A method for producing a tin bronze ingot

Abstract

The application discloses a preparation method of tin bronze ingot, which comprises the following steps: introducing copper water into a casting cavity of a crystallizer and then drawing the ingot out; the crystallizer comprises a body, a cooling water groove extending in the up-down direction is arranged on the body, and the cooling water groove is provided with a second water outlet facing upward; the casting cavity is arranged on the body and penetrates through the body in the up-down direction, and the number of the casting cavities is at least two and the casting cavities are arranged in the circumferential direction of the cooling water groove at intervals. On the one hand, the supercooling degree is increased, the crystallization potential is increased, and it is beneficial to obtain finer grains; on the other hand, the dendrites are reduced, the tin segregation problem is improved, the ingot organization is uniform as a whole, the plasticity is high, the performance consistency is high, the problems of cracking and wire breaking in the subsequent drawing are eliminated. The elongation of the cast blank is greater than or equal to 40%, and the tensile strength is greater than or equal to 450 MPa.

Description

Technical Field

[0001] This invention belongs to the field of copper alloy technology, specifically relating to a method for preparing tin bronze ingots. Background Technology

[0002] The casting technology for copper and copper alloys includes horizontal continuous casting, downward semi-continuous casting, upward continuous casting, and casting. Horizontal continuous casting has advantages such as high flexibility, high production efficiency, and relatively stable product quality. Therefore, it is widely used in the casting of wires, bars, and strips of brass, bronze, and cupronickel. Among them, the preparation of tin bronze wire usually adopts the horizontal continuous casting process to cast ingots.

[0003] When using horizontal continuous casting for tin bronze QSn6.5-0.1 and C54400, a porous crystallizer is used to achieve higher efficiency. However, this results in numerous quality problems with the horizontally cast ingots, such as microstructure segregation, cracking, porosity, inclusions, low elongation, and inconsistent tensile strength and hardness, leading to a higher product defect rate. Analysis of these quality problems reveals that the core cause is uneven cooling performance and insufficient cooling intensity during the casting process. This results in coarse grains and well-developed dendrites, causing severe local microstructure segregation. This directly manifests as an elongation below 38% and a tensile strength below 450 MPa. During subsequent wire drawing, this leads to wire breakage, poor straightness, large diameter fluctuations, and finished products with hollow centers, inclusions, and cracks.

[0004] Improving the uniformity and intensity of cooling in casting, refining the grain structure, and optimizing the microstructure and properties are technical problems that need to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing tin bronze ingots with small component segregation, fine grains, high plasticity and high performance consistency.

[0006] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a method for preparing tin bronze ingots, wherein molten copper is introduced into the casting cavity of a crystallizer and then cast into ingots; characterized in that: the crystallizer includes

[0007] The main body has a cooling water tank extending in the vertical direction, and the cooling water tank has a second water outlet facing upward; the casting cavity is arranged on the main body and runs vertically through it, and the number of the casting cavity is at least two, which are spaced apart around the circumference of the cooling water tank.

[0008] A cooling water jacket is fitted around the body and there is a gap between the body and the body. The body and the cooling water jacket together define a cooling cavity. The cooling water jacket has an inlet and a first outlet that are in fluid communication with the cooling cavity. The cooling water tank is in fluid communication with the cooling cavity.

[0009] Preferably, a first water-blocking plate is provided between the main body and the cooling water jacket, and the first water-blocking plate extends in the vertical direction. The first water-blocking plate divides the cooling cavity into an inner cooling cavity located between the first water-blocking plate and the main body and an outer cooling cavity located between the first water-blocking plate and the cooling water jacket. There are gaps between the first water-blocking plate and the top and bottom walls of the cooling cavity for water to flow through. A second water-blocking plate is provided between the first water-blocking plate and the cooling water jacket, and the second water-blocking plate divides the outer cooling cavity into an upper cooling cavity and a lower cooling cavity. The water inlet is located above the second water-blocking plate, and the first water outlet is located below the second water-blocking plate.

[0010] The cooling chamber is divided into an inner cooling chamber and an outer cooling chamber by setting a first baffle plate to avoid water flow directly impacting the copper sleeve and causing uneven cooling rate of the billet. The second baffle plate divides the outer cooling chamber into an upper cooling chamber and a lower cooling chamber. Cooling water enters the upper cooling chamber from the inlet, and the annular water flow gradually flows upward and evenly into the inner cooling chamber. At the same time, the water flow enters the cooling water tank to achieve uniform cooling of the middle and the outside of the billet.

[0011] Preferably, the distance between the first baffle plate and the main body is 1-3 mm. With a constant total water pressure, controlling the distance between the first baffle plate and the main body allows for rapid water flow, ensuring both high heat exchange efficiency and smooth water flow.

[0012] Preferably, the water inlet is located near the bottom of the second baffle plate, and the first water outlet is higher than the bottom wall of the first baffle plate. This arrangement allows the water to flow downwards and then upwards, which helps maintain the water pressure within the inner cooling chamber. A certain pressure can increase the heat storage capacity of the water flow and ensure uniform pressure in the narrow water gap, so that the entire inner cooling chamber is filled with water, achieving uniform cooling while improving subcooling.

[0013] Preferably, the main body is provided with a water flow channel connecting the cooling chamber and the cooling water tank. The water flow channel is arranged horizontally and is adjacent to the bottom of the cooling water tank. The water flows from the bottom of the cooling water tank upwards, which is more conducive to achieving uniform cooling of the ingot.

[0014] Preferably, there are four casting cavities and four water flow channels, which are arranged between adjacent casting cavities.

[0015] Preferably, the temperature difference between the water inlet and the first outlet is controlled above 35°C. A higher temperature difference results in higher heat exchange efficiency, while a temperature below 35°C reduces overall casting efficiency and makes it impossible to guarantee the casting speed.

[0016] Preferably, secondary cooling water is installed 30-100 mm from the crystallizer outlet. A distance below 30 mm results in coarse grains in the microstructure, while a distance above 100 mm reduces the cooling effect, significantly decreasing its impact on the crystallization of the casting melt.

[0017] Compared with the prior art, the advantages of this invention are as follows: A cooling water tank extending vertically is provided in the main body, and the cooling water tank has an upward-facing second outlet. The casting cavity is located on the main body and is vertically connected. There are at least two casting cavities, spaced circumferentially along the cooling water tank. The cooling water tank and the cooling cavity are in fluid communication, which solves the problem of insufficient cooling in the middle part of the crystallizer, achieving uniform cooling of the ingot and enhancing the cooling intensity. On the one hand, it increases the supercooling, thereby increasing the crystallization potential energy and facilitating the acquisition of finer grains. On the other hand, it reduces dendrites, improving the tin segregation problem. The resulting ingot has a uniform overall structure, high plasticity, and high performance consistency, eliminating problems such as cracking and wire breakage during subsequent wire drawing. The elongation of the cast billet is ≥40%, and the tensile strength is ≥450MPa. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the crystallizer according to an embodiment of the present invention.

[0019] Figure 2 This is a cross-sectional view of the crystallizer according to an embodiment of the present invention.

[0020] Figure 3 This is a cross-sectional view of the crystallizer according to an embodiment of the present invention.

[0021] Figure 4 This is a metallographic photograph (magnified 200x) of the ingot from Embodiment 1 of the present invention.

[0022] Figure 5 This is a metallographic photograph (magnified 200x) of the ingot from Embodiment 2 of the present invention.

[0023] Figure 6 This is a metallographic photograph (magnified 200x) of the ingot of Comparative Example 2 of this invention. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] This invention provides 5 embodiments and 5 comparative examples. The components of the embodiments are shown in Table 1. The embodiments use the crystallizer of this invention for casting. The crystallizer 1 includes a body 11 and a cooling water jacket 12.

[0026] The main body 11 has a cooling water tank 14 extending vertically, and the cooling water tank 14 has an upward-facing second outlet 142. Four casting cavities 111 are disposed on the main body 11 and extend vertically through it, spaced circumferentially along the cooling water tank 14. A cooling water jacket 12 is fitted around the main body 11, with a gap between it and the main body 11. The main body 11 and the cooling water jacket 12 together define the cooling cavity. The cooling water jacket 12 has an inlet 121 and a first outlet 122 that are in fluid communication with the cooling cavity. A water flow channel 15 is provided on the main body 11, connecting the cooling cavity and the cooling water tank 14. The water flow channel 15 is horizontally positioned and adjacent to the bottom of the cooling water tank 14. Four water flow channels 15 are arranged between adjacent casting cavities 111.

[0027] A first water-blocking plate 16 is provided between the main body 11 and the cooling water jacket 12, and is sleeved around the main body 11. The first water-blocking plate 16 extends vertically and divides the cooling cavity into an inner cooling cavity 131 located between the first water-blocking plate 16 and the main body 11, and an outer cooling cavity 132 located between the first water-blocking plate 16 and the cooling water jacket 12. There are gaps between the first water-blocking plate 16 and the top and bottom walls of the cooling cavity for water flow. A second water-blocking plate 17 is provided between the first water-blocking plate 16 and the cooling water jacket 12, and is sleeved around the first water-blocking plate 16. The second water-blocking plate 17 divides the outer cooling cavity 132 into an upper cooling cavity 1321 and a lower cooling cavity 1322. The water inlet 121 is located above the second water-blocking plate 17, and the first water outlet 122 is located below the second water-blocking plate 17. The distance between the first water-blocking plate 16 and the main body 11 is 1-3 mm. The inlet 121 is located near the bottom of the second baffle plate 17, and the first outlet 122 is higher than the gap between the first baffle plate 16 and the bottom wall of the cooling chamber.

[0028] The specifications of the tin bronze ingots in the example are as follows: The preparation method is as follows:

[0029] 1) Smelt in a 1.5t industrial frequency furnace, and prepare the materials according to the required composition. During the feeding process, add calcined charcoal with a thickness of 100mm to 150mm. After the feeding is completed, the melt temperature is 1240℃ to 1260℃. Add slag remover to remove slag, and then cover with charcoal again with 100mm to 150mm. Then refine. After refining, take a sample for composition spectrum testing at a temperature of 1200℃ to 1240℃. After the composition is qualified, start preparing for casting.

[0030] 2) After the molten copper is introduced into the casting chamber of the crystallizer, the ingot is cast. The casting temperature is 1240-1260℃. The surface of the melt is covered with charcoal with a thickness of 150mm to 200mm. The temperature difference between the water inlet 121 and the first outlet 122 is controlled above 35℃. The water pressure is 0.28MPa. The secondary cooling water is 50mm away from the crystallizer outlet.

[0031] The difference between Comparative Example 1 and Example 1 is that the crystallizer used is a conventional crystallizer, that is, without the cooling water tank 14, the first baffle plate 16 and the second baffle plate 17.

[0032] The difference between Comparative Example 2 and Example 2 is that the crystallizer used is a conventional crystallizer, that is, without the cooling water tank 14, the first water baffle 16 and the second water baffle 17.

[0033] The difference between Comparative Example 3 and Example 3 is that the crystallizer used is a conventional crystallizer, that is, without the cooling water tank 14, the first water baffle 16 and the second water baffle 17.

[0034] The difference between Comparative Example 4 and Example 4 is that the crystallizer used is a conventional crystallizer, that is, without the cooling water tank 14, the first water baffle 16 and the second water baffle 17.

[0035] The difference between Comparative Example 5 and Example 5 is that the crystallizer used is a conventional crystallizer, that is, without the cooling water tank 14, the first baffle plate 16 and the second baffle plate 17.

[0036] The following performance tests were performed on the obtained embodiments and comparative examples:

[0037] Grain size testing: according to the national standard GB / T 6394-2017 Method for determination of average grain size of metals.

[0038] Chemical composition analysis: The casting billet end face was cut open and divided into left 1 / 2, 0, right 1 / 2, upper 1 / 2 and lower 1 / 2 for spectral testing.

[0039] Mechanical property testing: The room temperature tensile test was conducted in accordance with GB / T 228.1-2010 Metallic materials, tensile testing - Part 1: Room temperature test method, on an electronic universal mechanical property testing machine, using a 20mm wide specimen with a head, and a tensile speed of 5mm / min.

[0040] The same drawing process was used on the obtained embodiments and comparative examples.

[0041] Table 1. Ingredient composition / wt% of the embodiments of the present invention

[0042] Example 1 C54400 3.6 0.02 4.1 4.3 margin Example 2 QSn6.5-0.1 6.2 0.2 - - margin Example 3 C54400 3.7 0.03 4.2 4.2 margin Example 4 QSn6.5-0.1 6.3 0.18 - - margin Example 5 QSn6.5-0.1 6.4 0.16 - - margin

[0043] Table 2. Grain size, Sn content, elongation, and tensile strength of the embodiments and comparative examples of the present invention.

[0044]

[0045] Table 3 Performance of wires in embodiments and comparative examples of the present invention

[0046]

Claims

1. A method for preparing tin bronze ingots, comprising introducing molten copper into the casting cavity (111) of a crystallizer (1) and then casting the ingot; characterized in that: The crystallizer (1) includes The main body (11) has a cooling water tank (14) extending in the vertical direction, and the cooling water tank (14) has an upward-facing second outlet (142); the casting cavity (111) is arranged on the main body (11) and is vertically connected, and the number of casting cavities (111) is at least two, and they are arranged at intervals along the circumference of the cooling water tank (14). A cooling water jacket (12) is fitted around the body (11) and there is a gap between the body (11) and the body (11). The body (11) and the cooling water jacket (12) together define a cooling cavity. The cooling water jacket (12) is provided with an inlet (121) and a first outlet (122) that are in fluid communication with the cooling cavity. The cooling water tank (14) is in fluid communication with the cooling cavity. A first water-blocking plate (16) is provided between the main body (11) and the cooling water jacket (12), and is sleeved around the main body (11). The first water-blocking plate (16) extends in the vertical direction and divides the cooling cavity into an inner cooling cavity (131) located between the first water-blocking plate (16) and the main body (11) and an outer cooling cavity (132) located between the first water-blocking plate (16) and the cooling water jacket (12). There are gaps between the first water-blocking plate (16) and the top and bottom walls of the cooling cavity for water to flow through. A second water baffle (17) is provided between the first water baffle (16) and the cooling water jacket (12), which is sleeved around the first water baffle (16). The second water baffle (17) divides the outer cooling cavity (132) into an upper cooling cavity (1321) and a lower cooling cavity (1322). The water inlet (121) is located above the second water baffle (17) and adjacent to the bottom of the second water baffle (17). The first water outlet (122) is located below the second water baffle (17) and higher than the bottom wall of the first water baffle (16). The main body (11) is provided with a water flow channel (15) connecting the cooling chamber and the cooling water tank (14). The water flow channel (15) is arranged in a horizontal direction and is adjacent to the bottom of the cooling water tank (14).

2. The method for preparing tin bronze ingots according to claim 1, characterized in that: The distance between the first water-blocking plate (16) and the body (11) is 1 to 3 mm.

3. The method for preparing tin bronze ingots according to claim 1, characterized in that: The number of casting cavities (111) is 4, and the number of water flow channels (15) is 4, which are arranged between adjacent casting cavities (111).

4. The method for preparing tin bronze ingots according to claim 1, characterized in that: The temperature difference between the water inlet (121) and the first water outlet (122) is controlled to be above 35℃.

5. The method for preparing tin bronze ingots according to claim 1, characterized in that: A secondary cooling water source is provided at a distance of 30-100 mm from the outlet of the crystallizer (1).

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