A heterogeneous metal laminated composite armor and its preparation method

Abstract

The present invention discloses a heterogeneous metal laminated composite armor and a preparation method thereof, comprising the following steps: A. Prepare different heterogeneous metal elements respectively and stack them along the thickness direction; B. Vacuum package the periphery of the interface of the stacked heterogeneous metal elements; C. Achieve metallurgical bonding of the heterogeneous metal interfaces through stacked forging and heat preservation diffusion treatment; D. Obtain a heterogeneous metal laminated composite armor with specific specifications through forging and precision rolling. The present invention uses a high-strength metal as the face plate and a high-toughness metal as the back plate, and at least one of the two metals is a high specific strength material. Through stacked forging and heat preservation diffusion treatment, strong metallurgical bonding is achieved at the heterogeneous metal interfaces, and combined with subsequent forging and precision rolling processes, a lightweight metal composite armor plate with excellent anti-ballistic performance is prepared, improving the anti-multi-projectile strike ability and comprehensive protection performance of the armor, and solving the problem of weak interfacial bonding strength of heterogeneous materials.

Description

Technical Field

[0001] The present invention relates to the technical field of armor protection, and particularly relates to a heterogeneous metal laminated composite armor and a preparation method thereof. Background Art

[0002] Protective armor is crucial for enhancing the battlefield survival ability of weaponry and combatants. Currently, there are mainly two common armor structures. One is the armor structure composed of a single material, such as armor steel, titanium alloy, aluminum alloy, etc.; the other is the armor structure prepared by a composite process with different materials, such as ceramic, organic matter, fiber-reinforced composite armor. In modern warfare, the complex battlefield environment requires that the armor not only has excellent bulletproof performance but also has light weight to improve the mobility of the equipment. Among single homogeneous armor materials, armor steel has a large density and cannot meet the requirement of armor lightweight. Although aluminum alloy has a low density, its strength is also low. The aluminum alloy armor needs to increase the thickness to achieve the same protection level, resulting in an insignificant overall weight reduction effect of the armor. Titanium alloy has a high specific strength and is an ideal lightweight armor material. However, there are various types of titanium alloys, and its mechanical properties are significantly affected by the microstructure. It is difficult for a single homogeneous titanium alloy to balance strength and toughness to improve the comprehensive protection performance of the armor. Composite armor is composed of a variety of materials with different properties combined in a certain way, and has more excellent protection performance and weight reduction effect compared with the armor prepared by a single material. However, the existing composite armor has the problem of weak interfacial bonding of heterogeneous materials, and cannot fully exert the performance advantages of different materials. For example, the fracture toughness of ceramic composite armor is low, and it is prone to cracking and spattering under the action of projectile impact load, and its anti-multiple-projectile-strike ability is weak. The strength of fiber-reinforced composite material is low, and the back convex is serious after being bombarded, and the protection effect against non-penetrating damage is poor. Therefore, preparing a composite material with high specific strength and strong metallurgical bonding at the interface has become the key to solving the above problems.

[0003] Chinese Patent CN111043909A discloses a Ti-Al intermetallic compound micro-laminated composite armor and a preparation method thereof. Its technical solution is roughly as follows: (1) After pre-treating TC4 foil and Al foil, stack them in the order of TC4 - Al - TC4, and then perform vacuum hot pressing and sintering to obtain a Ti - AlTi laminated material; (2) Stack TC4 foil and Al foil in the order of TC4 - Al - TC4 to obtain a Ti - Al3Ti - Al laminated material; (3) Place the treated Al foil in the middle of the Ti - AlTi laminated material and the Ti - Al3Ti - Al laminated material, and use TC4 foil for overall encapsulation and then perform diffusion welding connection in a graphite mold to obtain the product. This patented technology adopts the method of diffusion welding connection, which can make full use of the performance advantages of different materials and improve the anti-penetration performance of the composite armor. However, the technological process of this patented technology is cumbersome, and the metallurgical degree at the interface of heterogeneous materials is weak, and there is an obvious delamination phenomenon near the bullet hole, resulting in poor comprehensive protection effect when facing multiple projectiles.

[0004] Chinese Patent CN106180729A discloses a method for preparing a metal - encapsulated intermetallic - based laminated composite armor. Its technical solution is roughly as follows: (1) Surface - treat Ti foil and Al foil, then stack them alternately and perform cold - rolling treatment; (2) After cold - rolling, use Ti foil for jacket encapsulation, and then evacuate; (3) After evacuation, perform hot - press sintering to obtain the product. This patented technology combines cold - rolling and hot - press sintering to prepare a new type of metal - encapsulated intermetallic - based laminated composite armor, and the obtained composite armor has high anti - penetration ability. However, this patented technology does not well solve the problem of weak interfacial bonding of heterogeneous materials, and delamination is likely to occur during bullet penetration, unable to fully exert the performance advantages of different materials. Summary of the Invention

[0005] The object of the present invention is: In view of the above - mentioned problems, by combining the advantages of lightweight metal materials and composite - structure materials, to provide a heterogeneous metal laminated composite armor and its preparation method. The present invention uses a high - strength metal as the face plate and a high - toughness metal as the back plate, and at least one of the two metals is a high - specific - strength material. Through multi - forging and heat - preservation diffusion treatment, metallurgical bonding of the heterogeneous metal interface is achieved, and combined with subsequent forging and precision - rolling processes, a lightweight metal composite armor plate with excellent anti - ballistic performance is prepared, improving the anti - multiple - bullet - strike ability and comprehensive protection performance of the armor, and solving the problem of weak interfacial bonding strength of heterogeneous materials.

[0006] The technical solution adopted by the present invention is as follows: A method for preparing a heterogeneous metal laminated composite armor, comprising the following steps:

[0007] A. Prepare different heterogeneous metal elements respectively and stack them along the thickness direction;

[0008] B. Vacuum - encapsulate the periphery of the interface of the stacked heterogeneous metal elements to obtain a heterogeneous metal blank, so that the interface in the middle of the blank is in a vacuum state;

[0009] C. Achieve metallurgical bonding of the heterogeneous metal interface through multi - forging and heat - preservation diffusion treatment to obtain a heterogeneous metal forged blank;

[0010] D. Obtain a heterogeneous metal laminated composite armor with specific specifications through forging and precision - rolling.

[0011] In the present invention, the heterogeneous metal elements have different properties. For example, one has high - strength performance characteristics and the other has high - toughness characteristics, and respectively meet the performance requirements of the face plate and the back plate of the composite armor. Further, the heterogeneous metal elements are metal blocks or metal thick plates obtained by forging or rolling.

[0012] In the present invention, a milling machine is used to process heterogeneous metal panels and backplates with equal length and width. The thickness ratio of the high-strength metal panel and the high-toughness metal backplate elements is approximately 2:3, and the total thickness is more than twice the thickness of the rolled armor plate after finishing. The bonding surface is polished using a diamond angle grinder, and finally, organic solvents such as acetone are used for cleaning.

[0013] Furthermore, in step B of the present invention, the polished and cleaned heterogeneous metal elements are first stacked along the bonding surface, and the interface gap is required to be less than 0.2 mm. A vacuum electron beam welder is used to seal-weld the periphery of the interface in a vacuum chamber to obtain a heterogeneous metal blank. The vacuum degree in the vacuum chamber is required to be below 0.01 Pa, and the interface welding depth is 10 - 15 mm. If the welding depth is too shallow, the interface may crack during the deformation process. Conversely, if the welding depth is too deep, there will be too much melting area at the interface. The melting area belongs to the area with poor microstructure and will be removed after subsequent finishing. Excessive depth will result in too much removal and waste of materials.

[0014] Furthermore, in step C, the multi-forging and heat preservation diffusion treatment includes pre-forging heating, forging, and post-forging heat preservation diffusion treatment.

[0015] Furthermore, a pre-forging heating and temperature equalization treatment is performed on the encapsulated heterogeneous metal blank. The pre-forging heating temperature is 0.6 - 0.8T m , where T m is the melting point of the lower melting point metal in the heterogeneous metal, with the unit of °C. The heating temperature is selected as the lower temperature among the forging temperatures of the two metals to avoid severe coarsening of its microstructure.

[0016] Furthermore, after the pre-forging heating and temperature equalization treatment of the heterogeneous metal blank, it is placed on the operating platform of a forging press and compressed and deformed along the direction perpendicular to the interface. Among them, when the heterogeneous metal element is a metal block, during forging, along the thickness direction of the heterogeneous metal element, a single-pass deformation is carried out using the overall upsetting deformation process (multiple-pass deformation will cause a large temperature drop of the specimen and a poor bonding effect, while using single-pass deformation can well avoid this problem), and the deformation amount is more than 30%; when the heterogeneous metal element is a thick metal plate, limited by the press tonnage, the drawing-type step-by-step deformation is used during forging, and the cumulative deformation amount of each section is more than 30%, and finally a heterogeneous metal forged blank is obtained.

[0017] Furthermore, the post-forging heat preservation diffusion treatment includes: putting the forged heterogeneous metal blank obtained by forging into a furnace for heat preservation treatment. The heat preservation temperature is the same as the pre-forging heating temperature, and the heat preservation time is 6 - 12 h, to obtain a heterogeneous metal multi-forged blank with strong metallurgical bonding at the heterogeneous material interface.

[0018] Furthermore, the present invention also includes a heterogeneous metal laminated composite armor, and the heterogeneous metal composite armor is prepared by the above preparation method.

[0019] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0020] 1. The heterogeneous metal laminated composite armor of the present invention realizes the light weight of the armor and excellent comprehensive anti-ballistic performance by compounding high specific strength high-strength metals and high-toughness metals, and fully utilizes the mechanical property advantages of different metals;

[0021] 2. The preparation method of the heterogeneous metal laminated composite armor realizes strong metallurgical bonding at the heterogeneous metal interface through the processes of multi-forging and heat preservation diffusion treatment, overcomes the disadvantages of weak interface bonding and weak anti-multiple strike ability of traditional heterogeneous composite armor, and effectively improves the comprehensive protection performance of the prepared composite armor; moreover, the process of preparing the metal composite armor is simple, easy to form and machine, and is suitable for industrial production and the preparation of various structural forms of armor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of the heterogeneous metal composite armor prepared by the present invention;

[0023] Figure 2 is a process flow chart of the preparation of the heterogeneous metal thick plate composite armor;

[0024] Figure 3 is the microscopic structure of the interface between TC4 and Ti386 heterogeneous titanium alloys of the heterogeneous titanium alloy thick plate metal composite armor prepared in Example 1.

[0025] In the figure, the mark: 1 is the high-strength metal panel, and 2 is the high-toughness metal back panel. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present invention will be described in detail below with reference to the drawings.

[0027] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] Example 1

[0029] A heterogeneous titanium alloy thick plate metal laminated composite armor, and its preparation method includes the following steps:

[0030] S1. Select a titanium alloy with high specific strength as the composite armor metal material to meet the requirements of the light weight of the armor structure. For example, select the high-strength metastable β-type titanium alloy Ti-3Al-8V-6Cr-4Mo-4Zr-0.2O-0.1C (Ti386, R m = 1600 MPa) and the high-toughness duplex titanium alloy Ti-6Al-4V (TC4, K IC= 66 MPa·m 1 / 2 ) are used as the faceplate and backplate materials respectively (as shown in Figure 1 ), and then Ti386 elements with specifications of 280×360×15 mm and TC4 elements with specifications of 280×360×30 mm are cut respectively;

[0031] S2. Machine the surfaces of the Ti386 element and the TC4 element using a milling machine to remove the surface contaminant layer. Use a diamond angle grinder to polish one bonding surface of 280×360 mm of Ti386 and TC4 respectively to remove the surface oxide film, expose the fresh matrix metal, and clean it with acetone (as shown in Figure 2 a);

[0032] S3. Stack the Ti386 element and the TC4 element along the bonding surface to obtain a stacked metal blank of 280×360×45 mm. Use a vacuum electron beam welder to seal the weld around the interface of the stacked metal blank in a vacuum chamber to obtain a heterogeneous metal blank. The vacuum degree in the vacuum chamber is 0.01 Pa, and the welding depth is 14 mm (as shown in Figure 2 b);

[0033] S4. Preheat the heterogeneous metal blank before forging. The heating temperature is 950 °C, and the holding time after reaching the temperature is 2 h (as shown in Figure 2 c);

[0034] S5. Perform stacked forging on the preheated and evenly heated heterogeneous metal blank. Place the blank on the operation platform of the forging press and perform stretching deformation section by section along the height direction of the blank, pressing down 30% of the total height of the heterogeneous metal blank. After deformation, a heterogeneous metal forged blank with dimensions of approximately 500×320×25 mm is obtained (as shown in Figure 2 d);

[0035] S6. Perform heat preservation and diffusion treatment on the heterogeneous metal forged blank. Return the heterogeneous metal forged blank to the furnace for heat preservation and diffusion. The heat preservation temperature is 950 °C, and the holding time after reaching the temperature is 12 h (as shown in Figure 2 e);

[0036] S7. Finish rolling the heterogeneous metal forged blank after heat preservation and diffusion treatment into a plate with a thickness of 12 mm (as shown in Figure 2 f), and straighten the heterogeneous metal plate using a straightening machine (as shown in Figure 2 g). After machining, a heterogeneous titanium alloy laminated composite armor plate is obtained (as shown in Figure 2 h).

[0037] The microscopic structure of the interface between TC4 and Ti386 heterogeneous titanium alloys of the heterogeneous titanium alloy composite armor plate prepared in Example 1 is as shown in Figure 3 , and at Figure 3In this case, no interfacial bonding voids were found at the interface of the TC4 and Ti386 heterogeneous titanium alloys, indicating that metallurgical bonding at the interface was achieved between the two.

[0038] Example 2

[0039] A heterogeneous titanium alloy thick plate metal laminated composite armor, and its preparation method includes the following steps:

[0040] S1. Select the same experimental materials as in Example 1, with the difference being the different elementary specifications, that is, cut Ti386 block elements with specifications of 150×150×80 mm and TC4 block elements with specifications of 150×150×120 mm respectively.

[0041] S2. Use a milling machine to process the surfaces of the Ti386 and TC4 elementary elements to remove the surface contaminant layer. Use a diamond angle grinder to polish one bonding surface of 150×150 mm of Ti386 and TC4 respectively to remove the surface oxide film, expose the fresh base metal, and clean it with acetone.

[0042] S3. Stack the Ti386 and TC4 elementary elements along the 150×150 mm bonding surface to obtain a stacked metal blank of 150×150×200 mm. Use a vacuum electron beam welder to seal-weld the periphery of the interface of the stacked metal blank in a vacuum chamber to obtain a heterogeneous metal blank. The vacuum degree in the vacuum chamber is 0.01 Pa, and the welding depth is 14 mm.

[0043] S4. Perform pre-forging heating on the heterogeneous metal blank, with the heating temperature being 950 °C, and hold for 3 h after reaching the temperature.

[0044] S5. Perform multi-layer forging on the heterogeneous metal blank after heating and temperature equalization. Place the blank on the operating platform of a forging press and perform single-pass upsetting deformation along the height direction of the blank, compressing 40% of the total height of the heterogeneous metal blank. After deformation, a heterogeneous metal forged blank with dimensions of approximately 190×190×120 mm is obtained.

[0045] S6. Perform heat preservation and diffusion treatment on the heterogeneous metal forged blank. Return the heterogeneous metal forged blank to the furnace for heat preservation and diffusion. The heat preservation temperature is 950 °C, and the heat preservation time after reaching the temperature is 12 h, and then forge it into a heterogeneous metal blank with specifications of 350×200×60 mm.

[0046] S7. Precision roll the 350×200×60 mm heterogeneous metal forged blank after heat preservation into a plate with a thickness of 12 mm, and use a straightening machine to straighten the heterogeneous metal plate. After machining, a heterogeneous titanium alloy laminated composite armor plate is obtained.

[0047] Comparative Example 1

[0048] Comparative Example 1 is the same as Example 1, except that when performing the drawing-type progressive deformation, 20% of the total height of the heterogeneous metal blank is pressed down.

[0049] Comparative Example 2

[0050] Comparative Example 2 is the same as Example 1, except that in step S3, the welding depth is 8 mm.

[0051] Comparative Example 3

[0052] Comparative Example 3 is the same as Example 1, except that in step S4, the heterogeneous metal blank is placed in a hot pressing furnace, a pressure of 6 MPa is applied, and it is heated to 950 °C at the same heating rate as in Example 1, held for 15 h, and then cooled in the furnace to obtain the product.

[0053] Comparative Example 4

[0054] Comparative Example 4 is the same as Example 2, except that in step S3, the stacked metal blanks are encapsulated with 100-μm TC4 foil and evacuated, and the vacuum degree at the blank interface is 0.01 Pa to obtain a vacuum-encapsulated body, and then the vacuum-encapsulated body is subjected to single-pass upsetting deformation.

[0055] Comparative Example 5

[0056] Comparative Example 5 is the same as Example 2, except that in step S5, two-pass upsetting deformation is performed. In the first pass, 20% of the total height of the heterogeneous metal blank is pressed down, and in the second pass, 20% of the total height of the heterogeneous metal blank is pressed down, with a total of 40% of the total height of the heterogeneous metal blank being pressed down.

[0057] Test Results

[0058] Tensile experiments on the interfacial metallurgical bonding degree and ballistic experiments on the anti-ballistic performance of the composite plates obtained from the above examples and comparative examples were respectively carried out. The test gun was a Type 53 7.62-mm ballistic gun, firing armor-piercing bullets with a caliber of 7.62 mm. The experimental distance was 10 m, and the penetration was perpendicular. According to GJB59.18-88, the damage levels of the target plates were analyzed. The damage levels of the target plates were divided into 8 levels. Levels 1 to 4 were qualified damages, and levels 5 to 8 were unqualified damages. The specific grading is shown in Table 1, and the tensile experimental results and ballistic damage results of the composite plates are shown in Table 2.

[0059] Table 1 Evaluation Criteria for Damage Levels of Target Plates

[0060]

[0061]

[0062] Table 2 Test Results of Related Properties of Specimens in Examples and Comparative Examples

[0063]

[0064] It can be obtained from Table 1 that:

[0065] (1) In the tensile test, the tensile strength of Example 1 and Example 2 both reached 920 MPa, and the specimens all fractured on the side of the TC4 matrix, proving that the tensile strength of the interface is higher than that of the matrix. However, the tensile strength of Comparative Examples 1-5 was significantly lower than that of Example 1 and Example 2, and the specimens all fractured at the interface. Thus, it shows that the method of the present invention realizes strong metallurgical bonding at the heterogeneous metal interface. Meanwhile, in the ballistic test, when the projectile velocity was 467 m / s, there were no bulges on the back plates of Example 1 and Example 2, and the target plate had a damage level of 1. When the projectile velocity was 495 m / s, bulges formed on the back plates of Example 1 and Example 2, reaching a damage level of 2. When the projectile velocity was 524 m / s, cracks appeared on the back plates, reaching a damage level of 4. Under the same conditions, the ballistic test results of Comparative Examples 1-5 were significantly inferior to those of Example 1 and Example 2 of the present invention. For the homogeneous TC4 armor plate, bulges and cracks formed on the back surface at a projectile velocity of 467 m / s, reaching a damage level of 4, and it was penetrated at a projectile velocity of 495 m / s, reaching the maximum damage level of 8. Thus, it shows that the overall protection effect of the heterogeneous metal composite plate prepared by the present invention is far superior to that of the homogeneous armor plate.

[0066] (2) By comparing Example 1 with Comparative Example 1, it is obtained that when the deformation amount is insufficient, the interfacial tensile strength of the obtained heterogeneous metal composite plate significantly decreases, and the anti-ballistic effect in the ballistic test becomes poor. Thus, it shows that when forging, insufficient deformation amount will affect the metallurgical bonding effect of the heterogeneous metal composite plate, and further affect the overall protection effect of the composite plate;

[0067] (3) By comparing Example 1 with Comparative Example 2, it is obtained that when the welding depth is insufficient, the tensile strength of the obtained heterogeneous metal composite plate significantly decreases, and the anti-ballistic effect in the ballistic test becomes poor. Thus, it shows that the interfacial welding depth will affect the metallurgical bonding strength at the heterogeneous metal interface, thereby affecting the overall protection effect;

[0068] (4) By comparing Example 1 with Comparative Example 3, it is obtained that using the existing hot pressing and sintering method, the protection improvement effect is difficult to compare with that of the forging and heat preservation diffusion treatment adopted by the present invention;

[0069] (5) By comparing Example 2 with Comparative Example 4, it is obtained that using the existing vacuum package encapsulation method, the protection improvement effect is significantly inferior to that of the vacuum sealing welding adopted by the present invention;

[0070] (6) By comparing Example 2 with Comparative Example 5, it is obtained that the protection improvement effect of multi-pass upsetting deformation is inferior to that of single-pass upsetting deformation.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a heterogeneous metal laminated composite armor, characterized in that, Including the following steps: A. Prepare two heterogeneous metal elements with different properties respectively and stack them along the thickness direction; among them, a metal element with high strength performance is required to be used as the composite armor panel, and a metal element with high toughness performance is used as the composite armor back panel. The heterogeneous metal elements are metal blocks obtained by forging or rolling; B. Use a vacuum electron beam welder to perform vacuum sealing welding on the periphery of the interface of the stacked heterogeneous metal elements to achieve vacuum packaging; among them, the required vacuum degree is below 0.01 Pa, and the interface welding depth is 10 - 15 mm; C. Achieve metallurgical bonding of the heterogeneous metal interface through multi-pass forging and heat preservation diffusion treatment; wherein, the multi-pass forging and heat preservation diffusion treatment includes pre-forging heating, forging, and post-forging heat preservation diffusion treatment, and the pre-forging heating temperature is 0.6 - 0.8T m , where T m is the melting point of the lower melting point metal in the heterogeneous metal, with the unit of °C; the forging treatment includes: single-pass deformation along the thickness direction of the heterogeneous metal element during forging, with a deformation amount of more than 30%; the post-forging heat preservation diffusion treatment includes: returning the forged heterogeneous metal billet to the furnace for heat preservation treatment, with the heat preservation temperature being the same as the pre-forging heating temperature, and the heat preservation time being 6 - 12h; D. Obtain a heterogeneous metal laminated composite armor with specific specifications through forging and precision rolling.

2. The preparation method of the heterogeneous metal laminated composite armor according to claim 1, characterized in that, In step A, the heterogeneous metal elements are of equal length and width, and the total thickness after stacking along the thickness direction is not less than 2 times the thickness of the heterogeneous metal composite armor obtained by precision rolling.

3. The preparation method of the heterogeneous metal laminated composite armor according to claim 1, characterized in that, In step A, the preparation of the heterogeneous metal elements includes surface machining, grinding treatment of the bonding surface, and cleaning with organic solvents.

4. A heterogeneous metal laminated composite armor, characterized in that, The heterogeneous metal laminated composite armor is prepared by the preparation method described in any one of claims 1 - 3 above.

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