Thick stainless steel composite plate for bridge and preparation method therefor

Abstract

The present invention relates to the technical field of stainless steel composite plates, and in particular to a thick stainless steel composite plate for a bridge and a preparation method therefor. The method comprises: performing single slab assembly treatment to obtain a composite slab; performing primary heating and rolling on the composite slab; then performing secondary heating, controlled rolling and controlled cooling treatment to obtain a composite plate; performing tempering; and performing straightening, wherein the single slab assembly treatment specifically comprises: beveling four edges of a side to be composited of a substrate; drilling holes to form an air extraction hole; attaching a stainless steel surface to be composited of a cladding material to the substrate; and then performing sealing by welding, and performing vacuumizing treatment. The present invention solves the problems that it is difficult to produce a high-performance thick stainless steel composite plate for a bridge by symmetrical slab assembly rolling and it is difficult to achieve rolling by conventional single slab assembly. The produced stainless steel composite plate for a bridge has excellent interfacial bonding, shear strength greater than or equal to 380 MPa, and a yield ratio less than or equal to 0.83, the impact Akv of the substrate at −40°C is greater than or equal to 250 J, the cladding material has excellent intergranular corrosion resistance, and the stainless steel composite plate has good comprehensive performance and a good plate shape.

Description

Thick-gauge stainless steel composite plate for bridge and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of stainless steel composite plate, in particular to a thick-gauge stainless steel composite plate for bridge and a preparation method thereof. BACKGROUND

[0002] With the continuous improvement of steel bridge construction level and the increasingly high requirements for safety and reliability, bridges gradually develop towards high speed, heavy load, large span and non-coating, which has higher requirements for bridge steel: high strength and toughness, low yield ratio, high corrosion resistance, etc. The composite plate of bridge steel combined with stainless steel has high strength and toughness of the base layer and corrosion resistance of the cladding layer, and can better meet the requirements of lightweight, high corrosion resistance and long service life of the bridge deck structure.

[0003] The commonly used production methods of the stainless steel composite plate for bridge include explosion method and rolling method. The explosion method is more suitable for the production of large-thickness composite plates, but its production size still has limitations. If the finished product is wide, the cladding material needs to be spliced before explosion. Defects are prone to occur at the spliced part of the cladding material after explosion, and the initiation point cannot be combined. The method is also easily affected by the climate and environment, and has problems such as noise, environmental pollution, etc., and it is difficult to produce in batches and scale automatically. The plate width produced by the rolling method can be flexibly adjusted, and it can be efficiently produced in batches. It is a green and environmentally friendly sustainable production process, which is divided into symmetric blanking rolling and asymmetric blanking rolling. The symmetric blanking rolling can maintain good plate shape during the whole production process because the materials on the upper and lower composite blanks are consistent. However, when producing thick-gauge (finished product thickness ≥ 50 mm) composite plates, the rolling thickness can reach more than 100 mm, and the blank thickness of the symmetric blanking needs to be more than 500 mm, which has high requirements for blanking and rolling equipment. The greater the rolling thickness, the greater the difference in cold speed in the thickness direction, and the smaller the rolling compression ratio. The deformation of the bonding interface of the base and cladding materials and the core of the base material is insufficient, which affects the microstructure and performance of the final product. The asymmetric blanking, i.e. single carbon steel and single stainless steel combination, can improve the rolling compression ratio and reduce the cold speed difference in the thickness direction, thereby improving the performance of the composite plate. However, due to the differences in thermal expansion coefficient and deformation resistance between carbon steel and stainless steel, the rolling process is prone to warping and buckling, and in severe cases, the rolling process cannot be completed. SUMMARY

[0004] The present application aims at the above technical problems, overcomes the defects of the prior art, and provides a thick-gauge stainless steel composite plate for bridges and a preparation method thereof, solves the problems that symmetric assembly rolling is difficult to produce high-performance thick-gauge stainless steel composite plates for bridges and that conventional single assembly rolling is difficult to realize rolling, and the produced stainless steel composite plate for bridges has excellent interface combination, a shear strength of ≥380 MPa, a yield ratio of ≤0.83, a substrate Akv of -40 ℃ impact of ≥250 J, no cracking in 180° inner and outer bending, excellent intergranular corrosion resistance of the cladding material, and good comprehensive performance and plate shape.

[0005] In a first aspect, the present application provides a preparation method of a thick-gauge stainless steel composite plate for bridges, specifically comprising the following steps:

[0006] Performing single assembly processing to obtain a composite blank;

[0007] Performing one-time heating and rolling on the composite blank;

[0008] Performing secondary heating, controlled rolling and controlled cooling treatment on the rolled composite blank to obtain a composite plate;

[0009] Tempering:

[0010] And straightening;

[0011] In the single assembly processing, the following steps are specifically included:

[0012] a) beveling the four edges on the side of the substrate to be combined;

[0013] b) drilling holes on the substrate to form air extraction holes;

[0014] c) attaching the cladding stainless steel to be combined to the substrate;

[0015] d) welding and sealing and performing vacuum extraction treatment.

[0016] Optionally, in the single assembly processing, the chamfer angle of the bevel is 30-60°, the bevel height is 15-70 mm, the holes are drilled downward at a distance of 50-70 mm from the center of the short edge of the substrate, the hole depth is the bevel height plus 15-40 mm, and the holes are drilled inward at a distance of 15-40 mm from the bevel on the short edge side wall of the substrate, the hole depth is 50-70 mm, and the holes are connected to the holes on the upper surface of the substrate to form L-shaped air extraction holes. The air extraction holes are designed on the short edge of the substrate, and after rolling, the area that needs to be cut is less, the product yield is improved, and the cost is saved.

[0017] Optionally, the welding, sealing and vacuumizing specifically comprises: firstly, welding the joint of the base material and the clad material by gas shielded welding, pre-vacuumizing the gas extraction hole on one side, and blocking the gas extraction hole when the vacuum value is below 20 Pa; secondly, full welding the remaining part of the groove by submerged arc welding, and vacuumizing for the second time to make the final vacuum value not more than 10 Pa, so as to obtain the single-layer stainless steel + single-layer carbon steel composite blank in high interface vacuum state.

[0018] Optionally, the first heating and rolling specifically comprises:

[0019] The composite blank is sent to a heating furnace, and when loaded into the furnace, the clad stainless steel is upward and the base carbon steel is downward, the heating temperature is 1150-1250℃, the upper surface temperature is 20-50℃ higher than the lower surface temperature, and the total heating time is 9-18 min / cm;

[0020] After discharging, single-stage rolling is adopted, the reduction rate of multiple passes is not more than 5%, the total reduction rate is 18%-30%, and when the composite blank is bitten, the sledge coefficient is adjusted to be negative to reduce the degree of head warping, and only the lower descaling water is opened during rolling to descale the lower surface carbon steel.

[0021] Optionally, the second heating, controlled rolling and controlled cooling treatment specifically comprises:

[0022] The composite blank after the first rolling is turned over to ensure that the clad stainless steel is downward and the base carbon steel is upward, the composite blank is heated to 1180-1250℃, the lower surface temperature is 20-50℃ higher than the upper surface temperature, and the total heating time is 10-18 min / cm;

[0023] Two-stage rolling is adopted, the sledge coefficient is adjusted to be positive to reduce the degree of head warping, the opening rolling temperature in the finishing rolling stage is not higher than 860℃, the final rolling temperature is 720-850℃, and only the upper descaling water is opened and the lower descaling is closed during rolling.

[0024] The thickness of the intermediate blank is not less than 1.6 times the thickness of the finished product, and the intermediate blank is naturally air-cooled;

[0025] Pre-straightening is performed before entering the water, the water entry temperature is controlled to be 700-800℃, the red temperature is 380-640℃, and the lower-to-upper water ratio is 1.0-1.3.

[0026] Optionally, the tempering comprises: turning over the composite plate to make the clad stainless steel upward and the base carbon steel downward, the tempering temperature is 400-550℃, and the tempering time is 100-250 min.

[0027] Optionally, the straightening comprises: straightening treatment for more than 3 passes, the unevenness is not more than 5 mm / m, the surface of the composite plate is polished and cleaned, and the stainless steel composite plate product is obtained.

[0028] Optionally, before the haploid set blank processing, the base material blank and the cover material blank are provided, the cover material blank is consistent with the width and length of the base material blank, the iron oxide scale, drill dust, dust and oil stains on the composite surface are removed, the stainless steel composite surface of the cover material blank is placed on the base material blank with the composite surface facing down, and the cover material blank is aligned and centered.

[0029] Optionally, the chemical composition of the base material is: 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%, and the balance is Fe and a small amount of unavoidable impurities.

[0030] The chemical composition of the cover material is: 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%, and the balance is Fe and a small amount of unavoidable impurities.

[0031] In a second aspect, the application also provides a thick-gauge bridge stainless steel clad plate prepared by the thick-gauge bridge stainless steel clad plate preparation method of any one of the first aspect.

[0032] The application has the following advantages:

[0033] (1) The application uses single-hole vacuumizing to reduce the probability of seal rivet falling off at the air extraction hole, thereby reducing the risk of air leakage. Pre-vacuumizing is performed after sealing welding to extract air between the two composite sides of the base material and the cover material, which can reduce oxidation between the composite blank composite sides, especially at the edges, during subsequent welding. Vacuumizing is performed again after submerged arc welding. Pre-vacuumizing and secondary vacuumizing are performed after gas shielded welding and submerged arc welding, respectively, which greatly guarantees the high vacuum state between the cover material and the base material, and is beneficial to improving the bonding quality.

[0034] (2) The application uses a heating and rolling method with two different charging methods to effectively adjust the performance and shape of the thick-gauge clad plate. The temperature of the stainless steel side is set to be higher than that of the carbon steel side during both heating processes. This is because the thermal expansion coefficients of stainless steel and carbon steel are different, and the ductility difference is large. Increasing the temperature of the stainless steel side can make it and the carbon steel deform more coordinately.

[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 is a comparative schematic diagram of the cut-off portions of two composite boards (with air extraction holes located on the short and long sides of the board, 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] Table 2. Chemical composition (wt%) of the coating material in the embodiments of the present invention

[0045] Example 1

[0046] The base material of this example is a bridge steel with trace amounts of Nb+Ti added, and the specific compositions of the base material and the cladding material are shown in Table 1 and Table 2, respectively. The composite blank has a thickness of 300 mm, and the final stainless steel composite plate product has a thickness of 50 mm, including a cladding material thickness of 2 mm and a base material thickness of 48 mm.

[0047] (1) Base material and cladding material blank preparation: The base material is opened to the desired size, and the cladding material blank has the same width and length as the base material blank. The iron oxide scale on the surfaces to be bonded of the base material and the cladding material is removed, and the surfaces are inspected for defects.

[0048] (2) Single set blank: The four edges of the side of the base material to be bonded are beveled, with a bevel angle of 30° and a bevel height of 16 mm. A hole is drilled downward at a distance of 50 mm from the center of the short edge of the base material, with a hole depth of 51 mm. Another hole is drilled inward at a distance of 35 mm from the bevel in the thickness direction of the short edge of the base material, with a hole depth of 50 mm, connected to the hole on the upper surface of the base material, thereby forming an air extraction hole. After removing the drill chips, dust and oil on the surface of the base material, the cladding material stainless steel is placed on the base material with the bonding surface facing down, and is aligned and centered. The beveled portion of the base material is welded and sealed at the joint with the cladding material using gas shielded welding, and then a single-sided pre-vacuum is performed at the air extraction hole. When the vacuum value reaches below 20 Pa, the air extraction hole is plugged. Finally, the remaining portion of the bevel is fully welded using submerged arc welding, and a second vacuum is performed, with a final vacuum value of 0.20 Pa, thereby obtaining a single layer of stainless steel + single layer of carbon steel composite blank in a high interfacial vacuum state.

[0049] It can be understood that the plugging described in this application refers to temporary or permanent sealing treatment of the air extraction hole. Specifically, a rivet can be welded at the air extraction hole, vacuum extraction is performed through the rivet, and then the rivet is heated to plug it. The rivet is removed before the second vacuum extraction to remove the plugging state of the air extraction hole. Of course, in some other embodiments, other methods can be used to plug the air extraction hole. It should be noted that the air extraction hole in this application is opened at the short edge of the base material, mainly to save a large amount of steel. Referring to Figure 1, which is a finished composite plate 100, the air extraction hole 101 on the upper surface of the base material of the left finished composite plate 100 is opened at the short edge of the base material, while the right composite plate 100 is opened at the long edge of the base material. The specific difference lies in that the stainless steel composite plate needs to be cut after rolling to remove the position drilled with the air extraction hole. Compared with the air extraction hole 101 opened at the short edge of the base material, the range of the cutting area 102 is smaller, which can greatly improve the product yield and save costs.

[0050] (3) One heating, rolling: the composite billet is sent to the heating furnace, and the stainless steel surface of the clad material faces up and the carbon steel surface of the base material faces down when charging. The heating temperature is 1200°C, and the upper surface temperature is adjusted to be 30°C higher than the lower surface temperature. The total heating time is 15 min / cm. After discharging, single-stage rolling is adopted, and the reduction rate of multiple passes is ≤5%, and the total reduction rate is 18%. When the composite billet is bitten, the sled coefficient is adjusted to a negative value to reduce the degree of head warping. During rolling, only the lower side descaling water is turned on to descale the lower surface carbon steel.

[0051] (4) Second heating, controlled rolling and controlled cooling: the composite billet after the first rolling is turned over to ensure that the stainless steel surface of the clad material faces down and the carbon steel surface of the base material faces up. The heating temperature is 1210°C, and the lower surface temperature is adjusted to be 30°C higher than the upper surface temperature. 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 head warping. The intermediate waiting billet thickness is ≥1.6h (h is the product thickness, unit: mm), the intermediate billet water cooling device is closed, and the intermediate billet is naturally air cooled. The opening rolling temperature in the finishing rolling stage is 850°C, and the final rolling temperature is 830°C. During rolling, only the upper side descaling water is turned on, and the lower side descaling is turned off. Pre-straightening is performed before entering the water, and the water temperature is controlled to 800°C. The red temperature is 640°C, and the cooling lower and upper water ratio is 1.2. Then, according to the plate shape, multi-pass straightening treatment is performed.

[0052] (5) After rolling, the composite plate is turned over so that the stainless steel surface of the clad material faces up and the carbon steel surface of the base material faces down, and is sent to the tempering furnace. The tempering temperature is 550°C, and the tempering time is 100 min. After tempering, the composite plate is straightened for more than 3 passes, and the unevenness is 2 mm / m. The surface of the composite plate is polished and cleaned to obtain a 50 mm thick high-performance stainless steel composite plate product.

[0053] Example 2

[0054] In this example, the base material is a bridge steel with trace Nb and appropriate Cr. The specific compositions of the base material and the clad material are shown in Tables 1 and 2, respectively. The composite billet thickness is 400 mm, and the final stainless steel composite plate product thickness is 80 mm, including a 2 mm thick clad material and a 78 mm thick base material.

[0055] Base material and clad material preparation: The base material is bloomed to the required size, and the width and length of the clad material billet are consistent with those of the base material billet. The iron oxide scale on the surfaces to be compounded is removed, and the surface is inspected for defects.

[0056] The four edges of the base material to be combined are beveled, with a bevel angle of 60° and a bevel height of 68 mm. A hole is drilled downward at a distance of 65 mm from the center of the short edge of the base material, with a depth of 90 mm. Another hole is drilled inward at a distance of 22 mm from the bevel in the thickness direction of the short edge of the base material, with a depth of 65 mm, connected to the hole on the upper surface of the base material, thereby forming an air extraction hole. After removing the drill chips, dust and oil stains on the surface of the base material, the cladding material stainless steel is placed on the base material with the surface to be combined facing downward, and is aligned and centered. The beveled portion of the base material is welded and sealed with the cladding material at the joint, and then a one-sided pre-vacuum is performed at the air extraction hole. When the vacuum value reaches below 20 Pa, the air extraction hole is sealed. Finally, the remaining portion of the bevel is fully welded using submerged arc welding, and a second vacuum is performed, with a final vacuum value of 0.05 Pa, thereby obtaining a single-layer stainless steel + single-layer carbon steel composite blank with high interfacial vacuum state.

[0057] The heating and rolling production steps of the composite plate are the same as in Example 1, and the two rolling parameters are shown in Table 3.

[0058] After rolling, the composite plate is turned over so that the cladding material stainless steel faces upward and the base material carbon steel faces downward, and is sent into the tempering furnace. The tempering temperature is 520°C, and the tempering time is 240 min. After tempering, the composite plate is subjected to straightening treatment for more than 3 passes, with a unevenness of 1 mm / m. The surface of the composite plate is then polished and cleaned, and an 80 mm thick high-performance stainless steel composite plate product is obtained.

[0059] Example 3

[0060] In this example, the base material is a bridge steel with trace amounts of Nb+V+Ti and appropriate amounts of Cr+Ni, and the specific compositions of the base material and the cladding material are shown in Tables 1 and 2, respectively. The thickness of the composite blank is 350 mm, and the final thickness of the stainless steel composite plate product is 70 mm, including a cladding material thickness of 3 mm and a base material thickness of 67 mm.

[0061] Base material and cladding material blank preparation: The base material is bloomed to the desired size, and the width and length of the cladding material blank are consistent with those of the base material blank. The iron oxide scale on the surfaces of the base material and the cladding material to be combined is removed, and the surfaces are inspected for defects.

[0062] The four edges of the base material to be combined are beveled, the bevel angle is 45°, and the bevel height is 40 mm. A hole is drilled downward at a distance of 60 mm from the center of the short edge of the base material, and the hole depth is 56 mm. Then, a hole is drilled inward at a distance of 16 mm from the bevel in the thickness direction of the short edge of the base material, and the hole depth is 60 mm, which is connected to the hole on the upper surface of the base material, thereby forming an air extraction hole. After removing the drill chips, dust and oil stains on the surface of the base material, the cladding material stainless steel to be combined is placed on the base material with the combined surface facing downward, and is aligned and centered. The beveled part of the base material is welded and sealed with the cladding material at the joint, and then one-sided pre-vacuum is performed at the air extraction hole. When the vacuum value reaches below 20 Pa, the air extraction hole is plugged. Finally, the remaining part of the bevel is fully welded by submerged arc welding, and the second vacuum is performed, and the final vacuum value is 0.08 Pa, so as to obtain a single-layer stainless steel + single-layer carbon steel composite blank with high interfacial vacuum state.

[0063] The heating and rolling production steps of the composite plate are the same as those of Example 1, and the twice rolling parameters are shown in Table 3.

[0064] After rolling, the composite plate is turned over so that the cladding stainless steel surface faces upward and the base carbon steel surface faces downward, and is sent into the tempering furnace. The tempering temperature is 500℃, and the tempering time is 175 min. After tempering, the composite plate is subjected to straightening treatment for more than 3 passes, and the unevenness reaches 2 mm / m. Then, the surface of the composite plate is polished and cleaned, and a 70 mm thick high-performance stainless steel composite plate product is obtained.

[0065] Example 4

[0066] In this example, the base material is a bridge steel with trace Nb+Ti and appropriate Cu+Cr+Ni+Mo, and the specific compositions of the base material and the cladding material are shown in Tables 1 and 2, respectively. The thickness of the composite blank is 346 mm, and the thickness of the final stainless steel composite plate product is 65 mm, of which the thickness of the cladding material is 3 mm and the thickness of the base material is 62 mm.

[0067] Base material and cladding material blank preparation: The base material is bloomed to the required size, the width and length of the cladding material blank are consistent with those of the base material blank, the iron oxide scale on the surfaces of the base material and the cladding material to be combined is removed, and the surface is checked for defects.

[0068] The four edges of the base material to be combined are beveled, with a bevel angle of 50° and a bevel height of 46 mm. A hole is drilled downward at a distance of 55 mm from the center of the short edge of the base material, with a depth of 64 mm. Another hole is drilled inward at a distance of 18 mm from the bevel in the thickness direction of the short edge of the base material, with a depth of 55 mm, connected to the hole on the upper surface of the base material, thereby forming an air extraction hole. After removing the drill chips, dust and oil stains on the surface of the base material, the cladding material stainless steel is placed on the base material with the surface to be combined facing downward, and is aligned and centered. The beveled portion of the base material is welded and sealed with the cladding material at the joint, and then a one-sided pre-vacuum is performed at the air extraction hole. When the vacuum value reaches below 20 Pa, the air extraction hole is sealed. Finally, the remaining beveled portion is fully welded by submerged arc welding, and a second vacuum is performed, with a final vacuum value of 0.10 Pa, thereby obtaining a single-layer stainless steel + single-layer carbon steel composite blank with high interfacial vacuum state.

[0069] The heating and rolling production steps of the composite plate are the same as in Example 1, and the two rolling parameters are shown in Table 3.

[0070] After rolling, the composite plate is turned over so that the cladding material stainless steel faces upward and the base material carbon steel faces downward, and is sent into the tempering furnace. The tempering temperature is 480°C, and the tempering time is 165 min. After tempering, the composite plate is subjected to straightening treatment for more than 3 passes, with a unevenness of 2 mm / m. The surface of the composite plate is polished and cleaned, and a 65 mm thick high-performance stainless steel composite plate product is obtained.

[0071] Example 5

[0072] In this example, the base material is a 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 Tables 1 and 2, respectively. The thickness of the composite blank is 354 mm, and the final thickness of the stainless steel composite plate product is 59 mm, with a cladding material thickness of 1 mm and a base material thickness of 58 mm.

[0073] Base material and cladding material blank preparation: The base material is bloomed to the desired size, and the width and length of the cladding material blank are consistent with those of the base material blank. The iron oxide scale on the surfaces of the base material and the cladding material to be combined is removed, and the surfaces are inspected for defects.

[0074] The four edges of the base material to be combined are beveled, with a bevel angle of 40° and a bevel height of 32 mm. A hole is drilled downward at a distance of 68 mm from the center of the short edge of the base material, with a hole depth of 57 mm. Another hole is drilled inward at a distance of 25 mm from the bevel in the thickness direction of the short edge of the base material, with a hole depth of 68 mm, connected to the hole on the upper surface of the base material, thereby forming an air extraction hole. After removing the drill chips, dust and oil stains on the surface of the base material, the cladding material stainless steel is placed on the base material with the surface to be combined facing downward, and is aligned and centered. The beveled portion of the base material is welded and sealed with the cladding material at the joint, and then a one-sided pre-vacuum is performed at the air extraction hole. When the vacuum value reaches below 20 Pa, the air extraction hole is sealed. Finally, the remaining beveled portion is fully welded by submerged arc welding, and a second vacuum is performed, with a final vacuum value of 0.04 Pa, thereby obtaining a single-layer stainless steel + single-layer carbon steel composite blank with high interfacial vacuum state.

[0075] The heating and rolling production steps of the composite plate are the same as in Example 1, and the two rolling parameters are shown in Table 3.

[0076] After rolling, the composite plate is turned over so that the cladding material stainless steel faces upward and the base material carbon steel faces downward, and is sent into the tempering furnace. The tempering temperature is 450°C, and the tempering time is 148 min. After tempering, the composite plate is subjected to straightening treatment for more than 3 passes, with a unevenness of 1 mm / m. The surface of the composite plate is polished and cleaned, and a 59 mm thick high-performance stainless steel composite plate product is obtained.

[0077] Example 6

[0078] In this example, the base material is a 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 Tables 1 and 2, respectively. The thickness of the composite blank is 360 mm, and the final thickness of the stainless steel composite plate product is 75 mm, including a cladding material thickness of 5 mm and a base material thickness of 70 mm.

[0079] Base material and cladding material blank preparation: The base material is bloomed to the required size, and the width and length of the cladding material blank are consistent with those of the base material blank. The iron oxide scale on the surfaces of the base material and the cladding material to be combined is removed, and the surfaces are inspected for defects.

[0080] The four edges of the base material to be compounded are beveled, the bevel angle is 50°, and the bevel height is 48 mm. A hole is drilled downward at a distance of 58 mm from the center of the short edge of the base material, and the hole depth is 68 mm. Then, a hole is drilled inward at a distance of 20 mm from the bevel in the thickness direction of the short edge of the base material, and the hole depth is 58 mm, which is connected with the hole on the upper surface of the base material, thereby forming an air extraction hole. After removing the drill chips, dust and oil stains on the surface of the base material, the cladding material stainless steel to be compounded is placed on the base material with the surface to be compounded downward, and is aligned and centered. The bevel portion of the base material and the joint with the cladding material are welded and sealed by using gas shielded welding, then one-side pre-vacuum is performed at the air extraction hole, and the air extraction hole is plugged when the vacuum value is below 20 Pa. Finally, the remaining bevel portion is fully welded by using submerged arc welding, and the second vacuum is performed, and the final vacuum value is 0.01 Pa, so that the single-layer stainless steel + single-layer carbon steel composite blank with high interface vacuum state is obtained.

[0081] The heating and rolling production steps of the composite plate are the same as those in Example 1, and the twice rolling parameters are shown in Table 3.

[0082] After rolling, the composite plate is turned over, so that the cladding material stainless steel surface faces upward and the base material carbon steel surface faces downward, and is sent into the tempering furnace. The tempering temperature is 400℃, and the tempering time is 220 min. After tempering, the composite plate is subjected to straightening treatment for more than 3 passes, and the unevenness is 2 mm / m. Then, the surface of the composite plate is polished and cleaned, and the 75 mm thick high-performance stainless steel composite plate product is obtained.

[0083] Table 3 Rolling parameters of the examples of the present application

[0084] The performances of Examples 1-6 are shown in Table 4. It can be seen that the thick specification stainless steel composite plate for bridge produced by the present application has excellent comprehensive performance, the interface realizes good metallurgical bonding, the shear strength is ≥380 Mpa, the yield ratio is ≤0.83, the Akv at -40℃ is ≥250 J, the fiber fracture rate is ≥85%, the 180° inner and outer bending is qualified, and the cladding material has excellent intergranular corrosion resistance.

[0085] Table 4 Performances of Examples 1-6 of the present application

[0086] In addition to the above examples, the present application can have other implementation manners. Any technical solution formed by equivalent substitution or equivalent transformation falls within the protection scope of the present application.

Claims

1. A method for manufacturing a thick-gauge stainless steel clad plate for a bridge, characterized by, It comprises the following steps: carrying out single set blank treatment to obtain a composite blank; carrying out first heating and rolling on the composite blank; carrying out second heating, controlled rolling and controlled cooling treatment on the rolled composite blank to obtain a composite plate; tempering; and straightening; wherein the single set blank treatment specifically comprises: a) beveling the four edges on the side of the base material to be compounded; b) drilling holes on the base material to form an air extraction hole; c) attaching the surface of the cladding material to the base material; d) welding and sealing and carrying out vacuum treatment.

2. The method of claim 1, wherein the thick-gauge stainless steel clad plate for a bridge is prepared by the steps of: In the single set blank treatment: the chamfer angle of the bevel is 30-60°, and the bevel height is 15-70 mm; the hole is drilled downward at a distance of 50-70 mm from the center of the short edge of the base material, and the hole depth is the bevel height plus 15-40 mm; and a hole is drilled inward at a distance of 15-40 mm from the bevel on the short edge side wall of the base material, and the hole depth is 50-70 mm, connected with the hole on the upper surface of the base material to form an air extraction hole.

3. The method of claim 1, wherein the thick-gauge stainless steel clad plate for a bridge is prepared by the steps of: The welding and sealing and vacuum treatment specifically comprises: first, gas shielded welding is used to weld the joint between the base material and the cladding material, one-side pre-vacuum is carried out on the air extraction hole, and when the vacuum value is below 20 Pa, the air extraction hole is blocked; then, submerged arc welding is used to fully weld the remaining part of the bevel, and second vacuum is carried out, so that the final vacuum value is not greater than 10 Pa, to obtain a single layer stainless steel + single layer carbon steel composite blank in a high interface vacuum state.

4. The method of claim 1, wherein the thick-gauge stainless steel clad plate for a bridge is prepared by the steps of: The first heating and rolling specifically comprises: heating the composite blank to 1150-1250℃, and the upper surface temperature is 20-50℃ higher than the lower surface temperature, and the total heating time is 9-18 min / cm; single-stage rolling is adopted, the reduction rate of each pass is not greater than 5%, the total reduction rate is 18%-30%, and when the composite blank is bitten, the snowshoe coefficient is adjusted to a negative value, and only the lower side descaling water is opened during rolling to descale the lower surface carbon steel.

5. The method of claim 1, wherein the thick-gauge stainless steel clad plate for a bridge is prepared by the steps of: The second heating, controlled rolling and controlled cooling treatment specifically comprises: ​ turning the rolled composite blank to ensure that the surface of the cladding material stainless steel faces downward and the surface of the base material carbon steel faces upward, heating the composite blank to 1180-1250℃, and the lower surface temperature is 20-50℃ higher than the upper surface temperature, and the total heating time is 10-18 min / cm; two-stage rolling is adopted, the snowshoe coefficient is adjusted to a positive value to reduce the degree of upset, the opening rolling temperature in the finishing rolling stage is not higher than 860℃, and the finish rolling temperature is 720-850℃, and only the upper side descaling water is opened and the lower side descaling is closed during rolling; the thickness of the intermediate warm blank is not less than 1.6 times the thickness of the finished product; pre-straightening is carried out before entering the water, the water entry temperature is controlled to be 700-800℃, the red temperature is 380-640℃, and the lower-to-upper water ratio is 1.0-1.

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6. The method of claim 1, wherein the thick-gauge stainless steel clad plate for a bridge is prepared by the steps of: The tempering comprises: turning the composite plate to make the surface of the cladding material stainless steel face upward and the surface of the base material carbon steel face downward, the tempering temperature is 400-550℃, and the tempering time is 100-250 min.

7. The method of claim 1, wherein the thick-gauge stainless steel clad plate for a bridge is prepared by the steps of: The straightening comprises: carrying out more than 3 times of straightening treatment, the unevenness is ≤5 mm / m, the surface of the composite plate is polished and cleaned, and a stainless steel composite plate product is obtained. ​ 8. The method of claim 1, wherein the thick-gauge stainless steel clad plate for a bridge is prepared by the steps of: Before carrying out the single set blank treatment, it further comprises providing a base material blank and a cladding material blank, the width and length of the cladding material blank are consistent with those of the base material blank, and the iron oxide scale on the surface to be compounded is removed. ​ 9. The method of claim 1, wherein the thick-gauge stainless steel clad plate for a bridge is prepared by the steps of: The base material has the following chemical composition in mass percent: 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%, the balance being Fe and a small amount of unavoidable impurities; ​ The cladding material has the following chemical composition in mass percent: 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%, the balance being Fe and a small amount of unavoidable impurities.

10. A thick-gauge stainless steel clad plate for bridges, characterized by, The thick-gauge stainless steel clad plate for bridges is prepared by using the method according to any one of claims 1-9.

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