Single-sided stainless steel clad plate and hot continuous rolling method for manufacturing the same

Abstract

The application discloses a hot continuous rolling preparation method of single-sided stainless steel composite plate. In the preparation method, the composite blank is heated at a temperature of 1210-1270 DEG C; the heated composite blank is subjected to hot continuous rolling on a hot continuous rolling mill; firstly, R1 rough rolling mill is adopted to roll 1-3 passes at a temperature of 1180-1240 DEG C with a reduction of 30 mm or more; then, R2 rough rolling mill is adopted to roll 3-5 passes at a temperature of 1050-1170 DEG C with a reduction of 28 mm or more; finally, F1-F7 finishing rolling mill is adopted to roll 5-7 passes at a starting rolling temperature of 950 DEG C or more and a final rolling temperature of 850 DEG C or more to obtain a composite plate large plate; the composite plate large plate is subjected to laminar cooling in a laminar cooling system after being discharged from the hot continuous rolling mill, and then is coiled at a coiling temperature of 560-660 DEG C; the obtained composite coil is opened and flattened; and then the composite plate large plate is placed between two steel plates at a temperature of T f -T f +150 DEG C for stack cooling.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steel material preparation, and relates to a hot continuous rolling preparation method of a single-side stainless steel clad plate and a single-side stainless steel clad plate. BACKGROUND

[0002] With the continuous development of science and industry, ordinary alloys or single metals are difficult to meet the requirements of industrial development on the comprehensive performance of materials, and thus clad plates are developed. The stainless steel clad plate is prepared by taking carbon steel or low alloy steel as a base layer and taking stainless steel as a clad layer, realizing the metallurgical combination of a clad interface through explosion cladding, rolling cladding and the like, so as to save resources and reduce costs on the premise of not reducing the use effect (mechanical strength, corrosion resistance and the like). The stainless steel clad plate is widely applied to the petrochemical, pressure vessel, power equipment, pharmaceutical equipment, water conservancy, papermaking, bridge and the like industries.

[0003] The existing stainless steel clad plate is prepared by explosion cladding, non-vacuum preparation of a clad plate, vacuum electron beam welding preparation of a clad plate and the like, and has the problems of poor surface quality, difficult control of plate shape, poor interface combination quality, low material yield and low production efficiency. SUMMARY

[0004] The present application aims to provide a hot continuous rolling preparation method of a single-side stainless steel clad plate, which has excellent surface quality, plate shape and interface combination quality, and is high in production efficiency and material yield.

[0005] To achieve the above-mentioned application purpose, an embodiment of the present application provides a hot continuous rolling preparation method of a single-side stainless steel clad plate, which comprises the following steps:

[0006] 1) Preparation of a clad plate

[0007] Two carbon steel billets with a thickness T1, a length L1 and a width W1 are prepared as base materials, and two stainless steel billets with a thickness T2, a length L2 and a width W2 are prepared as clad materials; L2 < L1 and W2 < W1;

[0008] The base materials, the clad materials, the clad materials and the base materials are stacked in sequence to prepare a clad plate;

[0009] 2) Rolling of the clad plate

[0010] The clad plate is heated at a temperature of 1210-1270℃, and the total heating time is greater than or equal to 1.0xt min / mm, t is the thickness of the clad plate, and the holding time is 20-40min;

[0011] The heated composite blank is hot continuous rolled on a hot continuous rolling mill: first, an R1 rough rolling mill is used to roll 1-3 passes at 1180-1240℃ with a reduction of ≥30mm; then, an R2 rough rolling mill is used to roll 3-5 passes at 1050-1170℃ with a reduction of ≥28mm; finally, F1-F7 finishing rolling mills are used to roll 5-7 passes with a roughing temperature of ≥950℃ and a finishing temperature of ≥850℃, to obtain a composite plate large plate;

[0012] The composite plate large plate is cooled in a laminar flow cooling system after exiting the hot continuous rolling mill, and then is coiled at a coiling temperature of 560-660℃, to obtain a composite coil;

[0013] The obtained composite coil is opened and segmented according to the required length, and then the segmented composite plate large plates are placed between two steel plates at a temperature of T f ~T f +150℃ for stack cooling, with a stack cooling time of 0.4min / mmxt0±5min, t0 being the thickness of the composite plate large plate; wherein,

[0014] T f =550+30[Si]-20[Mn]+15[Cr]-15[Ni]+10[Mo], wherein [Si], [Mn], [Mo], [Cr] and [Ni] are 100 times the mass percentage of each element in the base material;

[0015] After the stack cooling is completed, the composite plate large plate is naturally cooled on a cooling bed;

[0016] 3) Composite plate separation and straightening

[0017] The two side edges of the segmented composite plate large plate are cut to remove the part outside the seal, and the composite plate large plate is separated into an upper and a lower composite plate small plate;

[0018] The composite plate small plate is transversely pressed flat and cold straightened to obtain a single-layer stainless steel composite plate finished product.

[0019] Preferably, the step 1) composite blank preparation further comprises:

[0020] The at least one surface of each of the two base materials and the two composite materials is surface treated;

[0021] An isolation agent is applied to one surface of one of the composite materials;

[0022] The blanks are assembled in the order of base material, composite material, composite material, base material; wherein the composite material is placed in the middle relative to the base materials, the surfaces of the base materials and the composite materials that are in contact with each other are both surface treated surfaces, and the surface on which the isolation agent is applied faces the other composite material;

[0023] Four sealing strips with width W3, W3 = 2T2-1~2mm, are prepared, and the sealing strips are attached to the four sides of the two composite materials, and the adjacent sealing strips and the sealing strips and the base materials are all air-tight welded, so that the two base materials and the sealing strips form an integral whole, and a composite blank is obtained;

[0024] A round hole is processed on the sealing strip at the groove of the side edge of the composite blank, and a seamless steel pipe is welded at the round hole;

[0025] The groove of the four side edges of the composite blank is built up welded;

[0026] The composite blank is vacuumized through the seamless steel pipe by a vacuum pump, and the vacuum degree is ≤10 -1 Pa, and the pressure is maintained for 4h or more, and finally the seamless steel pipe is sealed.

[0027] Preferably, the step of "surface treatment of at least one surface of each of the two base materials and the two composite materials" comprises:

[0028] One surface of each of the two composite materials is ground and polished to remove the surface oxide skin; and,

[0029] One surface of each of the two base materials is milled and ground in a relatively complementary manner, and the surface is processed into a transversely inclined surface with length L11 = L1 and width W11 > W1, and the base material is a non-equal-thickness blank with thickness varying in the transverse direction, or the surface is processed into a longitudinally inclined surface with length L11 > L1 and width W11 = W1, and the base material is a non-equal-thickness blank with thickness varying in the longitudinal direction.

[0030] Preferably, L2 = L11-L0, and W2 = W11-W0, and L0 and W0 are respectively in the range of 90-150mm;

[0031] In the "centering of the composite material relative to the base material", the distance from the side edge of the composite material in the transverse direction to the corresponding side edge of the base material is half of W0, and the distance from the side edge of the composite material in the longitudinal direction to the corresponding side edge of the base material is half of L0.

[0032] Preferably, the step of "surface treatment of at least one surface of each of the two base materials and the two composite materials" comprises:

[0033] One surface of each of the two substrates is milled to form an irregular concave-convex surface comprising n planes connected in sequence in the transverse direction, the substrate being a non-uniform-thickness substrate with non-monotonic thickness variation in the transverse direction, the irregular concave-convex surface having a length L12=L1 and a total width W12>W1; or the surface is milled to form an irregular concave-convex surface comprising n planes connected in sequence in the longitudinal direction, the substrate being a non-uniform-thickness substrate with non-monotonic thickness variation in the longitudinal direction, the irregular concave-convex surface having a total length L12>L1 and a width W12=W1; n≥2.

[0034] Each of the composite materials is ground on one surface to remove surface oxidation; and then each of the composite materials is bent to match the corresponding irregular concave-convex surface.

[0035] Preferably, L2=L12-L0 and W2=W12-W0, L0 and W0 are in the range of 90-150 mm.

[0036] In the "centering the composite material relative to the substrate", the distance from the side edge of the composite material to the corresponding side edge of the substrate in the transverse direction is half of W0, and the distance from the side edge of the composite material to the corresponding side edge of the substrate in the longitudinal direction is half of L0.

[0037] Preferably, in the step of "applying a release agent to one surface of one of the composite materials", the release agent used is a coating liquid containing silicon oxide and magnesium oxide, and the mass ratio of silicon oxide to magnesium oxide is 3:1.

[0038] The amount of the release agent applied is 20 ymg / m 2 , y being the thickness ratio of the composite blank to the large plate of the composite board.

[0039] Preferably, before the step of "stacking the substrates, the composite materials, the composite materials, and the substrates in the order of substrate, composite material, composite material, and substrate", the composite material coated with the release agent is heated and dried in a trolley furnace, the drying temperature is 340-360°C, and the drying time is 35-45 min.

[0040] Preferably, in the step of "applying a release agent to one surface of one of the composite materials", the release agent used comprises, by weight, 25-35% of silicon nitride, 5-10% of thermosetting amino resin, and 55-70% of water.

[0041] The thickness of the release agent applied is 0.2-0.5 mm.

[0042] Preferably, before the step of "stacking the substrates, the composite materials, the composite materials, and the substrates in the order of substrate, composite material, composite material, and substrate", the composite material coated with the release agent is heated and dried, the drying temperature is 100-250°C, and the drying time is 20-40 min.

[0043] Preferably, in the step of "gas shield welding between adjacent sealing strips and between sealing strips and the base material", the welding speed is 300-360 mm / min, and the interpass temperature is controlled to be 135-165 DEG C.

[0044] Preferably, in the step of "surfacing the grooves on the four sides of the composite blank", submerged arc surfacing is used.

[0045] Before welding, the flux is baked at 350 DEG C for 2 h, and then kept at 150 DEG C for 1 h.

[0046] During welding, the interpass temperature is controlled to be 135-165 DEG C, and the welding speed is 420-480 mm / min.

[0047] To achieve the above object, one embodiment of the present application provides a single-sided stainless steel composite plate prepared by the preparation method, wherein the chemical composition and mass percentage of the base layer of the composite plate are as follows: C: 0.13%-0.18%, Si≤0.16%, Mn: 0.30-1.60%, P≤0.025%, S≤0.015%, Nb≤0.030%, Ti≤0.070%, Al: 0.020-0.050%, and the balance is Fe and inevitable impurities.

[0048] The total thickness of the composite plate is ≤10 mm, the thickness of the composite layer is ≥0.2 mm, and the unevenness is ≤3 mm / m.

[0049] The bonding rate of the composite interface is 100%, and the shear strength is ≥210 MPa.

[0050] The yield strength is ≥235 MPa, and the tensile strength is ≥400 MPa.

[0051] Compared with the prior art, the single-sided stainless steel composite plate prepared by the preparation method has the advantages of retaining the corrosion resistance of stainless steel and the mechanical strength of carbon steel, having excellent surface quality, plate shape and interface bonding, for example, no obvious surface defects such as pits and side edge scratches, high production efficiency, high material yield, resource saving and cost reduction. BRIEF DESCRIPTION OF DRAWINGS

[0052] For the purpose of clear display and illustration, in each drawing of the present application, the size of some structures or parts is enlarged relative to other structures or parts, and therefore, only the basic structure of the subject of the present application is shown.

[0053] Figure 1a is a sectional view of a billet in the first embodiment of the billet surface treatment step in the present application;

[0054] Figure 1bis a schematic view of a transverse cross section of a billet of the second embodiment of the billet surface treatment step in the present invention, in which the surface shape change after the surface treatment is schematically shown with a dotted line;

[0055] Figure 1c is a schematic view of a longitudinal cross section of a billet of the third embodiment of the billet surface treatment step in the present invention, in which the surface shape change after the surface treatment is schematically shown with a dotted line;

[0056] Figure 1d is a schematic view of a transverse cross section of a billet of the fourth embodiment of the billet surface treatment step in the present invention, and the surface shape change before (A), after (B) the surface treatment is schematically shown;

[0057] Figure 1e is a schematic view of a longitudinal cross section of a billet of the fifth embodiment of the billet surface treatment step in the present invention, and the surface shape change before (A), after (B) the surface treatment is schematically shown;

[0058] Figure 2a is a schematic view of a cross section of a composite billet corresponding to Figure 1a ;

[0059] Figure 2b is a schematic view of a transverse cross section of a composite billet corresponding to Figure 1b ;

[0060] Figure 2c is a schematic view of a longitudinal cross section of a composite billet corresponding to Figure 1c ;

[0061] Figure 2d is a schematic view of a transverse cross section of a composite billet corresponding to Figure 1d ;

[0062] Figure 2e is a schematic view of a longitudinal cross section of a composite billet corresponding to Figure 1e ;

[0063] Figure 3a is a schematic view of a cross section of two composite plates rolled from a composite billet of Figure 2a ;

[0064] Figure 3b is a schematic view of a transverse cross section of two composite plates rolled from a composite billet of Figure 2b ;

[0065] Figure 3c is a schematic view of a longitudinal cross section of two composite plates rolled from a composite billet of Figure 2c ;

[0066] Figure 3d is a schematic view of a transverse cross section of two composite plates rolled from a composite billet of Figure 2d ;

[0067] Figure 3e is a longitudinal sectional view of two composite plates rolled from a composite blank; Figure 2e

[0068] Figure 4a is a flow chart of the rolling step of the composite blank according to an embodiment of the present application;

[0069] Figure 4b is a flow chart of the rolling step of the composite blank according to another embodiment of the present application. DETAILED DESCRIPTION

[0070] The present application provides a hot continuous rolling method for preparing a stainless steel composite plate, and a composite plate prepared based on the method.

[0071] Compared with the prior art, such as the explosive compounding, non-vacuum preparation of composite blank, vacuum electron beam welding preparation of blank, etc. mentioned in the background art, the composite plate prepared by the preparation method of the present application has the advantages of excellent surface quality, excellent plate shape, excellent interface bonding, etc., and adopts the hot continuous rolling process, thus having high production efficiency and high material yield.

[0072] Specifically, the preparation method comprises three total steps of composite blank preparation, composite blank rolling and composite plate separation and straightening.

[0073] The total step of the composite blank preparation comprises the following sub-steps:

[0074] Two carbon steel blanks with a thickness T1, a length L1 and a width W1 are prepared as base materials, and two stainless steel blanks with a thickness T2, a length L2 and a width W2 are prepared as composite materials;

[0075] The at least one surface of each of the two base materials and the two composite materials is subjected to surface treatment;

[0076] A release agent is applied on one surface of one of the composite materials;

[0077] The blanks are assembled in the order of base material, composite material, composite material, base material;

[0078] Four sealing strips with a width W3, W3 = 2T2-1~2mm, are prepared, and the sealing strips are attached to the four sides of the two composite materials, and the adjacent sealing strips and the base materials are subjected to gas shield welding, so that the two base materials and the sealing strips form an integral whole, obtaining a composite blank base blank;

[0079] A round hole is formed on the sealing strip at the groove of the side edge of the composite blank base blank, and a seamless steel pipe is welded at the round hole;

[0080] The groove of the four side edges of the composite blank base blank is subjected to surfacing;

[0081] ​Use a vacuum pump to evacuate the composite billet through this seamless steel pipe, with the vacuum degree ≤ 10 -1 Pa, and then maintain the pressure for more than 4 hours; finally, seal the seamless steel pipe.

[0082] Furthermore, the above steps are described in detail as follows.

[0083] The step of "preparing two carbon steel billets with length L1 and width W1 as the base material; and preparing two stainless steel billets with length L2 and width W2 as the composite material" is also the billet preparation step.

[0084] Among them, the carbon steel billet used as the base material has a thickness T1, a length L1, and a width W1, which is a rectangular steel billet; similarly, the stainless steel billet used as the composite material has a thickness T2, a length L2, and a width W2, which is also a rectangular steel billet. And, L2 < L1, W2 < W1, and the length and width dimensions of the composite material are smaller than those of the base material.

[0085] As a preferred solution, the surface oxide scale penetration depth and the surface pit depth of the carbon steel billet are both ≤ 0.3 mm, and the unevenness is ≤ 3 mm / m; the surface of the stainless steel billet has no scratches, and the unevenness is ≤ 2 mm / m. In this way, it is avoided that the steel billet enters the production line of the composite plate with obvious surface defects or shape defects.

[0086] Next, regarding the step of "performing surface treatment on at least one surface of each of the two base materials and the two composite materials", which is also the billet surface treatment step. The present invention provides five preferred implementation manners, and the following will introduce these five implementation manners respectively.

[0087] <The first implementation manner of the billet surface treatment step>

[0088] In this implementation manner, grind and polish one surface of each base material and each composite material to remove the surface oxide scale and expose the metallic luster.

[0089] Refer Figure 1a As shown, for example, for the surface p1a of the base material 11a, use a grinding wheel, a belt grinder or a milling machine to grind and polish to remove the surface oxide scale and expose the metallic luster; similarly, for the surface p2a of the prepared base material 12a, use a grinding wheel, a belt grinder or a milling machine to grind and polish to remove the surface oxide scale and expose the metallic luster.

[0090] For the surface p3a of the prepared composite material 21a, use a wire wheel to grind and polish to remove the surface oxide scale and expose the metallic luster; similarly, for the surface p4a of the prepared composite material 22a, use a wire wheel to grind and polish to remove the surface oxide scale and expose the metallic luster.

[0091] As can be seen from the following text, when forming the billet, the surfaces that have been surface-treated (in this embodiment, grinding and polishing) are used as the surfaces where the base material and the composite material contact each other. For example, surface p1a and surface p3a contact each other, and surface p4a and surface p2a contact each other. In this way, the interface bonding quality can be ensured.

[0092] <The second embodiment of the billet surface treatment step>

[0093] In this embodiment, similar to the aforementioned first embodiment, one surface of each composite material (such as Figure 1b surfaces p3b and p4b) is ground and polished to remove the surface oxide scale and expose the metallic luster, which will not be elaborated here.

[0094] In this embodiment, different from the aforementioned first embodiment, it is the surface treatment of the base material:

[0095] Refer to Figure 1b , the surface p1b of the base material 11b is milled to process this surface p1b into surface p1b0. This surface p1b0 is a transverse inclined surface with a length L11 = L1 and a width W11 > W1. Correspondingly, the base material 11b is processed into a non-uniform-thickness billet with a gradually changing thickness in the transverse direction (that is, in the width direction). That is to say, after the base material 11b is milled, the height gradually increases from one side to the other side in its width direction.

[0096] Similarly, the surface p2b of the base material 12b is milled to process this surface p2b into surface p2b0. This surface p2b0 is a transverse inclined surface with a length L11 = L1 and a width W11 > W1. Correspondingly, the base material 12b is processed into a non-uniform-thickness billet with a gradually changing thickness in the transverse direction.

[0097] Among them, when milling the surface p2b of the base material 12b and the surface p1b of the base material 11b, it is carried out in a relatively shape-complementary manner, that is, the processed surfaces p2b0 and p1b0 are shape-complementary when facing each other. For example, the transverse inclination angle of surface p2b0 (such as the angle with the original surface p2b) is equal to the transverse inclination angle of surface p1b0 (such as the angle with the original surface p1b). Thus, it can be ensured that the upper and lower surfaces of the composite billet are parallel when forming the billet subsequently.

[0098] It can be understood that through the above milling process, the surface oxide scale on the surface p1b of the base material 11b and the surface p2b of the base material 12b can also be removed, and the metallic luster is exposed.

[0099] As can be seen from the following text, when forming the billet, the surfaces that have been surface-treated (in this embodiment, milling) are used as the surfaces where the base material and the composite material contact each other. For example, surface p1b0 and surface p3b contact each other, and surface p4b and surface p2b0 contact each other. Similarly, the interface bonding quality can be ensured as in the aforementioned first embodiment. Moreover, this embodiment can further be used to prepare a non-uniform-thickness composite plate with a gradually changing transverse thickness, so as to expand the applicable scenarios and scope of the composite plate.

[0100] <The third embodiment of the billet surface treatment step>

[0101] This embodiment is basically the same as the aforementioned second embodiment (including the surface treatment of surfaces p3c and p4c), with the only difference being that: in the second embodiment, the thickness of the base material gradually changes in the transverse direction, while in this embodiment, the thickness of the base material gradually changes in the longitudinal direction (i.e., the length direction). The following introduces the difference points, and the other similarities are introduced in the second embodiment and will not be elaborated here.

[0102] Refer to Figure 1c , the surface p1c of the base material 11c is milled to process this surface p1c into surface p1c0, which is a longitudinal inclined plane with a length L11 > L1 and a width W11 = W1. Correspondingly, the base material 11c is processed into a non-uniform-thickness billet with a gradually changing thickness in the longitudinal direction.

[0103] Similarly, the surface p2c of the base material 12c is milled to process this surface p2c into surface p2c0, which is a longitudinal inclined plane with a length L11 > L1 and a width W11 = W1. Correspondingly, the base material 12c is processed into a non-uniform-thickness billet with a gradually changing thickness in the longitudinal direction.

[0104] Among them, when milling the surface p2c of the base material 12c and the surface p1c of the base material 11c, it is carried out in a complementary shape manner, that is, the processed surfaces p2c0 and p1c0 are complementary in shape when facing each other. For example, the longitudinal inclination angle of surface p2c0 (such as the angle with the original surface p2c) is equal to the longitudinal inclination angle of surface p1c0 (such as the angle with the original surface p1c), so as to ensure that the upper and lower surfaces of the composite billet are parallel during subsequent billet forming.

[0105] It can be understood that through the above milling process, the surface scale on the surface p1c of the base material 11c and the surface p2c of the base material 12c can also be removed, revealing a metallic luster.

[0106] <The fourth embodiment of the billet surface treatment step>

[0107] In this embodiment, one surface of each substrate is milled and ground to process the surface into an irregular concave-convex surface comprising n planes connected in sequence in the lateral direction, the substrate is a non-uniform-thickness substrate with non-monotonic thickness variation in the lateral direction, the length L12 of the irregular surface is L1, and the total width W12 of the irregular surface is greater than W1.

[0108] For example, refer to Figure 1d The surface p1d of the substrate 11d is milled and ground to process the surface p1d from Figure 1d (A) into Figure 1d (B) the irregular concave-convex surface p1d0 shown in the figure, which specifically comprises n planes connected in sequence in the lateral direction, where n≥2, and in the figure, an example of 8 planes is shown. As can be seen from the figure, the 1st, 3rd, 5th, and 7th planes from left to right in the figure are lateral inclined surfaces, and the 2nd, 4th, 6th, and 8th planes are horizontal surfaces. Of course, this is only an example, and n can also be other numbers, or the irregular concave-convex surface can also be implemented without horizontal surfaces and only with lateral inclined surfaces, etc.

[0109] For example, refer to Figure 1d Through the milling and grinding of the surface p1d, the substrate 11d is processed into a non-uniform-thickness substrate with non-monotonic thickness variation in the lateral direction.

[0110] The length L12 of the irregular concave-convex surface p1d0 is L1, that is, it does not change due to milling and grinding; and the total width W12 of the irregular concave-convex surface p1d0 is greater than W1. It can be understood that the total width W12 is the sum of the widths of the n planes.

[0111] For example, refer to Figure 1d The surface p2d of the substrate 12d is also milled and ground to process the surface p2d from Figure 1d (A) into Figure 1d (B) the irregular concave-convex surface p2d0 shown in the figure. When milling and grinding the surface p2d of the substrate 12d and the surface p1d of the substrate 11d, they are processed in a complementary manner, that is, the processed surface p2d0 and the surface p1d0 are complementary in shape when they are opposite to each other.

[0112] According to the complementary shape, the irregular concave-convex surface p2d0 also specifically comprises n planes connected in sequence in the lateral direction, and in the figure, an example of 8 planes is shown. The length L12 of the irregular concave-convex surface p2d0 is L1, that is, it does not change due to milling and grinding; and the total width W12 of the irregular concave-convex surface p2d0 is greater than W1. It can be understood that the total width W12 is the sum of the widths of the n planes of the irregular concave-convex surface p2d0.

[0113] For example, refer to Figure 1dBy milling surface p2d, substrate 12d is processed into a non-uniform thickness blank with a non-monotonic thickness variation in the transverse direction. Based on the complementary relative shapes of irregular uneven surfaces p2d0 and p1d0, if the milled substrates 12d and 11d are placed opposite each other, the sum of their thicknesses at all points remains constant. Thus, during subsequent blank assembly, the upper and lower surfaces of the composite blank are parallel.

[0114] The surface treatment of the two substrates in this embodiment has been described above. The surface treatment of the two composite materials will be described below.

[0115] In this embodiment, the surface p3d of the prepared composite material 21d is polished with a wire wheel to remove the surface oxide scale and expose the metallic luster; similarly, the surface p4d of the prepared composite material 22d is polished with a wire wheel to remove the surface oxide scale and expose the metallic luster.

[0116] Furthermore, to match the surface shapes of substrates 11d and 12d, after removing the surface oxide scale, this embodiment also bends each composite material so that each composite material matches the corresponding irregular uneven surface. For example, for composite material 21d, it is bent to match the corresponding irregular uneven surface p1d0 to facilitate bonding contact during subsequent assembly; and for composite material 22d, it is bent to match the corresponding irregular uneven surface p2d0 to facilitate bonding contact during subsequent assembly.

[0117] The surface treatment in this embodiment can ensure the quality of interface bonding in the same way as the first embodiment described above. Furthermore, it can be used to prepare non-uniform thickness composite plates with non-monotonic changes in transverse thickness, thereby expanding the application scenarios and scope of the composite plates. Compared with existing steel plates, it enhances corrosion resistance and avoids frequent welding and dissimilar welding between composite plates of different thicknesses.

[0118] <Fifth Implementation Method of Blank Surface Treatment Steps>

[0119] The difference between this embodiment and the fourth embodiment mentioned above is that the thickness of the substrate in the horizontal direction is not monotonically changed in the fourth embodiment, while the thickness of the substrate in the vertical direction is not monotonically changed in this embodiment.

[0120] For example, reference Figure 1e The surface p1e of the substrate 11e is milled to remove the surface p1e from the substrate 11e. Figure 1e The horizontal surface in (A) is processed into Figure 1eThe irregular concave-convex surface p1e0 shown in (B) specifically includes n planes connected in sequence along the longitudinal direction, where n≥2, and in the figure, 8 planes are shown as an example. As can be seen from the figure, the 1st, 3rd, 5th, and 7th planes from left to right are longitudinal inclined surfaces, and the 2nd, 4th, 6th, and 8th planes are horizontal planes. Of course, this is only an example, and n can also be other numbers, or the irregular concave-convex surface can not include horizontal planes but only longitudinal inclined surfaces.

[0121] Referring to FIG. 1B, the surface p1e of the base material 11e is machined by milling and grinding to form an irregular concave-convex surface p1e0 shown in (B). Figure 1e The base material 11e is machined to be a non-uniform-thickness blank with a non-monotonic change in thickness in the longitudinal direction through milling and grinding of the surface p1e.

[0122] The width W12 of the irregular concave-convex surface p1e0 is W1, that is, does not change due to milling and grinding; and the total length L12 of the irregular concave-convex surface p1e0 is greater than L1. It can be understood that the total length L12 is the sum of the lengths of the n planes.

[0123] Correspondingly, referring to FIG. 2B, the surface p2e of the base material 12e is also machined by milling and grinding to form an irregular concave-convex surface p2e0 shown in (B). Figure 1e The surface p2e of the base material 12e is machined by milling and grinding to form an irregular concave-convex surface p2e0 shown in (B). Figure 1e (A) is machined to be Figure 1e (B) shown. When milling and grinding the surface p2e of the base material 12e and the surface p1e of the base material 11e, the relative shapes are complementary, that is, the machined surfaces p2e0 and p1e0 are shape-complementary when placed opposite each other.

[0124] According to the relative shape complementarity, the irregular concave-convex surface p2e0 also specifically includes n planes connected in sequence along the longitudinal direction, and in the figure, 8 planes are shown as an example. The width W12 of the irregular concave-convex surface p2e0 is W1, and the total length L12 is greater than L1.

[0125] Correspondingly, referring to FIG. 2B, the surface p2e of the base material 12e is also machined by milling and grinding to form an irregular concave-convex surface p2e0 shown in (B). Figure 1e The base material 12e is machined to be a non-uniform-thickness blank with a non-monotonic change in thickness in the longitudinal direction through milling and grinding of the surface p2e. Based on the relative shape complementarity of the irregular concave-convex surface p2e0 and the irregular concave-convex surface p1e0, if the machined base materials 12e and 11e are placed opposite each other, the sum of the thicknesses at each location is constant. In this way, when the blanks are subsequently assembled, the upper and lower surfaces of the composite blank are parallel.

[0126] The above describes the surface treatment of the two base materials in this embodiment. The surface treatment of the two composite materials is described below.

[0127] In this embodiment, the surface p3e of the prepared composite 21e is polished by a wire wheel to remove the surface oxide and expose the metal luster; similarly, the surface p4e of the prepared composite 22e is polished by a wire wheel to remove the surface oxide and expose the metal luster.

[0128] Further, in order to match the surface shape of the base material 11e, 12e, after removing the surface oxide, each composite is bent in this embodiment to match the corresponding irregular concave-convex surface. For example, the composite 21e is bent to match the corresponding irregular concave-convex surface p1e0 to facilitate the contact and fit during the subsequent assembly; for another example, the composite 22e is bent to match the corresponding irregular concave-convex surface p2e0 to facilitate the contact and fit during the subsequent assembly.

[0129] Similarly to the fourth embodiment described above, this embodiment can also improve the application scenarios and range of the composite board, enhance the corrosion resistance of the existing steel plate, and avoid frequent welding and dissimilar welding between composite boards of different thicknesses.

[0130] The above describes the five preferred embodiments of the surface treatment sub-step in the preparation step of the composite blank. Although only one surface of each of the base material and the composite is treated, it should be noted that, regardless of which of the five embodiments described above, the other surface of each of the base material and the composite can also be treated to remove the oxide. Although this additional treatment to remove the oxide is not necessary to achieve the technical effects of the present application, it can be more optimal; for example, in addition to removing the oxide from the surface of the base material facing the composite, the surface of the base material away from the composite (i.e., the surface of the composite board) can also be treated to remove the oxide.

[0131] The following further describes other sub-steps of the preparation step of the composite blank.

[0132] The step of "applying a release agent to one surface of a composite" is the release agent application step.

[0133] As can be known from the foregoing, the surface treatment step of the blank in the foregoing is to polish the surface of the composite that will contact the base material during assembly to ensure the interface bonding quality of the composite board. The purpose of the release agent application step is to avoid the subsequent bonding of the surfaces of the composite that contact each other during assembly in the composite blank rolling step, which makes it difficult to separate the final product.

[0134] Based on this, the isolation agent is applied to either one of the two composite materials. If the selected composite material has one surface treated and the other surface untreated in the previous blank surface treatment step, the isolation agent is applied to the surface that is "untreated". If the selected composite material has both surfaces treated in the previous blank surface treatment step, the isolation agent is applied to the surface that is intended to face the other composite material when the blanks are assembled.

[0135] For example, the isolation agent can be applied to the surface p6a of the composite material 22a or the surface p5a of the composite material 21a. Figure 1a For example, the isolation agent can be applied to the surface p6a of the composite material 22a or the surface p5a of the composite material 21a.

[0136] Two preferred embodiments of the isolation agent are provided herein, which are described as follows.

[0137] <First embodiment of the isolation agent>

[0138] In this embodiment, the isolation agent is a coating liquid containing silicon oxide and magnesium oxide, and the mass ratio of silicon oxide to magnesium oxide is 3:1. The isolation agent of this embodiment can achieve good isolation effect and ensure the separation of the two composite platelets.

[0139] When the isolation agent is applied to the surface of the composite material, the amount of the isolation agent applied is 20 ymg / m 2 That is, the weight of the isolation agent per unit area of the surface of the composite material is 20 ymg. Wherein, y is the ratio of the thickness of the composite blank prepared in the composite blank preparation step to the thickness of the composite plate prepared by subsequent rolling, which is also referred to as the rolling compression ratio of the composite blank.

[0140] Further, based on this embodiment, after the isolation agent is applied and before the subsequent assembly of the blanks, the composite material coated with the isolation agent is placed in a trolley furnace for heating and drying. The drying temperature is 340-360°C, and the drying time is 35-45 min.

[0141] <Second embodiment of the isolation agent>

[0142] In this embodiment, the components of the release agent are in a weight ratio of 25-35% silicon nitride, 5-10% thermosetting amino resin, and 55-70% water. Compared with the prior art release agent, and even compared with the first embodiment of the aforementioned release agent, the release agent of this embodiment not only achieves a good release effect and ensures the separation of the two subsequent composite plates, but also has strong chemical stability and is resistant to high temperature and thermal shock. The thermosetting amino resin used as the adhesive can be cured at low temperature, is non-toxic, and has a strong adhesive effect with a small amount, so the overall price is low, the operation is simple, and the release and adhesion effects are good.

[0143] Here, a preferred preparation method of the release agent is provided, which comprises: first, placing 5-10% silicon nitride (by weight) in a beaker or other container, then pouring 15-25% water and stirring; after the silicon nitride has no particles and no bubbles, pouring 2-3% thermosetting amino resin and continuing to stir; when it becomes viscous, continue to pour the remaining silicon nitride and water, stir for 3-5 min, and then pour the remaining thermosetting amino resin; when it is stirred to a viscous state, the release agent is prepared.

[0144] When the release agent is used to brush the surface of the composite material, the thickness of the brushed release agent is 0.2-0.5 mm.

[0145] Further, based on this embodiment, after the brushing of the release agent is completed and before the subsequent assembly, the composite material brushed with the release agent is heated and dried, the drying temperature is 100-250°C, and the drying time is 20-40 min.

[0146] Next, after the step of brushing the release agent is completed, the step of "assembling according to the stacking order of the base material, the composite material, the composite material, and the base material" is introduced.

[0147] This step of "assembling according to the stacking order of the base material, the composite material, the composite material, and the base material" is also the assembly step. In addition to the stacking order of the base material, the composite material, the composite material, and the base material, it also needs to meet:

[0148] 1) The surfaces of the base material and the composite material that are in contact with each other are surfaces that have been subjected to the surface treatment; for example, in the first embodiment of the aforementioned blank surface treatment step, Figure 2a the surface p2a of the base material 12a and the surface p4a of the composite material 22a are in contact with each other, and the surface p1a of the base material 11a and the surface p3a of the composite material 21a are in contact with each other; in the second embodiment of the aforementioned blank surface treatment step, Figure 2b the surface p1b0 and the surface p3b are in contact with each other, and the surface p4b and the surface p2b0 are in contact with each other; in the third embodiment of the aforementioned blank surface treatment step,Figure 2c The surface p1c of the base material 11c and the surface p3c of the composite material 21c are in contact with each other, and the surface p2c of the base material 12c and the surface p4c of the composite material 22c are in contact with each other; in the fourth embodiment of the blank surface treatment step described above, refer to Figure 2d The irregular concave-convex surface p1d0 and the surface p3d of the composite material 21d are in contact with each other, and the irregular concave-convex surface p2d0 and the surface p4d of the composite material 22d are in contact with each other; in the fifth embodiment of the blank surface treatment step described above, refer to Figure 2e The irregular concave-convex surface p1e0 and the surface p3e of the composite material 21e are in contact with each other, and the irregular concave-convex surface p2e0 and the surface p4e of the composite material 22e are in contact with each other;

[0149] 2) The surface coated with the release agent faces the other composite material; for example, refer to Figure 2a One of the surface p6a and the surface p5a is coated with the release agent 30a; refer to Figure 2b One of the surface p6b and the surface p5b is coated with the release agent 30b; refer to Figure 2c One of the surface p6c and the surface p5c is coated with the release agent 30c; refer to Figure 2d One of the surface p6d and the surface p5d is coated with the release agent 30d; refer to Figure 2e One of the surface p6e and the surface p5e is coated with the release agent 30e;

[0150] 3) The composite material is placed centrally with respect to the base material; for this, it is introduced above that the length and width dimensions of the composite material are both smaller than those of the base material, L2 < L1, W2 < W1, and when the blank is assembled, the distance from the two side edges of the composite material in the transverse direction to the corresponding two side edges of the base material is equal, and the distance from the two side edges of the composite material in the longitudinal direction to the corresponding two side edges of the base material is also equal.

[0151] The following will describe the third point above for the five embodiments of the blank surface treatment step described above, respectively. And, since the composite blank is roughly arranged symmetrically up and down, only one set of base material + composite material in the composite blank will be described, such as the upper one.

[0152] For the first embodiment of the blank surface treatment step described above, refer to Figure 2a, the length L1, width W1 of the surface p1a of the base material 11a, the length L2, width W2 of the surface p3a of the clad material 21a, L2 = L1 - L0, W2 = W1 - W0, the preferred value range of L0 and W0 is 90-150mm respectively; in the blank assembly state, the distance from the lateral side of the clad material 21a in the transverse direction (corresponding to the long side of the surface p3a) to the lateral side of the base material 11a in the transverse direction (corresponding to the long side of the surface p1a) is half of W0, and the distance from the lateral side of the clad material 21a in the longitudinal direction (corresponding to the short side of the surface p3a) to the lateral side of the base material 11a in the longitudinal direction (corresponding to the short side of the surface p1a) is half of L0.

[0153] For the second embodiment of the blank surface treatment step described above, refer to Figure 2b , the length L1, width W1 of the surface p1b0 of the base material 11b, the length L2, width W2 of the surface p3b of the clad material 21b, L2 = L1 - L0, W2 = W1 - W0, the preferred value range of L0 and W0 is 90-150mm respectively; in the blank assembly state, the distance from the lateral side of the clad material 21b in the transverse direction (corresponding to the long side of the surface p3b) to the lateral side of the base material 11b in the transverse direction (corresponding to the long side of the surface p1b0) is half of W0, and the distance from the lateral side of the clad material 21b in the longitudinal direction (corresponding to the short side of the surface p3b) to the lateral side of the base material 11b in the longitudinal direction (corresponding to the short side of the surface p1b0) is half of L0.

[0154] For the third embodiment of the blank surface treatment step described above, refer to Figure 2c , the length L1, width W1 of the surface p1c0 of the base material 11c, the length L2, width W2 of the surface p3c of the clad material 21c, L2 = L1 - L0, W2 = W1 - W0, the preferred value range of L0 and W0 is 90-150mm respectively; in the blank assembly state, the distance from the lateral side of the clad material 21c in the transverse direction (corresponding to the long side of the surface p3c) to the lateral side of the base material 11c in the transverse direction (corresponding to the long side of the surface p1c0) is half of W0, and the distance from the lateral side of the clad material 21c in the longitudinal direction (corresponding to the short side of the surface p3c) to the lateral side of the base material 11c in the longitudinal direction (corresponding to the short side of the surface p1c0) is half of L0.

[0155] For the fourth embodiment of the blank surface treatment step described above, refer to Figure 2d, the length L12 and width W12 of the irregular concave-convex surface p1d0 of the base material 11d, the length L2 and width W2 of the surface p3d of the clad material 21d, L2 = L12 - L0, W2 = W12 - W0, the preferred value range of L0 and W0 is 90-150mm respectively; in the assembled billet state, the distance between the lateral side of the clad material 21d (corresponding to the long side of the surface p3d) and the lateral side of the base material 11d (corresponding to the long side of the irregular concave-convex surface p1d0) is half of W0, and the distance between the lateral side of the clad material 21d (corresponding to the short side of the surface p3d) and the lateral side of the base material 11d (corresponding to the short side of the irregular concave-convex surface p1d0) is half of L0.

[0156] For the fifth embodiment of the billet surface treatment step described above, the Figure 2e , the length L12 and width W12 of the irregular concave-convex surface p1e0 of the base material 11e, the length L2 and width W2 of the surface p3e of the clad material 21e, L2 = L12 - L0, W2 = W12 - W0, the preferred value range of L0 and W0 is 90-150mm respectively; in the assembled billet state, the distance between the lateral side of the clad material 21e (corresponding to the long side of the surface p3e) and the lateral side of the base material 11e (corresponding to the long side of the irregular concave-convex surface p1e0) is half of W0, and the distance between the lateral side of the clad material 21e (corresponding to the short side of the surface p3e) and the lateral side of the base material 11e (corresponding to the short side of the irregular concave-convex surface p1e0) is half of L0.

[0157] The above describes the assembling step, in a preferred embodiment, after the assembling step is implemented, the four stacked steel billets are placed as a whole under a four-column hydraulic machine, the opposite surfaces of the two base materials (i.e. the upper surface of the upper base material and the lower surface of the lower base material) are pressed, the pressure is ≥500 tons. Thus, the contact between the adjacent steel billets can be made more closely.

[0158] Further, in the step of "preparing four sealing strips with a width W3, attaching the sealing strips to the four lateral sides of the two clad materials, and performing gas shield welding between the adjacent sealing strips and between the sealing strips and the base materials, so that the two base materials and the sealing strips form a whole, and a composite billet base billet is obtained", based on the arrangement of the sealing strips, the four steel billets stacked together form a composite billet base billet as a whole. Specifically, the composite billet base billet has the following structure: the two base materials form the upper and lower surfaces, the two clad materials are located in the middle, and the four sealing strips form a four-sided frame around the two clad materials and connect the two base materials. Herein, Figures 2a-2e , the sealing strips are respectively marked as 40a, 40b, 40c, 40d and 40e.

[0159] The width W3 of the sealing strip is 2T2-1~2mm, i.e. the width of the sealing strip is slightly smaller than the sum of the thicknesses of the two composite materials by 1~2mm. The sealing strip with the width can wrap the upper and lower two composite materials, thereby improving the wrapping effect.

[0160] Further, among the four sealing strips, two sealing strips are respectively attached to the two sides in the transverse direction of the two composite materials, and the length L31 is L2-1~2mm; the other two sealing strips are respectively attached to the two sides in the longitudinal direction of the two composite materials, and the length L32 is W2-1~2mm.

[0161] Preferably, the thickness T3 of the sealing strip is 12~15mm.

[0162] As to the forming mode of each sealing strip, the sealing strip can be directly cut out on a steel plate according to the thickness T3, the width W3 and the length L31 or L32 without welding, or the sealing strip can be spliced by welding from multiple sealing strips with different lengths, for example, the sealing strips at the two sides in the longitudinal direction of the two composite materials in the fourth embodiment of the blank surface treatment step described above, and the sealing strips at the two sides in the transverse direction of the two composite materials in the fifth embodiment of the blank surface treatment step described above.

[0163] Further, the sealing strip is made of the same steel grade as the base material, and preferably, the material of the sealing strip is the same as that of the base material.

[0164] As a preferred embodiment, before the gas shield welding between the adjacent sealing strips and between the sealing strip and the base material, the two ends and the two sides of each sealing strip can be ground and polished to remove the surface oxide skin and improve the welding effect; and / or the two ends and the two sides of each sealing strip can be beveled.

[0165] Further, as a preferred embodiment, in the step of “gas shield welding between the adjacent sealing strips and between the sealing strip and the base material”, the welding speed is 300~360mm / min, and the interpass temperature during the welding process is controlled to be 135~165℃.

[0166] Next, as to the step of “processing a round hole on the sealing strip at the groove of the side edge of the composite blank blank, and welding a seamless steel pipe at the round hole”, the groove is a groove formed between the two base materials and outside the sealing strip; in this step, the round hole is processed to weld the seamless steel pipe, so as to facilitate subsequent vacuumizing of the inside of the composite blank.

[0167] As a preferred mode, the round hole is processed in the middle of the short edge (i.e. the side edge in the longitudinal direction) of the composite blank blank, but is not limited thereto.

[0168] As a preferred mode, the diameter of the round hole is 8-12 mm; correspondingly, the outer diameter of the seamless steel tube is consistent with the diameter of the round hole, being 8-12 mm, the wall thickness is 1.2-2 mm, and the length is 200-400 mm.

[0169] Next, for the step of "building up welding on the grooves of the four sides of the composite blank base blank", submerged arc welding is specifically adopted. It can be understood that, outside the four-side frame formed by the sealing strip, a filling layer in the shape of a four-side frame is formed by the butt welding of this step, referring to Figures 2a-2e wherein the filling layer formed by the building up welding is respectively marked as 50a, 50b, 50c, 50d and 50e.

[0170] As a preferred mode, before welding, the flux is baked at 350℃ for 2h, and then kept at 150℃ for 1h; and during the welding process, the interpass temperature is controlled to be 135-165℃, and the welding speed is 420-480 mm / min. In this way, the submerged arc welding technology, combined with the previous sealing strip wrapping and gas shielded welding, collectively realizes the stable connection of the four steel blanks, guarantees the connection strength, avoids the cracking abnormality in the subsequent composite blank rolling step, and further improves the interface bonding effect on the basis of realizing the quality advantages of the composite plate described in the foregoing.

[0171] In addition, during the welding process, the weld bead adherents need to be cleaned before each welding construction to keep the weld bead clean; and after the welding is completed, the heat preservation cotton is covered for heat preservation.

[0172] Next, in the step of "using a vacuum pump to pump the composite blank through the seamless steel tube to a vacuum degree

[0173] ≤10 -1 Pa, and then keeping the pressure for more than 4h; finally, the seamless steel tube is sealed" the suction port of the vacuum pump is connected with the seamless steel tube, and the space inside the seamless steel tube (such as the face-to-face gap between the composite material and the base material, the face-to-face gap between the composite materials, the end face gap between the composite material and the sealing strip, etc.) is connected in communication to discharge the air in the space until the vacuum degree is ≤10 -1 Pa, and keeping the pressure for more than 4h can guarantee the vacuum degree. In this way, the air in the space can be avoided to cause surface oxidation at the composite interface during the subsequent composite blank rolling, thereby guaranteeing the composite interface bonding quality.

[0174] Further, in this step, the sealing of the seamless steel tube can be implemented in the existing feasible manner in the steel field, for example, heating the seamless steel tube with a flame gun and flattening to realize the sealing.

[0175] The above describes the total step of preparing the composite blank. As described above, the preparation method of the present application further comprises a total step of rolling the composite blank after the total step of preparing the composite blank. Specifically, the total step of rolling the composite blank comprises the following sub-steps:

[0176] The composite blank is heated at a temperature of 1210-1270℃ for a total time of ≥1.0xt min / mm, where t is the thickness of the composite blank, and the soaking time is 20-40min.

[0177] The heated composite blank is subjected to hot continuous rolling on a hot continuous rolling mill: first, an R1 rough rolling mill is used to roll 1-3 passes at 1180-1240℃ with a reduction of ≥30mm; then, an R2 rough rolling mill is used to roll 3-5 passes at 1050-1170℃ with a reduction of ≥28mm; finally, F1-F7 finishing rolling mills are used to roll 5-7 passes at a starting rolling temperature of ≥950℃ and a final rolling temperature of ≥850℃, to obtain a composite plate large plate.

[0178] The composite plate large plate is subjected to laminar cooling after exiting the hot continuous rolling mill, and is then coiled at a coiling temperature of 560-660℃ to obtain a composite coil.

[0179] The obtained composite coil is opened and segmented according to the required length.

[0180] In the total step of rolling the composite blank, the control of the heating temperature, heating time, temperature in rolling, reduction, coiling temperature, and other parameters can ensure that the final composite plate has excellent mechanical properties.

[0181] Further, referring to the total step of rolling the composite blank, Figure 4a The total step of rolling the composite blank further comprises:

[0182] After the step of opening and segmenting the obtained composite coil, the segmented composite plate large plate is placed between two steel plates at a temperature of T f -T f +150℃ for stack cooling, for a time of 0.4min / mm×t0±5min, where t0 is the thickness of the composite plate large plate; wherein,

[0183] T f =550+30[Si]-20[Mn]+15[Cr]-15[Ni]+10[Mo], where [Si], [Mn], [Mo], [Cr], and [Ni] are 100 times the mass percentage of each element in the base material;

[0184] After the stack cooling is completed, the composite plate large plate is naturally cooled on a cooling bed.

[0185] Thus, the temperature of the two steel plates in the stack cooling, especially the temperature of the two steel plates in the stack cooling and the stack cooling time can further greatly improve the microstructure, performance and shape of the final composite plate. Of course, in the alternative embodiment, the stack cooling step can be omitted, and after the "opening and flattening of the obtained composite coil and segmenting according to the required length size", the subsequent composite plate separation and straightening step is directly entered, as shown in Figure 4b

[0186] The above describes the total step of the composite blank rolling, as described above, the preparation method of the present application further comprises a total step of composite plate separation and straightening. Specifically, the total step of the composite plate separation and straightening comprises the following sub-steps:

[0187] The composite plate large plate obtained by the foregoing total step of the composite blank rolling is cut on the side edges by a plasma cutting machine to remove the part outside the seal, and the composite plate large plate is separated into two composite plate small plates;

[0188] The composite plate small plates are transversely flattened and cold straightened to obtain the finished stainless steel composite plate.

[0189] Among them, the part outside the seal in the step of "cutting on the side edges to remove the part outside the seal" is the edge part on the composite plate large plate which is transformed from the seal and the filler layer in the composite blank after the foregoing composite blank rolling step. For the segmented composite plate large plates, in addition to the head composite plate large plate and the tail composite plate large plate, the other segmented composite plate large plates only need to cut on the two side edges, and the head composite plate large plate and the tail composite plate large plate need to additionally cut on the head and the tail. Thus, this part is removed to expose the stainless steel layer, and without the connecting effect of this part, the composite plate large plate is separated into two composite plate small plates. Referring to Figures 3a-3e Corresponding to the five embodiments of the blank surface treatment step described above, Figures 3a-3e The cross-sectional shape of the corresponding two composite plate small plates (i.e. the final composite plate) is shown respectively.

[0190] Each composite plate small plate is composed of a clad layer and a base layer, the clad layer is obtained from the original clad material through rolling, and the base layer is obtained from the original base material through rolling. Therefore, in Figures 3a-3e the original clad material is still marked with the original clad material mark, and the base layer is still marked with the original base material mark.

[0191] In addition, on the basis of the embodiments of the total step of the composite blank rolling described above, the present application further provides three preferred embodiments of the total step of the composite blank rolling, which will be introduced respectively.

[0192] <First embodiment of the total step of the composite blank rolling>​

[0193] In this embodiment, the total rolling steps of the composite blank specifically include the following steps:

[0194] The composite blank is heated at a temperature of 1220-1260℃, and the total heating time is ≥1.0xt min / mm, t being the thickness of the composite blank, and the soaking time is 20-40min;

[0195] The heated composite blank is subjected to hot continuous rolling on a hot continuous rolling mill: first, R1 rough rolling mill is used to roll 1-3 passes at 1190-1230℃, with a reduction of ≥30mm; then, R2 rough rolling mill is used to roll 3-5 passes at 1060-1160℃, with a reduction of ≥28mm; finally, F1-F7 finishing rolling mill is used to roll 5-7 passes, with a rough rolling temperature of ≥970℃ and a finish rolling temperature of ≥870℃, to obtain a composite plate slab;

[0196] The composite plate slab is cooled in a laminar flow cooling system after exiting the hot continuous rolling mill, and then is coiled at a coiling temperature of 600-660℃ to obtain a composite coil;

[0197] The obtained composite coil is opened and segmented according to the required length, and then the segmented composite plate slab is placed between two steel plates at a temperature of T f -T f +150℃ for stack cooling, with a stack cooling time of 0.4min / mm×t0±5min, t0 being the thickness of the composite plate slab; wherein,

[0198] T f =550+30[Si]-20[Mn]+15[Cr]-15[Ni]+10[Mo], wherein [Si], [Mn], [Mo], [Cr] and [Ni] are 100 times the mass percentage of each element in the base material;

[0199] After the stack cooling is completed, the composite plate slab is naturally cooled on a cooling bed to room temperature.

[0200] The composite plate prepared based on this embodiment has a base layer structure of 70-95% ferrite + 5-30% pearlite structure, and has excellent mechanical properties, interface bonding quality and plate shape.

[0201] The chemical composition and mass percentage of the base layer of the composite plate are as follows: C: 0.14% to 0.18%, Si≤0.05%, Mn: 0.30% to 0.40%, P≤0.020%, S≤0.015%, Al: 0.020% to 0.050%, and the rest is Fe and inevitable impurities; and the chemical composition and mass percentage of the composite layer are as follows: C≤0.15%, Si≤1.00%, Mn≤2.00%, P≤0.045%, S≤0.030%, Ni: 6.0% to 22.0%, Cr: 16.0% to 26.0%, Mo≤3.0%, and the rest is Fe and inevitable impurities.

[0202] The total thickness of the composite plate is ≤10mm, the thickness of the composite layer is ≥0.2mm, and the unevenness is ≤3mm / m.

[0203] The composite interface bonding rate of the composite plate is 100%, the shear strength is ≥210MPa, the yield strength is ≥235MPa, the tensile strength is ≥400MPa, and the elongation after fracture is ≥26%.

[0204] The composite plate is free of cracks in 180° outward bending and 180° inward bending.

[0205] The following provides a plurality of examples implemented by the embodiment. In these examples, the selected composite material and the steel grade / chemical composition of the base material are shown in Table 1.

[0206] Table 1

[0207]

[0208]

[0209] Here, each example is prepared according to the embodiment provided by the application, and the base material, the composite material, and the thickness of the composite blank are shown in Table 2.

[0210] Table 2

[0211] Substrate Composite Total thickness of the composite blank, mm Example 1 Q235 304 240 Example 2 Q235 304 240 Example 3 Q235 304L 240 Example 4 Q235 304L 240

[0212] Further, for each example, the composite blank rolling step according to the embodiment provided by the application is implemented, and the specific parameters in the composite blank rolling are shown in Table 3. In Table 3, “-” in the stack cooling temperature column indicates that the implementation is according to the “open, segmented, and directly enters the composite plate separation and straightening step” described above, and the numbers shown in the stack cooling temperature column indicate that the implementation is according to the “stacking the segmented composite plate between two steel plates with a temperature of T f ~T f +150℃” described above.

[0213] Table 3

[0214]

[0215] Further, the total thickness of the composite plate large plate and the thickness of the composite plate small plate (i.e. the composite plate product) prepared in each embodiment are shown in Table 4. In each embodiment, there are two different test examples of the substrate implemented as equal thickness and the substrate implemented as variable thickness, and in the test example of the substrate implemented as variable thickness, the corresponding composite plate thickness and the substrate thickness are in the thickness range (i.e. the minimum thickness ~ the maximum thickness) rather than a fixed value.

[0216] Table 4

[0217]

[0218] Further, the composite plates of each embodiment are sampled and tested, and the interfacial bonding rate of each embodiment is 100%, the inner bending 180° is qualified (no cracks), and the outer bending 180° is qualified (no cracks). The composite plates of Example 3 and Example 4 are sampled and tested, and after being boiled in a sulfuric acid-copper sulfate solution for 20h, the composite layer has no intergranular corrosion cracks after being bent 180°. In addition, the performance test results are shown in Table 5.

[0219] Table 5

[0220]

[0221] <Second embodiment of the total step of composite blank rolling>

[0222] In this embodiment, the total step of composite blank rolling specifically includes the following steps:

[0223] The composite blank is heated, the heating temperature is 1230-1270℃, the total heating time is ≥1.0xt min / mm, t is the thickness of the composite blank, and the soaking time is 20-40min;

[0224] The heated composite blank is subjected to hot continuous rolling on a hot continuous rolling mill: first, R1 rough rolling mill is used to roll 1-3 passes at 1200-1240℃, the reduction is ≥30mm; then, R2 rough rolling mill is used to roll 3-5 passes at 1070-1170℃, the reduction is ≥28mm; finally, F1-F7 finishing rolling mill is used to roll 5-7 passes, the rough rolling temperature is ≥960℃, and the finish rolling temperature is ≥860℃, to obtain a composite plate large plate;

[0225] The composite plate large plate is cooled in a laminar flow cooling system after exiting the hot continuous rolling mill, and then is coiled, the coiling temperature is 580-640℃, to obtain a composite coil;

[0226] The obtained composite coil is opened and flattened, and then the composite plate is placed between two steel plates at a temperature of T f ~T f +150℃ for stack cooling, and the stack cooling time is 0.4min / mmxt0±5min, t0 is the thickness of the composite plate; wherein, T f =550+30[Si]-20[Mn]+15[Cr]-15[Ni]+10[Mo], wherein [Si], [Mn], [Mo], [Cr], [Ni] are 100 times of the mass percentage of each element in the base material;

[0227] After the stack cooling is completed, the composite plate is naturally cooled on the cooling bed.

[0228] The composite plate prepared based on the present embodiment has a base layer structure of 70-92% ferrite + 5-25% pearlite + 3-5% bainite structure, and has excellent mechanical properties, interface bonding quality, and plate shape.

[0229] The chemical composition and mass percentage of the base layer of the composite plate are as follows: C: 0.14%-0.18%, Si: 0.06%-0.16%, Mn: 1.10%-1.20%, P≤0.025%, S≤0.012%, Ti: 0.050%-0.070%, Al: 0.020%-0.050%, and the rest is Fe and inevitable impurities; the chemical composition and mass percentage of the composite layer are as follows: C≤0.15%, Si≤1.00%, Mn≤2.00%, P≤0.045%, S≤0.030%, Ni: 6.0%-22.0%, Cr: 16.0%-26.0%, Mo≤3.0%, and the balance is Fe and inevitable impurities.

[0230] The total thickness of the composite plate is ≤10mm, the thickness of the composite layer is ≥0.2mm, and the unevenness is ≤3mm / m.

[0231] The composite plate has a composite interface bonding rate of 100%, a shear strength of ≥210MPa, a yield strength of ≥335MPa, a tensile strength of ≥450MPa, and an elongation after fracture of ≥21%.

[0232] The composite plate has no cracks when bent outward by 180°, and no cracks when bent inward by 180°.

[0233] The following provides a plurality of examples implemented by the present embodiment. In these examples, the selected composite materials and base materials have the steel grades / chemical compositions shown in Table 6.

[0234] Table 6

[0235]

[0236] In the present application, the composite billets are prepared according to the embodiments of the present application, and the base materials, the composite materials and the thicknesses of the composite billets are shown in Table 7.

[0237] Table 7

[0238] Substrate Composite Total thickness of the composite blank, mm Example 1 Q355 304 240 Example 2 Q355 304 240 Example 3 Q355 304L 240 Example 4 Q355 304L 240

[0239] Further, in the present application, the composite billets are rolled according to the embodiments of the present application, and the parameters in the rolling process are shown in Table 8. In Table 8, "-" in the column of "stack cooling temperature" means that the composite billets are directly put into the composite plate separation and straightening process after being cut into segments according to the above-mentioned embodiment, and the numbers in the column of "stack cooling temperature" mean that the composite billets are put between two steel plates with a temperature of T f ~ T f + 150°C according to the above-mentioned embodiment.

[0240] Table 8

[0241]

[0242] Further, the thicknesses of the composite plates prepared in the present application are shown in Table 9. In each embodiment, there are two different test examples, one with equal thickness of the base materials and the other with variable thickness of the base materials. In the test example with variable thickness of the base materials, the thicknesses of the composite plates and the base layers are ranges (i.e. the minimum thickness ~ the maximum thickness) rather than fixed values.

[0243] Table 9

[0244]

[0245] Further, the composite plates prepared in the present application are sampled and tested, and the interfacial bonding rates of the composite plates are all 100%, the inner bending 180° is qualified (no cracks), and the outer bending 180° is qualified (no cracks). The composite plates prepared in Example 3 and Example 4 are sampled and tested, and after being boiled in sulfuric acid-copper sulfate solution for 20 hours and being bent 180°, the composite layers have no intergranular corrosion cracks. In addition, the test results of other properties are shown in Table 10.

[0246] Table 10

[0247]

[0248] <Third embodiment of the rolling process of the composite billets>

[0249] In the present application, the rolling process of the composite billets includes the following steps:

[0250] The composite blank is heated at a temperature of 1210-1250℃, and the total heating time is ≥1.0xt min / mm, t being the thickness of the composite blank, and the soaking time is 20-40 min;

[0251] The heated composite blank is subjected to hot continuous rolling on a hot continuous rolling mill: first, the R1 rough rolling mill is used to roll 1-3 passes at 1180-1220℃, with a reduction of ≥30 mm; then, the R2 rough rolling mill is used to roll 3-5 passes at 1050-1150℃, with a reduction of ≥28 mm; finally, the F1-F7 finishing rolling mill is used to roll 5-7 passes, with a rough rolling temperature of ≥950℃ and a finish rolling temperature of ≥850℃, to obtain a composite plate slab;

[0252] The composite plate slab is cooled in a laminar flow cooling system after exiting the hot continuous rolling mill, and then is coiled at a coiling temperature of 560-620℃ to obtain a composite coil;

[0253] The obtained composite coil is opened and flattened, and then the composite plate slab is placed between two steel plates at a temperature of T f -T f +150℃ for stack cooling, with a stack cooling time of 0.4t0 min / mm±5 min, t0 being the thickness of the composite plate slab; wherein T f =550+30[Si]-20[Mn]+15[Cr]-15[Ni]+10[Mo], wherein [Si], [Mn], [Mo], [Cr] and [Ni] are 100 times the mass percentage of each element in the base material;

[0254] After the stack cooling is completed, the composite plate slab is naturally cooled on a cooling bed.

[0255] The composite plate prepared based on the present embodiment has a base layer structure of 70-90% ferrite + 5-20% pearlite + 5-10% bainite, and has excellent mechanical properties, interface bonding quality and plate shape. Furthermore, by optimizing the heating temperature, rolling temperature and coiling temperature, the mechanical properties, interface bonding quality and plate shape can be more excellent than in the prior art.

[0256] The chemical composition and mass percentage of the base layer of the composite plate are as follows: C: 0.13% to 0.17%, Si: 0.05% to 0.15%, Mn: 1.50% to 1.60%, P≤0.020%, S≤0.012%, Nb: 0.020% to 0.030%, Ti: 0.015% to 0.025%, Al: 0.010% to 0.040%, and the rest is Fe and inevitable impurities; the chemical composition and mass percentage of the composite layer are as follows: C≤0.15%, Si≤1.00%, Mn≤2.00%, P≤0.045%, S≤0.030%, Ni: 6.0% to 22.0%, Cr: 16.0% to 26.0%, Mo≤3.0%, and the rest is Fe and inevitable impurities.

[0257] The total thickness of the composite plate is ≤10mm, the thickness of the composite layer is ≥0.2mm, and the unevenness is ≤3mm / m.

[0258] The composite interface bonding rate of the composite plate is 100%, the shear strength is ≥300MPa, the yield strength is ≥420MPa, the tensile strength is ≥520MPa, and the elongation after fracture is ≥18%.

[0259] The composite plate is free of cracks after being bent outward by 180° and is free of cracks after being bent inward by 180°.

[0260] The following provides a plurality of examples implemented by the embodiment. In these examples, the selected steel grades / chemical compositions of the composite material and the base material are shown in Table 11.

[0261] Table 11

[0262]

[0263] Here, each example is prepared into a composite blank according to the embodiment provided by the application, and the base material, the composite material, and the thickness of the composite blank are shown in Table 12.

[0264] Table 12

[0265] Substrate Composite Total thickness of the composite blank, mm Example 1 Q420 304 240 Example 2 Q420 304 240 Example 3 Q420 304L 240 Example 4 Q420 304L 240

[0266] Further, for each example, the composite blank rolling step according to the embodiment provided by the application is implemented, and the specific parameters in the composite blank rolling are shown in Table 13. In Table 13, “-” in the column of stack cooling temperature indicates that the implementation is performed according to the “KaiPing, segmented and directly entering the composite plate separation and straightening step” described above, and the numbers shown in the column of stack cooling temperature indicate that the implementation is performed according to the “stacking the segmented composite plate between two steel plates with a temperature of T f ~T f +150℃” described above.

[0267] Table 13

[0268]

[0269]

[0270] Further, the total thickness of the large composite plate prepared in each embodiment and the thickness of the small composite plate (i.e. the finished composite plate) are shown in Table 14. Each embodiment has two different test examples of the substrate with equal thickness and the substrate with variable thickness, and in the test example of the substrate with variable thickness, the thickness of the corresponding composite plate and the thickness of the base layer are in the range (i.e. the minimum thickness to the maximum thickness) rather than a fixed value.

[0271] Table 14

[0272]

[0273] Further, the composite plates of each embodiment are sampled and tested, and the interfacial bonding rate of each embodiment is 100%, the inner bending 180° is qualified (no cracks), and the outer bending 180° is qualified (no cracks). The composite plates of Example 3 and Example 4 are sampled and tested, and after being boiled in a sulfuric acid-copper sulfate solution for 20 h, the composite layer has no intergranular corrosion cracks after being bent 180°. In addition, the results of other performance tests are shown in Table 15.

[0274] Table 15

[0275]

[0276]

[0277] Compared with the prior art, the single-sided stainless steel composite plate prepared by the preparation method of the present application not only retains the corrosion resistance of the stainless steel composite material and the mechanical strength of the carbon steel substrate, but also has the advantages of excellent surface quality, excellent plate shape, excellent interfacial bonding, etc. For example, there are no obvious surface defects such as pits and side scratches existing in the prior composite plate, and the production efficiency is high, the material yield is high, resources are saved, and costs are reduced. Further, by processing the substrate with variable thickness, the composite plate with variable thickness is obtained, which is more practical and has a wider range of applications.

Claims

1. A hot continuous rolling method for manufacturing a single-sided stainless steel clad plate, characterized by, The method comprises the following steps: 1) composite blank preparation two carbon steel blanks with thickness T1, length L1 and width W1 are prepared as base materials, and two stainless steel blanks with thickness T2, length L2 and width W2 are prepared as composite materials; L2 < L1 and W2 < W1; the blanks are assembled in the order of base material, composite material, composite material and base material to prepare a composite blank; 2) composite blank rolling the composite blank is heated at a temperature of 1210-1270℃, and the total heating time is ≥1.0×t min / mm, t being the thickness of the composite blank, and the soaking time is 20-40 min; the heated composite blank is subjected to hot continuous rolling on a hot continuous rolling mill: first, the R1 rough rolling mill is used to roll 1-3 passes at a temperature of 1180-1240℃ with a reduction of ≥30 mm; then, the R2 rough rolling mill is used to roll 3-5 passes at a temperature of 1050-1170℃ with a reduction of ≥28 mm; finally, the F1-F7 finishing rolling mill is used to roll 5-7 passes at a temperature of ≥950℃ for rough rolling and ≥850℃ for finish rolling, to obtain a composite plate large plate; the composite plate large plate is cooled in a laminar flow cooling system after leaving the hot continuous rolling mill, and then is coiled at a temperature of 560-660℃, to obtain a composite coil; the obtained composite coil is opened and segmented according to the required length; 3) composite plate separation and straightening the two sides of the segmented composite plate large plate are cut to remove the parts outside the seal, and the composite plate large plate is separated into an upper composite plate small plate and a lower composite plate small plate; the composite plate small plates are transversely flattened and cold straightened to obtain single-layer stainless steel composite plate products; And, in the step 1) composite blank preparation, one surface of the two substrates is milled and ground in a way that the surface is processed into a length L 11 =L1and a width W 11 >W1of a transversely inclined surface, so that the substrates become non-equal-thickness blanks with thickness varying in the transverse direction; wherein L2=L 11 -L0, W2=W 11 -W0, the range of L0and W0is 90-150 mm respectively; in the blank assembly, the composite is placed in the middle relative to the substrates, and the distance between the transverse and longitudinal sides of the composite and the corresponding sides of the substrates is W0 / 2 and L0 / 2 respectively.

2. The hot continuous rolling method of single-sided stainless steel clad plate according to claim 1, characterized by, the composite blank rolling step further comprises: After the composite coil is opened and segmented according to the required length, the segmented composite plate is placed between two steel plates with a temperature of T f f The stacked cooling time is 0.4 min / mm x t0±5 min, t0 is the thickness of the composite plate, and T f =550+30[Si]-20[Mn]+15[Cr]-15[Ni]+10[Mo], wherein [Si], [Mn], [Mo], [Cr] and [Ni] are 100 times the mass percentage of each element in the base material.​ after the stacking and cooling are completed, the composite plate large plate is naturally cooled on a cooling bed.

3. The hot continuous rolling method of single-sided stainless steel clad plate according to claim 1, characterized by, the composite blank preparation step 1) further comprises: surfaces of the two base materials and the two composite materials are treated; an isolation agent is applied to one surface of one of the composite materials; the blanks are assembled in the order of base material, composite material, composite material and base material; wherein the composite material is placed in the middle relative to the base material, the surfaces of the base material and the composite material that are in contact with each other are surfaces that have been treated, and the surface on which the isolation agent is applied faces the other composite material; four seal strips with a width of W3=2T2-1-2 mm are prepared, and the seal strips are attached to the four sides of the two composite materials, and the adjacent seal strips and the seal strips and the base material are air-arc welded, so that the two base materials and the seal strips form an integral whole, to obtain a composite blank base blank; a round hole is processed on the seal strip at the groove of the side edge of the composite blank base blank, and a seamless steel pipe is welded at the round hole; the grooves of the four side edges of the composite blank base blank are surfacing welded; The composite blank is pumped by the seamless steel tube through a vacuum pump, and the vacuum degree is ≤10 Pa -1 Pa, and then the pressure is maintained for 4 hours or more; finally, the seamless steel tube is sealed.

4. The hot continuous rolling method of single-sided stainless steel clad plate according to claim 3, characterized by, the step of "treating surfaces of the two base materials and the two composite materials" comprises: According to the relative shape complementation, one surface of each of the two substrates is milled and polished to be an irregular concave-convex surface containing n planes connected in sequence in the transverse direction, the substrate being a non-equal-thickness substrate with non-monotonic thickness variation in the transverse direction, the irregular concave-convex surface having a length L12=L1 and a total width W12>W1; or the surface is processed to be an irregular concave-convex surface containing n planes connected in sequence in the longitudinal direction, the substrate being a non-equal-thickness substrate with non-monotonic thickness variation in the longitudinal direction, the irregular concave-convex surface having a total length L12>L1 and a width W12=W1; n≥2. Each of the composite materials is polished on one surface to remove the surface oxide scale, and then is bent to match the corresponding irregular concave-convex surface.

5. The hot continuous rolling method for manufacturing a single-surface stainless steel clad plate according to claim 4, characterized in that, L2=L12-L0, W2=W12-W0, L0 and W0 are in the range of 90-150 mm. In the "centering the composite material relative to the substrate", the distance from the side edge of the composite material to the corresponding side edge of the substrate in the transverse direction is half of W0, and the distance from the side edge of the composite material to the corresponding side edge of the substrate in the longitudinal direction is half of L0.

6. The hot continuous rolling method of a single-surface stainless steel clad plate according to claim 3, characterized by, In the step of "applying a release agent on one surface of one of the composite materials", the release agent used is a coating liquid containing silicon oxide and magnesium oxide, and the mass ratio of silicon oxide to magnesium oxide is 3:

1. The amount of the brushing separator is 20 ymg / m 2 y is the ratio of the thickness of the composite blank to the thickness of the large plate of the composite plate.

7. The hot continuous rolling method of a single-surface stainless steel clad plate according to claim 3, characterized by, In the step of "applying a release agent on one surface of one of the composite materials", the components of the release agent used are in the weight ratio of 25-35% silicon nitride, 5-10% thermosetting amino resin, and 55-70% water. The thickness of the release agent is 0.2-0.5 mm.

8. The method of continuously hot rolling a single-sided stainless steel clad plate according to claim 3, wherein In the step of "carrying out gas shield welding between adjacent sealing strips and between the sealing strips and the substrate", the welding speed is 300-360 mm / min, and the interpass temperature is controlled to be 135-165°C during the welding process.

9. The method of continuously hot rolling a single-sided stainless steel clad plate according to claim 3, wherein In the step of "carrying out surfacing on the grooves on the four side edges of the composite substrate", submerged arc surfacing is used. Before welding, the flux is baked at 350°C for 2 h, and then is kept at 150°C for 1 h. During the welding process, the interpass temperature is controlled to be 135-165°C, and the welding speed is 420-480 mm / min.

10. A single-sided stainless steel clad plate, characterized by, Prepared by the preparation method of any one of claims 1-9; The total thickness of the composite board is ≤10 mm, the thickness of the composite layer is ≥0.2 mm, and the unevenness is ≤3 mm / m. The composite interface bonding rate is 100%, and the shear strength is ≥210 MPa. The yield strength is ≥235 MPa, and the tensile strength is ≥400 MPa.

11. The single-sided stainless steel clad plate according to claim 10, characterized in that, The yield strength is ≥355 MPa, the tensile strength is ≥450 MPa, and the shear strength is ≥210 MPa.

12. The single-sided stainless steel clad plate according to claim 10, characterized by The yield strength is ≥420 MPa, the tensile strength is ≥520 MPa, and the shear strength is ≥300 MPa.

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