Pseudo-ginseng brass for bullets and preparation method thereof

Abstract

The invention relates to pseudo-ginseng brass for bullets, which is prepared from the following components in percentage by mass: 0.005 to 0.02 weight percent of Al (aluminum), 0.005 to 0.01 weight percent of P (phosphorus), 0.003 to 0.01 weight percent of Cr (chromium), 0.0001 to 0.009 weight percent of Fe (iron), 71.4 to 72.3 weight percent of Cu (copper), 0.0001 to 0.009 weight percent of Pb (plumbum) and the balance of Zn (zinc) and inevitable impurities, a copper-zinc phase of the pseudo-ginseng brass for the bullet is an alpha single phase, the pseudo-ginseng brass for the bullet has high strength and high plasticity, the tensile strength, the ductility and the hardness are balanced, and the requirements for high-speed large deformation and cold and hot machining of bullet shell machining, especially the deep drawing machining requirement are met; by controlling trace adding elements, the copper material has good deep drawing processing performance, self-lubricating property and excellent corrosion resistance, the excitation life of a gun barrel can be prolonged, and the requirements of long-term stable storage and coping with a certain severe environment are met.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, in particular to Panax notoginseng brass for bullets and a preparation method thereof. Background Art

[0002] Brass, a general term for copper-zinc alloys, exhibits diverse performance characteristics depending on the zinc content and additive elements, and is widely used in numerous industries. When the zinc content is below 35%, the room-temperature microstructure of brass consists entirely of an α solid solution, resulting in α-single-phase brass. This type of brass, due to its excellent plasticity, high strength, superior thermal conductivity, corrosion resistance, and machinability, has long been a popular material in machining, construction, power equipment, automotive manufacturing, desalination systems, and aerospace.

[0003] With the continuous development of military power, the military industry's demand for military consumables is growing, and the requirements for the performance of cartridge case materials are becoming increasingly stringent. In modern warfare, the widespread use of fire suppression tactics has led to a sharp increase in bullet consumption. At the same time, the high requirements for shooting accuracy and shooting speed require that cartridge case materials possess properties such as non-deformation in high-temperature firing environments, excellent self-lubrication, and easy shell extraction. In addition, the continuous optimization and upgrading of bullet processing equipment and processes has prompted the industry to pursue shorter process flows, higher production efficiency, more precise dimensional control, higher material utilization, and lower production costs. The use of brass rods instead of brass sheets for cartridge case processing has become a new development direction, which places higher demands on brass's plastic processing properties such as strength, hardness, and elongation, as well as its turning processing capabilities.

[0004] However, existing brass has significant deficiencies in meeting the material strength, hardness, elongation and structural uniformity requirements of modern bullet casings. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and provide a 37 brass for bullets having better comprehensive performance, higher tissue uniformity and meeting the requirements of modern bullet casing processing and a preparation method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention is to provide a 37 brass for bullets, which comprises, by mass percentage, 0.005wt%-0.02wt% of Al, 0.005wt%-0.01wt% of P, 0.003wt%-0.01wt% of Cr, 0.0001wt%-0.009wt% of Fe, 71.4wt%-72.3wt% of Cu, 0.0001wt%-0.009wt% of Pb, and the balance of Zn and unavoidable impurities; wherein,

[0008] The copper-zinc phase of the Panax notoginseng brass for bullets is an α single phase. The Panax notoginseng brass for bullets also has a Cu3P phase and a Cu5Si phase. The particle sizes of the Cu3P phase and the Cu5Si phase are less than 1 μm.

[0009] Aluminum is dissolved in the alloy in the form of substitutional solid solution, which can improve the fluidity of the melt and has strong deoxidation ability. By removing it through slag formation (Al2O3), aluminum can improve the strength, hardness and corrosion resistance of the material. However, excessive aluminum will reduce the plasticity of the material. If the slag is not removed completely, Al2O3 may also become a source of fatigue cracks, leading to fatigue fracture.

[0010] Phosphorus is a common deoxidizer that can reduce Cu2O inclusions and reduce the risk of porosity. An appropriate amount of phosphorus can inhibit intergranular corrosion, thereby improving the corrosion resistance of the material. Trace amounts of phosphorus can be dissolved in the α phase to form interstitial solid solutions, thereby improving the strength and hardness of the alloy. However, excessive phosphorus will reduce the fluidity of the melt, and when the P content is greater than 0.1%, Cu3P intermetallic compounds may be formed, usually with a particle size of less than 1μm. Although this can increase strength, it will reduce plasticity.

[0011] Chromium can improve the oxidation resistance of the melt and effectively reduce the oxidation loss of zinc. In addition, chromium can also enhance the material's resistance to Cl - Corrosion resistance in the environment, which is crucial to improving the stability of materials in harsh environments.

[0012] The solubility of iron in brass is extremely low (about 0.1%), and it is usually distributed in the interdendritic region in the form of iron-rich particles. During the smelting process, iron will increase the viscosity of the melt and reduce the fluidity of the melt, which can easily lead to uneven solute distribution and thus cause segregation. However, during the casting process, iron can act as a nucleating agent to hinder the growth of grains, achieve the effect of grain refinement, and thus improve the strength of the material. However, when the iron content is greater than 0.02%, the material will become brittle.

[0013] Lead exists in the alloy in a free form and easily forms a low-melting-point eutectic film with copper, which is distributed on the grain boundaries. During hot working, this will cause intergranular cracking, thereby reducing the strength, hardness and elongation of brass. However, if the lead content is controlled below 100 ppm, it will not have an adverse effect on the hot working of the material, but can reduce the possibility of side wall cracking during deep drawing.

[0014] From the Cu-Zn binary phase diagram, it can be seen that when the zinc content of ordinary brass is less than 36%, its structure is a single-phase α solid solution. Zn atoms are dissolved in the face-centered cubic Cu matrix in a substitutional manner, and the α phase structure is evenly distributed in an equiaxed shape. This structure gives brass good plasticity, excellent processing performance, high corrosion resistance, and good welding and tinning capabilities, making it suitable for hot and cold processing. In addition, as the zinc content increases, the elongation of brass at room temperature also increases. When the zinc content reaches 30%-32%, the elongation reaches its maximum value.

[0015] Preferably, the mass percentage of the unavoidable impurities is not higher than 0.3 wt %.

[0016] By precisely controlling the content of each element, especially impurity elements, the 37 brass for bullets maintains high strength and hardness while also having good plasticity and toughness, making it adaptable to various application scenarios; it has excellent cutting performance and fluidity, and is easy to process into parts of various shapes and sizes, improving production efficiency; its corrosion resistance and oxidation resistance are enhanced, allowing the brass to remain stable in harsh environments such as moisture, acid, alkali, and oceans; it complies with current environmental protection standards, reduces the impact on the environment, and is conducive to sustainable development.

[0017] Preferably, the unavoidable impurities include: one or more elements of Si, Mn, S, or Ni.

[0018] Preferably, the average grain diameter of the copper-zinc phase of the 37 brass for bullets is 35 μm-60 μm.

[0019] The 37 brass for bullets of the present invention exhibits a single-phase α structure, wherein the grain size of the α phase is between 35 μm and 60 μm and is evenly distributed in an equiaxed shape. This structure enables the brass to achieve a good balance in tensile strength, elongation and hardness, and can meet the high-speed large deformation and hot and cold processing requirements during shell processing, especially deep drawing processing requirements.

[0020] A second aspect of the present invention is to provide a method for preparing the aforementioned Panax notoginseng brass for bullets, the steps comprising:

[0021] 1) Smelting the electrolytic copper plate and zinc ingot, and then adding a slag cleaning agent to remove the slag;

[0022] Component testing: If the components meet the standards, proceed to the next step; otherwise, make compensation or dilute and return to the component testing step;

[0023] 2) performing horizontal continuous casting to obtain wire rod ingots;

[0024] 3) The wire rod ingot is sequentially subjected to a first continuous rolling, a first stretching treatment, a first peeling treatment, a first recrystallization annealing, a first pickling treatment, a second continuous rolling, a second stretching treatment, a second peeling treatment, a second recrystallization annealing, a second pickling treatment, and a finished product stretching treatment to obtain.

[0025] The main purpose of the first continuous rolling, the first stretching treatment, and the first peeling treatment is to fully proliferate dislocations through large deformation to form a high-density dislocation cell structure. The grains are gradually broken under the stress environment of biaxial compression and uniaxial tension, and the original equiaxed crystals are elongated into fibrous structures. The lattice distortion storage energy can provide a driving force for recrystallization and promote the progress of recrystallization; the second continuous rolling, the second stretching treatment, and the second peeling treatment are the same; the above-mentioned trace elements mainly exist in the copper matrix in the form of solid solution and have not reached supersaturated solid solubility. During the cold working and recrystallization annealing process, there is no secondary precipitation and re-solidification process, so it mainly plays the role of solid solution strengthening and is conducive to smelting and casting.

[0026] Recrystallization annealing, also known as intermediate annealing, is a key metalworking process. Its specific operation is: heating the workpiece that has undergone cold deformation to above the recrystallization temperature, holding it for a certain period of time, and then cooling it to promote recrystallization of the workpiece, thereby eliminating the work hardening phenomenon.

[0027] From a principle perspective, after cold working, metals or alloys will experience lattice distortion, grain breakage, and internal stress. Heating and insulation steps can promote the re-nucleation and nucleus growth process inside the metals and alloys, ultimately forming a structure without internal stress and work hardening. Taking copper alloys as an example, the conventional operation is to heat them to above the recrystallization temperature, keep them warm for a period of time, and then slowly cool them down.

[0028] When copper alloy is plastically deformed by external force, its internal dislocation lines begin to move. As the deformation deepens, the dislocation lines gradually become entangled, the dislocation density increases significantly, the grain structure is elongated and broken, and elongated deformation cells and fibrous tissue are formed, leading to the occurrence of work hardening. At this time, although the tensile strength, yield strength and hardness of the material are improved, the plasticity indicators such as elongation are declining, and the difficulty of further processing increases. Recrystallization annealing can effectively eliminate the deformation caused by the previous cold working. <110> Fiber texture eliminates cold work hardening and makes the organization present a weak random orientation texture, thereby improving plasticity, improving cutting performance and calendering forming performance, restoring plastic deformation ability, and creating favorable conditions for subsequent deformation processing.

[0029] Preferably, in step 1), the slag cleaning agent is added at 1040°C-1080°C.

[0030] Preferably, in step 1), the slag removal agent is added and then left to stand for more than 10 minutes before the slag removal process is performed.

[0031] Preferably, in step 2), the temperature of the horizontal continuous casting is 1060° C.-1100° C., and the pulling speed of the horizontal continuous casting is 120 mm / min-140 mm / min.

[0032] Preferably, in step 3), the total processing rate is greater than 50%, and the total peeling amount is greater than 50 strands.

[0033] Ensure that the grains are fully deformed and the cast structure is completely eliminated, providing favorable conditions for the redistribution of grains during recrystallization annealing.

[0034] Preferably, in step 3), the processing rate from the first continuous rolling to the first peeling treatment is 43%-48%, and the peeling amount from the first continuous rolling to the first peeling treatment is 30-50 wires.

[0035] Preferably, in step 3), the processing rate from the second continuous rolling to the second peeling treatment is 25%-28%, and the peeling amount from the second continuous rolling to the second peeling treatment is 20-30 wires.

[0036] Preferably, in step 3), the processing rate of the finished product stretching treatment is 2%-4%.

[0037] Preferably, in step 3), the temperature of the first recrystallization annealing is 550°C-580°C, and the temperature of the second recrystallization annealing is 500°C-530°C.

[0038] It is beneficial to obtain equiaxed crystal structure with a size of 30μm-60μm and achieve grain homogenization.

[0039] The present invention adopts the above technical solution, which has the following technical effects compared with the prior art:

[0040] The 37 brass for bullets provided by the present invention has a single-phase α structure in the copper-zinc phase, a grain size of 35μm-60μm, and is evenly distributed in an equiaxed shape. It combines high strength with high plasticity, achieving a balance in tensile strength, elongation, and hardness, meeting the high-speed, large deformation, and hot and cold processing requirements of cartridge case processing, especially deep drawing requirements. By controlling the amount of added elements, the copper material has good deep drawing performance, self-lubricating properties, excellent corrosion resistance, and can also extend the firing life of the gun barrel, meeting the requirements of long-term stable storage and coping with certain harsh environments.

[0041] The preparation method of Panax notoginseng brass for bullets is simple, with clear control points, high yield rate, few annealing times, high processing efficiency, good product consistency in different production batches, and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 100 times magnified view of the metallographic structure of the wire rod ingot in Example 1;

[0043] Figure 2 This is a 100-fold magnified view of the metallographic structure of Panax notoginseng brass used in the neutron bullet in Example 1;

[0044] Figure 3 This is a 200-fold magnification of the metallographic structure of Panax notoginseng brass used for neutron bullets in Example 1. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present invention may be combined with each other.

[0046] Examples 1-2 & Comparative Examples 1-5

[0047] Examples 1-2 and Comparative Examples 1-5 provide a kind of Panax notoginseng brass for bullets, and the component compositions are shown in the following table:

[0048] Table 1

[0049]

[0050]

[0051] Examples 1-2 and Comparative Examples 1-5 also provide a method for preparing Panax notoginseng brass for bullets, the steps are the same as described above, and the process parameters are shown in the following table:

[0052] Table 2

[0053]

[0054]

[0055] Note: The zinc ingot uses 0# zinc ingot; the first temperature is the temperature when the slag cleaning agent is added, the second temperature is the temperature of horizontal continuous casting, the first processing rate is the processing rate from the first continuous rolling to the first peeling treatment, the first peeling amount is the peeling amount from the first continuous rolling to the first peeling treatment, the second processing rate is the processing rate from the second continuous rolling to the second peeling treatment, the second peeling amount is the peeling amount from the second continuous rolling to the second peeling treatment, the finished product processing rate is the processing rate of the finished product stretching treatment, the first annealing temperature is the temperature of the first recrystallization annealing, and the second annealing temperature is the temperature of the second recrystallization annealing.

[0056] It is obvious that the total processing rate is the sum of the first processing rate, the second processing rate, and the finished product processing rate, and the total peeling amount is the sum of the first peeling amount and the second peeling amount.

[0057] It should be noted that step 3) of Comparative Example 4 is: sequentially subjecting the wire rod ingot to a first stretching treatment, a first peeling treatment, a first recrystallization annealing treatment, a first pickling treatment, a second stretching treatment, a second peeling treatment, a second recrystallization annealing treatment, a second pickling treatment, a third stretching treatment, a third recrystallization annealing treatment, a third pickling treatment, and a finished product stretching treatment;

[0058] Among them, the processing rate from the first stretching treatment to the first peeling treatment is 28.5%, the peeling amount from the first stretching treatment to the first peeling treatment is 50 wires, the processing rate from the second stretching treatment to the second peeling treatment is 18%, the peeling amount from the second stretching treatment to the second peeling treatment is 140 wires, the processing rate from the third stretching treatment to the third peeling treatment is 18%, the processing rate of the finished product stretching treatment is 3%, the temperature of the first recrystallization annealing is 530°C, the temperature of the second recrystallization annealing is 520°C, and the temperature of the third recrystallization annealing is 510°C.

[0059] The metallographic structure of the wire rod ingot obtained in step 2) of Example 1 is magnified 100 times as shown in FIG. Figure 1 As shown, the metallographic structure of the bullet obtained in step 3) is magnified 100 times with 37 brass. Figure 2 As shown, it can be observed that its metallographic structure is α single phase, with an average grain diameter of 0.0380 mm. The metallographic structure of the bullet prepared in step 3) is magnified 200 times as shown in FIG. Figure 3 shown.

[0060] The performance test results of the 37 brass used for bullets in Examples 1-2 and Comparative Examples 1-5 are shown in the following table:

[0061] Table 2

[0062]

[0063] Note: The tensile specimen is lathe-machined to the R1 standard specimen, and the Brinell hardness measurement points are the center point of the sample and half the radius.

[0064] There are slight differences between Example 1 and Example 2 in copper content and pass processing rate. The main purpose is to explore the process control range. The actual test results show that under the conditions of this composition and processing technology, the product performance meets the requirements; Comparative Example 1 mainly controls the copper content. The product test shows that under the same process conditions, the grain size is obviously too small and does not meet the requirements. At the same time, the tensile strength is too high, the elongation is too low, and the hardness is too high, which does not meet the performance requirements; Comparative Example 2, Comparative Example 3, and Comparative Example 5 verify the influence of trace elements on product performance. The physical properties of the actual product match poorly and cannot fully meet the requirements; Comparative Example 4 adopts a three-pass processing technology, the product plasticity is poor, and the hardness does not meet the requirements.

[0065] It can be seen that the brass provided by the present invention achieves a simultaneous improvement in strength and plasticity, and its tensile strength, elongation and hardness reach a balanced state, making it suitable for high-speed and large-deformation cold and hot deep drawing processing. Its comprehensive performance is better than that of ordinary brass. Specifically, the brass produced by the present invention has a tensile strength of 300MPa-360MPa, an elongation of more than 50%, and a Brinell hardness between 70HBW10 / 1000 and 85HBW10 / 1000.

[0066] The above description is only a preferred embodiment of the present invention and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A kind of 37 brass for bullets, characterized in that: Calculated by mass percentage, it comprises: 0.005wt%-0.02wt% Al, 0.005wt%-0.01wt% P, 0.003wt%-0.01wt% Cr, 0.0001wt%-0.009wt% Fe, 71.4wt%-72.3wt% Cu, 0.0001wt%-0.009wt% Pb, and the balance Zn and unavoidable impurities; wherein, The copper-zinc phase of the Panax notoginseng brass for bullets is an α single phase. The Panax notoginseng brass for bullets also has a Cu3P phase and a Cu5Si phase. The particle sizes of the Cu3P phase and the Cu5Si phase are less than 1 μm.

2. The 37 brass for bullets according to claim 1, characterized in that: The mass percentage of the unavoidable impurities is not higher than 0.3 wt %.

3. The 37 brass for bullets according to claim 1, characterized in that: The unavoidable impurities include one or more elements selected from Si, Mn, S, and Ni.

4. The 37 brass for bullets according to claim 1, characterized in that: The average grain diameter of the copper-zinc phase of the 37 brass for bullets is 35 μm-60 μm.

5. A method for preparing Panax notoginseng brass for bullets according to any one of claims 1 to 4, characterized in that the steps include: 1) Smelting the electrolytic copper plate and zinc ingot, and then adding a slag cleaning agent to remove the slag; Component testing: If the components meet the standards, proceed to the next step; otherwise, make compensation or dilute and return to the component testing step; 2) performing horizontal continuous casting to obtain wire rod ingots; 3) The wire rod ingot is sequentially subjected to a first continuous rolling, a first stretching treatment, a first peeling treatment, a first recrystallization annealing, a first pickling treatment, a second continuous rolling, a second stretching treatment, a second peeling treatment, a second recrystallization annealing, a second pickling treatment, and a finished product stretching treatment to obtain.

6. The preparation method according to claim 5, characterized in that In step 3), the total processing rate is greater than 50%, and the total peeling amount is greater than 50 strips.

7. The preparation method according to claim 5 or 6, characterized in that: In step 3), the processing rate from the first continuous rolling to the first peeling treatment is 43%-48%, and the peeling amount from the first continuous rolling to the first peeling treatment is 30-50 wires.

8. The preparation method according to claim 5 or 6, characterized in that: In step 3), the processing rate from the second continuous rolling to the second peeling treatment is 25%-28%, and the peeling amount from the second continuous rolling to the second peeling treatment is 20-30 wires.

9. The preparation method according to claim 5 or 6, characterized in that: In step 3), the processing rate of the finished product stretching treatment is 2%-4%.

10. The preparation method according to claim 5, characterized in that In step 3), the temperature of the first recrystallization annealing is 550°C-580°C, and the temperature of the second recrystallization annealing is 500°C-530°C.

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