Preparation method of composite board with excellent interface bonding

Abstract

The invention provides a preparation method of a composite plate with excellent interface bonding, which comprises the steps of blank surface treatment, blank assembly and plate sealing, welding, vacuumizing, heating, rolling, cooling, heat treatment and plate splitting, in the blank assembly and plate sealing steps, blanks are placed according to the sequence of base material, covering material, covering material and base material to obtain a composite blank; in the rolling step, if tcp / tsp is larger than or equal to 4, the rough rolling single-pass rolling reduction is larger than or equal to 30 mm, and the rough rolling pass is larger than or equal to 1; the single-pass rolling reduction of the first three passes of finish rolling is larger than or equal to 25 mm, and the pass of finish rolling is smaller than or equal to 7; if tcp / tsp is smaller than 4, the rough rolling single-pass rolling reduction is larger than or equal to 35 mm, and the rough rolling pass is larger than or equal to 3; the finish rolling single-pass rolling reduction is smaller than or equal to 25 mm, the finish rolling pass is smaller than or equal to 7, and the total compression ratio CR is larger than or equal to 7; tcp is the target thickness of the base material in the composite board, tsp is the target thickness of the covering material in the composite board, and the unit is mm. The rolling reduction is controlled through the target proportion of the base material and the covering material in the composite board, and combination at different thickness ratios is promoted.

Description

Technical Field

[0001] This application relates to the field of composite board preparation technology, and in particular to a method for preparing a composite board with excellent interfacial bonding. Background Technology

[0002] Stainless steel composite plates are bimetallic materials made by combining stainless steel cladding and carbon steel substrate through a specific process. They combine the corrosion resistance of stainless steel with the mechanical properties and cost advantages of carbon steel, and are widely used in petrochemical, marine engineering, food and pharmaceutical fields. However, there are significant differences in the physicochemical properties of stainless steel and carbon steel, making interfacial bonding a key technical bottleneck restricting the performance of composite plates.

[0003] Stainless steel and carbon steel have significantly different coefficients of linear expansion, which can easily lead to thermal stress during hot working and service, resulting in decreased interfacial bonding strength or even delamination. In traditional rolling composite processes, interfacial bonding mainly relies on mechanical interlocking and atomic diffusion, but the bonding strength often fails to meet the requirements of harsh operating conditions. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing a composite plate with excellent interfacial bonding, which solves the problem that the interfacial bonding strength in the prior art does not meet the requirements for use.

[0005] To achieve one of the aforementioned objectives, one embodiment of this application provides a method for preparing a composite plate with excellent interfacial bonding. The method includes a sequential process of surface treatment of the billet, billet assembly and sealing, welding, vacuuming, heating, rolling, cooling, heat treatment, and plate separation.

[0006] In the billet assembly and sealing step, the billets are placed in the order of substrate-coating material-coating material-substrate material to obtain a composite billet; In the rolling step, if t cp / t sp If ≥4, then the single-pass reduction of roughing rolling is ≥30mm and the number of roughing rolling passes is ≥1; the single-pass reduction of the first three passes of finishing rolling is ≥25mm and the number of finishing rolling passes is ≤7. If t cp / t sp If the ratio is less than 4, the single-pass reduction in roughing rolling is ≥35mm and the number of roughing passes is ≥3; the single-pass reduction in finishing rolling is ≤25mm and the number of finishing passes is ≤7, the total compression ratio CR is ≥7, and controlled cooling is performed after rolling. t cp t represents the target thickness of the substrate in the composite board. sp The target thickness of the cladding material in the composite panel is given in mm.

[0007] As a further improvement of one embodiment of this application, in the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material, the inner side of the edge strips is tightly attached to the cover material, and round holes are opened on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 300~750A; welding voltage: 20~50V; welding speed: 300~500mm / min.

[0008] As a further improvement of one embodiment of this application, the temperature is preheated to 180~220°C before welding, the interpass temperature is controlled to 100~180°C during welding, and the temperature is allowed to cool naturally to room temperature after welding.

[0009] As a further improvement to one embodiment of this application, after welding, the cavity between the four edge strips and the two base material blanks is evacuated through a circular hole until the pressure is ≤10. -4 Torr, holding time is 2V~4V, unit is h, V is the total volume of the two-layer cladding blank, unit is m. 3 After the pressure holding period is completed, seal the round hole.

[0010] As a further improvement of one embodiment of this application, in the blank surface treatment step, one side of the substrate blank is ground until the surface roughness of the blank is Ra≤30μm; both sides of the cladding blank are ground until the surface roughness of the blank is Ra≤1μm.

[0011] As a further improvement to one embodiment of this application, in the heat treatment step, the composite plate obtained after rolling and cooling is subjected to normalizing, normalizing with water cooling, normalizing with water cooling combined with tempering, or quenching combined with tempering for heat treatment, wherein... In normalizing heat treatment, the normalizing temperature is T. N +30~T N +50℃, the final cooling temperature for normalizing water cooling is T NC +100~T NC +150℃; In quenching heat treatment, the quenching temperature is T. N +30~T N +50℃, In tempering heat treatment, the tempering temperature is T. T -10~T T +10℃, T N =900-203 -15[Ni]-45[Si]+104[V]+31.5[Mo]+t f , T NC=650-423[C]-30[Mn]-20[Si]-12[Cr]-18[Ni]-7[Mo]-t f , T T =700-0.16H+7CE, CE=[C]+[Mn] / 6+([Cr]+[Mo]+[V]) / 5+[Ni] / 15, where [C], [Mn], [Si], [Cr], [Ni], [Mo], and [V] are 100 times the mass percentage of the corresponding elements in the substrate, t f The thickness of the composite panel is in mm, and H is the maximum Brinell hardness required for the strength grade of the base steel plate in the composite panel.

[0012] As a further improvement of one embodiment of this application, the chemical composition of the substrate blank, by mass percentage, includes: C: 0.10~0.20%, Si: 0.15~0.35%, Mn: 0.6~1.7%, Cr≤0.30%, Ni≤0.30%, Mo≤0.20%, Nb≤0.030%, Ti≤0.030%, Al: 0.02~0.06%, V≤0.040%, P≤0.020%, S≤0.005%, CE: 0.22~0.50%, with the remainder being iron and unavoidable impurities; As a further improvement of one embodiment of this application, the chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.17%, Si: 0.15~0.25%, Mn: 0.60~1.00%, Nb≤0.020%, Cr≤0.30%, Ti≤0.030%, Al: 0.020~0.050%, P≤0.020%, S≤0.005%, CE: 0.22~0.32%, with the remainder being iron and unavoidable impurities.

[0013] Normalizing heat treatment is adopted, and the normalizing heat retention coefficient is 1.5~1.7 min / mm.

[0014] As a further improvement of one embodiment of this application, in the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material, the inner side of the edge strips is tightly attached to the cover material, and round holes are opened on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 300~500A; welding voltage: 20~40V; welding speed: 300~400mm / min.

[0015] As a further improvement of one embodiment of this application, the chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.18%, Si: 0.15~0.25%, Mn: 1.30~1.60%, Nb≤0.030%, Ti: 0.010~0.020%, Al: 0.020~0.050%, P≤0.015%, S≤0.005%, CE: 0.35~0.50%, with the remainder being iron and unavoidable impurities; The normalizing water-cooled heat treatment is adopted, and the normalizing insulation coefficient is 1.5~1.7 min / mm.

[0016] As a further improvement of one embodiment of this application, in the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material, the inner side of the edge strips is tightly attached to the cover material, and round holes are opened on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 400~600A; welding voltage: 25~45V; welding speed: 300~450mm / min.

[0017] As a further improvement of one embodiment of this application, the chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.20%, Si: 0.25~0.35%, Mn: 1.30~1.60%, Nb: 0.015~0.030%, Cr: 0.10~0.20%, Ti: 0.010~0.020%, V≤0.020%, Al: 0.020~0.060%, P≤0.013%, S≤0.003%, CE: 0.40~0.45%, with the remainder being iron and unavoidable impurities; The heat treatment is carried out by normalizing and water cooling combined with tempering. The normalizing holding coefficient is 1.5~1.7 min / mm, and the tempering holding coefficient is 2.8~3.2 min / mm.

[0018] As a further improvement of one embodiment of this application, in the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material, the inner side of the edge strips is tightly attached to the cover material, and round holes are opened on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 500~700A; welding voltage: 30~50V; welding speed: 300~500mm / min.

[0019] As a further improvement of one embodiment of this application, the chemical composition of the substrate blank, by mass percentage, includes: C: 0.10~0.15%, Si: 0.15~0.35%, Mn: 1.10~1.70%, Nb≤0.02%, Cr: 0.10~0.20%, Ti≤0.030%, V≤0.040%, Ni: 0.10~0.30%, Mo≤0.20%, Al: 0.020~0.060%, P≤0.013%, S≤0.003%, CE: 0.30~0.50%, with the remainder being iron and unavoidable impurities; The heat treatment is carried out by quenching and tempering. The holding coefficient for normalizing is 1.5~1.7 min / mm, and the holding coefficient for tempering is 2.8~3.2 min / mm.

[0020] As a further improvement of one embodiment of this application, in the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material, the inner side of the edge strips is tightly attached to the cover material, and round holes are opened on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 550~750A; welding voltage: 35~50V; welding speed: 300~500mm / min.

[0021] One or more technical solutions provided in this application have at least the following technical effects or advantages: The method for preparing a composite plate with excellent interface bonding provided in this application controls the reduction amount during rough rolling and finish rolling according to the different target thickness ratios of the substrate and cladding in the composite plate. When the cladding accounts for a large proportion, the internal stress is large. A large reduction is used to bond the substrate and cladding, and then a smaller reduction is controlled during finish rolling to avoid edge cracking. When the cladding accounts for a small proportion, the stress is small. The substrate and cladding are pre-bonded during the rough rolling stage, and a good metallurgical bond is achieved during the finish rolling stage. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This application provides a method for preparing a composite plate with excellent interface bonding. The preparation method includes a sequential process of surface treatment of the billet, assembly and sealing of the billet, welding, vacuuming, heating, rolling, cooling, heat treatment, and plate separation. In the billet assembly and sealing step, the billets are placed in the order of substrate-coating material-coating material-substrate material to form a composite billet; In the rolling step, if t cp / t sp If ≥4, then the single-pass reduction of roughing rolling is ≥30mm and the number of roughing rolling passes is ≥1; the single-pass reduction of the first three passes of finishing rolling is ≥25mm and the number of finishing rolling passes is ≤7. If t cp / t sp If the ratio is less than 4, the single-pass reduction in roughing rolling is ≥35mm and the number of roughing passes is ≥3; the single-pass reduction in finishing rolling is ≤25mm and the number of finishing passes is ≤7, the total compression ratio CR is ≥7, and controlled cooling is performed after rolling. t cp t represents the target thickness of the substrate in the composite board. sp The target thickness of the cladding material in the composite panel is given in mm.

[0024] Because the deformation resistance of the substrate and the cladding material differs significantly, a larger proportion of the cladding material results in a greater contribution of internal stress. This internal stress may cause delamination in the composite plate. Therefore, rough rolling requires a large reduction to ensure preferential bonding between the substrate and the cladding material. However, the large reduction in rough rolling, combined with the temperature drop during finish rolling, can lead to edge cracking in the composite plate if the reduction continues. Therefore, the reduction during finish rolling must be controlled to ≤25mm. When the cladding material constitutes a smaller proportion, the internal stress during rolling is relatively lower. A rough rolling reduction ≥30mm not only achieves pre-bonding of the composite plate but also reduces damage to the rolling mill. To ensure good metallurgical bonding of the composite plate, the reduction during finish rolling must be controlled to ≥25mm.

[0025] Based on the target thickness ratio of the substrate and the cladding material in the composite plate, this application controls different reduction amounts during rough rolling and finish rolling to achieve metallurgical bonding of the composite plate.

[0026] The composite billet is heated before rolling, with the heating temperature controlled at 1170~1200℃, and the total furnace time ≥1.1t. b The unit is min, t b The total thickness of the composite blank is expressed in mm.

[0027] In the rolling process, the initial rolling temperature for roughing is 1020~1080℃, and the initial rolling temperature for finishing is Ts-5~Ts+5, where Ts=Tr+200 / t f The final rolling temperature is Tr-10 to Tr+10, where Tr = 910-200. +50[Si]-30[Mn]-20[Ni]+70[P]+40[V]-10[Cr]-a×t f The unit is ℃, where a is 1~2, and t f The thickness of the composite panel is in mm.

[0028] In the cooling process, the final cooling temperature is Tc-20~Tc+20, where Tc = 680-20[Mn]+30[Si]-15[Ni]-b×t f The unit is ℃, where b is 1~2, and t f The thickness of the composite panel is in mm.

[0029] In some embodiments of this application, during the blanking and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material, the inner side of the edge strips is tightly attached to the cover material, and round holes are made on the edge strips.

[0030] Preferably, the thickness t of the edge strip bt 30~40mm, width W bt 2t sb +1~2t sb +10mm, length L bt The length L varies depending on whether it is attached to the long or short side of the covering material. bt The length of the strip varies depending on whether it is attached to the long or short side of the cladding blank. The length of the strip attached to the long side (length) of the cladding blank is equal to the length of the cladding blank, while the length of the strip attached to the short side (width) of the cladding blank is the width of the cladding blank + 2t. bt mm, where t sb The target thickness of the cladding blank.

[0031] In the welding process, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 300~750A; welding voltage: 20~50V; welding speed: 300~500mm / min.

[0032] By controlling the welding process, an excellent bond is achieved between the substrate and the edge strip, preventing cracking during rolling and ensuring that the vacuum between the substrate and the edge strip is maintained, thus affecting the bond between the substrate and the cladding.

[0033] A circular hole with a diameter of 15-30 mm is made on the edge strip at the middle position along the width direction of the composite blank. The vacuum tube is inserted into the circular hole to prepare for vacuuming.

[0034] In some embodiments of this application, preheating is performed at 180~220°C before welding, and the interpass temperature is controlled at 100~180°C during welding. After welding, the material is allowed to cool naturally to room temperature. Preheating can effectively prevent the generation of cold cracks in welding and avoid reducing the vacuum level of the vacuum pump. Maintaining the interpass temperature during welding can keep the substrate and edge strip at approximately the preheated temperature.

[0035] In some embodiments of this application, after welding is completed, the cavity between the four edge strips and the two base material blanks is evacuated through a circular hole until the pressure is ≤10. -4 Torr, holding time is 2V~4V, unit is h, V is the total volume of the two-layer cladding blank, unit is m. 3 (That is, when calculating the pressure holding time, the unit is meters.) 3 (Calculate the volume value at the time), and seal the round hole after the pressure holding is completed.

[0036] The cavity formed between the edge strip and the substrate blank maintains a high vacuum, resulting in fewer interface impurities between the substrate and the cladding, which is beneficial for the interfacial bonding between the substrate and the cladding.

[0037] In some embodiments of this application, in the blank surface treatment step, one side of the substrate blank is ground until the surface roughness Ra ≤ 30 μm; both sides of the cladding blank are ground until the surface roughness Ra ≤ 1 μm.

[0038] Since the substrate blank only contacts the cladding blank on one side, only that side needs to be sanded. The cladding blank contacts both the substrate blank and another cladding blank on its two sides, respectively, so both sides need to be sanded.

[0039] The difference in surface roughness between the cladding blank and the substrate blank allows for interlocking at the interface, which facilitates atomic diffusion and makes metallurgical bonding of the composite plate easier. A surface roughness Ra≤30μm between the substrate blank and the cladding blank (Ra≤1μm) prevents numerous unbonded pores at the interface, which could affect the bonding quality of the composite plate, or relative sliding between the substrate and cladding blanks, resulting in poor bonding quality.

[0040] After the substrate blank and the cladding blank are polished, a release agent is applied to one side of the two cladding blanks to facilitate the subsequent board separation process.

[0041] In some embodiments of this application, during the heat treatment step, the composite plate obtained after rolling and cooling is subjected to normalizing, normalizing with water cooling, normalizing with water cooling combined with tempering, or quenching combined with tempering for heat treatment. In normalizing heat treatment, the normalizing temperature is T. N +30~T N +50℃, the final cooling temperature for normalizing water cooling is T NC +100~T NC +150℃; In quenching heat treatment, the quenching temperature is T. N +30~T N +50℃, In tempering heat treatment, the tempering temperature is T. T -10~T T +10℃, TN =900-203 -15[Ni]-45[Si]+104[V]+31.5[Mo]+t f , T NC =650-423[C]-30[Mn]-20[Si]-12[Cr]-18[Ni]-7[Mo]-t f , T T =700-0.16H+7CE, CE=[C]+[Mn] / 6+([Cr]+[Mo]+[V]) / 5+[Ni] / 15, where [C], [Mn], [Si], [Cr], [Ni], [Mo], and [V] are 100 times the mass percentage of the corresponding elements in the substrate, t f The thickness of the composite panel is in mm, and H is the maximum Brinell hardness required for the strength grade of the base steel plate in the composite panel.

[0042] It should be noted here that t in each formula b t f All calculations are performed using the thickness values ​​corresponding to the unit.

[0043] Depending on the chemical composition of the base material, different heat treatments can be applied to the composite plate obtained after rolling and cooling. These include normalizing heat treatment only, water cooling after normalizing heat treatment, tempering heat treatment after normalizing and water cooling, and tempering heat treatment after quenching.

[0044] For lower-strength composite plates, normalizing can shorten the production process and reduce production costs. For high-strength composite plates, normalizing with water cooling and tempering or quenching and tempering can refine the grains and suppress the precipitation of brittle phases, thereby meeting the performance requirements of high strength, high toughness, easy welding, and low stress.

[0045] Excessive normalizing temperature leads to coarse grains, which is detrimental to toughness; insufficient normalizing temperature cannot completely eliminate rolling defects and results in uneven steel plate structure, affecting mechanical properties.

[0046] The selection of normalizing and final cooling temperatures can ensure uniform microstructure, eliminate rolling defects, and guarantee the strength and toughness of the composite plate. Higher normalizing and final cooling temperatures result in insufficient phase transformation of the base steel plate, leaving austenite residue and easily forming coarse lamellar pearlite, leading to uneven microstructure and lower plate strength. Lower final cooling temperatures, on the other hand, result in martensite formation, leading to decreased toughness.

[0047] In some embodiments of this application, the holding coefficient for normalizing and quenching heat treatment is 1.5~1.7 min / mm, and the holding coefficient for tempering is 2.8~3.2 min / mm. Here, mm refers to the thickness of the composite plate.

[0048] In the slab separation process, the composite board is subjected to heated straightening treatment at a temperature >200℃, and then straightened again after being left for 24 hours.

[0049] Warm straightening ensures the straightness of the steel plate, reduces internal stress in the composite plate, and prevents edge cracking during straightening. After 24 hours, some residual stress is released, allowing for re-straightening to ensure the shape of the finished composite plate and further reduce internal stress. This prevents the plates from springing apart due to excessive internal stress during separation, thus avoiding safety accidents.

[0050] Plasma cutting is used for plate separation. First, the plate is cut along its length, then the tail section is cut laterally, and finally the head section is cut laterally. This cutting sequence maximizes the release of internal stress. Placing the head section, which has the lowest stress, for the last cut prevents stress separation in the steel plate and avoids accidents.

[0051] The composite panels after separation are straightened, finished, water-polished, and inspected again.

[0052] In some embodiments of this application, the chemical composition of the substrate blank, by mass percentage, includes: C: 0.10~0.20%, Si: 0.15~0.35%, Mn: 0.6~1.7%, Cr≤0.30%, Ni≤0.30%, Mo≤0.20%, Nb≤0.030%, Ti≤0.030%, Al: 0.02~0.06%, V≤0.040%, P≤0.020%, S≤0.005%, CE: 0.22~0.50%, with the remainder being iron and unavoidable impurities. CE = [C] + [Mn] / 6 + ([Cr] + [Mo] + [V]) / 5 + [Ni] / 15, where [C], [Mn], [Cr], [Mo], [V], and [Ni] are 100 times the mass percentage of the corresponding element in the substrate blank.

[0053] The composite plate prepared based on the aforementioned chemical composition of the substrate and cladding material and the aforementioned process method achieves an area bonding rate of 100% and a shear strength ≥300MPa; the residual stress distribution of the entire plate is uniform, with the highest residual stress ≤120MPa; the steel plate has good shape, with an unevenness ≤2mm / m; it has excellent resistance to intergranular corrosion and can meet the requirements of various corrosion conditions; it does not crack after 180° inward bending, 180° lateral bending, and 180° outward bending; the yield strength is ≥245MPa, the tensile strength is 400~700MPa, the impact at -20℃ is ≥90J, and the Brinell hardness is ≤240HBW.

[0054] The following describes different heat treatment and welding processes for substrates with different strength levels: The substrate is 245MPa grade and is subjected to normalizing heat treatment with a normalizing heat retention coefficient of 1.5~1.7min / mm.

[0055] The chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.17%, Si: 0.15~0.25%, Mn: 0.60~1.00%, Nb≤0.020%, Cr≤0.30%, Ti≤0.030%, Al: 0.020~0.050%, P≤0.020%, S≤0.005%, CE: 0.22~0.32%, with the remainder being iron and unavoidable impurities.

[0056] Furthermore, in the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 300~500A; welding voltage: 20~40V; welding speed: 300~400mm / min.

[0057] The composite plate made by the aforementioned process of 245MPa grade substrate and cladding material has a 100% area bonding rate and a shear strength ≥400MPa; the residual stress distribution of the whole plate is uniform, with the highest residual stress ≤80MPa; the flatness of the steel plate is ≤2mm / m; it has excellent resistance to intergranular corrosion and can meet the requirements of various corrosion conditions; it does not crack after 180° inward bending, 180° lateral bending, and 180° outward bending; the yield strength is ≥245MPa, the tensile strength is 400~520MPa, the impact at -20℃ is ≥90J, and the hardness is ≤140HBW.

[0058] The substrate is 345MPa grade and is subjected to normalizing water-cooled heat treatment with a normalizing insulation coefficient of 1.5~1.7min / mm.

[0059] The chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.18%, Si: 0.15~0.25%, Mn: 1.30~1.60%, Nb≤0.030%, Ti: 0.010~0.020%, Al: 0.020~0.050%, P≤0.015%, S≤0.005%, CE: 0.35~0.50%, with the remainder being iron and unavoidable impurities.

[0060] Furthermore, in the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 400~600A; welding voltage: 25~45V; welding speed: 300~450mm / min.

[0061] The composite plate made by the aforementioned process of 345MPa grade substrate and cladding material has an area bonding rate of 100%, shear strength ≥380MPa; uniform residual stress distribution throughout the plate, with the highest residual stress ≤100MPa; steel plate unevenness ≤2mm / m; excellent resistance to intergranular corrosion, meeting the requirements of various corrosion conditions; no cracking after 180° inward bending, 180° lateral bending, and 180° outward bending; yield strength ≥345MPa, tensile strength 450~600MPa, impact at -20℃ ≥90J, and hardness ≤170HBW.

[0062] The 370MPa grade substrate is heat-treated by normalizing and water cooling combined with tempering. The normalizing holding coefficient is 1.5~1.7min / mm, and the tempering holding coefficient is 2.8~3.2min / mm.

[0063] The chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.20%, Si: 0.25~0.35%, Mn: 1.30~1.60%, Nb: 0.015~0.030%, Cr: 0.10~0.20%, Ti: 0.010~0.020%, V≤0.020%, Al: 0.020~0.060%, P≤0.013%, S≤0.003%, CE: 0.40~0.45%, with the remainder being iron and unavoidable impurities.

[0064] Furthermore, in the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 500~700A; welding voltage: 30~50V; welding speed: 300~500mm / min.

[0065] The composite plate made by the aforementioned process of 370MPa grade substrate and cladding material has a 100% area bonding rate and a shear strength ≥370MPa; the residual stress distribution of the whole plate is uniform, with the highest residual stress ≤100MPa; the flatness of the steel plate is ≤2mm / m; it has excellent resistance to intergranular corrosion and can meet the requirements of various corrosion conditions; it does not crack after 180° inward bending, 180° lateral bending, and 180° outward bending; the yield strength is ≥370MPa, the tensile strength is 500~650MPa, the impact at -20℃ is ≥90J, and the hardness is ≤200HBW.

[0066] The 420MPa grade substrate is heat-treated by quenching and tempering. The normalizing holding coefficient is 1.5~1.7min / mm, and the tempering holding coefficient is 2.8~3.2min / mm.

[0067] The chemical composition of the substrate blank, by mass percentage, includes: C: 0.10~0.15%, Si: 0.15~0.35%, Mn: 1.10~1.70%, Nb≤0.02%, Cr: 0.10~0.20%, Ti≤0.030%, V≤0.040%, Ni: 0.10~0.30%, Mo≤0.20%, Al: 0.020~0.060%, P≤0.013%, S≤0.003%, CE: 0.30~0.50%, with the remainder being iron and unavoidable impurities; Furthermore, in the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 550~750A; welding voltage: 35~50V; welding speed: 300~500mm / min.

[0068] The composite plate made by the aforementioned process of 420MPa grade substrate and cladding material has a 100% area bonding rate and a shear strength ≥370MPa; the residual stress distribution of the whole plate is uniform, with the highest residual stress ≤120MPa; the flatness of the steel plate is ≤2mm / m; it has excellent resistance to intergranular corrosion and can meet the requirements of various corrosion conditions; it does not crack after 180° inward bending, 180° lateral bending, and 180° outward bending; the yield strength is ≥420MPa, the tensile strength is 550~700MPa, the impact at -20℃ is ≥90J, and the hardness is ≤240HBW.

[0069] By applying different heat treatments and welding processes to substrates with different alloy contents, it is possible to ensure good interfacial bonding between the substrate and the cladding material, while also enabling the composite board to have high strength and high toughness.

[0070] The technical solution of this application will be further described below with reference to some specific embodiments.

[0071] Table 1. Chemical composition of the substrate (%)

[0072] Note: The CE results in Table 1 do not include %.

[0073] Table 2. Billet Dimensions

[0074] Table 3. Blank preparation and welding processes

[0075] Table 4 Rolling process

[0076] Table 5 Heat Treatment Process

[0077] Table 6 Composite Panel Performance

[0078] The aforementioned composite panel performance was tested according to the requirements of GB / T6396 and GB / T8165, specifically: shear strength was tested by shear test; residual stress was tested by drilling method, with specific operation methods in accordance with GB / T 31310; flatness was tested by straightedge + feeler gauge method (GB / T 709-2019); cold bending test was conducted by bending test, with sample preparation and testing methods in accordance with GB / T232; tensile test was conducted on the full thickness of the composite panel, with sample preparation and testing in accordance with GB / T228; impact test required the removal of the cladding material, retaining only the substrate, with sample size, processing, and testing methods in accordance with GB / T229; hardness was the substrate hardness, tested on the substrate cross-section using a Brinell hardness tester.

[0079] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0080] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this application and are not intended to limit the scope of protection of this application. All equivalent implementation methods or modifications made without departing from the spirit of the art of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a composite plate with excellent interfacial bonding, characterized in that, The preparation method includes a sequential process of billet surface treatment, billet assembly and sealing, welding, vacuuming, heating, rolling, cooling, heat treatment, and plate separation. In the assembly and sealing step, the blanks are placed in the order of substrate-coating material-coating material-substrate material to obtain a composite blank; In the rolling step, if t cp / t sp If the value is ≥4, then the single-pass reduction in roughing rolling is ≥30mm and the number of roughing rolling passes is ≥1; the single-pass reduction in the first three passes of finishing rolling is ≥25mm and the number of finishing rolling passes is ≤7. If t cp / t sp If the ratio is less than 4, the single-pass reduction in roughing rolling is ≥35mm and the number of roughing passes is ≥3; the single-pass reduction in finishing rolling is ≤25mm and the number of finishing passes is ≤7, and the total compression ratio CR is ≥7, with controlled cooling after rolling. t cp t represents the target thickness of the substrate in the composite board. sp The target thickness of the cladding material in the composite panel is given in mm.

2. The method for preparing a composite plate with excellent interfacial bonding according to claim 1, characterized in that, In the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material. The inner side of the edge strips is tightly attached to the cover material, and round holes are made on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 300~750A; welding voltage: 20~50V; welding speed: 300~500mm / min.

3. The method for preparing a composite plate with excellent interfacial bonding according to claim 2, characterized in that, Preheat the equipment to 180~220℃ before welding. Control the interpass temperature to 100~180℃ during welding. Allow the equipment to cool naturally to room temperature after welding.

4. The method for preparing a composite plate with excellent interfacial bonding according to claim 2, characterized in that, After welding, the cavity between the four edge strips and the two base material blanks is evacuated through the round hole until the pressure is ≤10. -4 Torr, holding time is 2V~4V, unit is h, V is the total volume of the two-layer cladding blank, unit is m. 3 After the pressure holding period is over, seal the round hole.

5. The method for preparing a composite plate with excellent interfacial bonding according to claim 1, characterized in that, In the blank surface treatment step, one side of the substrate blank is ground until the surface roughness Ra≤30μm; both sides of the cladding blank are ground until the surface roughness Ra≤1μm.

6. The method for preparing a composite plate with excellent interfacial bonding according to claim 1, characterized in that, In the heat treatment process, the composite plate obtained after rolling and cooling is subjected to normalizing, normalizing with water cooling, normalizing with water cooling combined with tempering, or quenching combined with tempering. In normalizing heat treatment, the normalizing temperature is T. N +30~T N +50℃, the final cooling temperature for normalizing water cooling is T NC +100~T NC +150℃; In quenching heat treatment, the quenching temperature is T. N +30~T N +50℃, In tempering heat treatment, the tempering temperature is T. T -10~T T +10℃, T N =900-203 -15[Ni]-45[Si]+104[V]+31.5[Mo]+t f , T NC =650-423[C]-30[Mn]-20[Si]-12[Cr]-18[Ni]-7[Mo]-t f , T T =700-0.16H+7CE, CE=[C]+[Mn] / 6+([Cr]+[Mo]+[V]) / 5+[Ni] / 15, where [C], [Mn], [Si], [Cr], [Ni], [Mo], and [V] are 100 times the mass percentage of the corresponding elements in the substrate, t f H represents the thickness of the composite panel in mm, and H represents the maximum Brinell hardness required for the strength grade of the base steel plate in the composite panel.

7. The method for preparing a composite plate with excellent interfacial bonding according to claim 6, characterized in that, The chemical composition of the substrate blank, by mass percentage, includes: C: 0.10~0.20%, Si: 0.15~0.35%, Mn: 0.6~1.7%, Cr≤0.30%, Ni≤0.30%, Mo≤0.20%, Nb≤0.030%, Ti≤0.03%, Al: 0.02~0.06%, V≤0.040%, P≤0.020%, S≤0.005%, CE: 0.22~0.50%, with the remainder being iron and unavoidable impurities.

8. The method for preparing a composite plate with excellent interfacial bonding according to claim 7, characterized in that, The chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.17%, Si: 0.15~0.25%, Mn: 0.60~1.00%, Nb≤0.020%, Cr≤0.30%, Ti≤0.030%, Al: 0.020~0.050%, P≤0.020%, S≤0.005%, CE: 0.22~0.32%, with the remainder being iron and unavoidable impurities; Normalizing heat treatment is adopted, and the normalizing heat retention coefficient is 1.5~1.7 min / mm.

9. The method for preparing a composite plate with excellent interfacial bonding according to claim 8, characterized in that, In the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material. The inner side of the edge strips is tightly attached to the cover material, and round holes are made on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 300~500A; welding voltage: 20~40V; welding speed: 300~400mm / min.

10. The method for preparing a composite plate with excellent interfacial bonding according to claim 7, characterized in that, The chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.18%, Si: 0.15~0.25%, Mn: 1.30~1.60%, Nb≤0.030%, Ti: 0.010~0.020%, Al: 0.020~0.050%, P≤0.015%, S≤0.005%, CE: 0.35~0.50%, with the remainder being iron and unavoidable impurities; The normalizing water-cooled heat treatment is adopted, and the normalizing insulation coefficient is 1.5~1.7 min / mm.

11. The method for preparing a composite plate with excellent interfacial bonding according to claim 10, characterized in that, In the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material. The inner side of the edge strips is tightly attached to the cover material, and round holes are made on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 400~600A; welding voltage: 25~45V; welding speed: 300~450mm / min.

12. The method for preparing a composite plate with excellent interfacial bonding according to claim 7, characterized in that, The chemical composition of the substrate blank, by mass percentage, includes: C: 0.14~0.20%, Si: 0.25~0.35%, Mn: 1.30~1.60%, Nb: 0.015~0.030%, Cr: 0.10~0.20%, Ti: 0.010~0.020%, V≤0.020%, Al: 0.020~0.060%, P≤0.013%, S≤0.003%, CE: 0.40~0.45%, with the remainder being iron and unavoidable impurities; The heat treatment is carried out by normalizing and water cooling combined with tempering. The normalizing holding coefficient is 1.5~1.7 min / mm, and the tempering holding coefficient is 2.8~3.2 min / mm.

13. The method for preparing a composite plate with excellent interfacial bonding according to claim 12, characterized in that, In the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material. The inner side of the edge strips is tightly attached to the cover material, and round holes are made on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 500~700A; welding voltage: 30~50V; welding speed: 300~500mm / min.

14. The method for preparing a composite plate with excellent interfacial bonding according to claim 7, characterized in that, The chemical composition of the substrate blank, by mass percentage, includes: C: 0.10~0.15%, Si: 0.15~0.35%, Mn: 1.10~1.70%, Nb≤0.02%, Cr: 0.10~0.20%, Ti≤0.030%, V≤0.040%, Ni: 0.10~0.30%, Mo≤0.20%, Al: 0.020~0.060%, P≤0.013%, S≤0.003%, CE: 0.30~0.50%, with the remainder being iron and unavoidable impurities; The heat treatment is carried out by quenching and tempering. The holding coefficient for normalizing is 1.5~1.7 min / mm, and the holding coefficient for tempering is 2.8~3.2 min / mm.

15. The method for preparing a composite plate with excellent interfacial bonding according to claim 14, characterized in that, In the blank assembly and sealing step, four edge strips are placed around the cover material blank. The edge strips are made of the same material as the base material. The inner side of the edge strips is tightly attached to the cover material, and round holes are made on the edge strips. In the welding step, the edge strip is welded to the base material blank. The welding process is as follows: welding wire extension length: 15~20mm; welding current: 550~750A; welding voltage: 35~50V; welding speed: 300~500mm / min.

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