonding interface.

[0065] In one embodiment of the present invention, the rolling process includes the following, as described above. This is a process of manufacturing large sheets of clad steel by rolling the composite material that has been removed from the heating furnace. The first n rolls in the entire rolling process are performed using widthwise rolling, and from the (n+1)th roll onward using longitudinal rolling. The reduction amount of the first roll is ≥ 25 mm and the rolling temperature is ≥ 1060°C. The width of the material obtained from the nth roll is Wt + (0~40) mm, where Wt is the target width of the large clad steel sheet, and the rolling temperature for the nth roll is ≥ 1030°C. Between the nth and (n+1)th cycles, and between the (n+2)th and (n+3)th cycles, the material is cooled once in a round trip using six sets of headers, with a cooling water volume of 120-180 ml in the upper header of each set of headers. 3 / h, the cooling water volume in the lower header is 160-220m 3 The flow rate is / h, and the roll table speed is 0.8 to 1.2 m / s, preferably, more preferably, the cooling water volume of the upper header of each set of headers is 150 m 3 / h, the cooling water volume in the lower header is 200m 3 The speed is / h, and the roll table speed is 1m / s. The reduction amount for each of the (n+1)th to (n+3)th rolling processes is all ≥ 40 mm, the rolling temperature for the (n+1)th rolling process is ≥ 950°C, and preferably, the reduction amount for the (n+2)th rolling process is ≥ 42 mm. In the mth rolling stage, the rolling temperature is ≥ 900°C, and the material is rolled until its thickness is 2.5 to 3.5 times the target thickness of the large clad steel sheet. After that, water cooling is performed until the surface temperature of the material drops below 840°C. Subsequently, a second stage of rolling is performed, and the material is rolled until it reaches the target thickness of the large clad steel sheet, completing the entire rolling process. In the second stage of rolling, the first rolling temperature is 810°C to 840°C, and the final rolling temperature is 780°C to 810°C.

[0066] Thus, the rolling process of this embodiment ensures, on the one hand, the deformation diffusion and penetration effect in the center, which is advantageous for joining the clad material and the base material, improving the interfacial bonding rate and bonding strength between the base layer and the clad layer of the final clad steel sheet. On the other hand, it guarantees the relevant mechanical performance, corrosion resistance, and low-temperature impact toughness of the large clad steel sheet, and prevents performance degradation due to the composite of the base material and the clad material.

[0067] Furthermore, in a preferred first embodiment, the cooling step is: A process of cooling a large sheet of clad steel obtained by rolling by placing it in an ultra-rapid cooling system, wherein the cooling start temperature is ≥ 730°C, the cooling rate is 6-20°C / s, and the final cooling temperature is 480-590°C. The process includes placing a large sheet of clad steel plate, separated from the ultra-rapid cooling system, onto a cooling bed and air-cooling it to room temperature.

[0068] In a more preferred second embodiment, the cooling step is: The process involves placing a large sheet of clad steel obtained by rolling into an ultra-rapid cooling system to cool it, wherein the ultra-rapid cooling system has 24 sets of cooling headers arranged at 1m intervals along a roll table, with a cooling distance of 1m for each set of cooling headers, and the opening and closing state of all 24 sets of cooling headers is controlled in such a manner that N sets of cooling headers are opened and then M sets of cooling headers are not opened as the large sheet of clad steel passes through the ultra-rapid cooling system, the cooling water pressure is 0.15~0.30MPa, the cooling rate is 3~15℃ / s, and the final cooling temperature is 380~590℃, where N takes the value of 2, 3 or 4, and M takes the value of 2, 3 or 4. The process includes placing a large sheet of clad steel plate, separated from the ultra-rapid cooling system, onto a cooling bed and air-cooling it to room temperature.

[0069] In the cooling process of the second embodiment, as the clad steel sheet passes through the ultra-rapid cooling system, the cooling header is opened and closed alternately, causing each part of the clad steel sheet to cycle through cooling, red-hot recovery, cooling, red-hot recovery, and so on, until the clad steel sheet leaves the ultra-rapid cooling system. In the cooling-red-hot recovery cycle, the carbon steel base material continuously undergoes phase transformation and self-tempering effects, and the phase transformation reaction gradually diffuses and penetrates to the center, until the entire carbon steel base material completes its phase transformation. Unlike conventional reciprocating cooling, this intermittent cooling process occurs after phase transformation is completed at or near the surface, resulting in large temperature differences or cooling rate differences between the surface and the core, and significant differences in structure and mechanical properties. However, in the intermittent cooling process of this embodiment, at the same time, a portion of the clad steel sheet is in a cooling state while other portions are in a red-hot / self-tempering state. Furthermore, each part of the clad steel sheet alternates between cooling and red-hot / self-tempering over time, resulting in smaller differences in temperature, cooling rate, structure, and performance between the surface and the core of the sheet. For example, the difference in Vickers hardness in the thickness direction of the base layer of the final clad steel sheet is ≤10, the strength difference between the front, middle, and rear is ≤40 MPa, and the strength difference between all parts of the sheet is ≤40 MPa. Moreover, intermittent cooling can further improve the shape of the clad steel sheet; that is, even with low flatness, a superior sheet shape can be obtained by directly cooling on a cooling bed without straightening after the cooling is complete.

[0070] More preferably, in the cooling process, if the thickness of the clad steel plate is ≤54 mm, for example, 10 to 54 mm, the roll table speed of the ultra-rapid cooling system is set to 0.4 to 0.8 m / s, and the clad steel plate passes through the ultra-rapid cooling system once before leaving it. Also, the control method for the 24 sets of cooling headers can be set to open the first to fourth sets of cooling headers, not open the fifth to sixth sets of cooling headers, open the seventh to eighth sets of cooling headers, not open the ninth to tenth sets of cooling headers, open the eleventh to twelfth sets of cooling headers, not open the thirteenth to fourteenth sets of cooling headers, open the fifteenth to sixteenth sets of cooling headers, not open the seventeenth to eighteenth sets of cooling headers, open the nineteenth to twenty sets of cooling headers, not open the twenty-first to twenty-second sets of cooling headers, and open the twenty-third to twenty-fourth sets of cooling headers.

[0071] In the aforementioned cooling process, when the thickness of the clad steel plate is >54mm, for example, >54mm and <70mm, the roll table speed of the ultra-rapid cooling system is set to 0.2m / s or more and less than 0.6m / s, and the clad steel plate passes through the ultra-rapid cooling system once before leaving it. In this way, shape control and uniformity control of the stainless clad steel plate are achieved, overcoming the challenges in the production of conventional stainless clad steel plate. Furthermore, the control method for the 24 sets of cooling headers can be set to open the first to fourth sets of cooling headers, not open the fifth to eighth sets of cooling headers, open the ninth to twelfth sets of cooling headers, not open the thirteenth to sixteenth sets of cooling headers, open the seventeenth to twenty sets of cooling headers, not open the twenty-first to twenty-second sets of cooling headers, and open the twenty-third to twenty-fourth sets of cooling headers.

[0072] In the aforementioned cooling process, when the thickness of the clad steel sheet is ≥ 70 mm, for example, 70 mm to 110 mm, the roll table speed of the ultra-rapid cooling system is set to 0.4 to 0.9 m / s. The clad steel sheet first enters the ultra-rapid cooling system in the forward direction, and when its leading edge reaches the 24th cooling header, the roll table reverses, and the clad steel sheet passes through the ultra-rapid cooling system in the reverse direction, moving away from the entrance of the ultra-rapid cooling system. In this way, shape control and uniformity control of extra-thick stainless steel clad sheets are achieved, overcoming the challenges in the production of conventional extra-thick stainless steel clad sheets. Furthermore, the control method for the 24 sets of cooling headers can be as follows: open the first to fourth sets of cooling headers, leave the fifth to eighth sets of cooling headers closed, open the ninth to twelfth sets of cooling headers, leave the thirteenth to sixteenth sets of cooling headers closed, open the seventeenth to twentyth sets of cooling headers, leave the twenty-first to twenty-second sets of cooling headers closed, and open the twenty-third to twenty-fourth sets of cooling headers.

[0073] In a preferred embodiment, the dividing step involves cutting the four sides of a large clad steel sheet to remove the portion other than the sealing strip, thereby separating the large clad steel sheet into two smaller clad steel sheets, one above the other.

[0074] The "parts other than the seal" refer to the edges of the large clad steel sheet that have been transformed from the seal 40 and the metal filling layer 50 in the composite material after the aforementioned rolling process. By removing these parts and exposing the stainless steel clad layer, the large clad steel sheet automatically separates into two smaller clad steel sheets, upper and lower, without the joining action of these edges.

[0075] In a preferred embodiment, the straightening process involves dimensionalizing, flattening, and cold straightening of clad steel sheet pieces to obtain two single-sided stainless steel sheet products.

[0076] Referring to Figure 4, two corresponding single-sided stainless clad steel sheet products are shown. Each stainless clad steel sheet consists of a clad layer and a base layer. The clad layer is obtained by rolling the original clad material, and the base layer is obtained by rolling the original base material. In light of this, in Figure 4, the clad layer still shows the symbol of the original clad material, and the base layer still shows the symbol of the original base material.

[0077] Next, one embodiment of the present invention further provides a stainless clad sheet, which is manufactured by the manufacturing method described in any of the embodiments described above. The base layer of the stainless clad sheet is carbon steel, and the clad layer is stainless steel.

[0078] The total thickness of the stainless steel clad sheet is 15-39 mm, the base layer thickness is 12-36 mm, and the clad layer thickness is 1-5 mm.

[0079] Specifically, sampling was performed from a single-sided stainless-clad steel sheet of one embodiment of the present invention in accordance with GB / T 2975 - Steel and Steel Products - "Sampling Location and Specimen Preparation for Mechanical Performance Tests," and, Regarding the interfacial bonding quality, tensile tests were conducted on the clad steel sheet in accordance with GB / T 6396 - "Methods for Testing the Mechanical and Process Performance of Clad Steel Sheets." The composite interfacial bonding rate of the clad steel sheet was 100%, and the shear strength was ≥360 MPa, far exceeding that of conventional clad steel sheets.

[0080] Regarding the shape, measurements were taken in accordance with GB / T 709 - "Dimensions, shape, weight and tolerances of hot-rolled steel sheets and strips," and the flatness of the clad steel sheet was ≤3 mm / m, and furthermore, ≤2 mm / m.

[0081] Regarding uniformity, tensile tests were performed in accordance with GB / T 6396 - "Methods for testing the mechanical and process performance of clad steel sheets" and GB / T 228.1 - "Tensile tests for metallic materials, Part 1: Methods for testing at room temperature". The results showed that the difference in Vickers hardness in the thickness direction of the base layer of the clad steel sheet was ≤10, the difference in strength between the front, middle, and rear sections was ≤40 MPa, and the difference in strength between all parts of the entire sheet was ≤40 MPa.

[0082] Regarding low-temperature impact toughness, tests were conducted according to GB / T 6396 - "Methods for testing the mechanical and process performance of clad steel sheets" and GB / T 229 - "Methods for testing metallic materials using a Charpy pendulum impact," and the clad steel sheets showed impact values ​​of ≥240J at 0°C, ≥200J at -20°C, and ≥150J at -40°C.

[0083] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention and do not limit the scope of protection of the present invention. Any equivalent embodiments or modifications that do not depart from the technical spirit of the present invention should be included within the scope of protection of the present invention.

[0084] The advantageous effects of the present invention will be further explained below with reference to several examples, but of course, these examples represent only a portion, not all, of the many variations included in the present invention.

[0085] Examples 1 to 4 provide single-sided stainless steel clad sheets, each containing a carbon steel matrix and a stainless steel clad layer. The thickness of the clad sheets, the thickness and material of the matrix, and the thickness and material of the clad layer in 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.

[0086] [Table 1]

[0087] Furthermore, samples were taken and tested from the clad steel sheets of each example. The interfacial bonding rate for each example was 100%, and both the inner and outer 180° bend tests passed (no cracks). In addition, no intergranular corrosion cracking occurred in the clad layer even after boiling in a sulfuric acid-copper sulfate solution for 20 hours followed by a 180° bend test. Other performance test results are shown in Table 2.

[0088] [Table 2]

[0089] The manufacturing methods for each of the above embodiments will be described step by step below.

[0090] <Steel material preparation process> Two base materials and two clad materials of the same dimensions were prepared. The materials of the base materials and clad materials matched those of the base layer and clad layer of the clad steel sheet, respectively, as shown in Table 1. The dimensions of the base materials and clad materials for each embodiment are shown in Table 3.

[0091] [Table 3]

[0092] The joining surfaces of each base material and each cladding material are polished. After polishing, the joining surfaces are free of oxide scale, exhibit a metallic luster, and have a surface roughness Ra < 5 μm.

[0093] <Application of mold release agent> Apply a release agent to the non-joining surface of one of the two clad materials.

[0094] In Examples 1 and 3, the release agent used was a coating solution containing silicon dioxide and magnesium oxide, with a mass ratio of silicon dioxide to magnesium oxide of 3:1. The total amount of release agent applied was 140 mg / m². 2 After the release agent has been applied, the clad material coated with the release agent is heated and dried in a trolley furnace at a drying temperature of 350°C for a drying time of 40 minutes.

[0095] The release agent used in Examples 2 and 4 had a composition of 25-35% silicon nitride + 5-10% thermosetting amino resin + 55-70% water by weight. The thickness of the release agent application was 0.35 mm. After the application of the release agent was completed, the clad material coated with the release agent was heated and dried at a drying temperature of 100-250°C and a drying time of 20-40 min.

[0096] <Lamination process> In each embodiment, the base material A, clad material A, clad material B, and base material B are sequentially laminated from bottom to top in that order. Here, the intended joining surface of base material A and the intended joining surface of clad material A are in contact, the intended joining surface of base material B and the intended joining surface of clad material B are in contact, the release agent is located between clad material A and clad material B, and the two clad materials are positioned centered relative to the two base materials (i.e., W01 is 60 mm and W02 is 60 mm as mentioned above).

[0097] After stacking base material A, clad material A, clad material B, and base material B, a four-column hydraulic press is used to apply pressure to the two base material surfaces facing away from each other, to a pressure of ≥ 500 tons.

[0098] Each embodiment prepares two long seals and two short seals, the dimensions of which are shown in Table 3 above. The four seals surround the two clad materials, and the upper ends of the seals are welded to base material B, and the lower ends are welded to base material A. In addition, a through hole with a diameter of 10 mm is machined in the center of one of the short seals, and a circular pipe with the same outer diameter as the through hole, a wall thickness of 1.2 to 2 mm, and a length of 200 to 400 mm is welded into the through hole.

[0099] <Seal welding process - Vacuuming process - Sealing process> The grooves on all four sides of the composite material base material, manufactured in the aforementioned lamination process, are filled by submerged arc overlay welding, meaning the penetration depth of the overlay welding is the same as the depth of the grooves.

[0100] Subsequently, the internal space of the composite material was subjected to three vacuum pumping and two vacuum breaking procedures, and the final vacuum level of the internal space of the composite material was reduced to ≤10. -2 Hold it in Pa.

[0101] Subsequently, the circular tube is sealed to obtain a composite material.

[0102] <Heating process> In each embodiment, the composite material is heated in a heating furnace in five stages: a preheating zone, a first heating zone, a second heating zone, a third heating zone, and a soaking zone. The specific temperatures and times are as shown in Table 4.

[0103] [Table 4]

[0104] <Rolling process> The composite material is rolled after being removed from the heating furnace to produce large clad steel sheets. The first n rolls in the entire rolling process are widthwise, and from the (n+1)th roll onwards, longitudinal rolling is used. The width of the material obtained from the nth roll is Wt + (0~40) mm, where Wt is the target width of the large clad steel sheet. Between the nth and (n+1)th rolls, and between the (n+2)th and (n+3)th rolls, the material is water-cooled once in a reciprocating motion using six sets of headers, with the cooling water volume of the upper header of each set being 120~180 m³. 3 / h, the cooling water volume in the lower header is 160-220m 3 The rolling speed is 0.8 to 1.2 m / s. The reduction amount from the (n+1)th to the (n+3)th rolling pass is all ≥ 40 mm. In the mth pass, the material is rolled until its thickness is 2.5 to 3.5 times the target thickness of the large clad steel sheet. Then, water cooling is performed until the surface temperature of the material is 840°C or lower. After that, the second stage of rolling is performed, and the material is rolled until its thickness is the target thickness of the large clad steel sheet, completing the entire rolling process. Other parameters are shown in Table 5.

[0105] [Table 5]

[0106] <Cooling process> The system employs an ultra-rapid cooling system, which has 24 sets of cooling headers arranged at 1m intervals along a roll table, with each set of cooling headers having a cooling distance of 1m.

[0107] For the large clad steel plates of Examples 1 and 2, they were cooled in an ultra-rapid cooling system, with a cooling start temperature of 770°C, a cooling rate of 12°C / s, and a final cooling temperature of 550°C. After removing the ultra-rapid cooling system, the large clad steel plates were placed on a cooling bed and air-cooled to room temperature.

[0108] The large clad steel plates of Examples 3 and 4 are cooled by placing them in an ultra-rapid cooling system. As the large clad steel plates pass through the ultra-rapid cooling system, the opening and closing states of all 24 sets of cooling headers are controlled by opening N sets of cooling headers and then keeping M sets of cooling headers closed. The cooling water pressure is 0.15 to 0.30 MPa, the cooling rate is 3 to 15 °C / s, and the final cooling temperature is 380 to 590 °C, where N is a value of 2, 3, or 4, and M is a value of 2, 3, or 4. After leaving the ultra-rapid cooling system, the large clad steel plates are placed on a cooling bed and air-cooled to room temperature. For specific parameters such as the thickness of the large clad steel plates, cooling water pressure, cooling rate, final cooling temperature, roll table speed, number of passes through the ultra-rapid cooling system (abbreviated as: number of water passes), and the opening and closing method of the cooling headers in each example, please refer to Table 6.

[0109] [Table 6]

[0110] <Dividing process-straightening process> The four sides of the large clad steel sheet are cut to remove the parts other than the sealing strips, separating the large clad steel sheet into two smaller clad steel sheets, one above the other.

[0111] Subsequently, the clad steel sheets are sized, flattened, and cold-corrected to obtain stainless steel clad sheets for each embodiment (for example, the clad steel sheets shown in Tables 1 and 2).

[0112] As can be seen from the above, the manufacturing method provided by preferred embodiments of the present invention, through technological improvements in the heating and rolling processes, not only guarantees superior mechanical performance and corrosion resistance compared to the prior art, but also improves interfacial bonding performance and significantly enhances interfacial bonding strength. Furthermore, the clad steel sheet can be given excellent shape, uniformity, and impact toughness through other further preferred methods such as cooling, lamination, and vacuum drawing processes.

Claims

1. A method for manufacturing stainless steel clad steel sheets, A process for manufacturing a composite material of thickness t, comprising the preparation of steel materials, application of a release agent, lamination, seal welding, vacuuming, and sealing, wherein the composite material includes an upper base material, a lower base material, an intermediate cladding material, and a quadrilateral frame that seals the intermediate cladding material between the upper and lower base materials. A process of heating the composite material in a heating furnace in five stages: a preheating zone, a first heating zone, a second heating zone, a third heating zone, and a uniform zone, wherein the preheating zone temperature is ≤ 850°C, the first heating zone temperature is 1080±30°C, the second heating zone temperature is 1160±30°C, the third heating zone temperature is 1220±20°C, the uniform zone temperature is 1190±20°C, the residence time in the third heating zone is (0.25 to 0.35) × t min / mm, and the residence time in the uniform zone is 15 min to 30 min. The process involves rolling a composite material removed from a heating furnace to produce a large sheet of clad steel, wherein the first n rolls in the entire rolling process are widthwise, and the (n+1)th rolls onward are longitudinal. The reduction amount of the first roll is ≥ 25 mm and the rolling temperature is ≥ 1060°C. The width of the material obtained from the nth roll is Wt + (0 to 40) mm, where Wt is the target width of the large sheet of clad steel. The rolling temperature for the nth roll is ≥ 1030°C. Between the nth and (n+1)th rolls, and between the (n+2)th and (n+3)th rolls, the material is water-cooled once in a reciprocating motion using six sets of headers, with a cooling water volume of 120 to 180 ml in the upper header of each set of headers. ３ / h, the cooling water volume in the lower header is 160-220 m³ ３ The process involves a roll table speed of 0.8 to 1.2 m / s, a reduction in rolling volume from the (n+1)th to the (n+3)th roll all being ≥ 40 mm, a rolling temperature of ≥ 950°C in the (n+1)th roll, a rolling temperature of ≥ 900°C in the mth roll, rolling until the material thickness is 2.5 to 3.5 times the target thickness of the clad steel sheet, then water cooling until the surface temperature of the material is 840°C or lower, then a second stage of rolling is performed, completing the entire rolling process until the material thickness is the target thickness of the clad steel sheet, with the first rolling temperature of the second stage being 810°C to 840°C and the final rolling temperature being 780°C to 810°C. The process includes the steps of cooling, dividing, and straightening the resulting large sheet of clad steel to obtain stainless steel clad steel product. A method for manufacturing stainless steel clad sheets.

2. The reduction amount in the (n+2)th rolling is ≥ 42 mm. A method for manufacturing stainless steel clad steel sheets according to claim 1.

3. The cooling step in the process of "cooling, dividing, and straightening the obtained clad steel sheet to obtain stainless clad steel sheet products" is: A step of cooling a large sheet of clad steel obtained by rolling by placing it in an ultra-rapid cooling system, wherein the cooling start temperature is ≥ 730°C, the cooling rate is 6 to 20°C / s, and the final cooling temperature is 480 to 590°C. The process includes placing a large clad steel plate, separated from the ultra-rapid cooling system, onto a cooling bed and air-cooling it to room temperature. A method for manufacturing stainless steel clad steel sheets according to claim 1.

4. The cooling step in the process of "cooling, dividing, and straightening the obtained clad steel sheet to obtain stainless clad steel sheet products" is: The process involves cooling a large sheet of clad steel obtained by rolling in an ultra-rapid cooling system, wherein the ultra-rapid cooling system has 24 sets of cooling headers arranged at 1m intervals along a roll table, with a cooling distance of 1m for each set of cooling headers, and the opening and closing state of all 24 sets of cooling headers is controlled in such a manner that N sets of cooling headers are opened and then M sets of cooling headers are not opened as the large sheet of clad steel passes through the ultra-rapid cooling system, the cooling water pressure is 0.15 to 0.30 MPa, the cooling rate is 3 to 15°C / s, and the final cooling temperature is 380 to 590°C, where N takes the value of 2, 3, or 4, and M takes the value of 2, 3, or 4. A method for manufacturing stainless steel clad steel sheets according to claim 1.

5. The cooling step in the process of "cooling, dividing, and straightening the obtained clad steel sheet to obtain stainless clad steel sheet products" is: The process includes placing a large sheet of clad steel plate, detached from the ultra-rapid cooling system, onto a cooling bed and air-cooling it to room temperature. A method for manufacturing a stainless steel clad sheet according to claim 4.

6. The thickness of the clad steel plate is 54 mm or less, the roll table speed of the ultra-rapid cooling system is 0.4 to 0.8 m / s, and the clad steel plate passes through the ultra-rapid cooling system once before leaving it. A method for manufacturing a stainless steel clad sheet according to claim 4.

7. The thickness of the clad steel plate is > 54 mm, the roll table speed of the ultra-rapid cooling system is 0.2 m / s or more and less than 0.6 m / s, and the clad steel plate passes through the ultra-rapid cooling system once before leaving the system. A method for manufacturing a stainless steel clad sheet according to claim 4.

8. When the thickness of a large clad steel plate is ≥ 70 mm, the roll table speed of the ultra-rapid cooling system is 0.4 to 0.9 m / s. The large clad steel plate first enters the ultra-rapid cooling system in the forward direction from the inlet. When its leading edge reaches the 24th set of cooling headers, the roll table reverses, and the large clad steel plate passes through the ultra-rapid cooling system in the reverse direction, moving away from the inlet of the ultra-rapid cooling system. A method for manufacturing a stainless steel clad sheet according to claim 4.

9. In the process of "manufacturing a composite material of thickness t through the preparation of steel materials, application of release agent, lamination, seal welding, vacuuming, and sealing," the vacuuming process is: The internal space of the composite material was subjected to three vacuum pumping and two vacuum breaking procedures, and the final vacuum level of the internal space of the composite material was reduced to ≤10. －２ To hold in Pa, A method for manufacturing stainless steel clad steel sheets according to claim 1.

10. "Three vacuum pumping and two vacuum breaking processes were performed on the internal space of the composite material, and the final vacuum level of the internal space of the composite material was set to ≤10." －２ The process of "holding in Pa" is First, vacuum is applied to the internal space of the composite material, with a vacuum level of ≤ 10. －２ The pressure is set to Pa, then held for 4 hours or more, followed by vacuum breaking of the composite material and filling with nitrogen. Subsequently, the composite material is subjected to vacuuming, and the vacuum level is ≤ 10. －１ The pressure is set to Pa, no holding pressure is applied, then the composite material is subjected to vacuum breaking and filled with nitrogen. Finally, a third vacuuming procedure was performed on the composite material, with a vacuum level of ≤ 10. －２ Let Pa be the value. The method for manufacturing a stainless clad steel sheet according to claim 9.

11. In a composite material obtained through the process of "preparing steel materials, applying a release agent, lamination, seal welding, vacuuming, and sealing," The intermediate cladding material includes two cladding materials arranged in a laminated configuration. The aforementioned four-sided frame includes a sealing strip surrounding the four sides of the intermediate base material, and a metal filler layer located within the groove surrounded by the sealing strip and the upper or lower base material. A method for manufacturing stainless steel clad steel sheets according to claim 1.

12. The upper end of the seal is welded to the upper base material by gas shield welding, and the lower end is welded to the lower base material by gas shield welding. A method for manufacturing a stainless steel clad sheet according to claim 11.

13. In the process of "manufacturing a composite material of thickness t through the preparation of steel materials, application of a release agent, lamination, seal welding, vacuuming, and sealing," the application of a release agent is, The process includes applying a release agent to at least one of the joining surfaces of two clad materials. A method for manufacturing a stainless steel clad sheet according to claim 11.

14. The release agent used is a coating liquid containing silicon dioxide and magnesium oxide, with a mass ratio of silicon dioxide to magnesium oxide of 3:

1. The method for manufacturing a stainless steel clad sheet according to claim 13.

15. The total amount of release agent to be applied between the two cladding materials is 18-22 mg / m². ２ Here, y is the ratio of the sum of the thicknesses of the two clad materials and the two base materials to the thickness of the large clad steel plate. A method for manufacturing a stainless steel clad sheet according to claim 14.

16. The mold release agent used consists of, by weight, 25-35% silicon nitride, 5-10% thermosetting amino resin, and 55-70% water. The method for manufacturing a stainless steel clad sheet according to claim 13.

17. The total thickness of the release agent applied between the two cladding materials is 0.2 to 0.5 mm. A method for manufacturing a stainless steel clad sheet according to claim 16.

18. In the lamination process of the "manufacturing of a composite material of thickness t through the preparation of steel materials, application of release agent, lamination, seal welding, vacuuming, and sealing" process, after the upper base material, lower base material, and intermediate cladding material are laminated and arranged, pressure is applied to the surfaces of the two base materials facing away from each other using a four-column hydraulic press, and the pressure at that time is ≥ 500 tons. A method for manufacturing stainless steel clad steel sheets according to claim 1.

19. Stainless steel clad sheet, The shear strength of the joint interface of the stainless clad steel sheet is ≥ 360 MPa, and in the manufacturing process of the stainless clad steel sheet, a composite material consisting of an upper base material, a lower base material, and an intermediate clad material is heated and then rolled to form a large sheet of clad steel sheet. In the first n times of the rolling process, width-direction rolling is adopted. After the (n + 1)-th time, length-direction rolling is adopted. And the reduction ratio of the first rolling is ≥ 25 mm and the rolling temperature is ≥ 1060 °C. The width of the material obtained by the n-th rolling is Wt + 0 to 40 mm, where Wt is the target width of the large plate of the clad steel plate. The rolling temperature of the n-th rolling is ≥ 1030 °C. Between the n-th and the (n + 1)-th times and between the (n + 2)-th and the (n + 3)-th times, the material is water-cooled once back and forth with 6 sets of headers. The cooling water volume of the upper header of each set of headers is 120 to 180 m ３ / h, and the cooling water volume of the lower header is 160 to 220 m ３ / h. And the roll table speed is 0.8 to 1.2 m / s. The reduction ratios of the rolling from the (n + 1)-th to the (n + 3)-th times are all ≥ 40 mm. The rolling temperature of the (n + 1)-th rolling is ≥ 950 °C. At the m-th time, the rolling temperature is ≥ 900 °C. Rolling is carried out until the thickness of the material becomes 2.5 to 3.5 times the target thickness of the large plate of the clad steel plate. Then, spraying cooling is carried out until the surface temperature of the material becomes 840 °C or lower. Then, the second-stage rolling is carried out. Rolling is carried out until the thickness of the material becomes the target thickness of the large plate of the clad steel plate to complete the entire rolling process. The rolling temperature of the first rolling in the second-stage rolling is 810 °C to 840 °C, and the rolling temperature of the last rolling is 780 to 810 °C. Stainless steel clad sheet metal.

20. The base material of the aforementioned clad steel sheet is carbon steel, and the clad layer is stainless steel. Stainless steel clad sheet according to claim 19.

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