Composite slab and method for producing the same

Abstract

The application relates to a composite slab and a production method thereof. The composite slab comprises a base layer, a cladding layer and a connecting structure. The base layer comprises iron elements and carbon elements, and the base layer comprises a notch structure. The cladding layer comprises iron elements and chromium elements, and the cladding layer is arranged on one side of the base layer along a first direction. The projection of the cladding layer in the first direction is arranged in the projection of the notch structure in the first direction. The connecting structure is arranged inside the notch structure and is connected between the base layer and the cladding layer along the first direction. The connecting structure comprises a first connecting part and a second connecting part connected to each other. The first connecting part is arranged on the side of the second connecting part away from the circumferential side surface. The grain size of the first connecting part is smaller than that of the second connecting part. The composite slab and the production method thereof provided by the application have good composite quality.

Description

Technical Field

[0001] This application relates to the field of steel manufacturing technology, and in particular to a composite slab and its production method. Background Technology

[0002] In practical applications of steel manufacturing, it is often necessary to balance both performance and cost. Carbon steel is a common structural material with low cost, but it is not corrosion-resistant; stainless steel has corrosion resistance, but its cost is higher. To achieve a balance between performance and cost, carbon steel and stainless steel can be combined to achieve a structural integration that meets practical application requirements.

[0003] In the process of bonding carbon steel and stainless steel, the carbon steel and stainless steel need to be initially joined together before the composite structure is further processed into the molding stage. The initial joining of the carbon steel and stainless steel significantly affects the quality of the subsequent molding of the composite structure. Summary of the Invention

[0004] The composite slab and its production method provided in this application have good composite quality.

[0005] In a first aspect, embodiments of this application provide a composite slab blank, comprising: The base layer includes iron and carbon elements. The base layer includes a first surface along a first direction. The base layer includes a peripheral side surface disposed around the first direction. The peripheral side surface is recessed inward along a second direction to form a notch structure. The notch structure communicates with the first surface. The second direction intersects with the first direction. The coating, comprising iron and chromium, is disposed on one side of the first surface of the base layer along the first direction, and the projection of the coating in the first direction overlaps with the projection of the notch structure in the first direction. A connecting structure is located inside the notch structure, and the connecting structure connects the base layer and the cover layer along the first direction; The connection structure includes a first connection portion and a second connection portion that are interconnected along the second direction. The first connection portion is located on the side of the second connection portion away from the peripheral side, and the grain size of the first connection portion is smaller than the grain size of the second connection portion.

[0006] In some embodiments, the notch structure includes a notch surface connecting the first surface and the peripheral side surface, the notch surface including a first sub-surface connected to the first surface and a second sub-surface connected to the peripheral side surface, the first sub-surface and the second sub-surface being interconnected; The angle between the first sub-face and the first surface is greater than the angle between the second sub-face and the first surface; the first connecting portion is in contact with the first sub-face, and the second connecting portion is in contact with the second sub-face.

[0007] In some embodiments, the second sub-surface includes a first sub-part connected to the first sub-surface and a second sub-part connected to the peripheral side surface, wherein the first sub-part and the second sub-part are interconnected. The angle between the first sub-part and the first surface is greater than the angle between the second sub-part and the first surface; the extension dimension of the projection of the first sub-part in the first direction along the second direction is smaller than the extension dimension of the projection of the second sub-part in the first direction along the second direction.

[0008] In some embodiments, the included angle between the first sub-face and the first surface is A1, where 55°≤A1≤65°; And / or, the angle between the second sub-face and the first surface is A2, 10°≤A2≤50°; And / or, the second sub-surface includes a first sub-part and a second sub-part connected to each other, the first sub-part being connected to the first sub-surface, the second sub-part being connected to the peripheral side surface, the angle between the first sub-part and the first surface being A3, 35°≤A3≤50°; the angle between the second sub-part and the first surface being A4, 10°≤A4≤20°.

[0009] In some embodiments, the notch structure includes a notch surface connecting the first surface and the peripheral side surface, the projection of the notch surface in the first direction extending along the second direction by an dimension L1, the extension dimension of the coating in the first direction by a dimension T1, L1=k1*T1, 5mm≤T1≤40mm, 3≤k1≤4; When 5mm≤T1≤15mm, 3.5≤k1≤4; when 15mm≤T1≤40mm, 3≤k1≤3.5.

[0010] In some embodiments, the projection of the first sub-surface in the first direction extends along the second direction by an dimension L2, where 7mm ≤ L2 ≤ 9mm.

[0011] The projection of the second sub-surface onto the first direction extends along the second direction by a dimension L3. The second sub-surface includes a first sub-part and a second sub-part that are connected to each other. The first sub-part is connected to the first sub-surface, and the second sub-part is connected to the peripheral side surface. The angle between the first sub-part and the first surface is greater than the angle between the second sub-part and the first surface. The projection of the first sub-part in the first direction extends along the second direction by a dimension L4, where L4 = k2 * L3, and 0.2 ≤ k2 ≤ 0.4.

[0012] In some embodiments, the connecting structure includes molybdenum, and the mass percentage of molybdenum in the connecting structure is B1, where 2.5 ≤ B1 ≤ 2.6. And / or, the connecting structure includes tungsten, and the mass percentage of tungsten in the connecting structure is B2, 0.1≤B2≤0.22.

[0013] In some embodiments, the base layer is provided with a connecting channel that connects the first surface and the peripheral side surface. The connecting channel is spaced apart from the notch structure, and the projection of the connecting channel in the first direction is located inside the projection of the cladding in the first direction.

[0014] Secondly, embodiments of this application provide a method for producing composite slabs, including: A base layer is provided, the base layer comprising iron and carbon elements, the base layer comprising a first surface along one side of a first direction and a peripheral side surface disposed around the first direction, the base layer comprising forming a notch structure, the notch structure connecting the first surface and the peripheral side surface; A coating is provided, the coating comprising iron and chromium, the coating being disposed on one side of the first surface, and the projection of the coating in the first direction overlapping the projection of the notch structure in the first direction; A connection structure is formed inside the notch structure, and the connection structure connects the base layer and the cladding layer; The connection structure includes forming a first connection portion and forming a second connection portion. The first connection portion is formed on the side of the notch structure near the first surface, and the second connection portion is formed on the side of the notch structure near the peripheral side. The grain size of the first connection portion is smaller than the grain size of the second connection portion.

[0015] In some embodiments, forming the notch structure includes forming a first sub-face and forming a second sub-face, wherein the first sub-face is connected to the first surface and the second sub-face is connected between the first sub-face and the peripheral surface; The angle between the first sub-face and the first surface is greater than the angle between the second sub-face and the first surface.

[0016] According to the composite slab and its production method provided in this application, the composite slab includes a base layer, a cladding layer, and a connecting structure. The base layer and the cladding layer are stacked along a first direction. The base layer includes a first surface in the first direction, and the cladding layer is disposed on one side of the first surface in the base layer along the first direction. The base layer also includes a peripheral side surface disposed around the first direction. The peripheral side surface is recessed inward along a second direction to form a notch structure, which communicates with the first surface. When the connecting structure is inside the notch structure, the side of the connecting structure facing the base layer can be connected to the base layer, and the side of the connecting structure facing the cladding layer can be connected to the cladding layer, thereby achieving the connection between the base layer and the cladding layer in the first direction. To improve the forming quality of the composite slab, the connecting structure includes a first connecting part and a second connecting part that are interconnected along the second direction. The first connecting part and the second connecting part are formed during two welding processes. The first connecting part is located on the side of the second connecting part away from the peripheral side surface, and the grain size of the first connecting part is smaller than that of the second connecting part. The welding process forming the first connection is highly precise, resulting in a first connection with a relatively high grain size. This reduces the probability of easily penetrating the root of the notch structure during welding, allowing the base layer and cladding to adhere relatively well under gravity. It also reduces the probability of weld metal flowing into the gap between the cladding and the base layer, ensuring a good bond between them. During the subsequent formation of the second connection, the probability of weld metal flowing into the gap between the cladding and the base layer can also be reduced to a certain extent, thus achieving a connection between the base layer and the cladding and ensuring the forming quality of the composite slab. Attached Figure Description

[0017] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0018] Figure 1 A schematic diagram of the isometric structure of a composite slab provided in some embodiments of this application; Figure 2 A schematic diagram of an isometric sectional view of a composite slab provided for some embodiments of this application; Figure 3 This is a first cross-sectional view of a composite slab provided in some embodiments of this application; Figure 4 This is a schematic second cross-sectional view of a composite slab structure provided in some embodiments of this application; Figure 5 A third cross-sectional view of a composite slab is provided for some embodiments of this application; Figure 6 A schematic flow diagram of a method for producing a composite slab provided for some embodiments of this application; Figure 7 This is a schematic diagram of a method for producing a composite slab, provided in some embodiments of this application.

[0019] Marker explanation: 10. Grassroots level; 20. Coating; 30. Connecting structure; 31. First connecting part; 32. Second connecting part; Q1. Gap structure; M1, First surface; M2, Peripheral surface; M3, Notched surface; M31, First sub-surface; M32, Second sub-surface; M321, First sub-section; M322, Second sub-section; D1, connecting channel; D2, vacuuming pipe; X, the first direction; Y, the second direction.

[0020] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale. Detailed Implementation

[0021] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0023] In the process of combining carbon steel and stainless steel, the carbon steel and stainless steel need to be initially joined together before proceeding to the next forming process. During the initial joining of carbon steel and stainless steel, welding can be used. Solder will form at the joint between the carbon steel and stainless steel, and the formation of this solder directly affects the stability of the connection between the carbon steel and stainless steel, thus impacting the quality of the subsequent composite structure.

[0024] In view of this, firstly, please refer to Figure 1 , Figure 2 and Figure 3 This application provides a composite slab, including a base layer 10, a cladding layer 20, and a connecting structure 30. The base layer 10 includes iron and carbon elements. The base layer 10 includes a first surface M1 along a first direction X and a peripheral side surface M2 arranged around the first direction X. The peripheral side surface M2 is recessed inward along a second direction Y to form a notch structure Q1, which communicates with the first surface M1. The second direction Y intersects the first direction X. The cladding layer 20 includes iron and chromium elements. The cladding layer 20 is disposed along the first direction X on one side of the first surface M1 in the base layer 10. The projection of the cladding layer 20 in the first direction X overlaps with the projection of the notch structure Q1 in the first direction X. The connecting structure 30 is located inside the notch structure Q1 and connects the base layer 10 and the cladding layer 20 along the first direction X. The connection structure 30 includes a first connection portion 31 and a second connection portion 32 that are interconnected along the second direction Y. The first connection portion 31 is located on the side of the second connection portion 32 that is away from the peripheral side surface M2. The grain size of the first connection portion 31 is smaller than the grain size of the second connection portion 32.

[0025] The composite slab provided in this embodiment includes a base layer 10, a cladding layer 20, and a connecting structure 30. The base layer 10 and the cladding layer 20 are two independent plate structures, connected by the connecting structure 30 to form the composite slab. The base layer 10 includes iron and carbon elements and can be made of carbon steel. The cladding layer 20 includes iron and chromium elements and can be made of stainless steel. The iron and carbon content in the base layer 10 is set based on the iron and carbon content in carbon steel, and the iron and chromium content in the cladding layer 20 can be set based on the iron and chromium content in stainless steel. The materials of the base layer 10 and the cladding layer 20 will not be described further in this embodiment.

[0026] In the composite slab, the base layer 10 and the cladding layer 20 are stacked along a first direction X, which is parallel to the thickness direction of the composite slab, the base layer 10, and the cladding layer 20. The base layer 10 includes a first surface M1 in the first direction X, and the cladding layer 20 is disposed on one side of the first surface M1 in the base layer 10 along the first direction X. To control costs, the thickness of the base layer 10 is usually greater than the thickness of the cladding layer 20. The cladding layer 20 covers at least one surface of the base layer 10 to improve the surface properties of the base layer 10.

[0027] To facilitate the connection between the base layer 10 and the cladding layer 20, a notch structure Q1 is provided on the base layer 10. The notch structure Q1 corresponds to the cladding layer 20. Technicians can utilize the space within the notch structure Q1 to form a connecting structure 30, thereby achieving a preliminary connection between the base layer 10 and the cladding layer 20. Specifically, the base layer 10 also includes a circumferential side surface M2 arranged around the first direction X. The circumferential side surface M2 is recessed inward along the second direction Y to form the notch structure Q1. The notch structure Q1 communicates with the first surface M1, and the second direction Y intersects with the first direction X. The second direction Y can be either the length or width direction of the composite slab. Because the notch structure Q1 is located on the base layer 10 and communicates with the first surface M1, on the one hand, the notch structure Q1 can expose part of the structure of the base layer 10; on the other hand, when the cladding layer 20 is located on one side of the base layer 10 along the first surface M1, the cladding layer 20 can cover the notch structure Q1 to a certain extent. In other words, the projection of the cladding 20 in the first direction X overlaps with the projection of the notch structure Q1 in the first direction X. When the connecting structure 30 is inside the notch structure Q1, the side of the connecting structure 30 facing the base layer 10 can be connected to the base layer 10, and the side of the connecting structure 30 facing the cladding 20 can be connected to the cladding 20, thereby realizing the connection between the base layer 10 and the cladding 20 in the first direction X.

[0028] Regarding the setting of the notch structure Q1, the notch structure Q1 can be set all around the first direction X of the base layer 10, so that the connecting structure 30 can be set all around the first direction X of the base layer 10, thereby increasing the connection area between the base layer 10 and the cover layer 20, and forming a connection force that surrounds the base layer 10 and the cover layer 20 around the first direction X, thereby improving the connection stability between the base layer 10 and the cover layer 20.

[0029] Considering that the notch structure Q1 is formed by the inward indentation of the peripheral side surface M2, during the formation of the connecting structure 30, technicians weld from the sides of the base layer 10 and the cladding layer 20, with the solder remaining inside the notch structure Q1 to form the connecting structure 30, thereby achieving the connection between the base layer 10 and the cladding layer 20. In related technologies, since the cladding layer 20 and the base layer 10 are only stacked under gravity before welding, there is inevitably a certain gap between the cladding layer 20 and the base layer 10, which will have a certain impact on the welding process and thus affect the connection stability between the base layer 10 and the cladding layer 20. Considering cost and applicability factors, submerged arc welding is usually used for welding. Since the cladding layer 20 and the base layer 10 are only stacked under the action of gravity, the root of the notch structure Q1 is easily penetrated during the welding process. This causes a gap to appear between the cladding layer 20 and the base layer 10 under the action of gravity, resulting in the weld metal flowing into the gap between the cladding layer 20 and the base layer 10. The weld metal flowing into the gap between the cladding layer 20 and the base layer 10 becomes an incomplete fusion defect, which hinders the subsequent rolling and composite of the composite slab and affects the forming quality of the composite slab.

[0030] To improve the forming quality of the composite slab, in this embodiment, the connecting structure 30 includes a first connecting portion 31 and a second connecting portion 32 interconnected along the second direction Y. The first connecting portion 31 and the second connecting portion 32 are formed during two welding processes. The first connecting portion 31 is located on the side of the second connecting portion 32 facing away from the peripheral side surface M2. First, a first welding is performed to form the first connecting portion 31, which initially connects the base layer 10 and the cladding layer 20. Then, a second welding is performed to form the second connecting portion 32, which can further increase the connection force between the base layer 10 and the cladding layer 20 based on the first connecting portion 31. After the connecting structure 30 is formed, the grain size of the first connecting part 31 is smaller than that of the second connecting part 32. That is to say, the welding process for forming the first connecting part 31 is different from the welding process for forming the second connecting part 32. The first connecting part 31 can be formed by the welding process of gas metal arc welding. The welding precision of gas metal arc welding is higher than that of submerged arc welding. By using the welding process of gas metal arc welding to form the first connecting part 31, the probability of easily penetrating the root of the notch structure Q1 during the welding process can be reduced, so that the base layer 10 and the cladding layer 20 are relatively close under the action of gravity, reducing the probability of weld metal flowing into the gap between the cladding layer 20 and the base layer 10. After the first connecting part 31 is formed, the second connecting part 32 can be formed by submerged arc welding. Since the first connecting part 31 has initially connected the base layer 10 and the cladding layer 20, the probability of weld metal flowing into the gap between the cladding layer 20 and the base layer 10 can be avoided to a certain extent during the submerged arc welding process, thereby realizing the connection between the base layer 10 and the cladding layer 20 and ensuring the forming quality of the composite slab.

[0031] In summary, in this embodiment of the application, the composite slab includes a base layer 10, a cladding layer 20, and a connecting structure 30. The base layer 10 and the cladding layer 20 are stacked along a first direction X. The base layer 10 includes a first surface M1 in the first direction X. The cladding layer 20 is disposed on one side of the first surface M1 in the base layer 10 along the first direction X. The base layer 10 also includes a peripheral side surface M2 disposed around the first direction X. The peripheral side surface M2 is recessed inward along a second direction Y to form a notch structure Q1. The notch structure Q1 communicates with the first surface M1. When the connecting structure 30 is inside the notch structure Q1, the side of the connecting structure 30 facing the base layer 10 can be connected to the base layer 10, and the side of the connecting structure 30 facing the cladding layer 20 can be connected to the cladding layer 20, thereby realizing the connection between the base layer 10 and the cladding layer 20 in the first direction X. To improve the forming quality of the composite slab, the connecting structure 30 includes a first connecting portion 31 and a second connecting portion 32 interconnected along the second direction Y. The first connecting portion 31 and the second connecting portion 32 are formed during two welding processes. The first connecting portion 31 is located on the side of the second connecting portion 32 facing away from the peripheral side surface M2, and the grain size of the first connecting portion 31 is smaller than that of the second connecting portion 32. The welding process forming the first connecting portion 31 has a high degree of precision, resulting in a first connecting portion 31 with a relatively high grain size. This reduces the probability of easily penetrating the root of the notch structure Q1 during welding, allowing the base layer 10 and the cladding layer 20 to adhere relatively well under gravity. This reduces the probability of weld metal flowing into the gap between the cladding layer 20 and the base layer 10, ensuring adhesion between them. During the subsequent formation of the second connecting portion 32, the probability of weld metal flowing into the gap between the cladding layer 20 and the base layer 10 can also be avoided to some extent, thus achieving connection between the base layer 10 and the cladding layer 20 and ensuring the forming quality of the composite slab.

[0032] In some embodiments, please refer to Figure 3 and Figure 4 The notch structure Q1 includes a notch surface M3 connecting the first surface M1 and the peripheral side surface M2. The notch surface M3 includes a first sub-surface M31 connected to the first surface M1 and a second sub-surface M32 connected to the peripheral side surface M2. The first sub-surface M31 and the second sub-surface M32 are interconnected. The included angle between the first sub-surface M31 and the first surface M1 is greater than the included angle between the second sub-surface M32 and the first surface M1. The first connecting portion 31 is in contact with the first sub-surface M31, and the second connecting portion 32 is in contact with the second sub-surface M32.

[0033] In this embodiment, the notch structure Q1 is formed by the inward indentation of the peripheral side surface M2 of the base layer 10. The two sides of the notch structure Q1 along the first direction X are closed by the base layer 10 and the cladding layer 20. The one side of the notch structure Q1 along the second direction Y is closed by the base layer 10. The notch structure Q1 forms an opening on the other side along the second direction Y so that technicians can weld through the opening to form a connection structure 30, thereby realizing the connection between the base layer 10 and the cladding layer 20.

[0034] Specifically, the first surface M1 is located on one side of the base layer 10 along the first direction X, and the peripheral side surface M2 is located on one side of the base layer 10 along the second direction Y. The notch structure Q1 includes a notch surface M3 connecting the first surface M1 and the peripheral side surface M2. The notch surface M3 is inclined, and the extension direction of the notch surface M3 intersects both the first direction X and the second direction Y. Considering that the first connecting part 31 and the second connecting part 32 are formed by two welding processes, the notch surface M3 is set in the form of a first sub-surface M31 and a second sub-surface M32. The first sub-surface M31 is connected to the first surface M1, and the second sub-surface M32 is connected to the peripheral side surface M2. The first sub-surface M31 and the second sub-surface M32 are interconnected. The first connecting part 31 is formed at the corresponding position of the first sub-surface M31, and the second connecting part 32 is formed at the corresponding position of the second sub-surface M32.

[0035] To further reduce the probability of the first connecting portion 31 penetrating the root of the notch structure Q1, the angle between the first sub-face M31 and the first surface M1 is set to be greater than the angle between the second sub-face M32 and the first surface M1, thus making the inclination of the first sub-face M31 greater than that of the second sub-face M32. During the first welding process, at the corresponding position of the first connecting portion 31 forming the first sub-face M31, based on the relatively large angle between the first sub-face M31 and the first surface M1, the first sub-face M31 has a relatively large inclination, which to some extent can make the weld metal tend to flow towards the side closer to the second sub-face M32, thereby reducing the probability of the weld metal flowing into the gap between the cladding layer 20 and the base layer 10.

[0036] Furthermore, the angle between the second sub-surface M32 and the first surface M1 is smaller than the angle between the first sub-surface M31 and the first surface M1. That is, the notch surface M3 changes angle at the junction of the first sub-surface M31 and the second sub-surface M32, and the inclination of the second sub-surface M32 is smaller than the inclination of the first sub-surface M31. When the weld metal tends to flow towards the side closer to the second sub-surface M32, there is a bending angle at the junction of the first sub-surface M31 and the second sub-surface M32. This bending angle can block the flow of the weld metal so that the first connecting part 31 is formed at the corresponding position of the first sub-surface M31, thereby realizing the initial connection between the base layer 10 and the cladding layer 20 by the first connecting part 31.

[0037] In some embodiments, please refer to Figure 3 , Figure 4 and Figure 5 The second sub-surface M32 includes a first sub-part M321 connected to the first sub-surface M31 and a second sub-part M322 connected to the peripheral side surface M2. The first sub-part M321 and the second sub-part M322 are interconnected. The angle between the first sub-part M321 and the first surface M1 is greater than the angle between the second sub-part M322 and the first surface M1. The extension dimension of the projection of the first sub-part M321 in the first direction X along the second direction Y is smaller than the extension dimension of the projection of the second sub-part M322 in the first direction X along the second direction Y.

[0038] After the first connecting portion 31 is formed, it can initially connect the base layer 10 and the cover layer 20. During the subsequent formation of the second connecting portion 32, when the stable connection area between the second connecting portion 32 and the base layer 10 and the cover layer 20 is constant, the connection stability between the second connecting portion 32 and the base layer 10 and the cover layer 20 does not exhibit a linear positive correlation with the volume of the second connecting portion 32. Therefore, to reduce the material used in the second connecting portion 32 and to facilitate its molding, the second sub-surface M32 is configured as a combination of a first sub-part M321 and a second sub-part M322. The first sub-part M321 is connected to the first sub-surface M31, and the second sub-part M322 is connected to the peripheral side surface M2. The first sub-part M321 and the second sub-part M322 are also connected to each other. Partial structures in the second connecting portion 32 are formed at corresponding positions in the first sub-part M321, and partial structures in the second connecting portion 32 are formed at corresponding positions in the second sub-part M322.

[0039] To facilitate the forming of the second connecting portion 32, the angle between the second sub-part M322 and the first surface M1 is set to be smaller than the angle between the first sub-part M321 and the first surface M1. Within the extension range of the second sub-surface M32, the second sub-part M322 is close to the opening side of the notch structure Q1, and the second sub-part M322 can form a tapered portion within the extension range of the second sub-surface M32, so as to facilitate the forming of the second connecting portion 32 on the opening side of the notch structure Q1. At the same time, by setting the angle between the second sub-part M322 and the first surface M1 to be relatively small, the volume between the second sub-surface M32 and the first surface M1 can be reduced, thereby reducing the material used in the second connecting portion 32 and lowering production costs.

[0040] Within the extension range of the second sub-surface M32 along the second direction Y, the extension dimension of the first sub-part M321 is smaller than the extension dimension of the second sub-part M322. The volume enclosed between the second sub-surface M32 and the first surface M1 is mainly formed by the second sub-part M322. Since the angle between the second sub-part M322 and the first sub-surface M31 is smaller than the angle between the first sub-part M321 and the first sub-surface M31, the closing dimension of the second sub-part M322 is relatively extended, which can reduce the volume enclosed between the second sub-surface M32 and the first surface M1, and further reduce the material used in the second connecting part 32.

[0041] In some embodiments, please refer to Figure 3 , Figure 4 and Figure 5 The angle between the first sub-face M31 and the first surface M1 is A1, 55°≤A1≤65°. The angle between the second sub-face M32 and the first surface M1 is A2, 10°≤A2≤50°. The second sub-face M32 includes a first sub-part M321 and a second sub-part M322 connected to each other. The first sub-part M321 is connected to the first sub-face M31, and the second sub-part M322 is connected to the peripheral surface M2. The angle between the first sub-part M321 and the first surface M1 is A3, 35°≤A3≤50°; the angle between the second sub-part M322 and the first surface M1 is A4, 10°≤A4≤20°.

[0042] In practical applications, the angle between the notch surface M3 and the first surface M1 needs to be considered in order to reduce the amount of weld metal entering the gap between the base layer 10 and the cladding layer 20, while also facilitating the formation of the connection structure 30. Therefore, the angle between the first sub-surface M31 and the first surface M1 should not be too large or too small. Controlling the angle between the first sub-surface M31 and the first surface M1 to between 55° and 65° facilitates the formation of the first connecting part 31, enabling the first connecting part 31 to initially connect the base layer 10 and the cladding layer 20.

[0043] During the formation of the first connecting portion 31, the first connecting portion 31 is mainly formed within the extension range of the first sub-surface M31. An angle change occurs at the junction of the first sub-surface M31 and the second sub-surface M32, which can provide a certain degree of limiting effect on the first connecting portion 31, thereby facilitating its forming. Simultaneously, the second connecting portion 32 is mainly formed within the extension range of the second sub-surface M32. Based on the included angle between the first sub-surface M31 and the first surface M1, the included angle between the second sub-surface M32 and the first surface M1 is controlled between 10° and 50°, allowing for an angle change with the first sub-surface M31, and also facilitating the forming of the second connecting portion 32.

[0044] Furthermore, in order to reduce the material used in the second connecting part 32 and facilitate the molding of the second connecting part 32, the angle of the connection interface between the first sub-part M321 and the second sub-part M322 in the second sub-surface M32 also changes. The angle between the first sub-part M321 and the first surface M1 is controlled between 35° and 50°, and the angle between the second sub-part M322 and the first surface M1 is controlled between 10° and 20°. By utilizing the change in the angle between the second sub-part M322 and the first sub-part M321, a certain narrowing setting can be formed at the second sub-part M322 to reduce the size of the notch structure Q1 on the opening side, thereby reducing the volume enclosed by the second sub-surface M32 and the first surface M1, and achieving the effect of reducing the material used in the second connecting part 32.

[0045] In some embodiments, please refer to Figure 3 , Figure 4 and Figure 5 The notch structure Q1 includes a notch surface M3 connecting the first surface M1 and the peripheral surface M2. The projection of the notch surface M3 in the first direction X extends along the second direction Y by a dimension L1. The extension dimension of the cladding layer 20 in the first direction X is T1. L1 = k1 * T1, 5mm ≤ T1 ≤ 40mm, 3 ≤ k1 ≤ 4. When 5mm ≤ T1 ≤ 15mm, 3.5 ≤ k1 ≤ 4; when 15mm ≤ T1 ≤ 40mm, 3 ≤ k1 ≤ 3.5.

[0046] In this embodiment, the connecting structure 30 is located inside the notch. The volume of the connecting structure 30 depends on the volume enclosed by the notch surface M3 and the first surface M1. Simultaneously, the shape of the connecting structure 30 depends on the shapes of the notch surface M3 and the first surface M1. The connecting structure 30 is used to connect the base layer 10 and the cladding layer 20. The area of ​​the notch surface M3 is the connection area between the connecting structure 30 and the base layer 10. The area of ​​the portion of the first surface M1 that overlaps with the projection of the notch surface M3 in the first direction X is the connection area between the connecting structure 30 and the cladding layer 20. The extension dimension of the notch surface M3 in the second direction Y directly affects the connection dimension between the connecting structure 30 and the base layer 10 and the cladding layer 20 in the second direction Y.

[0047] To ensure the connection stability between the connecting structure 30, the base layer 10, and the cladding layer 20, a specific setting is made for the extension dimension of the notch surface M3 in the second direction Y. In the composite slab provided in this embodiment, the cladding layer 20 is stacked on one side of the base layer 10 along the first direction X. The thickness of the cladding layer 20 is smaller than the thickness of the base layer 10, and the setting of the connecting structure 30 can be based on the thickness of the cladding layer 20. When the thickness of the cladding layer 20 is large, the connecting structure 30 needs to have a larger connecting force on the cladding layer 20, and the volume of the connecting structure 30 is also set to a relatively large form to ensure the connection stability between the cladding layer 20 and the base layer 10. The larger volume of the connecting structure 30 can be achieved by increasing the extension dimension of the notch surface M3 in the second direction Y. When the thickness of the cladding 20 is small, the volume of the connecting structure 30 is also set to be relatively small. The connecting structure 30 can exert a relatively small connecting force on the cladding 20. The volume of the connecting structure 30 can also be set to be relatively small to achieve the connection stability between the cladding 20 and the base layer 10. The small volume of the connecting structure 30 can be achieved by reducing the extension dimension of the notch surface M3 in the second direction Y.

[0048] The extension dimension (thickness) of the cladding layer 20 in the first direction X is typically set between 5mm and 40mm. The extension dimension of the projection of the notch surface M3 in the first direction X along the second direction Y is set based on the thickness of the cladding layer 20. The extension dimension of the projection of the notch surface M3 in the first direction X along the second direction Y is L1, and the extension dimension of the cladding layer 20 in the first direction X is T1. The relationship between the two can be expressed by a linear function: L1 = k1 * T1, where 5mm ≤ T1 ≤ 40mm, and 3 ≤ k1 ≤ 4. The relationship between the extension dimension of the projection of the notch surface M3 in the first direction X along the second direction Y and the extension dimension of the cladding layer 20 in the first direction X allows for a reasonable setting of the extension dimension of the notch surface M3 based on the thickness of the cladding layer 20. Combined with the tilt angle of the notch surface M3, the enclosed volume between the notch surface M3 and the first surface M1 can be obtained, thus determining the volume of the connecting structure 30 and ensuring the connection stability between the base layer 10 and the cladding layer 20.

[0049] Specifically, to balance the connection stability of the connecting structure 30 to the base layer 10 and the cladding layer 20, and the material usage of the connecting structure 30, when 5mm≤T1≤15mm, 3.5≤k1≤4; when 15mm≤T1≤40mm, 3≤k1≤3.5. It can be understood that when the thickness of the cladding layer 20 is relatively small, k1 takes a relatively large value within its range. Given that the notch surface M3 has a small extension dimension in the second direction Y, the extension dimension of the notch surface M3 in the second direction Y is appropriately increased, thereby appropriately increasing the volume of the connecting structure 30 to ensure the connection stability of the connecting structure 30 to the base layer 10 and the cladding layer 20. When the thickness of the cladding layer 20 is relatively large, k1 takes a relatively small value within its range. Given that the notch surface M3 has a large extension dimension in the second direction Y, the extension dimension of the notch surface M3 in the second direction Y is appropriately decreased, thereby appropriately reducing the volume of the connecting structure 30 to reduce the material usage of the connecting structure 30.

[0050] In some embodiments, please refer to Figure 3 , Figure 4 and Figure 5The projection of the first sub-surface M31 onto the first direction X extends along the second direction Y by a dimension L2, where 7mm ≤ L2 ≤ 9mm. The projection of the second sub-surface M32 onto the first direction X extends along the second direction Y by a dimension L3. The second sub-surface M32 includes a first sub-part M321 and a second sub-part M322 that are connected to each other. The first sub-part M321 is connected to the first sub-surface M31, and the second sub-part M322 is connected to the peripheral side surface M2. The angle between the first sub-part M321 and the first surface M1 is greater than the angle between the second sub-part M322 and the first surface M1. The projection of the first sub-part M321 onto the first direction X extends along the second direction Y by a dimension L4, where L4 = k2 * L3, and 0.2 ≤ k2 ≤ 0.4.

[0051] The notched surface M3 includes a first sub-surface M31 and a second sub-surface M32 that are interconnected. The connecting structure 30 includes a first connecting portion 31 and a second connecting portion 32 that are interconnected. The first connecting portion 31 is formed within the extension range of the first sub-surface M31, and the second connecting portion 32 is formed within the extension range of the second sub-surface M32. The purpose of the projection of the first sub-surface M31 in the first direction X along the second direction Y is mainly to form the first connecting portion 31 to initially connect the cladding layer 20 and the base layer 10. Considering that the first connecting portion 31 can be formed by a gas metal arc welding process, controlling it to be between 7mm and 9mm is sufficient. In the connecting structure 30, the second connecting portion 32 is the main part connecting the cladding layer 20 and the base layer 10. The projection of the second sub-surface M32 in the first direction X along the second direction Y is the projection of the notched surface M3 in the first direction X along the second direction Y minus the projection of the first sub-surface M31 in the first direction X along the second direction Y.

[0052] The second sub-surface M32 includes a first sub-part M321 and a second sub-part M322 that are interconnected. The first sub-part M321 is connected to the first sub-surface M31, and the second sub-part M322 is connected to the peripheral side surface M2. A second connecting part 32 is formed within the extension range of the second sub-surface M32. The change in the included angle between the second sub-part M322 and the first sub-part M321 facilitates the formation of the second connecting part 32 and also allows for a tapering configuration on the opening side of the notch structure Q1, thereby reducing the volume enclosed by the second sub-surface M32 and the first surface M1, and reducing the material used for the second connecting part 32. Specifically, since the angle between the first sub-part M321 and the first surface M1 is greater than the angle between the second sub-part M322 and the first surface M1, the extension dimension of the projection of the first sub-part M321 in the first direction X along the second direction Y is smaller than the extension dimension of the projection of the second sub-part M322 in the first direction X along the second direction Y. This results in the second sub-part M322 having a relatively small degree of inclination and a relatively large extension dimension, enabling the space enclosed by the second sub-surface M322 and the first surface M1 to have a relatively small volume. The extension dimension of the projection of the first sub-part M321 in the first direction X along the second direction Y is L4, where L4 = k2 * L3, 0.2 ≤ k2 ≤ 0.4. The extension dimension of the projection of the second sub-part M322 in the first direction X along the second direction Y is the extension dimension of the projection of the second sub-surface M32 in the first direction X along the second direction Y minus the extension dimension of the projection of the first sub-part M321 in the first direction X along the second direction Y.

[0053] Based on the angular relationship between the notch surface M3 and the first surface M1, and the length relationship between the notch surface M3 and the thickness dimension of the cladding layer 20, the specific setting of the notch surface M3 can be understood by referring to the following two cases.

[0054] In the first case, taking the composite of a 20mm thick cladding layer 20 and a 220mm thick base layer 10 as an example, stainless steel cladding layer 20 and carbon steel base layer 10 of the same length are used. A notch structure Q1 is formed on the peripheral side M2 ​​of the base layer 10. Since the thickness T1 of the stainless steel cladding layer 20 is 20mm, which is greater than 15mm, k1 can be taken as 3.25. The projection of the notch surface M3 on the first direction X extends along the second direction Y by L1 = 3.25 * 20mm = 65mm. The angle A1 between the first sub-surface M31 and the first surface M1 can be taken as 60°. The angle A3 between the first sub-part M321 and the first surface M1 can be taken as 45°. The angle A3 between the second sub-part M322 and the first surface M1 can be taken as 15°. The projection of the first sub-surface M31 onto the first direction X, extending along the second direction Y, has an extension dimension L2 of 8mm. For the relative dimensions between the first sub-part M321 and the second sub-part M322 in the second sub-surface M32, k2 can be 0.3. The projection of the first sub-part M321 onto the first direction X, extending along the second direction Y, has an extension dimension of 0.3*(65mm-8mm)=0.3*57mm=17.1mm. The projection of the second sub-part M322 onto the first direction X, extending along the second direction Y, has an extension dimension of 0.7*(65mm-8mm)=0.7*57mm=39.9mm. Thus, the design of the shape of the notched surface M3 is complete. Subsequently, a connecting structure 30 is formed in the notched structure Q1 to achieve the connection between the base layer 10 and the cladding layer 20.

[0055] In the second case, taking the composite of a cladding layer 20 with a thickness of 14mm and a base layer 10 with a thickness of 198mm as an example, stainless steel cladding layer 20 and carbon steel base layer 10 of the same length are used. A notch structure Q1 is formed on the peripheral side M2 ​​of the base layer 10. Since the thickness T1 of the stainless steel cladding layer 20 is 14mm, which is less than 15mm, k1 can be 4. The projection of the notch surface M3 on the first direction X extends along the second direction Y by L1 = 4 * 14mm = 56mm. The angle A1 between the first sub-surface M31 and the first surface M1 can be 65°. The angle A3 between the first sub-part M321 and the first surface M1 can be 40°. The angle A3 between the second sub-part M322 and the first surface M1 can be 16°. The projection of the first sub-surface M31 onto the first direction X, extending along the second direction Y, has an extension dimension L2 of 7.5mm. For the relative dimensions between the first sub-part M321 and the second sub-part M322 in the second sub-surface M32, k2 can be 0.3. The projection of the first sub-part M321 onto the first direction X, extending along the second direction Y, has an extension dimension of 0.3*(56mm-7.5mm)=0.3*48.5mm=14.55mm. The projection of the second sub-part M322 onto the first direction X, extending along the second direction Y, has an extension dimension of 0.7*(56mm-7.5mm)=0.7*48.5mm=33.95mm. Thus, the design of the shape of the notched surface M3 is complete. Subsequently, a connecting structure 30 is formed in the notched structure Q1 to achieve the connection between the base layer 10 and the cladding layer 20.

[0056] In some embodiments, the connecting structure 30 includes molybdenum, and the mass percentage of molybdenum in the connecting structure 30 is B1, where 2.5 ≤ B1 ≤ 2.6. The connecting structure 30 also includes tungsten, and the mass percentage of tungsten in the connecting structure 30 is B2, where 0.1 ≤ B2 ≤ 0.22.

[0057] In this embodiment, after the composite slab is joined, a high-temperature rolling process is required. In the overall structure of the composite slab, the structural strength of the connecting structure 30 directly affects the overall structural strength of the composite slab. To ensure the structural strength of the connecting structure 30, the first connecting part 31 and the second connecting part 32 in the connecting structure 30 are made of the same material. Even if the first connecting part 31 and the second connecting part 32 are formed by two different welding processes, the use of the same material ensures the connection stability between the first connecting part 31 and the second connecting part 32, thereby guaranteeing the structural strength of the connecting structure 30 itself.

[0058] Furthermore, to ensure the performance of the composite slab in subsequent high-temperature rolling, the connecting structure 30 includes molybdenum and tungsten. The mass percentage of molybdenum in the connecting structure 30 is B1, where 2.5 ≤ B1 ≤ 2.6; the mass percentage of tungsten in the connecting structure 30 is B2, where 0.1 ≤ B2 ≤ 0.22. By increasing the content of molybdenum and tungsten in the connecting structure 30, its high-temperature resistance can be improved, reducing the probability of cracking during subsequent high-temperature rolling in the furnace, thereby ensuring the performance of the composite slab in subsequent high-temperature rolling.

[0059] In some embodiments, please refer to Figure 1 and Figure 2 The base layer 10 has a connecting channel D1 that connects the first surface M1 and the peripheral side M2. The connecting channel D1 is spaced apart from the notch structure Q1. The projection of the connecting channel D1 in the first direction X is located inside the projection of the cladding layer 20 in the first direction X.

[0060] During the connection process between the cover layer 20 and the base layer 10, the connection structure 30 only connects the cover layer 20 and the base layer 10 at their edges. To further improve the tightness of the connection between the cover layer 20 and the base layer 10, a connecting channel D1 is provided within the base layer 10, connecting the first surface M1 and the peripheral side surface M2. One end of the connecting channel D1 near the first surface M1 connects to the middle gap between the base layer 10 and the cover layer 20, and the other end of the connecting channel D1 near the peripheral side surface M2 connects to the outside of the base layer 10 and is connected to a vacuum pump. Through the above arrangement, a vacuum can be drawn between the cover layer 20 and the base layer 10, thereby allowing the cover layer 20 and the base layer 10 to adhere to each other under atmospheric pressure, ensuring the tightness of the connection between the cover layer 20 and the base layer 10.

[0061] To reduce the mutual interference between the connecting channel D1 and the notch structure Q1, the connecting channel D1 and the notch structure Q1 are spaced apart. When the connecting structure 30 is formed in the notch structure Q1, the connecting channel D1 will not interfere with the formation of the connecting structure 30 due to the spacing between the connecting channel D1 and the notch structure Q1. When the connecting channel D1 is connected to a vacuum pump, since the projection of the connecting channel D1 in the first direction X is located inside the projection of the cladding 20 in the first direction X, the connecting channel D1 directly connects to the interior of the relative center of the cladding 20, and the vacuum pumping operation will not interfere with the connecting structure 30.

[0062] Specifically, the connecting channel D1 includes a first channel and a second channel that are interconnected. The first channel extends along a first direction X and is located on one side of the notch structure Q1 along a second direction Y. The end of the first channel away from the second channel is connected to the first surface M1. The second channel extends along the second direction Y and is located on one side of the notch structure Q1 along the first direction X. The end of the second channel away from the first channel is connected to the peripheral side surface M2. A vacuum pipe D2 can be welded to the end of the second channel away from the first channel to facilitate connection with vacuuming equipment. The inner diameters of the first channel, the second channel, and the vacuum pipe D2 are all equal and exceed 30mm to ensure smooth operation during vacuuming. The extension dimension of the first channel can be controlled between 20mm and 50mm, and the extension dimension of the second channel can be controlled between 200mm and 300mm to facilitate the installation of the connecting channel D1 inside the base layer 10. The vacuum pipe D2 can extend along the second direction Y, with its extension length controlled between 200mm and 400mm. The wall thickness of the vacuum pipe D2 is controlled between 2mm and 3mm to ensure its strength. When the vacuum pipe D2 is welded to the port of the second channel on the side surface M2 of the base layer, the weld leg size exceeds 5mm to ensure the airtightness of the connection between the vacuum pipe D2 and the second channel.

[0063] Secondly, please refer to Figure 5 , Figure 6 and Figure 7 This application provides a method for producing composite slabs, including: S10. Provide a base layer 10, which includes iron and carbon elements. The base layer 10 includes a first surface M1 along a first direction X and a peripheral side surface M2 arranged around the first direction X. The base layer 10 includes a notch structure Q1 that connects the first surface M1 and the peripheral side surface M2. S20, a coating 20 is provided, the coating 20 includes iron and chromium elements, the coating 20 is disposed on one side of the first surface M1, and the projection of the coating 20 in the first direction X overlaps with the projection of the notch structure Q1 in the first direction X. S30, forming a connecting structure 30, which is formed inside the notch structure Q1 and connects the base layer 10 and the cover layer 20; S30, forming the connecting structure 30 includes S31, forming the first connecting portion 31 and S32, forming the second connecting portion 32. The first connecting portion 31 is formed on the side of the notched structure Q1 near the first surface M1, and the second connecting portion 32 is formed on the side of the notched structure Q1 near the peripheral side surface M2. The grain size of the first connecting portion 31 is smaller than the grain size of the second connecting portion 32.

[0064] In step S10, the base layer 10 includes iron and carbon elements, and may include carbon steel. The base layer 10 may have a plate-like structure and includes a first surface M1 along a first direction X and a peripheral side surface M2 arranged around the first direction X. The first direction X is parallel to the thickness direction of the plate-like base layer 10. A notch structure Q1 is provided on the base layer 10, connecting the first surface M1 and the peripheral side surface M2. The notch structure Q1 may be arranged in a circle around the first direction X.

[0065] In S20, the cladding 20 includes iron and chromium elements, and may include stainless steel. The cladding 20 is stacked on one side of the base layer 10 along the first surface M1. The projection of the cladding 20 in the first direction X overlaps with the projection of the notch structure Q1 in the first direction X, and the projection of the cladding 20 in the first direction X does not exceed the projection of the base layer 10 in the first direction X.

[0066] In this embodiment, the smaller the gap between the base layer 10 and the cladding layer 20 in the composite slab, the better the forming quality of the composite slab. To minimize the gap between the base layer 10 and the cladding layer 20, a grinding operation is performed on the side of the base layer 10 facing the cladding layer 20, i.e., the side of the first surface M1, to remove oxide scale. During the grinding process, pits deeper than 0.2 mm or protrusions higher than 0.2 mm are avoided as much as possible to ensure the flatness of the side of the base layer 10 facing the cladding layer 20. Similarly, a grinding operation can also be performed on the side of the cladding layer 20 facing the base layer 10 to remove oxide scale. During the grinding process, pits deeper than 0.2 mm or protrusions higher than 0.2 mm are avoided as much as possible to ensure the flatness of the side of the cladding layer 20 facing the base layer 10. By grinding the base layer 10 and the cladding layer 20, it is ensured that the gap between the base layer 10 and the cladding layer 20 does not exceed 1 mm. After the base layer 10 and the cover layer 20 are stacked, the base layer 10 and the cover layer 20 can be clamped using a clamp to further reduce the gap between the base layer 10 and the cover layer 20.

[0067] In step S30, forming the connecting structure 30, the connecting structure 30 connects the base layer 10 and the cladding layer 20. The connecting structure 30 is formed by welding, and the connecting structure 30 is the solder left inside the notch structure Q1 during the welding process. Step S30, forming the connecting structure 30, includes steps S31, forming the first connecting portion 31, and S32, forming the second connecting portion 32. The first connecting portion 31 is formed on the side of the notch structure Q1 near the first surface M1, and the second connecting portion 32 is formed on the side of the notch structure Q1 near the peripheral side surface M2. The grain size of the first connecting portion 31 is smaller than the grain size of the second connecting portion 32. In other words, the welding process for forming the first connection 31 is different from the welding process for forming the second connection 32. The first connection 31 can be formed using gas metal arc welding (GMAW). GMAW offers a higher level of precision than submerged arc welding (SAW). Using GMAW to form the first connection 31 reduces the probability of easily penetrating the root of the notch structure Q1 during welding, allowing the base layer 10 and the cladding layer 20 to adhere relatively well under gravity, thus reducing the probability of weld metal flowing into the gap between the cladding layer 20 and the base layer 10. After forming the first connection 31, the second connection 32 can be formed using submerged arc welding. Since the first connection 31 has already preliminarily connected the base layer 10 and the cladding layer 20, the probability of weld metal flowing into the gap between the cladding layer 20 and the base layer 10 can also be reduced to some extent during submerged arc welding, thereby achieving a connection between the base layer 10 and the cladding layer 20 and ensuring the forming quality of the composite slab.

[0068] In step S31, forming the first connecting portion 31, the first connecting portion 31 can be formed using a gas metal arc welding (GMAW) process. The first connecting portion 31 may include two weld seams to ensure it has a large thickness, preventing burn-through during subsequent welding to form the second connecting portion 32. The welding parameters for the first weld seam in the first connecting portion 31 can be set as follows: welding current 100A-140A, welding voltage 12V-18V, welding speed 80mm / min-120mm / min. Since the welding parameters for the first weld seam are relatively small, the temperature will not be very high after one pass, allowing for direct welding of the second weld seam. The welding parameters for the second weld seam in the first connecting portion 31 can be set as follows: welding current 220A-260A, welding voltage 23V-28V, welding speed 240mm / min-320mm / min. During the formation of the first connecting portion 31, if welding defects are found, the existing weld seam is completely removed and re-welded. During the formation of the first connection part 31, the protective gas is an argon-rich mixture M12, and the oxygen content in the argon-rich mixture is controlled to be 1%-2% to ensure that the oxidizing property of the protective gas is at a low level, thereby reducing the burn-off of alloying elements in the solder and increasing the transition coefficient of alloying elements, so as to ensure that the weld has good welding quality and high mechanical properties, thereby ensuring the performance of the first connection part 31.

[0069] In step S32, forming the second connection 32, the second connection 32 is formed by submerged arc welding. The welding parameters for the second connection 32 can be set as follows: welding current 420A-880A, welding voltage 31V-55V, and welding speed 320mm / min-450mm / min. Because the second connection 32 is relatively thick, multiple layers of welds are required until the notch structure Q1 is filled. During multiple welding processes, the interpass temperature must be kept ≤85℃ to avoid overheating and deterioration of the weld and heat-affected zone performance. Welding defects must also be inspected layer by layer; if a welding defect is found in a layer, it must be cleaned before welding the next layer. In the submerged arc welding process, the mass percentage of silicon dioxide and carbon dioxide in the flux is controlled between 5-10%, the mass percentage of calcium oxide and magnesium oxide is controlled between 6-10%, the mass percentage of aluminum oxide and manganese oxide is controlled between 30-40%, the mass percentage of calcium fluoride is controlled between 40-50%, the mass percentage of sulfur does not exceed 0.02%, and the mass percentage of phosphorus does not exceed ≤0.03%.

[0070] To ensure the connection stability between the first connecting part 31 and the second connecting part 32, the welding wires of the first connecting part 31 and the second connecting part 32 are made of the same material. Even if the first connecting part 31 and the second connecting part 32 are formed by two different welding processes, the connection stability between the first connecting part 31 and the second connecting part 32 can be guaranteed based on the setting of the same material, thereby ensuring the structural strength of the connecting structure 30 itself.

[0071] During the formation of the first connecting part 31, a solid welding wire with a diameter of 1.2 mm is used. During the formation of the second connecting part 32, a solid welding wire with a diameter of 4 mm is used.

[0072] Considering that the composite slab will undergo high-temperature rolling, in order to reduce the probability of cracking of the connecting structure 30 during high-temperature rolling, the welding wire composition includes carbon (0.02-0.026% by mass), silicon (0.42-0.8% by mass), manganese (0.75-0.95% by mass), chromium (22.5-23.5% by mass), nickel (12.8-13.4% by mass), molybdenum (2.5-2.6% by mass), and tungsten (0.1-0.22% by mass). In addition, the welding wire composition also includes sulfur and phosphorus, with sulfur not exceeding 0.01% by mass and phosphorus not exceeding 0.02% by mass.

[0073] Chromium provides corrosion resistance and oxidation resistance, forming a dense passivation film on the weld surface to resist chemical corrosion; its content should be controlled within the range of 22.5-23.5%. Nickel stabilizes the austenitic structure, ensuring good toughness and plasticity of the weld metal and preventing welding cracks; its content should be controlled within the range of 12.8-13.4%. Carbon impairs resistance to intergranular corrosion and should be controlled at a low level to effectively inhibit the precipitation of chromium carbide at grain boundaries; its content should be controlled within the range of 0.02-0.026%. Manganese and silicon are mainly used to improve the deoxidation capacity of the weld and the arc stability of the welding process. Silicon can also improve the fluidity of the molten pool and improve welding quality; the content of manganese and silicon should be controlled within the range of 0.75-0.95% and 0.42-0.8%, respectively. Sulfur and phosphorus are impurity elements that significantly increase the tendency of welds to hot crack. Theoretically, the less the better, but due to process and cost reasons, they can be controlled below 0.01 and 0.02 respectively. Molybdenum and tungsten strengthen high-temperature strength through solid solution, thereby preventing welds from cracking during subsequent furnace rolling. The levels of molybdenum and tungsten are controlled at 2.5-2.6 and 0.1-0.22 respectively.

[0074] In some embodiments, forming the notch structure Q1 includes forming a first sub-surface M31 and forming a second sub-surface M32. The first sub-surface M31 is connected to the first surface M1, and the second sub-surface M32 is connected between the first sub-surface M31 and the peripheral surface M2. The angle between the first sub-surface M31 and the first surface M1 is greater than the angle between the second sub-surface M32 and the first surface M1.

[0075] Considering that the first connecting part 31 and the second connecting part 32 are formed by two welding processes respectively, the notch surface M3 is set as a first sub-surface M31 and a second sub-surface M32. The first sub-surface M31 is connected to the first surface M1, and the second sub-surface M32 is connected to the peripheral surface M2. The first sub-surface M31 and the second sub-surface M32 are connected to each other. The first connecting part 31 is formed at the corresponding position of the first sub-surface M31, and the second connecting part 32 is formed at the corresponding position of the second sub-surface M32.

[0076] Setting the angle between the first sub-face M31 and the first surface M1 to be greater than the angle between the second sub-face M32 and the first surface M1 allows the inclination of the first sub-face M31 to be greater than that of the second sub-face M32. During the first welding process, the first connecting portion 31 is formed at the corresponding position of the first sub-face M31. Based on the relatively large angle between the first sub-face M31 and the first surface M1, the first sub-face M31 has a relatively large inclination, which to some extent allows the weld metal to tend to flow towards the side closer to the second sub-face M32, thereby reducing the probability of weld metal flowing into the gap between the cladding layer 20 and the base layer 10.

[0077] The angle between the second sub-surface M32 and the first surface M1 is smaller than the angle between the first sub-surface M31 and the first surface M1. That is, the notch surface M3 changes angle at the junction of the first sub-surface M31 and the second sub-surface M32, and the inclination of the second sub-surface M32 is smaller than the inclination of the first sub-surface M31. When the weld metal has a tendency to flow towards the side closer to the second sub-surface M32, there is a bending angle at the junction of the first sub-surface M31 and the second sub-surface M32. This bending angle can block the flow of the weld metal so that the first connecting part 31 is formed at the corresponding position of the first sub-surface M31, thereby realizing the initial connection between the base layer 10 and the cladding layer 20 by the first connecting part 31.

[0078] In some embodiments, during S10, when providing the base layer 10, a connecting channel D1 is provided inside the base layer 10, connecting the first surface M1 and the peripheral side surface M2. The connecting channel D1 is spaced apart from the notch structure Q1, and the projection of the connecting channel D1 in the first direction X is located inside the projection of the covering layer 20 in the first direction X. One end of the connecting channel D1 near the first surface M1 can connect to the middle gap between the base layer 10 and the covering layer 20, and the other end of the connecting channel D1 near the peripheral side surface M2 can connect to the outside of the base layer 10 and be connected to a vacuum pump. With the above arrangement, a vacuum can be drawn between the covering layer 20 and the base layer 10, so that the covering layer 20 and the base layer 10 adhere to each other under atmospheric pressure, ensuring the tightness of the connection between the covering layer 20 and the base layer 10.

[0079] During the vacuuming process, high-purity argon gas (≥99.99%) is introduced between the cladding layer 20 and the base layer 10 to remove air from the gap between them. The vacuuming process can be divided into two stages. The first stage involves vacuuming for 10-12 hours after welding the composite slab, maintaining a vacuum level of ≤0.12 Pa, followed by pressure holding. The second stage involves maintaining a vacuum level of ≤0.01 Pa for 1-3 hours before furnace rolling, followed by pressure holding. By performing vacuuming in these two stages, the tightness of the connection between the cladding layer 20 and the base layer 10 can be ensured, facilitating the subsequent preparation of the composite slab.

[0080] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A composite slab, characterized in that, include: The base layer includes iron and carbon elements. The base layer includes a first surface along a first direction. The base layer includes a peripheral side surface disposed around the first direction. The peripheral side surface is recessed inward along a second direction to form a notch structure. The notch structure communicates with the first surface. The second direction intersects with the first direction. The coating, comprising iron and chromium, is disposed on one side of the first surface of the base layer along the first direction, and the projection of the coating in the first direction overlaps with the projection of the notch structure in the first direction. A connecting structure is located inside the notch structure, and the connecting structure connects the base layer and the cover layer along the first direction; The connection structure includes a first connection portion and a second connection portion that are interconnected along the second direction. The first connection portion is located on the side of the second connection portion away from the peripheral side, and the grain size of the first connection portion is smaller than the grain size of the second connection portion.

2. The composite slab according to claim 1, characterized in that, The notch structure includes a notch surface connecting the first surface and the peripheral side surface. The notch surface includes a first sub-surface connected to the first surface and a second sub-surface connected to the peripheral side surface. The first sub-surface and the second sub-surface are connected to each other. The angle between the first sub-face and the first surface is greater than the angle between the second sub-face and the first surface; the first connecting portion is in contact with the first sub-face, and the second connecting portion is in contact with the second sub-face.

3. The composite slab according to claim 2, characterized in that, The second sub-surface includes a first sub-part connected to the first sub-surface and a second sub-part connected to the peripheral side surface, wherein the first sub-part and the second sub-part are interconnected. The angle between the first sub-part and the first surface is greater than the angle between the second sub-part and the first surface; the extension dimension of the projection of the first sub-part in the first direction along the second direction is smaller than the extension dimension of the projection of the second sub-part in the first direction along the second direction.

4. The composite slab according to claim 3, characterized in that, The angle between the first sub-face and the first surface is A1, where 55°≤A1≤65°; And / or, the angle between the second sub-face and the first surface is A2, 10°≤A2≤50°; And / or, the second sub-surface includes a first sub-part and a second sub-part connected to each other, the first sub-part being connected to the first sub-surface, the second sub-part being connected to the peripheral side surface, the angle between the first sub-part and the first surface being A3, 35°≤A3≤50°; the angle between the second sub-part and the first surface being A4, 10°≤A4≤20°.

5. The composite slab according to claim 1, characterized in that, The notch structure includes a notch surface connecting the first surface and the peripheral side surface. The projection of the notch surface in the first direction extends along the second direction by an dimension L1. The extension dimension of the coating in the first direction is T1. L1 = k1 * T1, 5mm ≤ T1 ≤ 40mm, 3 ≤ k1 ≤ 4. When 5mm≤T1≤15mm, 3.5≤k1≤4; when 15mm≤T1≤40mm, 3≤k1≤3.

5.

6. The composite slab according to claim 5, characterized in that, The projection of the first sub-face in the first direction extends along the second direction by a dimension L2, where 7mm ≤ L2 ≤ 9mm. The projection of the second sub-surface onto the first direction extends along the second direction by a dimension L3. The second sub-surface includes a first sub-part and a second sub-part that are connected to each other. The first sub-part is connected to the first sub-surface, and the second sub-part is connected to the peripheral side surface. The angle between the first sub-part and the first surface is greater than the angle between the second sub-part and the first surface. The projection of the first sub-part in the first direction extends along the second direction by a dimension L4, where L4 = k2 * L3, and 0.2 ≤ k2 ≤ 0.

4.

7. The composite slab according to claim 1, characterized in that, The connecting structure includes molybdenum, and the mass percentage of molybdenum in the connecting structure is B1, where 2.5 ≤ B1 ≤ 2.

6. And / or, the connecting structure includes tungsten, and the mass percentage of tungsten in the connecting structure is B2, 0.1≤B2≤0.

22.

8. The composite slab according to claim 1, characterized in that, The base layer has a connecting channel that connects the first surface and the peripheral side. The connecting channel is spaced apart from the notch structure. The projection of the connecting channel in the first direction is located inside the projection of the cladding in the first direction.

9. A method for producing a composite slab, characterized in that, include: A base layer is provided, the base layer comprising iron and carbon elements, the base layer comprising a first surface along one side of a first direction and a peripheral side surface disposed around the first direction, the base layer comprising forming a notch structure, the notch structure connecting the first surface and the peripheral side surface; A coating is provided, the coating comprising iron and chromium, the coating being disposed on one side of the first surface, and the projection of the coating in the first direction overlapping the projection of the notch structure in the first direction; A connection structure is formed inside the notch structure, and the connection structure connects the base layer and the cladding layer; The connection structure includes forming a first connection portion and forming a second connection portion. The first connection portion is formed on the side of the notch structure near the first surface, and the second connection portion is formed on the side of the notch structure near the peripheral side. The grain size of the first connection portion is smaller than the grain size of the second connection portion.

10. The method for producing composite slabs according to claim 9, characterized in that, The notch-forming structure includes forming a first sub-face and forming a second sub-face, wherein the first sub-face is connected to the first surface and the second sub-face is connected between the first sub-face and the peripheral surface; The angle between the first sub-face and the first surface is greater than the angle between the second sub-face and the first surface.

Images