Multi-layer composite explosive welding method for high-strength low-toughness metal plate and composite plate

Abstract

The invention relates to the technical field of metal material welding, in particular to a multi-layer composite explosive welding method for a high-strength low-toughness metal plate and the composite plate. The method solves the problem of multi-layer compounding of high-strength and low-toughness metal materials such as aluminum alloy, magnesium alloy and titanium alloy. The method specifically comprises the steps that aluminum alloy serves as a base plate, magnesium alloy serves as a middle plate, titanium alloy serves as a compound plate, and the base plate, the middle plate and the compound plate are stacked in sequence; a metal transition layer is arranged between adjacent layers; the gap is fixed through the supporting column; the laminated structure is sealed and vacuumized to be smaller than or equal to-0.08 MPa; uniformly smearing water glass on the surface of the compound plate to form a protective layer; an explosive containing an inert diluent is arranged above the compound plate, and the explosive is regulated and controlled; the interface bonding strength of the high-strength low-toughness metal multilayer composite board is remarkably improved, interface cracks and intermetallic compound layers are eliminated, and the prepared composite board has excellent corrosion resistance and impact resistance and can be widely applied to the fields of aerospace, weapon protection and the like.

Description

Technical Field

[0001] The present invention relates to the field of metal welding technology, specifically a method for explosively welding multilayer composite high-strength, low-toughness metal sheets and the composite sheets produced thereby. By optimizing explosive welding process parameters and structural design, this method solves the challenge of multilayer composite welding of high-strength, low-toughness heterogeneous metals such as aluminum alloys, magnesium alloys, and titanium alloys. The method is suitable for lightweight equipment manufacturing in fields such as aerospace, weapon protection, and new energy vehicles. Background Art

[0002] In high-end equipment manufacturing fields such as aerospace, weapons protection, and transportation, the requirements for the comprehensive performance of materials are becoming increasingly stringent. Although traditional single metal materials have certain advantages, they often find it difficult to simultaneously meet multiple performance requirements such as lightweight, high strength, corrosion resistance, electromagnetic shielding, shock absorption, and impact resistance when faced with complex and changing service environments. For example, aluminum alloys are widely used in the aerospace field due to their advantages such as light weight, high specific strength, and low price, but their corrosion resistance and impact resistance still need to be improved; magnesium alloys have the characteristics of low density and excellent shock absorption properties, but their strength and corrosion resistance are insufficient; titanium alloys have high strength and excellent corrosion resistance, but their high cost and processing difficulty limit their widespread application. Therefore, combining metal materials with different properties to prepare multi-layer metal composite sheets has become an effective way to solve the above problems.

[0003] Multilayer metal composite sheets, by combining two or more metal materials with different properties in layers, can not only inherit the excellent properties of each component material, but also make up for the shortcomings of a single material, achieving complementary and optimized performance. However, traditional welding methods (such as fusion welding and brazing) are difficult to achieve effective bonding between heterogeneous metals. During fusion welding, due to the differences in melting points and thermal expansion coefficients between metals, cracks and defects are easily generated at the weld; brazing is difficult to ensure interface bonding strength due to the selection and wettability of brazing filler metals. In addition, traditional welding methods will produce a large heat-affected zone during the welding process, which may lead to a decrease in material properties. Explosive welding, as a special solid-state welding process, uses the huge energy generated by the detonation of explosives to drive the composite metal and the base metal to collide obliquely at high speed, forming a metal jet, thereby achieving metallurgical bonding between heterogeneous metals. This technology has significant advantages such as high bonding strength, small heat-affected zone, strong heterogeneous metal welding capability, and high production efficiency.

[0004] Although explosive welding technology has been applied to a certain extent in the preparation of conventional bimetallic composite plates, it still faces many difficulties in the preparation of high-strength, low-toughness multilayer metal composite plates. First, the differences in physical and chemical properties between dissimilar metal materials in multilayer metal composite plates (such as thermal expansion coefficient mismatch, low solid solubility, etc.) lead to unstable interface bonding quality during welding. In addition, the plasticity of high-strength, low-toughness metals (such as magnesium alloys, hard aluminum alloys, and titanium alloys) is significantly different. During the explosive impact, microcracks and brittle intermetallic compounds are easily formed at the interface, resulting in low interface shear strength, which seriously restricts the bearing capacity of the composite plate. Secondly, the current conventional open-air explosive welding mostly uses an air medium environment. The residual gas in the gap of the multilayer plate is prone to form defects such as pores and oxidation inclusions under high-pressure impact, resulting in insufficient interface bonding rate of the composite plate. At the same time, the existing explosive welding process technology has limited control accuracy of explosive energy, which is difficult to adapt to the dynamic deformation behavior differences of multilayer heterogeneous metals, and is prone to cause overload cracking of the composite plate or rebound peeling of the substrate.

[0005] Therefore, developing an explosive welding method that can effectively solve the problem of multi-layer composite of high-strength and low-toughness metal plates has important practical significance for promoting the development of lightweight equipment structures in the fields of aerospace, weapons protection, etc. Summary of the Invention

[0006] The present invention aims to provide a multi-layer composite explosive welding method for high-strength, low-toughness metal plates, which realizes efficient composite of hard aluminum alloys, magnesium alloys, and high-strength titanium alloys through solid-phase connection technology, solves the problems of poor interface bonding quality, complex process, and inaccurate energy control in the existing technology, and prepares lightweight, high-specific strength, corrosion-resistant, and interface-defect-free composite plates.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a method for multi-layer composite explosive welding of high-strength and low-toughness metal sheets, comprising the following steps:

[0009] S1. A hard aluminum alloy is used as the substrate, a magnesium alloy as the intermediate plate, and a titanium alloy as the composite plate. The layers are stacked in the order of substrate-intermediate plate-composite plate.

[0010] S2. A solid solution metal transition layer is provided between adjacent layers;

[0011] S3. The gap is fixed by support columns. The gaps from top to bottom are 3-7mm, 2-5mm, 2-5mm, and 4-10mm.

[0012] S4. Seal the laminated structure in S1 and evacuate to ≤-0.08 MPa;

[0013] S5. Apply water glass evenly on the surface of the composite plate to form a protective layer;

[0014] S6. Place explosives containing inert diluent above the double plate and adjust the explosive detonation velocity to 1800-2500 m / s and density to 0.7-1.0 g / cm 3 , the charge height is 10-50mm;

[0015] S7. Detonate the explosive to achieve one-time welding.

[0016] In an optional embodiment, the substrate is a 2 series or 7 series aviation aluminum alloy with a thickness of 5-12 mm;

[0017] The middle plate is made of AZ31B or ZK61M magnesium alloy with a thickness of 2-4 mm;

[0018] The composite plate is made of TC4 or TC10 titanium alloy and has a thickness of 3-5 mm.

[0019] In an optional embodiment, the transition layer is industrial pure aluminum or titanium with a thickness of 0.5-2 mm.

[0020] In an optional embodiment, the support column is an aluminum cylinder with a height matching the gap.

[0021] In an optional embodiment, the local vacuum between the laminated structures is achieved by sealing the multilayer board as a whole with a sealant or a sealing bag, and evacuating the air with a vacuum pump.

[0022] In an optional embodiment, the inert diluent is quartz sand or glass microspheres, and the added amount is 5%-35% of the total mass of the explosive.

[0023] In an optional embodiment, the water glass protective layer has a coating thickness of 0.1-1 mm and is removed by water washing after explosion welding.

[0024] In an optional embodiment, the charge size of the special powdered emulsion explosive is larger than the size of the double plate, the length of the charge box is 1.2-1.5 times the length of the double plate, and the width is 1.3-1.5 times the width of the double plate.

[0025] Second aspect: The present invention provides a high-strength, low-toughness metal composite plate, which is produced by the above-mentioned high-strength, low-toughness metal plate multi-layer composite explosion welding method. The interface bonding strength of the composite plate is ≥200MPa, and it has no cracks or holes.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This invention effectively addresses the difficulty in welding high-strength, low-toughness multilayer metal sheets due to significant performance differences between them, by vacuum-treating the gaps between them. This combines precise control of explosive energy with the placement of a metal transition layer with good solid solubility. This significantly improves the interfacial bonding strength of high-strength, low-toughness metal multilayer composite sheets, ensuring their overall performance. Furthermore, by optimizing the stacking arrangement, interplate gap control, and detonation method, the composite sheet is formed in one step, significantly increasing the success rate and quality stability of explosive welding while reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 : Schematic diagram of explosive welding of high-strength, low-toughness multi-layer metal sheets, showing the detonator, explosives, water glass protective layer, gap between plates and local vacuum arrangement;

[0030] Figure 2 : Cross-sectional view of the finished product of the explosively welded multi-layer composite plate of Example 2, showing good welding quality and complete layered structure;

[0031] Figure 3 : The interface microstructure diagram of Example 2 proves that there are no obvious defects such as cracks and holes in the welding interface.

[0032] In the figure: 1. detonator; 2. explosive; 3. water glass; 4. composite plate; 5. metal transition layer; 6. intermediate plate; 7. base plate; 8. sand foundation; 9. support column; 10. local vacuum sealed space. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0034] Example 1:

[0035] 1. Material selection:

[0036] Substrate 7: 2024 hard aviation aluminum alloy (800mm×400mm×10mm)

[0037] Middle plate 6: ZK61M high-strength magnesium alloy (800mm×400mm×3mm)

[0038] Complex plate 4: TC4 titanium alloy (800mm×400mm×5mm)

[0039] Transition layer 5: 1060 industrial pure aluminum (800mm×400mm×1mm)

[0040] 2. Explosion welding process:

[0041] ① Surface treatment: The surfaces of the substrate 7, the intermediate plate 6, and the composite plate 4 are ground and polished (roughness Ra ≤ 1.6 μm), and then cleaned with acetone to remove oil stains.

[0042] ②Layer arrangement: such as Figure 1 As shown, the plates are stacked in the order of sand foundation 8 → base plate 7 → transition layer 5 → middle plate 6 → transition layer 5 → composite plate 4, and the gaps are fixed by aluminum cylindrical support columns 9. The gaps from top to bottom are 5mm, 3mm, 3mm, and 7mm respectively.

[0043] ③ Local vacuum between the plates: The laminated and fixed multi-layer plate structure is packaged in a sealed bag with an exhaust hole at the end. The inter-layer gap is evacuated to a vacuum degree of less than -0.08 MPa by a vacuum pump, forming a local vacuum sealed space 10 between the laminated multi-layer plate structure.

[0044] ④ Protective layer coating: evenly apply water glass 3 on the top of the composite plate 4, specifically liquid sodium silicate, with a coating thickness of 0.5 mm.

[0045] ⑤ Explosive 2 arrangement: Special powdered emulsion explosive 2 (density 0.87g / cm 3 , detonation velocity 2000m / s) are loosely loaded in a pre-made medicine box with a size of 1000mm×600mm×50mm, a charging height of 35mm, and covering the surface of the composite plate 4.

[0046] Quartz sand accounting for 25% of the total mass of explosive 2 is added as an inert diluent to regulate the detonation energy distribution.

[0047] ⑥ Detonation and welding: Fix the detonator 1 at the midpoint of the end of the cartridge, detonate the explosive 2, and the composite plate 4 moves at high speed under the detonation of the explosive to collide with the middle plate 6 and the base plate 7, forming a metallurgical bonding interface, such as Figure 2 shown.

[0048] 3. Welding result verification:

[0049] Interface strength: The interface bonding strength measured by shear test is 215MPa, which is higher than the 180MPa of traditional explosive welding process.

[0050] Microstructure: such as Figure 3 As shown in Figure 3, the metallographic microscope results show that the interface is a continuous metallurgical bond with obvious wavy structural characteristics and no obvious defects such as cracks and holes.

[0051] Yield rate: The one-time welding forming rate reaches 95%, with no delamination or warping defects.

[0052] Example 2:

[0053] 1. Material selection:

[0054] Substrate 8: 7075 hard aviation aluminum alloy (800mm×400mm×10mm)

[0055] Middle plate 7: ZK61M magnesium alloy (800mm×400mm×3mm)

[0056] Composite plate 4: TC4 high-strength titanium alloy (800mm×400mm×5mm)

[0057] Transition layer 5: 1060 industrial pure aluminum (800mm×400mm×1mm)

[0058] 2. Explosion welding process adjustment:

[0059] Explosive 2 parameters: density 0.75g / cm 3 , detonation velocity 1900m / s, charge height 40mm.

[0060] Gap setting: The gaps from top to bottom are 6mm, 4mm, 4mm, and 8mm respectively.

[0061] The remaining steps are the same as in Example 1.

[0062] 3. Welding result verification:

[0063] The results of metallographic microscopy showed that the interface was a continuous metallurgical bond with obvious wavy structural characteristics, without obvious defects such as cracks and holes, and the entire plate had no obvious fracture damage.

[0064] Example 3:

[0065] 1. Material selection:

[0066] Substrate 8: 7075 hard aviation aluminum alloy (800mm×400mm×8mm)

[0067] Middle plate 7: AZ31B magnesium alloy (800mm×400mm×3mm)

[0068] Composite plate 4: TC10 titanium alloy (800mm×400mm×3mm)

[0069] Transition layer 5: TA2 industrial pure titanium (800mm×400mm×1mm)

[0070] 2. Explosion welding process adjustment:

[0071] Diluent adjustment: the amount of glass microspheres added is increased to 35%, and the detonation velocity is reduced to 1800 m / s to avoid impact damage to the titanium composite plate 4 caused by high detonation velocity.

[0072] The remaining steps are the same as in Example 1.

[0073] 3. Welding result verification:

[0074] The results of a metallographic microscope (manufacturer: Shanghai Cewei Optoelectronics Technology Co., Ltd., model: LW600LJT) showed that the interface was a continuous metallurgical bond with obvious wavy structural characteristics, without obvious defects such as cracks and holes, and the overall plate had no obvious fracture damage.

[0075] In summary, the present invention forms a local vacuum sealing space 10 by vacuuming the gaps between the high-strength, low-toughness multi-layer metal plates, and combines the setting of a metal transition layer 5 with good solid solubility, thereby effectively solving the welding difficulties caused by the large performance differences between high-strength, low-toughness metals such as aluminum alloys, magnesium alloys, and titanium alloys. Based on the good gap setting and the precise control of the explosion energy of the explosive 2, the interface bonding strength and the interface bonding rate of the high-strength, low-toughness metal multi-layer composite plate are significantly improved, ensuring the overall performance of the composite plate. It is suitable for the lightweight needs of aerospace structural parts, military armor, new energy vehicle battery housings and other fields, and has broad application prospects.

[0076] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A multi-layer composite explosive welding method for high-strength and low-toughness metal sheets, characterized in that: The following steps are involved: S1. A hard aluminum alloy is used as the substrate, a magnesium alloy as the intermediate plate, and a titanium alloy as the composite plate. The layers are stacked in the order of substrate-intermediate plate-composite plate. S2. A solid solution metal transition layer is provided between adjacent layers; S3. The gap is fixed by support columns. The gaps from top to bottom are 3-7mm, 2-5mm, 2-5mm, and 4-10mm. S4. Seal the laminated structure in S1 and evacuate to ≤-0.08 MPa; S5. Apply water glass evenly on the surface of the composite plate to form a protective layer; S6. Place explosives containing inert diluent above the double plate and adjust the explosive detonation velocity to 1800-2500 m / s and density to 0.7-1.0 g / cm 3 , the charge height is 10-50mm; S7. Detonate the explosive to achieve one-time welding.

2. The multi-layer composite explosive welding method of high-strength and low-toughness metal sheets according to claim 1 is characterized in that: The substrate is 2 series or 7 series aviation aluminum alloy with a thickness of 5-12 mm; The middle plate is made of AZ31B or ZK61M magnesium alloy with a thickness of 2-4 mm; The composite plate is made of TC4 or TC10 titanium alloy and has a thickness of 3-5 mm.

3. The multi-layer composite explosive welding method of high-strength and low-toughness metal sheets according to claim 1 is characterized in that: The transition layer is made of industrial pure aluminum or titanium and has a thickness of 0.5-2 mm.

4. The multi-layer composite explosive welding method of high-strength and low-toughness metal sheets according to claim 1, characterized in that: The support column is an aluminum cylinder with a height matching the gap.

5. The multi-layer composite explosive welding method of high-strength and low-toughness metal sheets according to claim 1 is characterized in that: The local vacuum between the laminated structures is achieved by sealing the multi-layer board as a whole with a sealant or a sealing bag and evacuating the air with a vacuum pump.

6. The multi-layer composite explosive welding method of high-strength and low-toughness metal sheets according to claim 1 is characterized in that: The inert diluent is quartz sand or glass microspheres, and the added amount is 5%-35% of the total mass of the explosive.

7. The multi-layer composite explosive welding method of high-strength and low-toughness metal sheets according to claim 1 is characterized in that: The coating thickness of the water glass protective layer is 0.1-1 mm, and is removed by water washing after explosion welding.

8. The multi-layer composite explosive welding method of high-strength and low-toughness metal sheets according to claim 1, characterized in that: The charge size of the special powdered emulsion explosive is larger than the size of the double plate, the length of the charge box is 1.2-1.5 times the length of the double plate, and the width is 1.3-1.5 times the width of the double plate.

9. The high-strength, low-toughness metal multi-layer composite sheet prepared by the method according to any one of claims 1 to 8, characterized in that: The composite plate has an interface bonding strength of ≥200 MPa and is free of cracks and holes.

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