Stainless steel clad plate and method for manufacturing the same

Abstract

The application discloses a stainless steel composite plate and a preparation method thereof. Three sides of a complex layer of the composite plate are flush with those of a base layer, and the other side of the complex layer is an inclined side and is located in the middle of the upper surface of the base layer. The preparation method comprises the following steps: preparing two carbon steel base materials with X direction size L1 and Y direction size W1; preparing stainless steel composite A and composite B, both of which have X direction size L2, Y direction size W21 and W22 respectively, thickness T2, and the inclined side with width V in the Y direction, and W1=W21+W22-V+90-150mm; coating the isolating agent on the smaller surfaces and the inclined side of the two composites; assembling the base material, the composite A+the composite B and the base material in sequence, and sealing the middle layer with the sealing strip and welding the sealing strip with the base material; and then performing vacuumizing, sealing, heating, rolling, cooling, plate separating and straightening to obtain the stainless steel composite plate. Thus, the problem of dissimilar metal welding is solved, the firmness is high, the cost is low and the efficiency is high during use.

Description

TECHNICAL FIELD

[0001] The present application relates to a stainless steel clad plate and a preparation method thereof, and belongs to the technical field of steel material preparation. BACKGROUND

[0002] In recent years, with the increasing requirements for the safety and long service life of steel bridges, the problem of rust and corrosion prevention of steel bridge structures is becoming more and more prominent. If a layer of corrosion-resistant protective material is coated on the surface of the bridge steel to replace the single bridge steel plate, the long-term corrosion prevention goal that cannot be achieved by spraying process can be achieved. Therefore, the stainless steel clad plate emerges as the times require.

[0003] The stainless steel clad plate is a clad plate material with stainless steel as the clad layer and carbon steel or low alloy steel as the base layer. It has both the corrosion resistance of the clad layer and the good mechanical properties of the base layer, and can achieve the perfect combination of low cost and high performance on the premise of not reducing the use effect (mechanical strength, corrosion resistance, etc.), thereby achieving good economic and social benefits.

[0004] The existing stainless steel clad plate for bridge structure needs to be butt-jointed with the bridge structure steel plate during the processing and use in the downstream structure factory.

[0005] At the butt-joint position, the base layer of the stainless steel clad plate and the bridge structure steel plate belong to the same material, and the welding strength can be guaranteed. However, the stainless steel clad layer of the stainless steel clad plate and the bridge structure steel plate belong to different materials, and the welding is difficult and not firm, which has a certain influence on the safety of the overall structure. In addition, in order to avoid the step (height difference) between the edge of the stainless steel clad layer and the bridge structure steel plate, an additional stainless steel plate is needed for transition, which not only increases the material cost, but also the additional stainless steel plate needs to be welded with the clad layer of the stainless steel clad plate and the bridge structure steel plate at the same time, greatly increasing the welding workload and affecting the construction efficiency. SUMMARY

[0006] In order to solve the problem of dissimilar welding of the existing stainless steel clad plate, the present application aims to provide a stainless steel clad plate and a preparation method thereof.

[0007] To achieve the above-mentioned application purpose, one embodiment of the present application provides a stainless steel clad plate, which is composed of a carbon steel base layer below and a stainless steel clad layer above. The three side edges of the clad layer are flush with the three side edges of the base layer, and the other side edge of the clad layer is located in the middle of the upper surface of the base layer and is set as an oblique edge with an obtuse angle to the upper surface of the clad layer.

[0008] As a further improvement of one embodiment, the total thickness of the clad plate is 15-39 mm, the thickness of the base layer is 12-36 mm, and the thickness of the clad layer is 3 mm.

[0009] As a further improvement of the embodiment, the Vickers hardness difference in the thickness direction of the base layer of the composite plate is ≤10, the head-to-tail strength difference is ≤40 MPa, the strength difference at all parts of the whole plate is ≤40 MPa, and the unevenness is ≤2 mm / m.

[0010] As a further improvement of the embodiment, the 0℃ impact energy of the composite plate is ≥240 J, the -20℃ impact energy is ≥200 J, and the -40℃ impact energy is ≥150 J.

[0011] To achieve the above-mentioned purposes, an embodiment of the present application provides a preparation method of a stainless steel composite plate, which comprises three stages of composite blank preparation, composite blank rolling and plate straightening, wherein the composite blank preparation stage comprises the following steps:

[0012] Two carbon steel square blanks with X direction size L1 and Y direction size W1 are prepared as two base materials;

[0013] A stainless steel square blank with X direction size L2, Y direction size W21 and thickness T2 is prepared, and one side edge in the Y direction is processed into a bevel with a width V, and the blank is used as composite material A;

[0014] L1 = L2 + 90-150 mm;

[0015] A stainless steel square blank with X direction size L2, Y direction size W22 and thickness T2 is prepared, and one side edge in the Y direction is processed into a bevel with a width V, and the blank is used as composite material B; W1 = W21 + W22-V + 90-150 mm;

[0016] The smaller surfaces and the bevels of the composite material A and the composite material B in their respective thicknesses are coated with a release agent;

[0017] The base material is used as the upper layer, the other base material is used as the lower layer, the composite material A and the composite material B are used as the middle layer in the Y direction, and the four side edges of the middle layer are surrounded by a seal and welded together with the two base materials, thereby forming a composite blank base; wherein the bevel of the composite material A and the bevel of the composite material B are parallel to each other;

[0018] The composite blank base is subjected to vacuum extraction and sealing to obtain a composite blank.

[0019] As a further improvement of the embodiment, the composite blank rolling stage comprises the following steps:

[0020] The obtained composite blank is heated, the soaking temperature is 1150-1220℃, the total heating time is ≥1.2×tmin / mm, t is the thickness of the composite blank, and the soaking time in the soaking section is 30-50 min;

[0021] The two-stage controlled rolling of rough rolling + finish rolling is adopted, in the rough rolling stage, the starting rolling temperature is ≤1050℃, the final rolling temperature is ≥900℃, the rolling is first transversely and then longitudinally, at least one pass has a reduction of ≥35mm, the total reduction of rough rolling is 40-60%, the rough rolling is ended when the thickness of the intermediate blank is 2.5-3.5 times of the target thickness of the clad plate big plate; then the intermediate blank is cooled by water spraying, when the surface temperature of the intermediate blank is reduced to ≤60℃, the finish rolling stage is started; the final rolling temperature of the finish rolling stage is ≥700℃, the total reduction of finish rolling is 55-≥5%, the clad plate big plate is obtained.

[0022] As a further improvement of the embodiment, the rolling stage of the composite blank comprises the following steps:

[0023] The obtained composite blank is heated by five-stage heating of preheating, first heating, second heating, third heating and soaking, the preheating temperature is ≤≥50℃, the residence time is (0.45-0.55)t min / mm, the first heating temperature is 1030-1090℃, the residence time is (0.35-0.45)t min / mm, the second heating temperature is 1100-1160℃, the residence time is (0.25-0.35)t min / mm, the third heating temperature is 1140-11≥0℃, the residence time is (0.15-0.25)t min / mm, the soaking temperature is 11≥0-1210℃, the residence time is (0.10-0.20)t min / mm, t is the thickness of the composite blank;

[0024] The two-stage controlled rolling of rough rolling + finish rolling is adopted, the first pass is longitudinal rolling with a reduction of ≥46mm; the second pass starts transverse rolling, until the n-th pass, the composite blank is rolled to the target width of the final clad plate big plate, the rolling reduction of the second pass is ≥25mm; the n+1-th pass starts longitudinal rolling, the rolling reduction of the n+1-th pass is ≥30mm; in the whole rough rolling stage, the rolling temperature of the first pass is ≥1060℃, the starting rolling temperature of the remaining passes is ≤1050℃, the final rolling temperature is ≥1000℃; the rough rolling is ended when the thickness of the intermediate blank is 2.5-3.5 times of the target thickness of the clad plate big plate, the intermediate blank is cooled by water spraying, when the surface temperature of the intermediate blank is reduced to ≤40℃, the finish rolling stage is started, the starting rolling temperature of the finish rolling stage is ≥10℃-≤40℃, the final rolling temperature is ≥0℃-≥10℃.

[0025] As a further improvement of the embodiment, the rolling stage of the composite blank comprises the following steps:

[0026] After the clad plate big plate is obtained by rolling, the clad plate big plate enters the ultra-fast cooling system for cooling, the starting cooling temperature is ≥≥30℃, the cooling speed is 6-20℃ / s, the final cooling temperature is 4≥0-590℃.

[0027] As a further improvement of the embodiment, the composite blank rolling stage comprises the following steps:

[0028] After the composite plate large plate is rolled, the composite plate large plate enters an ultra-fast cooling system for intermittent cooling: the ultra-fast cooling system has 24 groups of cooling headers arranged at an interval of 1 m along the roller way, the cooling distance of each group of cooling headers is 1 m, when the composite plate large plate passes through the ultra-fast cooling system, the opening and closing states of the 24 groups of cooling headers are controlled in a manner that N groups of cooling headers are opened and then M groups of cooling headers are not opened, the cooling water pressure is 0.15-0.30 MPa, the cooling speed is 3-15 ℃ / s, and the final cooling temperature is 3≥0-590 ℃; wherein N is 2, 3 or 4, and M is 2, 3 or 4.

[0029] As a further improvement of the embodiment, the composite blank rolling stage comprises the following steps:

[0030] After the composite plate large plate leaves the ultra-fast cooling system, the composite plate large plate directly enters a straightening machine for straightening, and then is naturally cooled on a cooling bed.

[0031] Compared with the prior art, the beneficial effects of the present application are: one end of the stainless steel composite plate is a composite structure composed of carbon steel and stainless steel, and this end can have the corrosion resistance of the composite layer and the good mechanical properties of the base layer, like the existing composite plate; the other end of the stainless steel composite plate is a carbon steel plate, which is directly integrally formed without welding with the composite structure, so that the existing dissimilar welding problem is avoided in use, the stainless steel composite plate has strong firmness, low production difficulty, low cost and high construction efficiency, and there is no step between the stainless steel composite layer edge and the steel plate for bridge structure, which affects the layout of the overall bridge structure. BRIEF DESCRIPTION OF DRAWINGS

[0032] For the purpose of clear display and illustration, the sizes of some structures or parts are enlarged relative to other structures or parts in each drawing of the present application, and therefore, only the basic structures of the subject of the present application are used for illustration.

[0033] Figure 1 is a cross-sectional view of a stainless steel composite plate in an embodiment of the present application;

[0034] Figure 2 is a flowchart of a preparation method of a stainless steel composite plate in an embodiment of the present application;

[0035] Figure 3 is a cross-sectional view of a base material and a composite material in an embodiment of the present application;

[0036] Figure 4 is a cross-sectional view of a composite blank in an embodiment of the present application;

[0037] Figure 5 Figure 1 is a schematic diagram of the cross section of the stainless steel composite plate prepared by the method of the present application. DETAILED DESCRIPTION

[0038] The present application will be described in detail below with reference to the accompanying drawings.

[0039] Referring to Figure 1, the present application provides a stainless steel composite plate, which is composed of a carbon steel base layer 100 at the bottom and a stainless steel composite layer 200 at the top. Figure 1

[0040] In the present application, the three side edges 201, 202 and 203 of the composite layer 200 are flush with the three side edges of the base layer 100, and the other side edge 204 of the composite layer 200 is located in the middle of the upper surface of the base layer 100, and is arranged as an oblique edge with an obtuse angle β to the upper surface of the composite layer 200.

[0041] Thus, the stainless steel composite plate of the present application has a composite structure of carbon steel and stainless steel at one end (e.g. the left end in Figure 1), which can have the corrosion resistance of the composite layer and the good mechanical properties of the base layer, and a carbon steel plate at the other end (e.g. the right end in Figure 1), which is integrally formed without welding with the composite structure. Figure 1 Figure 1 Thus, the stainless steel composite plate of the present application avoids the problem of dissimilar welding in the prior art, has high firmness, low production difficulty, low cost and high construction efficiency, and does not have a step between the edge of the stainless steel composite layer and the steel plate for bridge structure, which does not affect the layout of the overall bridge structure.

[0042] Preferably, the total thickness of the composite plate is 15-39 mm, the thickness of the base layer is 12-36 mm, and the thickness of the composite layer is 3 mm.

[0043] Next, referring to Figure 2, the present application further provides a method for preparing a stainless steel composite plate. Figure 2

[0044] In the present application, the preparation of the composite blank includes the steps of preparing the steel blank, applying the isolation agent, assembling the blank, vacuumizing and sealing, which will be described in detail below.

[0045] <Preparing the steel blank step>

[0046] In this step, the base material and the composite material are prepared. Figure 3

[0047] ​​​​Specifically comprising: preparing two carbon steel square billets with X direction size L1 and Y direction size W1 as two substrates, such as Figure 3 Substrate 1 and substrate 2. Wherein the X direction and the Y direction, one of which is the longitudinal direction (i.e. the length direction of the square billet), and the other is the transverse direction (i.e. the width direction of the square billet).

[0048] In addition, the thickness of the substrate 1 and the substrate 2 can be set to be the same or different, and if set to be different, corresponding stainless steel composite plates of different thickness specifications can be prepared.

[0049] This step specifically further comprises: preparing a stainless steel square billet with X direction size L2, Y direction size W21 and thickness T2, and processing one side edge in the Y direction into a bevel with width V (such as Figure 3 bevel 33s), and the steel billet as composite A, such as Figure 3 composite 3;

[0050] Preparing a stainless steel square billet with X direction size L2, Y direction size W22 and thickness T2, and processing one side edge in the Y direction into a bevel with width V (such as Figure 3 bevel 43s), and the steel billet as composite B, such as Figure 3 composite 4.

[0051] Based on the above dimensions, that is, the size of the composite 3 and the composite 4 in the X direction is the same, and the thickness is also the same; while the size of the composite 3 and the composite 4 in the Y direction can be the same (i.e. W21=W22), or different (i.e. W21≠W22). If W21=W22, corresponding stainless steel composite plates of the same size specification in the Y direction can be prepared; if W21≠W22, corresponding stainless steel composite plates of different size specifications in the Y direction can be prepared.

[0052] Wherein, the width V of the bevel refers to the span of the bevel in the Y direction. Due to the existence of the bevel, the two surfaces of the composite 3 in the thickness direction, one of which is a larger surface with size W21 in the Y direction, such as Figure 3 surface 32s, and the other is a smaller surface with size W21-V in the Y direction, such as Figure 3 surface 31s. Similarly, the two surfaces of the composite 4 in the thickness direction, surface 42s is a larger surface with size W22 in the Y direction, and surface 41s is a smaller surface with size W22-V in the Y direction.

[0053] Furthermore, regarding the size relationship of the composite 3, the composite 4 and the substrate 1, the substrate 2, L1=L2+90-150mm, W1=W21+W22-V+90-150mm.

[0054] In a further preferred embodiment, this step specifically includes: polishing one surface of each substrate and the larger surface in the thickness direction of each composite material to remove surface oxide scale and expose a metallic luster. Specifically, see... Figure 3 As shown, for example, for substrate 1 and substrate 2, either of the two surfaces in the thickness direction can be ground and polished, such as surface 1s of substrate 1 and surface 2s of substrate 2. This can be done using a grinding wheel, belt sander, or milling machine. For composite materials 3 and 4, the larger surface in the thickness direction is ground and polished, such as surface 32s of substrate 3 and surface 42s of substrate 4. This can be done using a wire wheel. Thus, through grinding and polishing, these polished surfaces become the contact surfaces for lamination in subsequent assembly, thereby improving the interfacial bonding strength of the final stainless steel composite plate.

[0055] As a preferred option, the two composite materials are preferably austenitic stainless steel. Its chemical composition, by mass percentage, is: C≤0.15%, Si≤1.00%, Mn≤2.00%, P≤0.045%, S≤0.030%, Ni: 6.0~22.0%, Cr: 16.0~26.0%, Mo≤3.0%, with the balance being Fe and unavoidable impurities. Using stainless steel billets with this chemical composition can further guarantee the performance of the composite plate, especially the corrosion resistance of the cladding, while maintaining the aforementioned technical effects. For example, the cladding of the obtained composite plate (i.e., obtained by rolling the composite material) shows no intergranular corrosion cracks after being boiled in a sulfuric acid-copper sulfate solution for 20 hours and then bent at ≥0°.

[0056] It should be noted that the chemical composition of the two composite materials can be the same or different. Only one of them can use the chemical composition provided by the above-mentioned preferred scheme, or both of them can use or not use the chemical composition provided by the above-mentioned preferred scheme.

[0057] As a preferred embodiment, the chemical composition of the substrate, by mass percentage, is as follows: C: 0.03–0.16%, Si: 0.11–0.29%, Mn: 1.31–1.54%, P ≤ 0.01%, S ≤ 0.0030%, Cr: 0.06–0.29%, Nb: 0.011–0.034%, Ti: 0.011–0.019%, Al: 0.030–0.040%, with the remainder being Fe and unavoidable impurities.

[0058] Further preferably, the chemical composition of the substrate is, in mass percent: C: 0.0≥~0.12%, Si: 0.16~0.24%, Mn: 1.36~1.44%, P≤0.015%, S≤0.0025%, Cr: 0.11~0.19%, Ni: 0.06~0.14%, Nb: 0.016~0.024%, Ti: 0.011~0.019%, Al: 0.030~0.040%, and the balance of Fe and inevitable impurities.

[0059] Further preferably, the chemical composition of the substrate is, in mass percent: C: 0.0≥~0.12%, Si: 0.16~0.24%, Mn: 1.36~1.44%, P≤0.015%, S≤0.0025%, Cr: 0.11~0.19%, Ni: 0.06~0.14%, Nb: 0.016~0.024%, Ti: 0.011~0.019%, Al: 0.030~0.040%, and the balance of Fe and inevitable impurities.

[0060] Further preferably, the chemical composition of the substrate is, in mass percent: C: 0.0≥~0.12%, Si: 0.16~0.24%, Mn: 1.36~1.44%, P≤0.015%, S≤0.0025%, Cr: 0.11~0.19%, Ni: 0.06~0.14%, Nb: 0.016~0.024%, Ti: 0.011~0.019%, Al: 0.030~0.040%, and the balance of Fe and inevitable impurities.

[0061] Here, the chemical compositions of the two substrates can be the same or different, and the two substrates can adopt the chemical composition provided in the above preferred schemes only one of them, or both or none of them.

[0062] <coating release agent step>

[0063] This step is specifically: coating release agent on the smaller surfaces and bevels of the two composites in the respective thickness directions thereof.

[0064] Continuing to refer to Figure 4It is to be noted that for the composite 3, the surface 31s and the bevel 33s are coated with the release agent; for the composite 4, the surface 41s and the bevel 43s are coated with the release agent. In this way, by means of the release agent, for the surfaces of the composites and the base material which are in contact with each other but do not need to be compounded in the subsequent assembly, such as between the bevel 33s and the bevel 42s, between the surface 31s and the surface 1s of the base material 1, and between the surface 41s and the surface 2s of the base material 2, the accidental compounding can be avoided based on the effect of the release agent in the subsequent heating, rolling and other steps, so as to ensure that the final surfaces which do not need to be compounded are separated from each other.

[0065] As to the chemical composition of the release agent, the first embodiment is a coating liquid containing silicon oxide and magnesium oxide, wherein the mass ratio of silicon oxide to magnesium oxide is 3:1. The preparation method of the release agent is to mix release agent powder, binder powder and water in a mass ratio of 2:3:0 to obtain a fluid release agent coating liquid. The release agent powder is silicon oxide and magnesium oxide mixed in a mass ratio of 3:1. The binder powder is polyvinyl alcohol and thermosetting phenolic resin mixed in a mass ratio of 1:1.

[0066] The release agent of the present embodiment can achieve good isolation effect and ensure the separation of the two composite plate small plates in the subsequent step. The coating amount of the release agent on each surface is 20 ymg / m 2 , that is, 20 ymg of the release agent is coated on each square meter of the surface, 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 large plate prepared in the subsequent rolling step, which is also called the rolling compression ratio of the composite blank. After the release agent is applied, the composite material coated with the release agent is placed in a trolley furnace for heating and drying before the subsequent assembly step. The drying temperature is 340-360°C, and the drying time is 35-45 min.

[0067] As to the chemical composition of the release agent, the second embodiment is that the components are silicon nitride 25-35%, thermosetting amino resin 5-10% and water 55-0% by weight. Compared with the existing release agent and even the first embodiment of the aforementioned release agent, the release agent of the present embodiment not only can achieve good isolation effect and ensure the separation of the two composite plate small plates in the subsequent step, but also has strong chemical stability, high temperature resistance and thermal shock resistance of the effective component silicon nitride, the thermosetting amino resin as the binder can be cured at low temperature, is non-toxic, and can achieve strong bonding effect with a small amount, so the overall price is low, the operation is simple, and the isolation and adhesion effects are good.

[0068] In this regard, a preferred preparation method of the isolation agent of the second embodiment is provided, which comprises: firstly, putting 5-10% of silicon nitride (in terms of weight percentage) into a beaker or other container, then pouring 15-25% of water into the container and stirring; after the silicon nitride is free of particles and bubbles, pouring 2-3% of thermosetting amino resin into the container and continuing to stir; when the mixture presents a viscous state, pouring the remaining silicon nitride and water into the container and stirring for 3-5 minutes, then pouring the remaining thermosetting amino resin into the container; when the mixture presents a viscous state, the isolation agent is prepared.

[0069] For the isolation agent of the second embodiment, each surface is coated with a thickness of 0.2-0.5 mm; after the coating of the isolation agent is completed, and before the subsequent assembly step, the coated composite material is heated and dried, the drying temperature is 100-250°C, and the drying time is 20-40 minutes.

[0070] In this regard, it should be noted that in the drawings, the isolation agent coating layer is not shown in the drawings because the thickness of the isolation agent coating layer is very small relative to each steel plate.

[0071] <Assembly step>

[0072] Specifically, the step comprises: assembling a base material as an upper layer, another base material as a lower layer, two composite materials side by side in the Y direction as an intermediate layer, and a sealing strip surrounding the four sides of the intermediate layer and welded together with the two base materials, to form a composite base base; wherein the bevels of the two composite materials are parallel to each other.

[0073] In combination with the accompanying drawings, Figure 4 The formed composite base base comprises:

[0074] 1) the base material 1 as the upper layer, and the base material 2 as the lower layer;

[0075] 2) the composite material 3 and the composite material 4 are side by side in the Y direction, and the bevels 33s of the composite material 3 and the bevels 43s of the composite material 4 are parallel to each other, the composite material 3 and the composite material 4 together constitute an intermediate layer, i.e. between the base material 1 and the composite material 2;

[0076] 3) the sealing strip 5 surrounds the four sides of the intermediate layer; specifically, the two sides of the intermediate layer in the Y direction are respectively one side of the composite material 3 and one side of the composite material 4, one side of the intermediate layer in the X direction is respectively composed of one side of the composite material 3 and one side of the composite material 4, and the other side of the intermediate layer in the X direction is also respectively composed of the other side of the composite material 3 and the other side of the composite material 4; the four sealing strips 5 surround the four sides of the intermediate layer, and roughly form a four-sided frame;

[0077] 4) and the upper edge of the sealing strip 5 is welded with the lower surface of the base material 1, and the lower edge of the sealing strip 5 is welded with the upper surface of the base material 2.

[0078] The above describes the basic structure of the composite blank, and it can be understood that the blank forming sequence of the composite blank has various modes, for example: the base material 2, the composite material 3+the composite material 4, and the base material 1 can be stacked in sequence first, and then the four sealing strips 5 are wrapped around the composite material 3+the composite material 4, and finally the upper and lower edges of the sealing strip 5 are welded with the base material 1 and the base material 2; or, the sealing strip 5 can be welded with the base material 1 first, so that the surface of the base material 1 forms a four-sided frame surrounded by the sealing strip 5, and then the base material 2, the composite material 3+the composite material 4, and the base material 1 are stacked in sequence, and in the stacking process, the four-sided frame on the surface of the base material 1 is buckled around the composite material 3+the composite material 4, and finally the lower edge of the sealing strip 5 is welded with the base material 2. Here, only two sequences are exemplified, and the present application is not limited thereto, as long as the above-mentioned composite blank can be formed.

[0079] In this way, the prepared steel blank, the coated isolation agent, and the blank forming are performed according to the preparation method of the present application, the obtained composite blank is vacuumized and sealed, and then the composite blank is rolled and the plate is straightened, and the obtained stainless steel composite plate product is a composite structure composed of carbon steel and stainless steel at one end and a carbon steel plate at the other end, thereby solving the problem of dissimilar metal welding existing in the prior art, and having the advantages of strong use firmness, low production difficulty, low cost, and high construction efficiency compared with the existing composite plate.

[0080] Preferably, the sealing strip 5 is selected from carbon steel blanks, and specifically, for example, is the same steel grade as the base material 1 and the base material 2.

[0081] Furthermore, regarding the size of the four sealing strips 5, the width of the sealing strip 5 (i.e. the span in the thickness direction of the composite blank) is T2-2mm~T2, that is, the width is equal to the thickness T2 of the composite material or slightly less than the thickness T2 of the composite material within about 2mm; the thickness of the sealing strip 5 is 12~15mm.

[0082] At the two side edges in the Y direction of the composite blank, the length of the sealing strip 5 is L2-2mm~L2, that is, the length is equal to the X direction size L2 of the composite material or slightly less than L2 within about 2mm; and at the two side edges in the X direction of the composite blank, the length of the sealing strip 5 is W21+W22-V-2mm~W21+W22-V. That is, the length is equal to the Y direction size of the corresponding side edge of the intermediate layer composed of the composite material 3+the composite material 4 or slightly less than the size within about 2mm.

[0083] Regarding the forming mode of each sealing strip, it can be directly cut out according to the thickness on a steel plate without welding, or it can be spliced by welding from multiple sealing strips of different lengths.

[0084] In a further preferred embodiment, the lower surface of the upper substrate 1 is a surface 1s which has been subjected to the polishing and grinding treatment described above, so that both the surface 1s and the surface 42s in contact with it have been subjected to the polishing and grinding treatment, and the bonding quality of the composite interface is good; similarly, the upper surface of the lower substrate 2 is a surface 2s which has been subjected to the polishing and grinding treatment described above, so that both the surface 2s and the surface 32s in contact with it have been subjected to the polishing and grinding treatment, and the bonding quality of the composite interface is good.

[0085] In a further preferred embodiment, in this step, the upper edge of the seal 5 and the lower surface of the substrate 1, and the lower edge of the seal 5 and the upper surface of the substrate 2, are welded together by gas shielded welding. Preferably, the welding speed during gas shielded welding is 300-360 mm / min, and the interpass temperature is controlled at 135-165°C. In addition, before gas shielded welding, the substrate 1 and the substrate 2 are preferably preheated by a flame gun, and the preheating temperature is 100-200°C.

[0086] In a further preferred embodiment, the intermediate layer formed by the composite 3 and the composite 4 is placed in the middle with respect to the substrates. In this regard, the size relationship between the composite 3, the composite 4, the substrate 1 and the substrate 2 is described above to satisfy L1=L2+90-150 mm and W1=W21+W22-V+90-150 mm, and when the green composite is assembled, the distance between the two side edges of the intermediate layer in the X direction to the corresponding two side edges of the substrates is equal, such as L1-L2 / 2, and the distance between the two side edges of the intermediate layer in the Y direction to the corresponding two side edges of the substrates is also equal, such as W1-(W21+W22-V) / 2.

[0087] In a further preferred embodiment, the four side edges of the composite green composite have grooves formed outside the seal 5 between the two substrates. This step further comprises: machining a circular through hole on the seal 5 at one side edge of the composite green composite, and sealing welding a circular pipe with the same diameter as the through hole in the through hole; and surfacing the grooves of the four side edges of the composite green composite.

[0088] In which, the surfacing can be submerged arc surfacing. It can be understood that outside the four-edge frame formed by the seal 5, a four-edge frame-shaped filling layer is formed by the surfacing of this step, as shown in Figure 5 In which, the filling layer formed by surfacing is marked as 6.

[0089] As a preferred mode, before the surfacing 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 at 135-165℃, the welding current is 5≥0-630A, the welding voltage is 2≥-32V, and the welding speed is 420-4≥0mm / min. In this way, the submerged arc surfacing technology, combined with the previous sealing strip surrounding and gas shielded welding, 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 of the final composite plate.

[0090] In addition, during the surfacing welding process, the weld bead adherents need to be cleaned before each weld bead construction to keep the weld bead clean; and after the surfacing welding is completed, the heat preservation cotton is covered for heat preservation.

[0091] <vacuumizing step and sealing step>

[0092] In the vacuumizing step, the suction port of the vacuum pump is connected to the circular pipe, and the circular pipe is connected to the space inside the composite blank base blank (such as the face-to-face gap between the composite material and the base material, the end face gap between the composite material and the sealing strip, etc.), so as to exhaust the air in the space until the vacuum degree is ≤10 -1 Pa, and then the pressure is maintained for 4h or more. 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, and the composite interface bonding quality is guaranteed.

[0093] And in the sealing step, the circular pipe is sealed, so as to prepare the composite blank. The sealing method can be implemented in the existing feasible way in the steel field, for example, the seamless steel pipe is heated by a flame gun and is clamped to realize sealing.

[0094] The specific implementation of the composite blank preparation stage is introduced in detail above, as described before, the preparation method further includes a composite blank rolling stage, in which the composite blank prepared in the composite blank preparation stage is processed by heating, rolling, cooling and the like. In this regard, various preferred embodiments of the composite blank rolling stage are provided, which will be introduced respectively as follows.

[0095] <first embodiment>

[0096] In this embodiment, the composite blank rolling stage includes the following steps.

[0097] heating step: the obtained composite blank is heated, the soaking temperature is 1150-1220℃, the total heating time is ≥1.2xt min / mm, t is the thickness of the composite blank, and the soaking time in the soaking section is 30-50min;

[0098] rolling step: two-stage controlled rolling of rough rolling+precision rolling is adopted, in the rough rolling stage, the opening rolling temperature is 1150-1220℃, the rolling reduction is 20-30%, the precision rolling temperature is 950-1050℃, and the rolling reduction is 40-50%.

[0099] ≤1050℃, final rolling temperature ≥90℃, first transverse rolling and then longitudinal rolling, at least one pass reduction ≥35mm, total rough rolling reduction 40-60%, rough rolling stage ends when the thickness of the intermediate billet is 2.5-3.5 times the target thickness of the clad plate; then waiting for temperature, during which water cooling is performed, when the surface temperature of the intermediate billet is reduced to ≤60℃, the fine rolling stage begins; final rolling temperature ≥70℃, total fine rolling reduction 55-65%;

[0100] cooling step: after exiting the rolling mill, the rolled plate enters the ultra-fast cooling system for cooling, the opening cooling temperature ≥30℃, the cooling speed is 6-20℃ / s, and the final cooling temperature is 40-590℃; after the rolled plate exits the ultra-fast cooling system, it directly enters the straightening machine for 1-3 passes of warm straightening, and then is naturally cooled on the cooling bed until the surface temperature of the rolled plate is ≤200℃, and then is cold straightened on the cooling bed to obtain the clad plate.

[0101] In this embodiment, the heating and rolling techniques are adopted, and through control of the heating temperature, heating time, holding time, each temperature in rolling, reduction, temperature in cooling, and cooling speed, the mechanical properties of the finally obtained clad plate can be ensured, and the corrosion resistance of the clad layer can be prevented from being reduced due to the preparation process of the clad plate.

[0102] <Second embodiment>

[0103] This embodiment is the same as the first embodiment of the aforementioned clad billet rolling stage in the heating and rolling steps, and the difference lies in the cooling step. Only the cooling step is introduced below.

[0104] Specifically, the cooling step in this embodiment is as follows:

[0105] After exiting the rolling mill, the rolled plate enters the ultra-fast cooling system for intermittent cooling; the ultra-fast cooling system has 24 groups of cooling headers arranged at an interval of 1m along the roller way, and each group of cooling headers has a cooling distance of 1m. When the rolled plate passes through the ultra-fast cooling system, the opening and closing states of all 24 groups of cooling headers are controlled in the manner that N groups of cooling headers are opened and then M groups of cooling headers are not opened, the cooling water pressure is 0.15-0.30MPa, the cooling speed is 3-15℃ / s, and the final cooling temperature is 30-590℃; wherein N is 2, 3 or 4, and M is 2, 3 or 4;

[0106] After the rolled plate exits the ultra-fast cooling system, it is naturally cooled on the cooling bed to room temperature to obtain the clad plate.

[0107] In addition to the advantages of the first embodiment, the composite plate can be cooled by the intermittent cooling method. The composite plate travels through the cooling system with the cooling set pipe opened and closed alternately. Each part of the composite plate is cooled, re- red, cooled, re-red, and so on, until the composite plate leaves the cooling system. In this way, the carbon steel substrate is continuously phase-transformed and self-tempered in the cooling-re- red cycle, and the phase transformation gradually penetrates to the core until the entire carbon steel substrate is phase-transformed. The intermittent cooling process is different from the conventional reciprocating cooling. The re- red and self-tempering of the reciprocating cooling occur after the surface layer or near-surface layer is phase-transformed, and the temperature difference between the surface and the core or the cooling speed difference is large, resulting in a large difference in microstructure and mechanical properties. However, in the intermittent cooling process of the present embodiment, some parts of the composite plate are in a cooling state and some parts are in a re- red / self-tempering state at the same time. Each part of the composite plate alternately cools and re- reds / self-temper over time, resulting in a small difference in temperature, cooling speed, microstructure, and performance between the surface and the core of the composite plate. For example, the difference in Vickers hardness in the thickness direction of the base layer of the final composite plate is ≤10, the difference in head-tail strength is ≤40 MPa, and the difference in strength throughout the plate is ≤40 MPa. At the same time, the intermittent cooling can further improve the plate shape of the composite plate, i.e., low unevenness. Even if the plate is not straightened after cooling and is directly cooled on the cooling bed, an excellent plate shape can be obtained.

[0108] Further preferably, in the intermittent cooling process, if the thickness of the rolled plate is less than 54 mm, for example, 10-54 mm, the roller speed of the ultra-fast cooling system is 0.4-0.≥m / s, the first-fourth cooling set pipes are opened, the fifth-sixth cooling set pipes are not opened, the seventh-eighth cooling set pipes are opened, the ninth-tenth cooling set pipes are not opened, the eleventh-twelfth cooling set pipes are opened, the thirteenth-fourteenth cooling set pipes are not opened, the fifteenth-sixteenth cooling set pipes are opened, the seventeenth-eighteenth cooling set pipes are not opened, the nineteenth-twentieth cooling set pipes are opened, the twenty-first-twenty-second cooling set pipes are not opened, and the twenty-third-twenty-fourth cooling set pipes are opened. The rolled plate passes through the ultra-fast cooling system once, i.e., completes the intermittent cooling.

[0109] Further preferably, in the intermittent cooling, if the thickness of the rolled piece plate is > 54 mm, the roller speed of the ultrafast cooling system is > 0.2 m / s and < 0.6 m / s, the first to fourth groups of cooling headers are opened, the fifth to > groups of cooling headers are not opened, the ninth to twelfth groups of cooling headers are opened, the thirteenth to sixteenth groups of cooling headers are not opened, the first > to twentieth groups of cooling headers are opened, the twenty-first to twenty-second groups of cooling headers are not opened, and the twenty-third to twenty-fourth groups of cooling headers are opened; the rolled piece plate passes through the ultrafast cooling system once, i.e. the intermittent cooling is completed. In this way, the shape control and uniformity control of the thick stainless steel clad plate are realized, and the production difficulty of the existing thick stainless steel clad plate is overcome.

[0110] <Third embodiment>

[0111] The embodiment is the same as the second embodiment of the preceding composite blank rolling stage in the cooling step, and the difference lies in the heating step and the rolling step. Only the heating step and the rolling step are introduced below.

[0112] Specifically, in the embodiment, the heating step is:

[0113] The obtained composite blank is subjected to five-stage heating of preheating, first heating, second heating, third heating and soaking, the preheating temperature is ≤≥50℃, the residence time is (0.45-0.55)t min / mm, the first heating temperature is 1030-1090℃, the residence time is (0.35-0.45)t min / mm, the second heating temperature is 1100-1160℃, the residence time is (0.25-0.35)t min / mm, the third heating temperature is 1140-11≥0℃, the residence time is (0.15-0.25)t min / mm, the soaking temperature is 11≥0-1210℃, and the residence time is (0.10-0.20)t min / mm, t being the thickness of the composite blank.

[0114] The rolling step is:

[0115] Adopt two-stage control rolling of rough rolling + finish rolling, the first pass adopts longitudinal rolling, the rolling reduction is ≥ 46mm; the second pass adopts transverse rolling, until the n pass, the composite blank is rolled to the target width of the final composite plate big plate, the rolling reduction of the second pass is ≥ 25mm; the n+1 pass adopts longitudinal rolling, the rolling reduction of the n+1 pass is ≥ 30mm; in the whole rough rolling stage, the rolling temperature of the first pass is ≥ 1060℃, the opening rolling temperature of the remaining passes is ≤ 1050℃, and the finish rolling temperature is ≥ 1000℃; when the thickness of the intermediate blank is 2.5-3.5 times of the target thickness of the composite plate big plate, the rough rolling stage is ended, and the temperature is waited, and the water cooling is carried out during the waiting, when the surface temperature of the intermediate blank is reduced to ≤ 40℃, the finish rolling stage is started, the opening rolling temperature of the finish rolling stage is ≥ 10℃-≥ 40℃, and the finish rolling temperature is ≥ 0℃-≥ 10℃.

[0116] Compared with the prior art, the heating technology of the embodiment can better control the temperature rising rate of the composite blank in each section, ensure uniform heating of the blank, avoid cracking and gas leakage of the composite blank due to the difference in material thermal performance of the base material and the composite material, and thus ensure the interface bonding effect; moreover, the rolling process of the embodiment adopts the mode of longitudinal rolling, transverse rolling and longitudinal rolling in sequence, which can ensure the realization of large reduction rolling, promote the deformation of the core, and ensure the bonding rate of the composite interface; the instant cooling device is used for cooling during the temperature waiting, the temperature waiting time is reduced, the rolling efficiency is improved, and the carbon steel base material is prevented from growing in size due to long temperature waiting time; the temperature control in the finish rolling stage can refine the grains and ensure good low-temperature impact toughness of the thick composite plate.

[0117] It can be understood that, as a further variation, the heating step and the rolling step provided in the embodiment can also be combined with the cooling step of the first embodiment to prepare a composite plate big plate, and the beneficial effects of the embodiment can also be achieved.

[0118] The composite blank rolling stage is described in detail above, and next, the preparation method of the application further includes a plate separating and straightening stage. Specifically, the plate separating and straightening stage includes the following steps:

[0119] The composite plate big plate obtained through the foregoing composite blank rolling total step is cut by a plasma cutting machine to remove the part outside the seal strip, and the composite plate big plate is separated into two composite plate small plates;

[0120] Finally, the composite plate small plate is sized, flattened and cold straightened, such as Figure 5, to obtain two finished single-sided stainless steel clad plates.

[0121] Referring to Figure 5 , cross-sectional shapes of the two finished single-sided stainless steel clad plates are shown, and each of the obtained clad plates 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 Figure 5 , the original clad material is still marked with the original clad material number, and the base layer is still marked with the original base material number. For example, one clad plate is composed of a carbon steel base layer 1 and a stainless steel clad layer 4, and the other clad plate is composed of a carbon steel base layer 2 and a stainless steel clad layer 3.

[0122] The stainless steel clad plate prepared by the preparation method provided by the present application has ​ , three side edges (for example, two side edges in the X direction and one side edge in the Y direction) of the clad layer are flush with three side edges of the base layer; and the other side edge (for example, the other side edge in the Y direction) of the clad layer is located in the middle of one surface of the base layer, and the side edge is arranged as an obtuse-angled bevel edge with the smaller surface of the clad layer.

[0123] Therefore, the stainless steel clad plate prepared by the preparation method of one embodiment of the present application has a composite structure composed of carbon steel and stainless steel at one end, which can have the corrosion resistance of the clad layer and the good mechanical properties of the base layer as in the existing clad plate; and the other end is a pure carbon steel plate. Therefore, the stainless steel clad plate avoids the existing dissimilar welding problem in use, has strong firmness in use, has low production difficulty, low cost and high construction efficiency in later use, and there is no step between the edge of the stainless steel clad layer and the steel plate for bridge structure, which does not affect the layout of the overall bridge structure.

[0124] Preferably, the total thickness of the clad plate is 15-39 mm, the thickness of the base layer is 12-36 mm, and the thickness of the clad layer is 3 mm.

[0125] Further, the stainless steel clad plate is prepared by the preparation method of the further preferred embodiment described above, which also has excellent mechanical properties and corrosion resistance, and has excellent plate shape, interface bonding quality, uniformity, impact toughness and surface quality compared with the prior art.

[0126] Specifically, the unevenness of the composite plate is ≤3mm / m, even the unevenness is ≤2mm / m; the composite interface bonding rate is 100%, the shear strength is ≥300MPa; the yield strength is ≥345MPa, the tensile strength is ≥490MPa, the elongation after fracture is ≥1≥%, the yield strength ratio is ≤0.≥6; the Vickers hardness difference in the thickness direction of the base layer of the composite plate is ≤10, the head-middle-tail strength difference is ≤40MPa, the strength difference of the whole plate is ≤40MPa; the impact energy at 0℃ is ≥240J, the impact energy at -20℃ is ≥200J, the impact energy at -40℃ is ≥150J; the outer bending 1≥0° is free of cracks, the inner bending 1≥0° is free of cracks; after being boiled in sulfuric acid-copper sulfate solution for 20h, the composite layer is free of intergranular corrosion cracks after 1≥0° bending.

[0127] The above detailed description is only a specific description of the feasible embodiments of the present application, and is not used to limit the protection scope of the present application. Equivalent embodiments or changes made without departing from the spirit of the present application should be included in the protection scope of the present application.

[0128] The beneficial effects of the present application are further illustrated by the following examples, which are only a part of the numerous changeable embodiments of the present application, not all.

[0129] Examples 1-≥

[0130] In these examples, the steel grades / chemical compositions of the selected composite and base material are shown in Table 1. Among them, “-” represents that the corresponding element is not actively added during the preparation of the steel billet (the content is zero or close to zero).

[0131] Table 1

[0132]

[0133] The base material and the composite material in Table 1 above are implemented according to the preparation method of an embodiment of the present application. For each example, the base material and the composite material used are shown in Table 2; in Examples 1-≥, Examples 1-3 are implemented according to the first embodiment of the composite billet rolling stage, Examples 4-6 are implemented according to the second embodiment of the composite billet rolling stage, and Examples ≥-≥ are implemented according to the third embodiment of the composite billet rolling stage.

[0134] The total thickness, base layer thickness, and composite layer thickness of the single-sided stainless steel composite plate product obtained in Examples 1-≥ are shown in Table 2.

[0135] Table 2

[0136]

[0137] The composite plates of each embodiment are sampled and tested, the interface bonding rate of each embodiment is 100%, the shear strength is ≥300MPa; the inner bend 1 is ≥0° qualified (no crack), the outer bend 1 is ≥0° qualified (no crack); and after being boiled in sulfuric acid-copper sulfate solution for 20h, after bending 1 ≥0°, the composite layer has no intergranular corrosion crack; the impact energy at 0℃ is ≥240J, the impact energy at-20℃ is ≥200J, the impact energy at-40℃ is ≥150J; the yield strength is ≥345MPa, the tensile strength is ≥490MPa, the elongation after fracture is ≥1≥%, the yield strength ratio is ≤0.≥6; and the unevenness is ≤3mm / m, the unevenness of embodiments 4~≥ is even ≤2mm / m.

Claims

1. A method for producing a stainless steel clad plate, characterized by, The preparation method comprises three stages of composite blank preparation, composite blank rolling and plate splitting straightening, wherein the composite blank preparation stage comprises the following steps: Prepare two carbon steel square billets with an X-direction size of L1 and a Y-direction size of W1 as two substrates; Prepare one stainless steel square billet with an X-direction size of L2, a Y-direction size of W21 and a thickness of T2, and process one side edge in the Y direction into a bevel with a width of V, and the steel billet is used as composite A; L1 = L2 + 90~150 mm; Prepare one stainless steel square billet with an X-direction size of L2, a Y-direction size of W22 and a thickness of T2, and process one side edge in the Y direction into a bevel with a width of V, and the steel billet is used as composite B; W1 = W21 + W22 - V + 90~150 mm; Coat the smaller surfaces on the respective thicknesses of the composite A and the composite B and the bevels with release agent; Assemble the billets in a manner that one substrate is used as the upper layer, the other substrate is used as the lower layer, the composite A and the composite B are used as the middle layer in the Y direction, and the four side edges of the middle layer are surrounded by the sealing strip and welded together to form a composite blank base billet; wherein the bevel of the composite A and the bevel of the composite B are parallel to each other; Vacuumize and seal the composite blank base billet to obtain a composite blank; The composite blank rolling stage comprises the following steps: After rolling, the rolled plate enters the ultra-fast cooling system for intermittent cooling: the ultra-fast cooling system has 24 groups of cooling headers arranged at an interval of 1 m along the roller way, and the cooling distance of each group of cooling headers is 1 m; when the rolled plate passes through the ultra-fast cooling system, the opening and closing states of the 24 groups of cooling headers are controlled in a manner that N groups of cooling headers are opened and then M groups of cooling headers are not opened; the cooling water pressure is 0.15~0.30 MPa, the cooling speed is 3~15 ℃ / s, and the final cooling temperature is 380~590 ℃; wherein N is 2, 3 or 4, and M is 2, 3 or 4.

2. The method of claim 1, wherein the stainless steel clad plate is prepared by the steps of: The composite blank rolling stage comprises the following steps: ​ Heat the obtained composite blank, the soaking temperature is 1150~1220 ℃, the total heating time is ≥1.2×t min / mm, t is the thickness of the composite blank, and the soaking time is 30 min~50 min; Control rolling in two stages of rough rolling and finish rolling; in the rough rolling stage, the starting rolling temperature is ≤1050 ℃, the final rolling temperature is ≥980 ℃, the rolling is first performed in the transverse direction and then in the longitudinal direction, at least one pass of the longitudinal rolling has a reduction of ≥35 mm, the total reduction of the rough rolling is 40~60%, and the rough rolling is ended when the intermediate billet thickness is 2.5~3.5 times the target thickness of the composite plate large plate; then, the intermediate billet is allowed to cool by watering, and when the surface temperature of the intermediate billet is reduced to below 860 ℃, the finish rolling stage is started; the final rolling temperature of the finish rolling stage is ≥780 ℃, and the total reduction of the finish rolling is 55~75%, and the composite plate large plate is obtained.

3. The method of claim 1, wherein the stainless steel clad plate is prepared by the steps of: preparing a stainless steel plate; preparing a carbon steel plate; and joining the stainless steel plate and the carbon steel plate. The composite blank rolling stage comprises the following steps: The composite blank is subjected to five-stage heating of preheating, first heating, second heating, third heating and soaking, the preheating temperature is ≤850℃, the residence time is (0.45~0.55)t min / mm, the first heating temperature is 1030~1090℃, the residence time is (0.35~0.45)t min / mm, the second heating temperature is 1100~1160℃, the residence time is (0.25~0.35)t min / mm, the third heating temperature is 1140~1180℃, the residence time is (0.15~0.25)t min / mm, the soaking temperature is 1170~1210℃, and the residence time is (0.10~0.20)t min / mm, wherein t is the thickness of the composite blank; The composite blank is subjected to two-stage controlled rolling of rough rolling and finish rolling, the first pass is longitudinal rolling with a rolling reduction≥46mm; the second pass is transverse rolling until the n-th pass, the target width of the composite blank is reached, the rolling reduction of the second pass is≥25mm; the n+1-th pass is longitudinal rolling with a rolling reduction≥30mm; the rolling temperature of the first pass in the whole rough rolling stage is≥1060℃, the rolling temperature of the remaining passes is≤1050℃, and the finish rolling temperature is≥1000℃; the rough rolling stage ends when the thickness of the intermediate blank is 2.5~3.5 times of the target thickness of the composite blank, and the temperature is kept, during which water cooling is performed; when the surface temperature of the intermediate blank is reduced to≤840℃, the finish rolling stage starts, the start rolling temperature is 810℃~840℃, and the finish rolling temperature is 780℃~810℃.

4. The method of claim 1, wherein the stainless steel clad plate is prepared by the steps of: preparing a stainless steel plate; preparing a carbon steel plate; and joining the stainless steel plate and the carbon steel plate. The four side edges of the composite blank base blank have grooves formed between the two base materials outside the seal; The composite blank preparation stage further comprises: machining a circular through hole on the seal at one side edge of the composite blank base blank, sealing welding a circular pipe with the same diameter as the through hole in the through hole; and surfacing the grooves of the four side edges of the composite blank base blank.

5. A stainless steel clad plate characterized by, The stainless steel composite plate is prepared by the method of any one of claims 1~4; The composite plate is composed of a lower carbon steel base layer and an upper stainless steel composite layer, three side edges of the composite layer are flush with three side edges of the base layer, and the other side edge of the composite layer is located in the middle of the upper surface of the base layer and is arranged as an oblique edge with an obtuse angle to the upper surface of the composite layer.

6. The stainless steel clad plate according to claim 5, characterized by The total thickness of the composite plate is 15~39mm, the thickness of the base layer is 12~36mm, and the thickness of the composite layer is 3mm.

7. The stainless steel clad plate according to claim 5, characterized by The Vickers hardness difference in the thickness direction of the base layer of the composite plate is ≤10, the head-middle-tail strength difference is ≤40MPa, the strength difference of the whole plate is ≤40MPa, and the unevenness is ≤2mm / m.

8. The stainless steel clad plate according to claim 5, characterized by The 0℃ impact energy of the composite plate is≥240J, the -20℃ impact energy is≥200J, and the -40℃ impact energy is≥150J.

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