A thick-gauge stainless steel composite plate for bridges and its preparation method

Abstract

This invention relates to the field of stainless steel composite plate technology, and in particular to a thick-gauge stainless steel composite plate for bridges and its preparation method. The method includes: obtaining a composite billet through single-component billet processing; subjecting the composite billet to primary heating and rolling; followed by secondary heating, controlled rolling, and controlled cooling to obtain the composite plate; tempering; and straightening. Specifically, the single-component billet processing involves beveling the four sides of the substrate to be composited, drilling holes to form evacuation vents, bonding the cladding stainless steel surface to be composited with the substrate, welding and sealing, and then performing vacuum treatment. This invention solves the problems of difficulty in producing high-performance thick-gauge stainless steel composite plates for bridges using symmetrical billet rolling and the difficulty in achieving rolling using conventional single-component billet rolling. The produced bridge-use stainless steel composite plate exhibits excellent interfacial bonding, shear strength ≥380MPa, yield strength ratio ≤0.83, substrate impact Akv ≥250J at -40℃, and excellent resistance to intergranular corrosion of the cladding material, demonstrating good comprehensive performance and plate shape.

Description

Technical Field

[0001] This invention relates to the field of stainless steel composite plate technology, and in particular to a thick-gauge stainless steel composite plate for bridges and its preparation method. Background Technology

[0002] As steel bridge construction standards continue to improve and safety and reliability requirements become increasingly stringent, bridges are gradually evolving towards high-speed, heavy-load, long-span, and paint-free designs. This places higher demands on bridge steel, requiring high strength and toughness, low yield strength ratio, and high corrosion resistance. Composite plates combining bridge steel and stainless steel possess both the high strength and toughness of the base layer and the corrosion resistance of the coating, better meeting the requirements of lightweight, high corrosion resistance, and long service life for bridge deck structures.

[0003] Common production methods for stainless steel composite plates used in bridges include explosive pressing and rolling. Explosive pressing is more suitable for producing thicker composite plates, but its production dimensions are still limited. If the finished product is wide, the cladding material needs to be welded before the explosion, and defects are prone to appear at the weld joints after the explosion, and the cladding point cannot be fully bonded. This method is also easily affected by climate and environment, and has problems such as noise and environmental pollution, making it difficult to mass-produce automatically. Rolling, on the other hand, allows for flexible adjustment of plate width and high-efficiency mass production. It is a green, environmentally friendly, and sustainable production process, and is divided into symmetrical billet rolling and asymmetrical billet rolling. Symmetrical billet rolling maintains good plate shape throughout the production process because the upper and lower materials of the composite billet are consistent. However, when producing thick-gauge composite plates (finished thickness ≥ 50mm), the rolling thickness can reach over 100mm, and the billet thickness for symmetrical billets needs to be over 500mm. This places high demands on the billet assembly and rolling equipment. The greater the rolling thickness, the greater the difference in cooling rate along the thickness direction, and the smaller the rolling compression ratio. Insufficient deformation at the interface between the base and cladding materials and in the core of the base material affects the microstructure and properties of the final product. Asymmetrical billet assembly, combining a single sheet of carbon steel and a single sheet of stainless steel, can increase the rolling compression ratio and reduce the difference in cooling rate along the thickness direction, thereby improving the performance of the composite plate. However, due to the differences in thermal expansion coefficients and deformation resistance between carbon steel and stainless steel, warping and buckling are prone to occur during rolling, which can even prevent the rolling process from being completed in severe cases. Summary of the Invention

[0004] This invention addresses the aforementioned technical problems and overcomes the shortcomings of existing technologies by providing a thick-gauge stainless steel composite plate for bridges and its preparation method. It solves the problems of difficulty in producing high-performance thick-gauge stainless steel composite plates for bridges using symmetrical billet rolling and the difficulty in achieving rolling with conventional single-bill billets. The produced bridge stainless steel composite plate exhibits excellent interfacial bonding, shear strength ≥380MPa, yield strength ratio ≤0.83, substrate impact Akv ≥250J at -40℃, and no cracking observed during 180° internal and external bending. The cladding material demonstrates excellent resistance to intergranular corrosion, exhibiting good overall performance and plate shape.

[0005] In a first aspect, the present invention provides a method for preparing thick-gauge stainless steel composite plates for bridges, specifically including the following steps:

[0006] A composite billet is obtained by performing a single-component billet treatment;

[0007] The composite billet is heated and rolled in one step;

[0008] The composite billet is subjected to secondary heating, controlled rolling, and controlled cooling to obtain a composite plate;

[0009] Tempering:

[0010] And straightening;

[0011] Specifically, the single-component billet processing includes:

[0012] a) Beveling the four sides of the substrate to be laminated;

[0013] b) Drill holes in the substrate to form venting holes;

[0014] c) Lay the stainless steel surface of the cladding material to be laminated with the substrate;

[0015] d) Weld and seal the seal and then perform a vacuum treatment.

[0016] Optionally, in the single-component billet processing: the bevel angle is 30-60°, and the bevel height is 15-70mm; a hole is drilled downwards at a distance of 50-70mm from the center of the short side edge of the substrate, with a hole depth of bevel height plus 15-40mm; and a hole is drilled inwards at a distance of 15-40mm from the bevel on the short side wall of the substrate, with a hole depth of 50-70mm, which connects with the hole on the upper surface of the substrate to form an L-shaped vent hole. By designing the vent hole at the short side of the substrate, less area needs to be removed after rolling, which can improve product yield and save costs.

[0017] Optionally, the welding sealing and vacuuming process specifically includes: first, welding the connection between the substrate and the cladding material using gas shielded welding, pre-vacuuming the evacuation hole on one side, and sealing the evacuation hole when the vacuum value reaches below 20 Pa; then, fully welding the remaining part of the bevel using submerged arc welding, and performing a second vacuuming to ensure that the final vacuum value is no greater than 10 Pa, thereby obtaining a composite billet of single-layer stainless steel + single-layer carbon steel in a high interfacial vacuum state.

[0018] Optionally, the primary heating and rolling specifically includes:

[0019] The composite billet is sent to the heating furnace with the stainless steel cladding facing up and the carbon steel base facing down. The heating temperature is 1150-1250℃, and the upper surface temperature is 20-50℃ higher than the lower surface temperature. The total heating time is 9-18 min / cm.

[0020] After exiting the furnace, single-stage rolling is adopted, with the reduction rate of multiple passes not exceeding 5%, and the total reduction rate being 18% to 30%. When the composite billet bites in, the sled coefficient is adjusted to a negative value to reduce the degree of head lifting. During the rolling process, only the lower descaling water is turned on to descal the carbon steel on the lower surface.

[0021] Optionally, the secondary heating, controlled rolling, and controlled cooling treatment specifically includes:

[0022] After one rolling, the composite billet is flipped to ensure that the stainless steel cladding is facing down and the carbon steel base is facing up. The composite billet is heated to 1180-1250℃, with the lower surface temperature being 20-50℃ higher than the upper surface temperature. The total heating time is 10-18 min / cm.

[0023] Two-stage rolling is adopted, and the sled coefficient is adjusted to a positive value to reduce the degree of deduction. The starting rolling temperature of the finishing rolling stage is not higher than 860℃, and the finishing rolling temperature is 720~850℃. During the rolling process, only the upper descaling water is turned on and the lower descaling water is turned off.

[0024] The thickness of the intermediate billet to be heated should be no less than 1.6 times the thickness of the finished product, and the intermediate billet should be naturally air-cooled;

[0025] Pre-straightening is performed before immersion in water, with the immersion water temperature controlled at 700–800℃, the reddening temperature at 380–640℃, and the cooling water-to-water ratio at 1.0–1.3.

[0026] Optionally, the tempering includes: flipping the composite plate so that the stainless steel cladding is facing up and the carbon steel substrate is facing down, tempering at a temperature of 400-550°C, and tempering for 100-250 minutes.

[0027] Optionally, the straightening includes: performing straightening treatments for more than 3 times, with an unevenness of ≤5mm / m, and grinding and cleaning the surface of the composite plate to obtain a stainless steel composite plate product.

[0028] Optionally, before performing single-component preform processing, the method further includes providing a base material preform and a cladding material preform, wherein the width and length of the cladding material preform are the same as those of the base material preform, removing iron oxide scale, drill chips, dust and oil stains from the surfaces to be laminated, placing the stainless steel surface of the cladding material preform facing down on the base material preform, and fitting and aligning them.

[0029] Optionally, the chemical composition of the substrate by mass percentage is as follows: C: ≤0.14%, Si: 0.15~0.50%, Mn: 1.00~1.70%, P≤0.025%, S≤0.020%, Nb: 0.010~0.060%, V: ≤0.050%, Ti: 0.006~0.020%, Alt: 0.015~0.050%, Cu: ≤0.40%, Cr: ≤0.60%, Ni: ≤0.50%, Mo: ≤0.30%, with the balance being Fe and a small amount of unavoidable impurities;

[0030] The chemical composition of the cladding material by mass percentage is as follows: C: ≤0.08%, Si: ≤1.50%, Mn: ≤2.00%, P≤0.045%, S≤0.030%, Cr: 16.00~26.00%, Ni: 8.00~22.00%, Mo: ≤4.00%, Ti: ≤0.40%, N≤0.16%, with the balance being Fe and a small amount of unavoidable impurities.

[0031] Secondly, the present invention also provides a thick-gauge stainless steel composite plate for bridges, which is prepared using the method for preparing thick-gauge stainless steel composite plates for bridges described in any one of the first aspects.

[0032] The beneficial effects of this invention are:

[0033] (1) The present invention adopts single-hole vacuuming, which reduces the chance of the sealing rivet falling off at the air extraction hole and reduces the risk of air leakage. After sealing welding, pre-vacuuming is performed to remove the air between the two sides of the substrate and the cover material to be composited, which can reduce the problem of oxidation between the two sides of the composite blank to be composited, especially at the edge, during subsequent welding. Vacuuming is performed after submerged arc welding. Pre-vacuuming and secondary vacuuming are performed after gas shielded welding and submerged arc welding, respectively, which greatly ensures the high vacuum state between the cover material and the substrate and is conducive to improving the bonding quality.

[0034] (2) The present invention adopts a heating and rolling method with two different furnace feeding methods to effectively adjust the performance and shape of the thick composite plate. In both heating processes, the temperature of the stainless steel side is set to be higher than that of the carbon steel side. This is because stainless steel and carbon steel have different coefficients of thermal expansion and large differences in ductility. Increasing the temperature of the stainless steel side can make it deform more in a coordinated manner with the carbon steel.

[0035] (3) In the first rolling process, the stainless steel surface faces upward, and the interface between the stainless steel and carbon steel is subjected to greater compression, which promotes the bonding of the interface. The flaw detection results show that the stainless steel and carbon steel are completely bonded at this time. This avoids the situation where the stainless steel and carbon steel are delaminated and the stainless steel is rolled into the roll gap if the head is buckled during the second rolling process. During the second rolling process, if the stainless steel is on the upper side, it is not restrained by the roller table and the temperature drops faster than the lower side, making it easier to buckle. However, if the stainless steel surface faces downward, the head can be reduced by adjusting the sled coefficient to a positive value, and the descaling on the stainless steel side can be closed to reduce the temperature drop and thus reduce shrinkage. All of these are conducive to a good plate shape.

[0036] (4) The composite plate prepared by the present invention has excellent interfacial bonding, shear strength ≥380MPa, yield strength ratio ≤0.83, substrate impact Akv ≥250J at -40℃, no cracking was found in 180° inner and outer bending, and the cladding material has excellent resistance to intergranular corrosion. Attached Figure Description

[0037] Figure 1 This is a comparative schematic diagram of the cut-off portions of two types of composite boards (with air extraction holes located on the short and long sides of the boards, respectively) in a specific embodiment of the present invention.

[0038] In the diagram: 100, finished composite board; 101, air extraction hole on the upper surface of the substrate; 102, cut-off area. Detailed Implementation

[0039] The following detailed description, in conjunction with the accompanying drawings, illustrates the thick-gauge stainless steel composite plate for bridges and its preparation method according to the present invention. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not limit the scope of the invention.

[0040] The thick-gauge stainless steel composite plate for bridges provided in Embodiments 1-6 of this invention has a base layer (substrate) of bridge steel and a cladding layer (cladding material) of austenitic stainless steel.

[0041] Tables 1 and 2 show the chemical composition (mass percentage) of the substrate and coating material in Examples 1-6 of this invention, with the remainder being Fe and a small amount of unavoidable impurities.

[0042] In the table below, the atmospheric corrosion resistance index I = 26.01 (% Cu) + 3.88 (% Ni) + 1.20 (% Cr) + 1.49 (% Si) + 17.28 (% P) - 7.29 (% Cu)(% Ni) - 9.10 (% Ni)(% P) - 33.39 (% Cu) 2

[0043] Table 1. Chemical composition (wt%) of the substrate in the embodiments of the present invention

[0044]

[0045] Table 2. Chemical composition (wt%) of the coating material in the embodiments of the present invention.

[0046]

[0047] Example 1

[0048] In this embodiment, bridge steel with trace amounts of Nb+Ti was selected as the base material. The specific compositions of the base material and the cladding material are shown in Table 1 and Table 2, respectively. The composite billet thickness is 300mm, and the final stainless steel composite plate thickness is 50mm, of which the cladding material thickness is 2mm and the base material thickness is 48mm.

[0049] (1) Preparation of base and cladding blanks: The base material blank is cut to the required size. The width and length of the cladding blank are the same as those of the base material blank. Remove the iron oxide scale from the surfaces of the base and cladding blanks to be laminated, and check that there are no defects on the surface.

[0050] (2) Single-layer composite billet: Beveling is performed on the four sides of the substrate to be composited, with a bevel angle of 30° and a bevel height of 16mm. A hole 51mm deep is drilled 50mm from the center of the short side of the substrate; then, a hole 50mm deep is drilled 35mm from the bevel along the thickness direction of the short side of the substrate, connecting with the hole on the upper surface of the substrate, thus forming a vacuum hole. After removing drill chips, dust, and oil from the surface of the substrate, the stainless steel cladding to be composited is placed face down on the substrate and aligned. Gas shielded welding is used to weld and seal the beveled part of the substrate to the cladding, and then a single-sided pre-vacuum is performed at the vacuum hole. When the vacuum value reaches below 20Pa, the vacuum hole is sealed. Finally, the remaining beveled part is fully welded using submerged arc welding, and a second vacuum is performed, with a final vacuum value of 0.20Pa, thus obtaining a composite billet of single-layer stainless steel + single-layer carbon steel in a high interface vacuum state.

[0051] It is understood that the sealing described in this application refers to a temporary or permanent sealing treatment of the vent hole. Specifically, this can be achieved by welding a rivet to the vent hole, drawing a vacuum through the rivet, then heating the rivet to seal it. Before the second vacuuming, the rivet is removed to release the vent hole from the seal. Of course, in some other embodiments, other methods can also be used to seal the vent hole. It should also be noted that in this application, all vent holes are located on the short side of the substrate, mainly to save a significant amount of steel. See [link to relevant documentation]. Figure 1 Both are finished composite panels 100. The air extraction hole 101 on the upper surface of the substrate of the finished composite panel 100 on the left is opened at the short side of the substrate, while the air extraction hole 101 on the upper surface of the substrate of the composite panel 100 on the right is opened at the long side of the substrate. The specific difference is that after the stainless steel composite panel is rolled, the position where the air extraction hole is drilled needs to be cut off. In comparison, when the air extraction hole 101 on the upper surface of the substrate is opened at the short side of the substrate, the area to be cut off is smaller, which can greatly improve the product yield and save costs.

[0052] (3) Single heating and rolling: The composite billet is sent to the heating furnace with the stainless steel cladding facing upwards and the carbon steel base facing downwards. The heating temperature is 1200℃, and the temperature of the upper surface is adjusted to be 30℃ higher than that of the lower surface. The total heating time is 15 min / cm. After exiting the furnace, single-stage rolling is adopted, with the reduction rate of each pass ≤5% and the total reduction rate 18%. When the composite billet bites in, the sled coefficient is adjusted to a negative value to reduce the degree of head lifting. During the rolling process, only the lower descaling water is turned on to descal the carbon steel on the lower surface.

[0053] (4) Secondary heating, controlled rolling and cooling: The composite billet after the first rolling is flipped to ensure that the stainless steel cladding is facing down and the carbon steel base is facing up. The heating temperature is 1210℃, and the temperature of the lower surface is adjusted to be 30℃ higher than that of the upper surface. The total heating time is 16 min / cm. Two-stage rolling is adopted, and the sled coefficient is adjusted to a positive value to reduce the degree of trimming. The thickness of the intermediate billet waiting to be heated is ≥1.6h (h is the finished thickness in mm). The intermediate billet water spray cooling device is turned off, and the intermediate billet is naturally air-cooled. The starting rolling temperature of the finishing rolling stage is 850℃, and the finishing rolling temperature is 830℃. During the rolling process, only the upper descaling water is turned on and the lower descaling water is turned off. Pre-straightening is performed before entering the water, and the water temperature is controlled at 800℃. The reddening temperature is 640℃, and the cooling water ratio of the lower and upper water is controlled at 1.2. Then, according to the shape of the plate, multiple straightening processes are performed.

[0054] (5) After rolling, the composite plate is flipped so that the stainless steel cladding is facing up and the carbon steel substrate is facing down, and then sent into the tempering furnace. The tempering temperature is 550℃ and the tempering time is 100min. After tempering, it undergoes straightening treatment at least 3 times to achieve an unevenness of 2mm / m. The surface of the composite plate is then polished and cleaned to obtain a 50mm thick high-performance stainless steel composite plate product.

[0055] Example 2

[0056] In this embodiment, bridge steel with trace amounts of Nb and appropriate amounts of Cr was selected as the base material. The specific compositions of the base material and the cladding material are shown in Table 1 and Table 2, respectively. The composite billet thickness is 400 mm, and the final stainless steel composite plate thickness is 80 mm, of which the cladding material thickness is 2 mm and the base material thickness is 78 mm.

[0057] Preparation of base and cladding blanks: Cut the base material to the required size. The width and length of the cladding blank should be the same as those of the base material blank. Remove the iron oxide scale from the surfaces of the base and cladding blanks to be laminated and check that there are no defects on the surfaces.

[0058] Single-layer preform assembly: Beveling is performed on all four sides of the substrate to be laminated, with a bevel angle of 60° and a bevel height of 68mm. A hole 90mm deep is drilled 65mm from the center of the short side of the substrate; then, a hole 65mm deep is drilled 22mm from the bevel along the thickness direction of the short side of the substrate, connecting to the hole on the upper surface of the substrate, thus forming a vacuum vent. After removing drill debris, dust, and oil from the substrate surface, the stainless steel cladding to be laminated is placed face down on the substrate and aligned. Gas shielded welding is used to seal and fix the beveled portion of the substrate to the cladding at the interface. A pre-vacuum is then performed on one side at the vacuum vent, and the vent is sealed when the vacuum value reaches below 20Pa. Finally, submerged arc welding is used to fully weld the remaining beveled portion, followed by a second vacuum, with a final vacuum value of 0.05Pa, thus obtaining a composite preform of single-layer stainless steel + single-layer carbon steel in a high interfacial vacuum state.

[0059] The heating and rolling production steps of the composite plate are the same as those in Example 1, and the rolling parameters for the two rolling processes are shown in Table 3.

[0060] After rolling, the composite plate is flipped so that the stainless steel cladding side faces up and the carbon steel substrate side faces down, and then sent into a tempering furnace. The tempering temperature is 520℃, and the tempering time is 240 minutes. After tempering, it undergoes at least three straightening treatments to achieve an unevenness of 1mm / m. Finally, the surface of the composite plate is ground and cleaned to obtain an 80mm thick high-performance stainless steel composite plate product.

[0061] Example 3

[0062] In this embodiment, the base material is bridge steel with trace amounts of Nb+V+Ti and appropriate amounts of Cr+Ni. The specific compositions of the base material and the cladding material are shown in Table 1 and Table 2, respectively. The composite billet thickness is 350mm, and the final stainless steel composite plate thickness is 70mm, of which the cladding material thickness is 3mm and the base material thickness is 67mm.

[0063] Preparation of base and cladding blanks: Cut the base material to the required size. The width and length of the cladding blank should be the same as those of the base material blank. Remove the iron oxide scale from the surfaces of the base and cladding blanks to be laminated and check that there are no defects on the surfaces.

[0064] Single-layer preform assembly: Beveling is performed on all four sides of the substrate to be laminated, with a bevel angle of 45° and a bevel height of 40mm. A hole 56mm deep is drilled 60mm from the center of the short side of the substrate; then, a hole 60mm deep is drilled 16mm from the bevel along the thickness direction of the short side of the substrate, connecting to the hole on the upper surface of the substrate, thus forming a vacuum hole. After removing drill chips, dust, and oil from the substrate surface, the stainless steel cladding to be laminated is placed on the substrate with the laminated side facing down, and aligned and centered. Gas shielded welding is used to weld and seal the beveled portion of the substrate to the cladding, and then a single-sided pre-vacuum is performed at the vacuum hole. When the vacuum value reaches below 20Pa, the vacuum hole is sealed. Finally, submerged arc welding is used to fully weld the remaining beveled portion, and a second vacuum is performed, with a final vacuum value of 0.08Pa, thus obtaining a composite preform of single-layer stainless steel + single-layer carbon steel in a high interfacial vacuum state.

[0065] The heating and rolling production steps of the composite plate are the same as those in Example 1, and the rolling parameters for the two rolling processes are shown in Table 3.

[0066] After rolling, the composite plate is flipped so that the stainless steel cladding side faces up and the carbon steel substrate side faces down, and then sent into a tempering furnace. The tempering temperature is 500℃, and the tempering time is 175 minutes. After tempering, it undergoes at least three straightening treatments to achieve an unevenness of 2mm / m. Finally, the surface of the composite plate is ground and cleaned to obtain a 70mm thick high-performance stainless steel composite plate product.

[0067] Example 4

[0068] In this embodiment, the base material is bridge steel with trace amounts of Nb+Ti and appropriate amounts of Cu+Cr+Ni+Mo. The specific compositions of the base material and the cladding material are shown in Table 1 and Table 2, respectively. The composite billet thickness is 346 mm, and the final stainless steel composite plate thickness is 65 mm, of which the cladding material thickness is 3 mm and the base material thickness is 62 mm.

[0069] Preparation of base and cladding blanks: Cut the base material to the required size. The width and length of the cladding blank should be the same as those of the base material blank. Remove the iron oxide scale from the surfaces of the base and cladding blanks to be laminated and check that there are no defects on the surfaces.

[0070] Single-layer preform assembly: Beveling is performed on all four sides of the substrate to be laminated, with a bevel angle of 50° and a bevel height of 46mm. A hole 64mm deep is drilled 55mm from the center of the short side of the substrate; then, a hole 55mm deep is drilled 18mm from the bevel along the thickness direction of the short side of the substrate, connecting to the hole on the upper surface of the substrate, thus forming a vacuum vent. After removing drill debris, dust, and oil from the substrate surface, the stainless steel cladding to be laminated is placed face down on the substrate and aligned. Gas shielded welding is used to seal and fix the beveled portion of the substrate to the cladding at the interface. A pre-vacuum is then performed on one side at the vacuum vent, and the vent is sealed when the vacuum value drops below 20Pa. Finally, submerged arc welding is used to fully weld the remaining beveled portion, followed by a second vacuum, resulting in a final vacuum value of 0.10Pa, thus obtaining a composite preform of single-layer stainless steel + single-layer carbon steel in a high interfacial vacuum state.

[0071] The heating and rolling production steps of the composite plate are the same as those in Example 1, and the rolling parameters for the two rolling processes are shown in Table 3.

[0072] After rolling, the composite plate is flipped so that the stainless steel cladding side faces up and the carbon steel substrate side faces down, and then sent into a tempering furnace. The tempering temperature is 480℃, and the tempering time is 165 minutes. After tempering, it undergoes at least three straightening treatments to achieve an unevenness of 2mm / m. Finally, the surface of the composite plate is ground and cleaned to obtain a 65mm thick high-performance stainless steel composite plate product.

[0073] Example 5

[0074] In this embodiment, the base material is bridge steel with trace amounts of Nb+Ti and appropriate amounts of Cu+Cr+Ni+Mo. The specific compositions of the base material and the cladding material are shown in Table 1 and Table 2, respectively. The composite billet thickness is 354 mm, and the final stainless steel composite plate thickness is 59 mm, of which the cladding material thickness is 1 mm and the base material thickness is 58 mm.

[0075] Preparation of base and cladding blanks: Cut the base material to the required size. The width and length of the cladding blank should be the same as those of the base material blank. Remove the iron oxide scale from the surfaces of the base and cladding blanks to be laminated and check that there are no defects on the surfaces.

[0076] Single-layer preform assembly: Beveling is performed on all four sides of the substrate to be laminated, with a bevel angle of 40° and a bevel height of 32mm. A hole 57mm deep is drilled 68mm from the center of the short side of the substrate; then, a hole 68mm deep is drilled 25mm from the bevel along the thickness direction of the short side of the substrate, connecting to the hole on the upper surface of the substrate, thus forming a vacuum vent. After removing drill debris, dust, and oil from the substrate surface, the stainless steel cladding to be laminated is placed face down on the substrate and aligned. Gas shielded welding is used to seal and fix the beveled portion of the substrate to the cladding at the interface. A single-sided pre-vacuum is then performed at the vacuum vent, and the vent is sealed when the vacuum value reaches below 20Pa. Finally, submerged arc welding is used to fully weld the remaining beveled portion, followed by a second vacuum, with a final vacuum value of 0.04Pa, thus obtaining a composite preform of single-layer stainless steel + single-layer carbon steel in a high interfacial vacuum state.

[0077] The heating and rolling production steps of the composite plate are the same as those in Example 1, and the rolling parameters for the two rolling processes are shown in Table 3.

[0078] After rolling, the composite plate is flipped so that the stainless steel cladding side faces up and the carbon steel substrate side faces down, and then sent into a tempering furnace. The tempering temperature is 450℃, and the tempering time is 148 minutes. After tempering, it undergoes at least three straightening treatments to achieve an unevenness of 1mm / m. Finally, the surface of the composite plate is ground and cleaned to obtain a 59mm thick high-performance stainless steel composite plate product.

[0079] Example 6

[0080] In this embodiment, the base material is bridge steel with trace amounts of Nb+V+Ti and appropriate amounts of Cu+Cr+Ni+Mo. The specific compositions of the base material and the cladding material are shown in Table 1 and Table 2, respectively. The composite billet thickness is 360mm, and the final stainless steel composite plate thickness is 75mm, of which the cladding material thickness is 5mm and the base material thickness is 70mm.

[0081] Preparation of base and cladding blanks: Cut the base material to the required size. The width and length of the cladding blank should be the same as those of the base material blank. Remove the iron oxide scale from the surfaces of the base and cladding blanks to be laminated and check that there are no defects on the surfaces.

[0082] Single-layer preform assembly: Beveling is performed on all four sides of the substrate to be laminated, with a bevel angle of 50° and a bevel height of 48mm. A hole 68mm deep is drilled downwards at a distance of 58mm from the center of the short side of the substrate; then, a hole 58mm deep is drilled inwards at a distance of 20mm from the bevel along the thickness direction of the short side of the substrate, connecting to the hole on the upper surface of the substrate, thus forming a vacuum vent. After removing drill debris, dust, and oil from the substrate surface, the stainless steel cladding to be laminated is placed face down on the substrate and aligned. Gas shielded welding is used to weld and seal the beveled portion of the substrate to the cladding, followed by a one-sided pre-vacuum at the vacuum vent. When the vacuum value reaches below 20Pa, the vacuum vent is sealed. Finally, submerged arc welding is used to fully weld the remaining beveled portion, followed by a second vacuum, ultimately achieving a vacuum value of 0.01Pa, thus obtaining a composite preform of single-layer stainless steel + single-layer carbon steel in a high interfacial vacuum state.

[0083] The heating and rolling production steps of the composite plate are the same as those in Example 1, and the rolling parameters for the two rolling processes are shown in Table 3.

[0084] After rolling, the composite plate is flipped so that the stainless steel cladding side faces up and the carbon steel substrate side faces down, and then sent into a tempering furnace. The tempering temperature is 400℃, and the tempering time is 220 minutes. After tempering, it undergoes at least three straightening treatments to achieve an unevenness of 2mm / m. Finally, the surface of the composite plate is ground and cleaned to obtain a 75mm thick high-performance stainless steel composite plate product.

[0085] Table 3 Rolling parameters of the embodiments of the present invention

[0086]

[0087] The performance of Examples 1-6 is shown in Table 4. It can be seen that the thick-gauge stainless steel composite plate for bridges produced by the present invention has excellent comprehensive performance, good metallurgical bonding at the interface, shear strength ≥380Mpa, yield strength ratio ≤0.83, Akv ≥250J at -40℃ and fiber cross-sectional area ≥85%, qualified for 180° inner and outer bending, and the cladding material has excellent resistance to intergranular corrosion.

[0088] Table 4. Performance of Examples 1-6 of the Present Invention

[0089]

[0090] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for preparing a thick-gauge stainless steel composite plate for bridges, characterized in that, Includes the following steps: A composite billet is obtained by performing a single-component billet treatment; The composite billet is heated and rolled in one step; The composite billet is subjected to secondary heating, controlled rolling, and controlled cooling to obtain a composite plate; Tempering: And straightening; Specifically, the single-component billet processing includes: a) Beveling the four sides of the substrate to be laminated; b) Drill holes in the substrate to form venting holes; c) Lay the stainless steel surface of the cladding material to be laminated with the substrate; d) Weld and seal the seal, then perform vacuum treatment; The primary heating and rolling process specifically includes: The composite blank is heated to 1150~1250℃, with the upper surface temperature being 20~50℃ higher than the lower surface temperature, and the total heating time is 9~18min / cm; Single-stage rolling is adopted, with the reduction rate of multiple passes not exceeding 5% and the total reduction rate being 18%~30%. When the composite billet bites in, the sled coefficient is adjusted to a negative value. During the rolling process, only the lower descaling water is turned on to descal the carbon steel on the lower surface. The secondary heating, controlled rolling, and controlled cooling processes specifically include: After one rolling, the composite billet is flipped to ensure that the stainless steel cladding is facing down and the carbon steel base is facing up. The composite billet is heated to 1180~1250℃, and the temperature of the lower surface is 20~50℃ higher than that of the upper surface. The total heating time is 10~18min / cm. Two-stage rolling is adopted, and the sled coefficient is adjusted to a positive value to reduce the degree of deduction. The starting rolling temperature of the finishing rolling stage is not higher than 860℃, and the finishing rolling temperature is 720~850℃. During the rolling process, only the upper descaling water is turned on and the lower descaling water is turned off. The thickness of the intermediate billet awaiting heating should be no less than 1.6 times the thickness of the finished product; Pre-straightening is performed before immersion in water, and the immersion water temperature is controlled at 700~800℃, the reddening temperature at 380~640℃, and the cooling water-to-water ratio at 1.0~1.

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2. The method for preparing thick-gauge stainless steel composite plates for bridges according to claim 1, characterized in that, In the single-component preform processing: the chamfer angle of the bevel is 30~60°, and the bevel height is 15~70mm; a hole is drilled downward at a distance of 50~70mm from the center of the short edge of the substrate, and the hole depth is the bevel height plus 15~40mm; a hole is drilled inward at a distance of 15~40mm from the bevel on the short sidewall of the substrate, and the hole depth is 50~70mm, which is connected to the hole on the upper surface of the substrate to form an air extraction hole.

3. The method for preparing thick-gauge stainless steel composite plates for bridges according to claim 1, characterized in that, The welding sealing and vacuuming process specifically includes: first, welding the connection between the substrate and the cladding material using gas shielded welding, pre-vacuuming the evacuation hole on one side, and sealing the evacuation hole when the vacuum value is below 20Pa; then, fully welding the remaining part of the bevel using submerged arc welding, and performing a second vacuuming to ensure that the final vacuum value is no greater than 10Pa, thereby obtaining a composite billet of single-layer stainless steel + single-layer carbon steel in a high interface vacuum state.

4. The method for preparing thick-gauge stainless steel composite plates for bridges according to claim 1, characterized in that, The tempering process includes: flipping the composite plate so that the stainless steel cladding is facing up and the carbon steel substrate is facing down, tempering at a temperature of 400~550℃, and tempering for 100~250 minutes.

5. The method for preparing thick-gauge stainless steel composite plates for bridges according to claim 1, characterized in that, The straightening process includes: performing straightening treatments at least three times, with an unevenness of ≤5mm / m, and grinding and cleaning the surface of the composite plate to obtain the stainless steel composite plate product.

6. The method for preparing thick-gauge stainless steel composite plates for bridges according to claim 1, characterized in that, Before performing single-component preform processing, the process also includes providing a base material preform and a cover material preform. The width and length of the cover material preform are the same as those of the base material preform, and the iron oxide scale on the surface to be laminated is removed.

7. The method for preparing thick-gauge stainless steel composite plates for bridges according to claim 1, characterized in that, The chemical composition of the substrate, by mass percentage, is as follows: C: ≤0.14%, Si: 0.15~0.50%, Mn: 1.00~1.70%, P≤0.025%, S≤0.020%, Nb: 0.010~0.060%, V: ≤0.050%, Ti: 0.006~0.020%, Alt: 0.015~0.050%, Cu: ≤0.40%, Cr: ≤0.60%, Ni: ≤0.50%, Mo: ≤0.30%, with the balance being Fe and a small amount of unavoidable impurities; The chemical composition of the cladding material by mass percentage is as follows: C: ≤0.08%, Si: ≤1.50%, Mn: ≤2.00%, P≤0.045%, S≤0.030%, Cr: 16.00~26.00%, Ni: 8.00~22.00%, Mo: ≤4.00%, Ti: ≤0.40%, N≤0.16%, with the balance being Fe and a small amount of unavoidable impurities.

8. A thick-gauge stainless steel composite plate for bridges, characterized in that, The thick-gauge stainless steel composite plate for bridges is prepared using the method described in any one of claims 1-7.

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