A tin-phosphor bronze / q235b composite sheet and a preparation method thereof

Abstract

This invention discloses a tin-phosphorus bronze / Q235B composite thin plate and its preparation method, belonging to the field of metal material forming. The method employs an optimized process route of "explosive bonding—stepped annealing—hot rolling—cold rolling." Explosive welding is used to metallurgically bond tin-phosphorus bronze plates with Q235B steel plates to obtain a composite thick plate. This is followed by stepped annealing heat treatment, preheating, and hot rolling, and finally cold rolling to obtain the composite thin plate. This method overcomes the limitations of single-component technologies, featuring high efficiency, stability, and low production cost, and can produce composite thin plates with excellent performance. The prepared tin-phosphorus bronze / Q235B composite thin plate has a room temperature yield strength of 580~640MPa, a tensile strength of 660~700MPa, and an elongation after fracture of 5%~6.5%.

Description

Technical Field

[0001] This invention relates to a tin-phosphor bronze / Q235B composite thin plate and its preparation method, belonging to the field of metal material forming. Background Technology

[0002] Tin-phosphorus bronze alloy is the most widely used elastic copper alloy material. Due to its excellent wear resistance, elasticity, antimagnetism, and corrosion resistance, it is widely used in the manufacture of electronic components. However, its high raw material cost severely restricts its development. To address this issue, a composite material combining tin-phosphorus bronze and Q235B steel is proposed, aiming to obtain a composite material that combines the excellent properties of tin-phosphorus bronze with the low-cost advantages of Q235B, thereby broadening the material's application range.

[0003] However, achieving high-quality composites faces severe technical challenges: First, the solid solubility between copper and iron is extremely low at room temperature, and copper is easily oxidized under heating conditions. If conventional rolling composite methods are used, it is difficult to form an effective metallurgical bond at the interface, making reliable composites impossible. Second, if explosive composite methods are used alone, although preliminary metallurgical bonding can be achieved, it is difficult to produce thin plates, especially thin plates with a tin-phosphor bronze layer thickness of less than 0.5 mm.

[0004] Therefore, it is evident that neither single rolling nor single explosive welding techniques can easily yield high-performance tin-phosphor bronze / Q235B steel composite sheets. To overcome the bottlenecks of these single technologies, the "explosive bonding + rolling" process route has emerged. This route aims to achieve a strong metallurgical bond between dissimilar metals through explosive welding, and then use rolling to improve the sheet morphology, precisely control the sheet thickness, and produce thin sheets. This process effectively overcomes the limitations of single bonding methods in terms of specifications and thickness ratios, significantly improving the flexibility and applicability of industrial production. However, due to the significant difference in deformation capabilities between tin-phosphor bronze and Q235B steel, it is difficult to control the coordinated deformation of the two during rolling. Therefore, for this specific combination of tin-phosphor bronze and Q235B steel, the "explosive bonding + rolling" composite process technology is still lacking, and a mature and reliable integrated technical solution is missing. Summary of the Invention

[0005] In view of the lack of existing technology, the first objective of this invention is to provide a method for preparing tin-phosphor bronze / Q235B composite thin plates, so as to overcome the bottleneck in the existing technology and achieve efficient and stable preparation of high-performance, low-cost tin-phosphor bronze / Q235B composite thin plates.

[0006] The second objective of this invention is to provide a tin-phosphor bronze / Q235B composite sheet prepared by the above-described preparation method.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This invention discloses a method for preparing a tin-phosphor bronze / Q235B composite thin plate, wherein a tin-phosphor bronze plate and a Q235B steel plate are explosively welded together to obtain a tin-phosphor bronze / Q235B composite thick plate, and then the tin-phosphor bronze / Q235B composite plate is subjected to stress-relief annealing heat treatment, followed by hot rolling and cold rolling to obtain the tin-phosphor bronze / Q235B composite thin plate.

[0009] The heat treatment process is as follows: first, the temperature is raised to 300-400℃ at a heating rate of 120-150℃ / h and held for 20-40 minutes; then, the temperature is raised to 580-600℃ at a heating rate of 80-100℃ / h and held for 1-2 hours; then, the temperature is cooled to below 300℃ in the furnace and finally air-cooled to room temperature.

[0010] The preparation method of this invention adopts a process path of "explosive bonding - stepped annealing - hot rolling - cold rolling". The explosive bonding process yields a composite plate with a high bonding strength and high bonding rate. Then, an intermediate stepped annealing heat treatment step serves as a key bridging step. This stepped annealing heat treatment step aims to eliminate work hardening caused by the explosion, optimize the interface microstructure, and prepare a billet with good plasticity and low internal stress for the next hot rolling step. This effectively solves the problem of synergistic integration of interface bonding and thin plate forming. This invention overcomes the limitations of single composite technology, and the preparation method is efficient, stable, and has low production costs, and can produce composite thin plates that meet the requirements.

[0011] The preparation method of this invention uses inexpensive Q235B steel as the base material, reducing material costs and solving the problem that the development of tin-phosphor bronze is limited due to its high cost. It utilizes explosive welding to achieve metallurgical bonding, effectively solving the problem that tin-phosphor bronze and Q235B steel are difficult to form an effective metallurgical bond and have poor bonding quality when conventionally rolled together. Through explosive welding + rolling, it solves the problem that explosive welding is difficult to prepare thin plates.

[0012] In a preferred embodiment, the tin-phosphor bronze plate is of type QSn6.5-0.1, and the Q235B steel plate is a commercially available hot-rolled plate. In this invention, the selected QSn6.5-0.1 tin-phosphor bronze in its M-state (soft state) already possesses excellent plasticity and formability, and its properties meet subsequent processing requirements. The Q235B steel plate, being a commercially available hot-rolled plate, also possesses good plasticity; neither requires heat treatment to meet processing needs.

[0013] In a preferred embodiment, the thickness of the tin-phosphor bronze plate is 2-5 mm, and the thickness of the Q235B steel plate is 8-20 mm. During the explosive welding process, the composite plate will undergo a certain degree of thinning deformation under the impact load, and the final thickness of the tin-phosphor bronze / Q235B steel composite thick plate is 10-23 mm.

[0014] In a preferred embodiment, the thickness of the tin-phosphor bronze / Q235B composite thick plate is 10~23 mm.

[0015] In a preferred embodiment, the explosive used for the explosive welding composite has the following composition by mass percentage: 65% to 75% rock-expanded ammonium nitrate explosive, 12% to 15% calcium carbonate, 8% to 14% perlite powder, 3% to 8% dried fine wood powder, and 2% to 6% melamine-formaldehyde resin powder; the explosive has a detonation velocity of 2000 to 2200 m / s and a saturation of 7 to 8.5 mm.

[0016] Furthermore, the particle size of the dried fine wood powder is ≤1mm.

[0017] This invention relates to an explosive based on rock-expanded ammonium nitrate explosive, modified by adding calcium carbonate, perlite powder, dried fine wood powder, and melamine resin powder. Calcium carbonate, as an endothermic regulator, effectively absorbs explosive energy through its high-temperature decomposition reaction, thereby reducing detonation velocity and intensity. The synergistic effect of perlite powder and dried fine wood powder reduces the explosive's unit volume density and effectively compensates for the potential decrease in initiation sensitivity caused by the addition of large amounts of inert materials, ensuring the likelihood of detonation. The addition of melamine-formaldehyde resin powder further stabilizes the explosive. The synergistic effect of the components achieves a low detonation velocity of 2000–2200 m / s and a low brittleness of 7–8.5 mm. Using this low-detonation-velocity explosive formulation enables the formation of a stable, continuous, and controllable metal jet at the impact point, effectively removing surface oxides and achieving metallurgical bonding. This significantly reduces the impact damage caused by the explosion to the tin-phosphor bronze composite plate and steel substrate, which have significant differences in plasticity. It promotes the formation of a uniform, fine, and highly elastic waveform interface with a small amplitude, allowing it to be flattened and welded after rolling. Ultimately, this results in a composite sheet with excellent interfacial bonding strength and good mechanical properties. Experiments have shown that if an inappropriate explosive is used, such as an explosive with an excessively high detonation velocity, the resulting waveform amplitude is larger. While this may seem more conducive to the bonding of the composite plate, it creates excessively thick molten zones and cracks, which cannot be effectively eliminated during subsequent rolling, leading to lower mechanical properties after rolling.

[0018] In a preferred embodiment, the process of explosively welding a tin-phosphor bronze plate with a Q235B steel plate to obtain a tin-phosphor bronze / Q235B composite plate is as follows: A wooden base, a Q235B steel plate, a support column, a tin-phosphor bronze plate, a protective layer, and an explosive layer are laid sequentially from bottom to top in an explosive field. Finally, the explosive is detonated to obtain the tin-phosphor bronze / Q235B steel composite thick plate. In this invention, the Q235B steel plate serves as the substrate, and the tin-phosphor bronze plate as the cladding plate. The explosive welding method enables the tin-phosphor bronze and Q235B steel to achieve interfacial metallurgical bonding during high-speed collision, thus preparing the tin-phosphor bronze / Q235B steel composite thick plate.

[0019] The preferred method involves preheating the tin-phosphor bronze / Q235B steel composite thick plate before hot rolling. The preheating temperature is 690~750℃, and the time is 30~60 minutes. Preheating the composite slab before hot rolling ensures that both materials are in their optimal plasticity state, thus preventing cracking during subsequent rolling. In actual operation, the composite slab should be immediately transferred to the rolling mill after preheating and hot rolled while still hot to fully utilize the high plasticity of the material at this temperature and achieve efficient rolling.

[0020] In a preferred embodiment, during hot rolling, the deformation per pass is controlled at 15%~25%, the total deformation at 70%~85%, and the thickness of the hot-rolled tin-phosphor bronze / Q235B steel composite plate is controlled at 3~4mm. By controlling the hot rolling deformation within the range of this invention, it can be ensured that the interfacial structure is refined, the corrugated interfacial structure is flattened and welded, and the composite plate has excellent interfacial bonding strength. If the total deformation is insufficient, insufficient interfacial bonding and incomplete microstructure refinement are likely to occur; if the total deformation is too large, micro-defects are easily induced, leading to plate cracking. In addition, this invention controls the thickness of the hot-rolled composite plate at 3~4mm, providing an ideal billet for subsequent cold rolling. The thickness of 3~4mm ensures sufficient cold rolling deformation for precise control of the finished product thickness, excellent plate shape, and surface finish. Too thick a plate will result in excessive cold rolling reduction, leading to significant work hardening; too thin a plate will result in insufficient cold rolling deformation.

[0021] In a further preferred embodiment, during the hot rolling process, if the thickness of the resulting tin-phosphor bronze / Q235B steel composite plate is still greater than 3-4 mm after 5-7 consecutive hot rolling passes, the hot-rolled slab is returned to the heating furnace and held at 690-750℃ for 5-10 minutes before being hot-rolled again. This reheating process restores the plasticity of the hot-rolled slab.

[0022] In actual operation, the hot-rolled composite slab is cooled to room temperature and then cold-rolled.

[0023] In a preferred embodiment, during cold rolling, the deformation per pass is controlled to be 10% to 20%, and the total deformation is 60% to 80%.

[0024] The present invention also provides a tin-phosphor bronze / Q235B composite thin plate prepared by the above preparation method.

[0025] In a preferred embodiment, the thickness of the tin-phosphor bronze / Q235B composite sheet is 0.5~1mm.

[0026] In a preferred embodiment, the tin-phosphor bronze / Q235B composite sheet has a room temperature yield strength of 580~640MPa, a tensile strength of 660~700MPa, and an elongation after fracture of 5%~6.5%.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. A composite thick plate of tin-phosphorus bronze / Q235B steel was obtained by explosive welding, effectively solving the interfacial bonding problems caused by the extremely low solid solubility of copper and iron at room temperature and the easy oxidation of iron during heating. Compared with conventional composite methods, this process has significant advantages: the use of low-explosion-velocity rock-expanded ammonium nitrate explosive can effectively control the interfacial waveform, forming a uniform small-amplitude wavy interface, thereby obtaining an interface with high bonding strength and high bonding rate, while ensuring good plasticity of the composite plate.

[0029] 2. One of the core innovations of this invention lies in establishing an optimized route of "explosive bonding—stepped annealing—hot rolling—cold rolling". Specifically, the annealing process following explosive welding employs a stepped stress-relief annealing heat treatment regime. This process achieves two key objectives: first, it eliminates the enormous residual stress generated by the explosion, eliminates work hardening caused by the explosion, and optimizes the interface microstructure; second, it optimizes the interface microstructure and billet properties, providing a uniform and highly plastic billet for rolling, laying a plastic foundation for subsequent deformation. This not only facilitates shape control but also ultimately ensures high-quality interface bonding and the high efficiency, stability, and low cost of the entire preparation process, achieving efficient, stable, and low-cost preparation of composite thin plates.

[0030] The technical solution of the present invention will be further described in detail below through embodiments. Attached Figure Description

[0031] Figure 1 The tin-phosphorus bronze / Q235B steel composite sheet prepared in Example 1.

[0032] Figure 2 Interface morphology of explosively welded composite plates. Detailed Implementation

[0033] The following are preferred embodiments of the present invention, but not all embodiments. Without departing from the innovative principles of this process, any equivalent process modifications made based on the content of this specification, or direct or indirect applications in other related technical fields, shall be considered within the scope of patent protection of this invention.

[0034] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to specific embodiments.

[0035] Example 1

[0036] This invention provides a method for forming a tin-phosphor bronze / Q235B composite sheet, wherein the tin-phosphor bronze is a QSn6.5-0.1 M state (soft state) sheet, and the Q235B is a commercially available hot-rolled sheet whose properties can meet the requirements of subsequent processing and do not require heat treatment.

[0037] Includes the following steps:

[0038] Step 1: Select a tin-phosphorus bronze plate with dimensions of 350mm × 250mm × 3mm and a Q235B steel plate blank with dimensions of 300mm × 200mm × 9mm. Use low-detonation-velocity ammonium nitrate oil rock-expanded explosive with a layer thickness of 25mm. Prepare a composite thick plate of tin-phosphorus bronze plate and Q235B steel plate using an explosive composite method. The total thickness of the resulting tin-phosphorus bronze / Q235B steel composite plate is approximately 12mm (of which the tin-phosphorus bronze layer is approximately 3mm and the Q235B steel layer is approximately 9mm).

[0039] The composition of the explosive by mass percentage is as follows: 65% rock-expanded ammonium nitrate explosive, 13% calcium carbonate, 11% perlite powder, 5% dried fine wood powder (particle size ≤ 1 mm), and 6% melamine-formaldehyde resin powder. The explosive has a detonation velocity of 2000 m / s and a saturation of 7.8 mm.

[0040] Step Two: Take the middle section of the explosively welded composite thick plate obtained in Step One and cut a plate blank with a length × width of 120mm × 110mm. Place it in a heating furnace and perform a stepped annealing heat treatment. The specific steps are as follows:

[0041] a) Heat the billet to 300℃ at a heating rate of 120℃ / h and hold for 30 minutes for low-temperature preheating;

[0042] b) Then, continue heating at a rate of 80℃ / h to 580℃ and hold for 1 hour;

[0043] c) After the heat preservation is completed, the furnace is cooled to below 300°C, and then air-cooled to room temperature.

[0044] Step 3: Preheat the annealed composite thick plate obtained in Step 2. The preheating steps are as follows: Place the composite thick plate in a heating furnace and heat it to 690℃, holding it for 30 minutes. Then, immediately send the preheated composite thick plate into a rolling mill for hot rolling. The rolling orientation is with the tin-phosphor bronze layer facing upwards, and the deformation per pass is controlled at 18%.

[0045] a) First round of hot rolling: Five consecutive rolling passes are performed to obtain a composite plate with a thickness of 4.45 mm. Because this thickness is greater than the preset intermediate target thickness, a second rolling process is required.

[0046] b) Intermediate reheating: The slab after the first rolling is sent into a heating furnace and reheated at 690°C for 5 minutes to restore its thermoplasticity.

[0047] c) Second round of hot rolling: The cooled slab is fed back into the rolling mill and rolled for three more passes to obtain a hot-rolled slab with a thickness of 2.45 mm. The hot rolling process is then complete. (Total deformation during hot rolling is approximately 79.6%)

[0048] Step 4: The hot-rolled composite sheet obtained in Step 3 and air-cooled to room temperature is cold-rolled with a deformation of 12% per pass. This is repeated for 6 passes to obtain a tin-phosphor bronze / Q235B steel composite sheet with a thickness of 0.88 mm. The tin-phosphor bronze layer is approximately 0.22 mm thick, and the Q235B steel layer is approximately 0.66 mm thick. (Total cold rolling deformation is approximately 64.1%)

[0049] The present invention prepares a tin-phosphor bronze / Q235B steel composite sheet with a thickness of 0.88 mm, wherein the tin-phosphor bronze layer is approximately 0.22 mm thick and the Q235B steel layer is approximately 0.66 mm thick. The composite sheet exhibits a room temperature yield strength of 646 MPa, a tensile strength of 689 MPa, and an elongation after fracture of 5.9%.

[0050] Example 2

[0051] This invention provides a method for forming a tin-phosphor bronze / Q235B composite sheet, wherein the tin-phosphor bronze is a QSn6.5-0.1 M state (soft state) sheet, and the Q235B is a commercially available hot-rolled sheet whose properties can meet the requirements of subsequent processing and do not require heat treatment.

[0052] Includes the following steps:

[0053] Step 1: Select a tin-phosphorus bronze plate with dimensions of 350mm × 250mm × 3mm and a Q235B steel plate blank with dimensions of 300mm × 200mm × 15mm. Use low-detonation-velocity ammonium nitrate oil rock-expanded explosive with a 30mm explosive layer thickness to prepare a composite thick plate of tin-phosphorus bronze plate and Q235B steel plate using an explosive composite method. The total thickness of the resulting tin-phosphorus bronze / Q235B steel composite plate is approximately 18mm (3mm tin-phosphorus bronze + 15mm Q235B steel).

[0054] The composition of the explosive by mass percentage is as follows: 70% rock-expanded ammonium nitrate explosive, 12% calcium carbonate, 10% perlite powder, 4% dried fine wood powder (particle size ≤ 1 mm), and 4% melamine-formaldehyde resin powder. The explosive has a detonation velocity of 2050 m / s and a saturation of 7.9 mm.

[0055] Step Two: Take the middle section of the explosively welded composite thick plate obtained in Step One and cut a plate blank with a length × width of 120mm × 110mm. Place it in a heating furnace and perform a stepped annealing heat treatment. The specific steps are as follows:

[0056] c) Heat the billet to 320℃ at a heating rate of 130℃ / h and hold for 30 minutes for low-temperature preheating;

[0057] d) Then, continue heating at a rate of 90℃ / h to 590℃ and hold for 1.5h;

[0058] c) After the heat preservation is completed, the furnace is cooled to below 300°C, and then air-cooled to room temperature.

[0059] Step 3: Preheat the annealed composite thick plate obtained in Step 2. The preheating steps are as follows: Place the composite thick plate in a heating furnace and heat it to 710℃, holding it for 40 minutes. Then, immediately send the preheated composite thick plate into a rolling mill for hot rolling. The rolling orientation is with the tin-phosphor bronze layer facing upwards, and the deformation per pass is controlled at 20%.

[0060] d) First round of hot rolling: Five consecutive rolling passes are performed to obtain a composite plate with a thickness of 5.90 mm. Because this thickness is greater than the preset intermediate target thickness, a second rolling process is required.

[0061] e) Intermediate reheating: The slab after the first rolling is sent into a heating furnace and reheated at 750°C for 5 minutes to restore its thermoplasticity.

[0062] f) Second round of hot rolling: The cooled slab is fed back into the rolling mill and rolled for two more passes to obtain a hot-rolled slab with a thickness of 3.78 mm. The hot rolling process is then complete. (Total deformation during hot rolling is approximately 79.0%)

[0063] Step 4: The hot-rolled composite sheet obtained in Step 3 and air-cooled to room temperature is cold-rolled with a deformation of 15% per pass. This is repeated for 6 passes to obtain a tin-phosphor bronze / Q235B steel composite sheet with a thickness of 0.87 mm. The tin-phosphor bronze layer is approximately 0.14 mm thick, and the Q235B steel layer is approximately 0.73 mm thick. (Total cold rolling deformation is approximately 77.0%)

[0064] The present invention prepares a tin-phosphorus bronze / Q235B steel composite sheet with a thickness of 0.87 mm, wherein the tin-phosphorus bronze layer is approximately 0.14 mm thick and the Q235B steel layer is approximately 0.73 mm thick. The composite sheet exhibits a room temperature yield strength of 632 MPa, a tensile strength of 678 MPa, and an elongation after fracture of 5.6%.

[0065] Example 3

[0066] This invention provides a method for forming a tin-phosphor bronze / Q235B composite sheet, wherein the tin-phosphor bronze is a QSn6.5-0.1 M state (soft state) sheet, and the Q235B is a commercially available hot-rolled sheet whose properties can meet the requirements of subsequent processing and do not require heat treatment.

[0067] Includes the following steps:

[0068] Step 1: Select a tin-phosphorus bronze plate with dimensions of 350mm × 250mm × 3mm and a Q235B steel plate blank with dimensions of 300mm × 200mm × 20mm. Use low-detonation-velocity ammonium nitrate oil rock-expanded explosive with a layer thickness of 35mm. Prepare a composite thick plate of tin-phosphorus bronze plate and Q235B steel plate using an explosive composite method. The total thickness of the resulting tin-phosphorus bronze / Q235B steel composite plate is approximately 23mm (3mm tin-phosphorus bronze + 20mm Q235B steel).

[0069] The composition of the explosive by mass percentage is as follows: 72% rock-expanded ammonium nitrate explosive, 13% calcium carbonate, 8% perlite powder, 5% dried fine wood powder (particle size ≤ 1 mm), and 2% melamine-formaldehyde resin powder. The explosive has a detonation velocity of 2150 m / s and a saturation of 7.8 mm.

[0070] Step Two: Take the middle section of the explosively welded composite thick plate obtained in Step One and cut a plate blank with a length × width of 120mm × 110mm. Place it in a heating furnace and perform a stepped annealing heat treatment. The specific steps are as follows:

[0071] e) Heat the billet to 350℃ at a heating rate of 140℃ / h and hold for 40 minutes for low-temperature preheating;

[0072] f) Then, continue heating at a rate of 100℃ / h to 600℃ and hold for 2 hours;

[0073] c) After the heat preservation is completed, the furnace is cooled to below 300°C, and then air-cooled to room temperature.

[0074] Step 3: Preheat the annealed composite thick plate obtained in Step 2. The preheating steps are as follows: Place the composite thick plate in a heating furnace and heat it to 730℃, holding it for 50 minutes. Then, immediately send the preheated composite thick plate into a rolling mill for hot rolling. The rolling orientation is with the tin-phosphor bronze layer facing upwards, and the deformation per pass is controlled at 22%.

[0075] g) First round of hot rolling: Five consecutive rolling passes are performed to obtain a composite plate with a thickness of 6.64 mm. Because this thickness is greater than the preset intermediate target thickness, a second rolling process is required.

[0076] h) Intermediate reheating: The slab after the first rolling is sent into a heating furnace and reheated at 730°C for 5 minutes to restore its thermoplasticity.

[0077] i) Second round of hot rolling: The slab, after being cooled, is fed back into the rolling mill and rolled for three more passes to obtain a hot-rolled slab with a thickness of 3.15 mm. The hot rolling process is then complete. (The total deformation during hot rolling is approximately 85.0%)

[0078] Step 4: The hot-rolled composite sheet obtained in Step 3 and air-cooled to room temperature is cold-rolled with a deformation of 18% per pass. This is repeated for 7 passes to obtain a tin-phosphor bronze / Q235B steel composite sheet with a thickness of 0.78 mm. The tin-phosphor bronze layer is approximately 0.10 mm thick, and the Q235B steel layer is approximately 0.68 mm thick. (Total cold rolling deformation is approximately 75.2%)

[0079] This invention prepares a tin-phosphorus bronze / Q235B steel composite sheet with a thickness of 0.78 mm. The tin-phosphorus bronze layer has a thickness of approximately 0.10 mm, and the Q235B steel layer has a thickness of approximately 0.68 mm. The composite sheet exhibits a room temperature yield strength of 625 MPa, a tensile strength of 670 MPa, and an elongation after fracture of 5.5%.

[0080] Comparative Example 1

[0081] The other conditions are the same as in Example 1, except that: after obtaining the required slab in step 2, no annealing treatment was performed. After preheating, hot rolling was carried out. After rolling 5 times, cracks appeared on the edge of the composite plate, and the bonding strength of the finished product interface was significantly reduced.

[0082] Comparative Example 2

[0083] The other conditions are the same as in Example 1, except that: continuous rolling is performed during hot rolling in step 4 without reheating. After 10 rolling passes, the plate shape is poor and warping occurs due to the sharp increase in rolling force in subsequent passes.

[0084] Comparative Example 3

[0085] Other conditions were the same as in Example 1, except that the heat treatment process in step 2 was changed to single-temperature annealing: after holding at 580℃ for 1 hour, the temperature was cooled in the furnace to 300℃ and then air-cooled to room temperature. The yield strength of the tin-phosphor bronze / Q235B steel composite sheet obtained after rolling was 520MPa, which was much lower than that in Example 1. Single-temperature annealing is difficult to completely eliminate residual stress from explosive welding.

[0086] Comparative Example 4

[0087] The other conditions are the same as in Example 1, except that step one explosive bonding is not performed, but step three hot rolling bonding is performed directly. As a result, the composite plate obtained by rolling has poor bonding strength and delamination occurs during subsequent cold rolling.

[0088] Comparative Example 5

[0089] Other conditions are the same as in Example 1, except that the explosive composition used in step 1, by mass percentage, is: 78% rock-expanded ammonium nitrate explosive, 12% calcium carbonate, 8% perlite powder, and 2% diatomaceous earth. This rock-expanded ammonium nitrate explosive has a detonation velocity of 2250 m / s and a saturation of 7.8 mm. This formulation does not contain fine wood flour or resin powder. The room temperature mechanical properties of the resulting composite sheet after rolling are: yield strength 581 MPa, tensile strength 602 MPa, and elongation after fracture 4.3%. Compared to Example 1, its yield strength and tensile strength decreased by approximately 10% and 13%, respectively, while the elongation after fracture, a key indicator of plasticity, decreased significantly by approximately 27%.

Claims

1. A method for preparing a tin-phosphor bronze / Q235B composite thin plate, characterized in that: The tin-phosphor bronze plate and Q235B steel plate are explosively welded together to obtain a tin-phosphor bronze / Q235B composite thick plate. Then, the tin-phosphor bronze / Q235B composite thick plate is subjected to stress-relief annealing heat treatment, and then hot rolling and cold rolling are performed in sequence to obtain a tin-phosphor bronze / Q235B composite thin plate. The process of explosively welding tin-phosphor bronze plate with Q235B steel plate to obtain tin-phosphor bronze / Q235B composite thick plate is as follows: in the explosion field, wooden pads, Q235B steel plate, support column, tin-phosphor bronze plate, protective layer, explosive layer are laid from bottom to top, and finally the explosive is detonated. The explosive used for the explosive welding composite has the following composition by mass percentage: 65% to 75% rock-expanded ammonium nitrate explosive, 12% to 15% calcium carbonate, 8% to 14% perlite powder, 3% to 8% dried fine wood powder, and 2% to 6% melamine-formaldehyde resin powder. The explosive has a detonation velocity of 2000 to 2200 m / s and a saturation of 7 to 8.5 mm. The heat treatment process is as follows: first, the temperature is raised to 300-400℃ at a heating rate of 120-150℃ / h and held for 20-40 minutes; then, the temperature is raised to 580-600℃ at a heating rate of 80-100℃ / h and held for 1-2 hours; then, the temperature is cooled to below 300℃ in the furnace and then air-cooled to room temperature. Before hot rolling, the tin-phosphor bronze / Q235B steel composite thick plate is preheated at a temperature of 690~750℃ for 30~60 min. During hot rolling, the deformation per pass is controlled at 15%~25%, the total deformation is controlled at 70%~85%, and the thickness of the hot-rolled tin-phosphor bronze / Q235B steel composite plate is controlled at 3~4mm. During the cold rolling process, the deformation per pass is controlled at 10% to 20%, and the total deformation is 60% to 80%.

2. The method for preparing a tin-phosphor bronze / Q235B composite thin plate according to claim 1, characterized in that: The tin-phosphor bronze plate is of type QSn6.5-0.1, and the Q235B steel plate is a hot-rolled plate.

3. The method for preparing a tin-phosphor bronze / Q235B composite thin plate according to claim 1, characterized in that: The thickness of the tin-phosphor bronze plate is 2-5mm, and the thickness of the Q235B steel plate is 8-20mm. The thickness of the tin-phosphor bronze / Q235B composite thick plate is 10~23 mm.

4. The method for preparing a tin-phosphor bronze / Q235B composite thin plate according to claim 1, characterized in that: If, during the hot rolling process, the thickness of the resulting tin-phosphorus bronze / Q235B steel composite plate is still greater than 3-4 mm after 5-7 consecutive hot rolling passes, the hot-rolled slab is returned to the heating furnace and held at 690-750℃ for 5-10 minutes before being hot rolled again.

5. A tin-phosphor bronze / Q235B composite thin plate prepared by the preparation method according to any one of claims 1-4, characterized in that: The thickness of the tin-phosphor bronze / Q235B composite sheet is 0.5~1mm; The tin-phosphor bronze / Q235B composite sheet has a room temperature yield strength of 580~640MPa, a tensile strength of 660~700MPa, and an elongation after fracture of 5%~6.5%.

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