Large-area ti-w-al-w-ti fiber reinforced layered composite plate and vacuum interface explosive welding method

Abstract

The application discloses a large-area Ti-W-Al-W-Ti fiber reinforced layered composite plate and a vacuum interface explosive welding method, relates to the field of metal composite material processing, and discloses a preparation method of the large-area Ti-W-Al-W-Ti fiber reinforced layered composite plate, wherein the layered composite plate is composed of an upper Ti composite plate, an Al base plate, a lower Ti composite plate and interlayer reinforcing fibers; different high-strength and different specification tungsten fibers are used to reinforce the multi-layer large-area layered composite plate by designing stress-reducing layer structures and reinforcing fiber structures and a symmetric layering pattern, macroscopic large deformation, internal stress concentration and coupling problems are solved, and the large-area Ti-W-Al-W-Ti fiber reinforced layered composite plate explosive welding process design and parameter calculation are carried out for large-area and different physical and chemical property metals (the base plate, the composite plate and the metal reinforcing fiber), and the problems of low welding rate and interface bonding defects are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite materials and explosive welding manufacturing technology, in particular to a large-area Ti-W-Al-W-Ti fiber-reinforced layered composite plate and process and parameter problems in explosive welding method. BACKGROUND

[0002] Aluminum alloy is a relatively common light metal with strong corrosion resistance and high specific strength, and has a very high application proportion in various industries, especially in the military industry. However, the strength of aluminum alloy cannot meet the armor requirements of mobile equipment in the military field. In order to avoid its advantages and disadvantages, in engineering and military protection applications, it is often prepared into a layered composite material with titanium alloy which has higher strength and specific strength and better comprehensive performance to meet the application requirements of strength, weight, corrosion resistance, etc. In the preparation of large-area titanium-aluminum layered composite plate, the explosive welding process is often selected because it has simple operation process, fewer process parameters, lower cost and equipment demand, and higher benefits and production efficiency.

[0003] The titanium-aluminum composite plate for armor protection cannot meet the impact and penetration requirements in terms of strength. In the study of improving the strength of the layered composite plate, researchers add higher strength reinforcing fibers between the metal plates to further improve the impact resistance and penetration resistance of the composite plate. However, the preparation methods mostly choose diffusion welding, laser welding, magnetic pulse welding and hot rolling welding, and less use explosive welding method. The reasons can be summarized as follows: 1) The huge impact energy of explosives in the explosion process easily damages the hard and brittle reinforcing fibers; 2) The reinforcing fibers can seriously reduce the bonding rate and success rate of the base composite plate; 3) The interface bonding quality of the reinforcing fibers and the base composite plate is poor, and intermetallic compounds, cracks, voids and pores often exist at the interface; 4) Explosive welding can easily cause macro bending of the composite plate, and the reinforcing fibers in the middle layer can intensify the coupling stress of the composite plate, making it difficult to flatten and damaging the bonding interface of the fibers and metal plates.

[0004] There is only a small amount of research on explosive welding of metal fiber-reinforced layered metal composite plates by explosive energy. In his doctoral thesis (Research on Anti-penetration Performance and Damage Mechanism of Explosive Composite Functional Gradient Target, 2014), Zhou Nan studied the damage mechanism of the reinforcing fiber composite plate and the influence of fiber spacing and fiber sequence on the penetration resistance. However, the research object is small-sized 304L and LY12 which is easy to weld, and there is internal stress concentration and coupling problem caused by asymmetric structure of the composite plate. In the study of producing small-area steel fiber reinforced aluminum plate through explosive welding method, the bonding quality between fiber and aluminum plate, aluminum plate and aluminum plate is poor, and the composite plate produces a large macroscopic distortion. Chen et al. (Effect of the Addition of Steel Fibers on the Bonding Interface and Tensile Properties of Explosive welded 2A12 Aluminum Alloy and SS-304 Steel, 2022) prepared small-area S20910 steel fiber interlayer reinforced 2A12-304 composite plate by explosive welding method, the yield strength of the reinforcing fiber is lower than the strength of the substrate, the research value and application value is low, and there are a large number of intermetallic compounds, cracks and pores between S20910 steel fiber, 2A12 aluminum alloy and SS-304 steel plate, the macroscopic distortion of the composite plate is serious. The above studies have realized the composite of reinforcing fiber and base composite plate, but there are generally the following problems: 1) The process and auxiliary device are complex; 2) The interface bonding quality is poor; 3) The composite plate structure is asymmetric, and a serious distortion and stress coupling text are produced; 4) Only small-area composite plate based on experiment.

[0005] In summary, there are many technical problems in the preparation of fiber reinforced metal composite plate by explosive welding. The process and the structure of the fiber and the layering style of the invention can solve the problems of unsuccessful compounding of large-area Ti-W-Al-W-Ti fiber reinforced layered composite plate in engineering and the warping caused by extremely uneven internal stress after compounding, and can also reduce the generation of interfacial intermetallic compounds, cracks, voids and pores to a certain extent, so that the quality of the reinforced composite plate meets the engineering application. SUMMARY

[0006] The present invention includes two aspects, one is the design of the structure of the reinforcing fiber and the symmetrical layering style, which fundamentally and theoretically solves the problems of macroscopic large deformation, internal stress concentration and coupling; the second is the explosive compounding process for large-area, physically and chemically different metals (substrate, composite plate, metal reinforcing fiber), which tries to solve the problems of low welding rate and interface bonding defects in engineering production from the manufacturing process.

[0007] I. Design of stress-reducing reinforcing fiber structure and layering style

[0008] The fiber reinforced layered composite plate has extremely uneven internal stress due to unreasonable fiber structure and layering style, especially using explosive welding method with high temperature, high pressure and high speed, which causes the composite plate to warp, especially large area composite plate will have extremely serious warping deformation. The subsequent heat treatment, cold pressing and stretching processes not only cannot eliminate the warping of the composite plate, but also will damage the surface of the reinforcing fiber, reduce the strength of the reinforcing fiber, change the mechanical properties of the reinforcing fiber, and destroy the bonding interface between the reinforcing fiber and the base composite plate. The warping and subsequent leveling difficulty is a bottleneck that needs to be solved for the engineering preparation of large area Ti-W-Al-W-Ti fiber reinforced layered composite plate by explosive welding method.

[0009] The regular symmetric orthogonal laid-up laminate is a commonly used laminate structure in non-metallic materials, and its advantages can be described as follows: 1) good strength uniformity, which is formed by alternating laying of multiple layers of fibers, each layer has the same laying direction and thickness, so the strength and stiffness of the composite plate are uniformly distributed, and local stress concentration and stress coupling problems are less likely to occur, which can improve the strength and durability of the composite plate, and reduce the twisting deformation of the composite plate; 2) good tensile, compressive and bending properties, which have good tensile, compressive and bending properties in multiple directions, and can withstand multidirectional load; 3) isotropic, which makes the composite plate have the same physical properties in different directions, and can avoid the shrinkage rate of dissimilar metals with large difference in linear thermal expansion coefficient to remain balanced in each direction. The regular symmetric orthogonal laid-up laminate is shown in the accompanying drawings as follows: Figure 3

[0010] The stiffness matrix of each layer of plate can be represented as

[0011]

[0012] The in-plane stiffness coefficient A ij of the composite plate, the coupling stiffness matrix B ij , and the bending stiffness matrix D ij can be represented as

[0013] wherein z k and z k-1 represent the lower surface coordinate and the upper surface coordinate of the kth layer respectively. Since the laid fibers are symmetric to the center of the base plate, according to the definition formula, A 16 = A 26 = 0, B ij = 0, and D 16 = D 26 = 0. For the kth layer consistent with the x direction, the stiffness coefficient can be represented as

[0014] ​

[0015] For the m layers consistent with the y direction, the stiffness coefficient can be expressed as

[0016]

[0017] In the formula, E1, E2, v 12 , v 21 are the in-plane elastic modulus and Poisson's ratio respectively. Therefore, the internal force-strain relationship of the symmetric orthotropic laminated plate can be expressed as

[0018]

[0019] In the formula, N, M, ε, γ, κ represent the axial force, bending moment, linear strain, shear strain, and curvature respectively.

[0020] According to the stress-strain formula of the symmetric orthotropic laminated plate, when the composite plate is prepared by the explosive welding method, the reinforcing fiber structure and the layering style should be designed to avoid the internal stress concentration and coupling problem caused by the reinforcing fiber. Based on the theoretical relationship of the stress-strain of the composite plate, the coupling effect caused by the reinforcing fiber is reduced by designing the fiber structure and the layering style, and the cross-shaped and concentric circular reinforcing fiber structures are proposed for different shapes of the composite plate. The two fiber structures are respectively for large-area rectangular composite plates and large-area circular composite plates. 1) The cross-shaped layering is to lay the cross-shaped and symmetric reinforcing fibers in the gap between the upper and lower composite plates and the substrate. The upper composite plate, the reinforcing fiber, the lower composite plate, and the reinforcing fiber are symmetric about the center plane of the substrate. The overall composite plate is symmetric about the xz plane and the yz plane. The unit grid of the fiber is a square, and the grid single side size is greater than or equal to 3 mm. The fiber diameter is less than half of the thickness of the composite plate, and the maximum diameter is not more than 3 mm. 2) The concentric circular layering is that the circular reinforcing fibers of each layer are on the same center, and the radius difference is less than or equal to 10 mm. The circular reinforcing fibers of the upper and lower layers are respectively symmetric about the center plane of the substrate. The overall composite plate is symmetric about the xz plane and the yz plane. The fiber diameter is less than half of the thickness of the composite plate, and the maximum diameter is not more than 3 mm. The reasonable design of the fiber structure and the layering style can greatly reduce the warping deformation of the composite plate. In addition, in order to accurately control the arrangement of the fiber and avoid the jet and explosion shock wave caused by the explosive welding from washing away the reinforcing fiber, resulting in uneven strength and stiffness of the composite plate, the reinforcing fiber is a mesh structure connected to each other, and the area is slightly larger than the area of the substrate composite plate.

[0021] Two, the explosive welding process and parameters of the large-area Ti-W-Al-W-Ti fiber reinforced laminated composite plate

[0022] The reasonable fiber structure and layering style can theoretically avoid the coupling effect of the internal stress of the base plate, and the process of the explosion welding machine is the decisive factor for whether the base plate produces the internal stress coupling. In addition, the process of the explosion welding machine will directly determine the bonding rate and success rate of the base plate, whether the reinforcing fiber is brittle, the bonding quality of the reinforcing fiber and the base plate interface, and the defects such as intermetallic compound, crack, void and porosity on the bonding interface. Therefore, the present application proposes a new explosion welding process, which can significantly reduce the coupling response of the internal stress, greatly improve the success rate and bonding rate, and eliminate the brittle fracture of the fiber surface and the interface defects. The welding process and parameter innovation points are described as follows:

[0023] (1) A Cu interface layer is prepared on the surface of the reinforcing fiber by using an electroplating device, the wettability of the fiber and the aluminum plate bonding interface is improved, that is, an ideal bonding interface can be obtained, and the brittle fracture of the reinforcing fiber can be avoided to a certain extent, the plating layer is uniform and the thickness is greater than or equal to 0.3mm;

[0024] (2) The side surfaces of adjacent base plates are sealed by a sealing material, an exhaust hole for vacuum extraction is reserved on each layer, and a certain vacuum degree is extracted in the sealed space, which can effectively solve the problem of air exhaust caused by the reinforcing fiber between the base plates, and the vacuum degree is less than or equal to 5×10 -3 ;

[0025] (3) A certain thickness of flat water film is coated on the top of the uppermost Ti plate, and then the explosive frame and explosive are placed on the water film, which can greatly reduce the impact of the explosive on the reinforcing fiber and the base plate, and the thickness of the water film is 2-5mm;

[0026] (4) A flat buffer rubber is bonded to the lower surface of the lower plate to avoid the impact of air in the buffer layer and the air between the buffer layer and the anvil plate interface on the composite plate during the exhaust process, and the thickness of the buffer rubber is 4-6mm;

[0027] (5) The total height of the roughness of the bonding surface is less than or equal to 100um, and the flatness tolerance of the base plate is less than or equal to 8×(1+d / 1000)um (d is the diagonal length). BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is an explosion diagram of an explosion welding device, wherein 1 is a detonator, 2 is an explosive frame and explosive, 3 is a buffer water film, 4 is an upper Ti plate, 5 is a circumferential sealing glue, 6 is an Al base plate, 7 is a cross-reinforced fiber, 8 is a lower Ti plate, 9 is a buffer rubber, 10 is an anvil plate, and 11 is an air hole on the circumferential sealing glue. Figure 2 is a configuration schematic diagram of an explosion welding device in actual production. Figure 3 is a schematic diagram of a regular symmetric orthogonal laminated plate. DETAILED DESCRIPTION

[0029] The application will be described in detail below with reference to the drawings and specific implementation steps. Before the detailed description of the embodiments, the traditional characteristics of the composite plate and the traditional explosive welding method will be described: (1) there is no case of using explosive welding method to prepare large-area fiber-reinforced layered metal composite plate. In the only preparation case, it is explosive welding to prepare small-area fiber-reinforced layered metal composite plate, and it is not Ti-W-Al-W-Ti metal material with large difference in physical and chemical properties; (2) the traditional preparation method does not consider the symmetry of the reinforcing fiber layer. Whether the reinforcing fiber is symmetrical or not will directly determine whether there is internal stress coupling in the composite plate after explosive welding. Its macroscopic performance is the distortion of the composite plate, the displacement, distortion and brittle fracture of the fiber; (3) the traditional explosive welding method for preparing such composite plate does not use the method of placing a buffer water layer on the upper surface of the upper composite plate and the lower surface of the lower composite plate to reduce the impact and explosion temperature of the explosive, so that it is more prone to problems such as damage of the reinforcing fiber, failure of the reinforcing fiber strength, and large-area deformation of the composite plate; (4) the traditional explosive welding method for preparing such composite plate does not consider that the placement of the reinforcing fiber between the gaps of the base composite plate will affect the discharge of the gap gas, thereby causing the appearance of a large amount of molten material at the bonding interface. In view of the above problems of the traditional characteristics of the reinforcing fiber of the composite plate and the traditional explosive welding method, the technical solutions of the application will be described in detail and completely below with examples. The described examples are part of the specifications and styles in the application.

[0030] Example 1: Explosive welding of cross-intersection type rectangular Ti-W-Al-W-Ti composite plate. The size of the base composite plate is 2000mm×2000mm×(4+20)mm, and the flatness error is ≤30.73um. One base plate and two composite plates are used. The base plate material is Al5083, and the composite plate material is TA1. The cross-reinforcing fiber is pure white tungsten wire with a purity of 99%, a diameter of 0.2mm, and a length and width of 2000mm×2000mm. The implementation diagram is shown in Figure 1 .

[0031] The surface of the base plate and the bonding surface of the base plate are treated to remove the oxide skin, passivation film and oil stains, etc. on the surface, so that the active and clean surface is exposed. The base material and the composite material are leveled, and the parallelism is less than or equal to 1%. The tungsten fiber is treated by Cu coating on the surface by electroplating device, and the coating thickness is greater than or equal to 0.3 mm. After the electroplating is completed, the electroplated tungsten fiber is repeatedly cleaned in deionized water, and then dried for standby. The steel anvil plate is placed on the flat foundation, the foundation material is sand, and the buffer layer with a size of 2010 mm x 2010 mm x 5 mm, the Ti composite plate, the tungsten fiber, the Al base plate, the tungsten fiber, and the Ti composite plate are sequentially placed on the anvil plate, and the gap between the base plate and the composite plate is 3.1 mm. Then, a flat water film with a thickness of 2 mm is placed above the uppermost Ti composite plate, and the water film is as flat as possible. The explosive frame and the explosive are placed above the water film, and the detonator is placed at the central position of the explosive. The circumference of the base plate is sealed by sealing glue, and one through hole for vacuumizing is drilled at each sealing layer, and the diameter is The gap between the sealed base plates is vacuumized by a molecular vacuum pump, and the vacuum degree is about 4 x 10 -3 torr.

[0032] Example 2: Concentric circular ring type Ti-W-Al-W-Ti composite plate explosion welding. The size of the base plate is Φ1500 mm x (3+20) mm, and the flatness error is less than or equal to 20 um. One base plate and two composite plates are used, the base plate material is Al5083, and the composite plate material is TA1. The circular ring type reinforcing fiber is white tungsten wire with a purity of 99%, and the diameter is 0.2 mm. The center of the circular ring is consistent with the center of the circular ring, and the diameter difference is 10 mm.

[0033] The surface of the base plate and the bonding surface of the base plate are treated to remove the oxide skin, passivation film and oil stains, etc. on the surface, so that the active and clean surface is exposed. The base material and the composite material are leveled, and the parallelism is less than or equal to 1%. The tungsten fiber is treated by Cu coating on the surface by electroplating device, and the coating thickness is greater than or equal to 0.3 mm. After the electroplating is completed, the electroplated tungsten fiber is repeatedly cleaned in deionized water, and then dried for standby. The steel anvil plate is placed on the flat foundation, the foundation material is sand, and the buffer layer with a size of 2010 mm x 2010 mm x 5 mm, the Ti composite plate, the tungsten fiber, the Al base plate, the tungsten fiber, and the Ti composite plate are sequentially placed on the anvil plate, and the gap between the base plate and the composite plate is 3.1 mm. Then, a flat water film with a thickness of 2 mm is placed above the uppermost Ti composite plate, and the water film is as flat as possible. The explosive frame and the explosive are placed above the water film, and the detonator is placed at the central position of the explosive. The circumference of the base plate is sealed by sealing glue, and one through hole for vacuumizing is drilled at each sealing layer, and the diameter is The gap between the sealed base plates is vacuumized by a molecular vacuum pump, and the vacuum degree is about 4 x 10 -3 torr.

Claims

1. A vacuum interfacial explosive welding method of a large-area Ti-W-Al-W-Ti fiber-reinforced layered composite plate, characterized by, The layered composite plate is composed of an upper Ti composite plate, an Al base plate, a lower Ti composite plate and interlayer reinforcing fibers, and through design of stress-reducing layer structure and explosive welding method, different high-strength and different specifications of tungsten fibers are used to reinforce the multi-layer large-area layered composite plate, and the specific implementation steps are as follows: (1) Determine the Ti plate, reinforcing fiber, Al plate material and specification, reinforcing fiber structure and layering style: the Al plate is a 5 series aluminum alloy, the length and width range is 1000-5000 mm, and the thickness range is 1-20 mm; the titanium plate is 1-18 series, the length and width range is 1000-5000 mm, and the thickness range is 0.5-5 mm, the thickness ratio of the base composite plate satisfies: 1:1-1:10, the tungsten wire diameter range of the reinforcing fiber is Φ0.02-Φ0.5 mm, the wire diameter is less than half of the thickness of the composite plate, the content of tungsten in the tungsten wire is greater than 98.5%; the base plate and the composite plate have a flatness tolerance of ≦8×(1+d / 1000)um, d is the diagonal length, the roughness of the interface to be contacted is ≦100um, which is less than the microwave amplitude of the bonding area; the reinforcing fiber structure is a cross type, and the cross-shaped reinforcing fibers are symmetrically arranged in the gap between the upper and lower composite plates and the base plate; the upper composite plate, the reinforcing fiber and the lower composite plate, the reinforcing fiber are symmetric about the center plane of the base plate; (2) Constructing the static and dynamic parameters of explosive welding: collision velocity V p The upper and lower thresholds are 304-2401 m / s, according to the density of explosive ρ 0, the density of the clad plate ρ f , the thickness of the clad plate δ f The lower limit of the charge thickness parameter δ 0=(14.1-15.2) δ f ; the gap between the base plate and the clad plate s=3.1~4.1 mm; the explosive is selected as a powdery emulsion explosive with 55% quartz sand added; (3) Clean the welding surface of each plate to be welded, and use an electroplating device to prepare a Cu interface layer on the surface of the reinforcing fiber, the plating layer is uniform and sufficient, and the plating layer thickness is ≧0.3 mm; (4) Place the anvil plate on a flat sand soil foundation, and place the buffer layer, Ti composite plate, reinforcing fiber, Al base plate, reinforcing fiber, Ti composite plate on the anvil plate in sequence, then place a flat water film with a certain thickness on the uppermost Ti composite plate, place the explosive frame and explosive on the water film, and place the detonator at the center position of the explosive; (5) The side surface of adjacent base plates is sealed by sealing material, and exhaust hole for vacuumizing is reserved in each layer, and a certain vacuum degree is extracted from the sealed space, and the vacuum degree is controlled to be less than or equal to 8x10 -3 torr, and the sealing material is polyvinyl chloride vacuum sealing film.

2. The vacuum-arc explosion bonding method of a large-area Ti-W-Al-W-Ti fiber-reinforced layered composite plate according to claim 1, characterized in that The use of the buffer layer, the buffer layer on the upper surface of the anvil plate is selected to have a thickness of 3-5 mm and be as flat as possible, and the buffer rubber is adhered to the lower surface of the lower composite plate, which not only plays a buffering role, but also can avoid damage to the base composite plate caused by air in the buffer layer and air between the buffer layer and the anvil plate during the exhaust process; the buffer layer between the Ti composite plate and the explosive is a flat water film with a thickness of 2 mm and a size slightly larger than the base composite plate, which can effectively reduce the burning of the upper base composite plate by the explosive and improve the welding quality of the bonding interface.

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