Silicon bronze bar and method for producing the same

Abstract

The application provides a silicon bronze bar and a preparation method thereof. The silicon bronze bar contains the following elements and mass percentages: Si: 2.5-3.8 wt%, Mn: 1.0-1.8 wt%, Ni: 0.5-2.0 wt%, Fe: 0.01-0.3 wt%, Zn: 0.01-0.5 wt%, and the balance of Cu and inevitable impurities. The microstructure of the cross section of the silicon bronze bar includes alpha phase, Ni2Si phase, Fe3Si phase and Mn2Si phase, and the area ratio of the Mn2Si phase is 4-8%. The alloy composition and microstructure are designed, and the content ranges of Si, Mn, Ni and Fe elements are controlled. The microstructure of the silicon bronze bar has second phase particles of Ni2Si, Fe3Si and Mn2Si with certain sizes in addition to the matrix phase alpha phase. The Ni2Si phase and Fe3Si phase are strengthening phases, which can improve the strength of the alloy. The Mn2Si phase is a brittle phase, and the area ratio of the Mn2Si phase is controlled, so that the silicon bronze bar has high strength and excellent cutting performance.

Description

Technical Field

[0001] This invention relates to the field of copper alloy technology, and more specifically, to a silicon bronze rod and its preparation method. Background Technology

[0002] Silicon bronze is a special type of bronze with silicon (Si) as the main alloying element, and in addition to Si, elements such as manganese (Mn) are also added. QSi3-1 is a representative grade of silicon bronze, corresponding to the American standard grade C65500. Its main alloying elements are Si and Mn, and its chemical composition is: Si: 2.7–3.5 wt%, Mn: 1.0–1.5 wt%, Fe ≤ 0.3 wt%, Ni ≤ 0.2 wt%, Sn ≤ 0.25 wt%, Pb ≤ 0.03 wt%, Zn ≤ 0.5 wt%, and total impurities ≤ 1.1 wt%. QSi3-1 can be pressure-processed in both cold and hot states and is currently widely used in the machinery, chemical, petroleum, and shipbuilding industries.

[0003] Silicon bronze possesses excellent mechanical properties, corrosion resistance, wear resistance, and ease of welding, making it suitable for manufacturing fasteners, elastic elements, and wear-resistant parts that operate in corrosive media. However, when used as fasteners and elastic elements, silicon bronze requires high material strength. The highest tensile strength of existing QSi3-1 bars can only reach 800 MPa, which cannot meet the requirements of specific fields that demand both high strength and excellent straightness. This is because QSi3-1 is a deformation-strengthened alloy, with its strength primarily obtained through high-processing-rate deformation strengthening. Due to the strong work hardening effect, while the tensile strength increases, the yield strength also increases. The high yield strength leads to difficulties in straightening the bars. Bars with poor straightness will run around during machining on a Swiss-type CNC lathe, causing deviations in part tolerances. Furthermore, QSi3-1's chemical composition does not contain elements that facilitate chip breaking, resulting in poor machinability and failing to meet the requirements of high-speed machining on CNC lathes. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to provide a silicon bronze rod with excellent straightness, high strength and good machinability.

[0005] To solve the above-mentioned technical problems, the present invention provides a silicon bronze rod containing the following elements and mass percentages: Si: 2.5-3.8 wt%, Mn: 1.0-1.8 wt%, Ni: 0.5-2.0 wt%, Fe: 0.01-0.3 wt%, Zn: 0.01-0.5 wt%, with the balance being Cu and unavoidable impurities. The microstructure of the cross-section of the silicon bronze rod includes α phase, Ni2Si phase, Fe3Si phase and Mn2Si phase, with the Mn2Si phase accounting for 4%-8% of the area.

[0006] This invention designs the alloy composition and microstructure, and controls the content range of Si, Mn, Ni, and Fe elements. In addition to the matrix α phase, the microstructure of silicon bronze also contains Ni2Si, Fe3Si, and Mn2Si second-phase particles of a certain size. The Ni2Si and Fe3Si phases are strengthening phases that can improve the alloy strength, while the Mn2Si phase is a brittle phase. By controlling the proportion of the Mn2Si phase, the silicon bronze rod has high strength and excellent machinability.

[0007] In a preferred or optional embodiment, the Ni2Si particles are smaller than 200 μm, the Fe3Si phase particles are smaller than 100 μm, and the Mn2Si particles are smaller than 3 μm. The size of the second-phase particles is designed to ensure the alloy's machinability.

[0008] In a preferred or optional embodiment, the silicon bronze rod includes <111> Directional fiber texture and <100> Directional fiber texture, the <111> The directional fiber texture area accounts for 60% to 80%, the aforementioned <100> The area ratio of directional fiber texture is 10% to 20%. <111> Directional fiber texture has a stronger effect on improving the strength of silicon bronze than <100> Directional fiber texture, <100> The effect of directional fiber texture on the plasticity of silicon bronze is less than <111> Directional fiber texture, by designing the proportion of fiber texture, can improve the mechanical properties of materials such as strength and plasticity.

[0009] In a preferred or optional embodiment, the silicon bronze rod has a tensile strength ≥900 MPa, a yield strength ratio of 0.8–0.9, and a straightness ≤0.3 mm / m. The silicon bronze rod of the present invention has high strength, and by controlling the yield strength ratio below 0.9, excellent straightness is ensured after straightening.

[0010] In a preferred or optional embodiment, the silicon bronze rod has a cutting performance index ≥ 60% compared to leaded brass HPb63-3, where the cutting performance index = (cutting force of silicon bronze rod / cutting force of HPb63-3) × 100%. The silicon bronze rod exhibits good cutting performance, meeting the requirements of high-speed machining on CNC lathes.

[0011] Another aspect of the present invention provides a method for preparing the above-mentioned silicon bronze rod, comprising the following steps:

[0012] S1. Smelting: Mixing materials according to the required composition and melting all the metal;

[0013] S2, Horizontal Continuous Casting;

[0014] S3. High-temperature annealing: The annealing temperature is 630-750℃, and the holding time is 60-180min;

[0015] S4, Circular stretching;

[0016] S5. Medium-temperature annealing: A two-stage annealing process is adopted. The first-stage annealing temperature is 360-450℃ and the holding time is 120-240min. The second-stage annealing temperature is 480-570℃ and the holding time is 60-120min.

[0017] S6, Leave a bottom stretch;

[0018] S7. Low-temperature annealing: Low-temperature annealing is carried out under an inert gas protective atmosphere. The low-temperature annealing temperature is 230-300℃ and the holding time is 180-360min.

[0019] S8, Joint Pull-up.

[0020] The preparation method of the present invention uses a special heat treatment process to induce the formation of strengthening phases Ni2Si and Fe3Si and brittle phase Mn2Si in the alloy, and controls the size and proportion of the strengthening phase and brittle phase to prepare high-strength, easy-to-cut silicon bronze rods.

[0021] In a preferred or optional embodiment, step S2 employs a pull-stop-reverse-pull traction process. The casting temperature is 1150–1250°C, the cooling water inlet temperature of the crystallizer is 15–30°C, the cooling water pressure is 0.2–0.6 MPa, the outlet water temperature is 20–40°C, the traction speed is 0.4–1.5 m / min, the traction pitch is 2–15 mm, the first reverse-pull length is 0.1–1.5 mm, the second reverse-pull length is 0.01–0.2 mm, and the billet size is Φ10–20 mm. This special horizontal continuous casting process facilitates the crystallization and formation of the alloy liquid, improving the surface quality of the billet.

[0022] In a preferred or optional embodiment, step S4 specifically includes continuously stretching the cast billet into a wire blank of intermediate specifications on a wire drawing machine, with a processing rate of 50% to 70%. This step stretches the cast billet into a wire blank, and controlling the processing rate ensures uniform deformation of the inner and outer layers of the wire blank.

[0023] In a preferred or optional embodiment, step S6 specifically includes stretching the wire blank to the specified allowable size on a wire drawing machine, with a processing rate of 40% to 55%. This allowable stretching achieves a high processing rate deformation, further improving the strength of the wire blank.

[0024] In a preferred or optional embodiment, step S8 specifically includes processing the wire rod into finished bars of the required specifications through an integrated process of drawing, polishing, straightening, cutting, and end-flattening on a combined drawing unit. The finished bars prepared by this invention have high strength and easy-to-cut properties, and excellent straightness. Attached Figure Description

[0025] Figure 1This is a metallographic photograph (500X) of the silicon bronze rod material of Example 1 of the present invention.

[0026] Figure 2 This is a metallographic photograph (500X) of the silicon bronze rod material of Comparative Example 11 of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] It should be noted that similar symbols and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] A specific embodiment of the present invention provides a silicon bronze rod containing the following elements and mass percentages: Si: 2.5-3.8 wt%, Mn: 1.0-1.8 wt%, Ni: 0.5-2.0 wt%, Fe: 0.01-0.3 wt%, Zn: 0.01-0.5 wt%, impurities, and the balance being Cu. Its chemical composition is shown in the table below.

[0031] Table 1. Composition of Silicon Bronze Alloy Material

[0032] 2.5-3.8 1.0-1.8 0.5-2.0 0.01-0.3 0.01-0.5 <0.1 margin

[0033] The microstructure of the cross-section of silicon bronze rods includes α phase, Ni2Si phase, Fe3Si phase and Mn2Si phase. Ni2Si phase and Fe3Si phase are strengthening phases that can improve the strength of the alloy, while Mn2Si phase is a brittle phase that can improve the machinability of the alloy.

[0034] The specific design principles of the alloy composition are as follows:

[0035] Si: The maximum solubility of Si can reach 5.3% at 852℃, but it decreases as the temperature decreases. Part of Si enhances the strength of silicon bronze through solid solution strengthening, and another part enhances the strength of silicon bronze by forming Ni2Si and Fe3Si strengthening phases with Ni and Fe. When the Si content is below 2.5wt%, no matter how the content of other alloying elements and processing technology are adjusted, the tensile strength of the alloy cannot reach above 900MPa. When the Si content exceeds 3.8wt%, the tendency of silicon bronze to self-crack in the natural aging state intensifies, mainly because Si combines with Mn to form a large number of brittle Mn2Si phases. Therefore, the Si content of the silicon bronze in this invention is controlled at 2.5-3.8wt%.

[0036] Mn: Mn is dissolved in copper and can improve the strength of silicon bronze. In the alloy of this invention, the Mn content is appropriately controlled between 1.0 and 1.8 wt%. When the Mn content is less than 1.0 wt%, on the one hand, the strength of the alloy is not easy to reach 900 MPa, and on the other hand, Mn is completely dissolved in Cu, and there is no excess Mn to form the Mn2Si brittle phase with Si to improve the machinability of silicon bronze. When the Mn content exceeds 1.8 wt%, the amount of Mn2Si brittle phase in the alloy is too large, which reduces the plasticity of the alloy, limits the machinability, and cannot fully utilize the work hardening effect to improve the strength of the alloy.

[0037] Ni: In the silicon bronze alloy of this invention, Ni forms the compound Ni2Si with Si. When they precipitate from the solid solution, they can significantly improve the strength of the alloy. The solubility of Ni2Si in Cu decreases with decreasing temperature and is almost zero at room temperature. When the Ni content is less than 0.5 wt%, the amount of Ni2Si compound formed is small and the precipitation strengthening effect is weak. When the Ni content exceeds 2 wt%, the Ni2Si compound is prone to agglomeration, and the mechanical properties deteriorate.

[0038] Fe: Fe has extremely low solubility in silicon bronze. Trace amounts of Fe play two roles in silicon bronze. First, Fe exceeding the solubility precipitates as Fe-rich phase particles, which act as "artificial crystal nuclei" to refine the microstructure and inhibit the growth of recrystallized grains during annealing, thereby improving the strength of the alloy. Second, a small amount of Fe can reduce the tendency of silicon bronze bars to self-crack under natural aging. However, when Fe exceeds 0.3wt%, the size of the Fe3Si phase grows from granular to blocky and strip-like, resulting in poor cold working properties of the alloy.

[0039] Zn: Zn is more reactive than Si and Mn. A small amount of Zn can prevent oxygen in the melt from combining with Si and Mn to form SiO2 and MnO oxides, thus preventing Si and Mn oxides from remaining in the melt. Zn can also narrow the liquid-solid range of silicon bronze, preventing porosity in the ingot. The lower limit of the effective Zn content is not less than 0.01 wt%, but the maximum Zn content should not exceed 0.5 wt%, otherwise the corrosion resistance of the alloy will deteriorate.

[0040] In a specific embodiment, the method for preparing silicon bronze rods includes the following steps:

[0041] S1, Smelting

[0042] Prepare the required ingredients and melt them in an induction furnace at a temperature of 1100–1280°C. After all the metal has melted and the composition has been tested and found to be qualified, keep it at the desired temperature.

[0043] S2, Horizontal Continuous Casting

[0044] The process employs a pull-stop-reverse thrust traction technique. The billet size is Φ10~20mm, the casting temperature is 1150~1250℃, the cooling water inlet temperature of the crystallizer is 15~30℃, the cooling water pressure is 0.2~0.6Mpa, the outlet water temperature is 20~40℃, the traction speed is 0.4~1.5m / min, the traction pitch is 2~15mm, the first reverse thrust length is 0.1~1.5mm, the second reverse thrust length is 0.01~0.2mm, and the duty cycle is 10%~50%.

[0045] S3, High-temperature annealing

[0046] The annealing temperature is 630–750℃, the time to rise from room temperature to this temperature is 40–90 min, and the holding time is 60–180 min. High-temperature annealing has two purposes: first, it promotes the complete dissolution of Si, Mn, and Ni elements into Ni2Si and Mn2Si second-phase particles in the alloy matrix, preparing for precipitation in subsequent heat treatment; second, it allows solid metal atoms to diffuse, eliminates inhomogeneities in the as-cast composition and structure, improves the plasticity of the cast billet, and provides a basis for high-rate stretching in the next process.

[0047] S4, Circular stretching

[0048] Φ10~20mm billets are continuously stretched to φ6~14mm on a wire drawing machine, and the total machining rate needs to be controlled between 50% and 70%. If the machining rate is too low, the uneven deformation of the inner and outer layers of the billet will easily lead to stress cracking after annealing. If the machining rate is too high, the yield strength ratio will increase. When the yield strength ratio exceeds 0.9, it will result in poor straightness after the bar is straightened.

[0049] S5, Medium-temperature annealing

[0050] The effect of medium-temperature annealing is to promote the precipitation of Ni2Si, Fe3Si, and Mn2Si second phases that have been fully dissolved during high-temperature annealing, thereby improving the strength and machinability of the alloy. Since Ni2Si, Fe3Si, and Mn2Si have different precipitation temperatures, a two-stage annealing process is employed. The first-stage annealing temperature is 360–450℃, with a heating time of 30–60 min from room temperature and a holding time of 120–240 min. The purpose is to preferentially allow the Ni2Si and Fe3Si phases, which have lower precipitation temperatures, to precipitate from the matrix. The second-stage annealing temperature is 480–570℃, with a heating time of 30–60 min from room temperature and a holding time of 60–120 min. The purpose is to allow the Mn2Si phase, which has a higher precipitation temperature, to fully precipitate from the matrix. If the first and second stage annealing temperatures exceed the upper limit, excessive precipitation of the precipitated phase will occur, and the precipitated phase will begin to grow. If the annealing temperature is below the lower limit, the second phase will not precipitate sufficiently. If the annealing time is shorter than the lower limit, the second phase will not precipitate sufficiently, affecting the precipitation strengthening effect and machinability of the alloy. Conversely, if the annealing time is too long, the second phase will agglomerate and grow, which will also reduce the precipitation strengthening effect and machinability of the alloy. Limiting the heating time is crucial. If the heating time is less than 30 minutes, the heating rate will be too fast, and the set temperature may be exceeded. If the heating time exceeds 60 minutes, the heating rate will be too slow, and the actual annealing time of the billet will be longer.

[0051] S6, Leave a bottom stretch

[0052] The φ6~14mm wire blank is drawn on the wire drawing machine to the minimum specification of φ3.3~9mm. The minimum drawing rate needs to reach 40%~55% to further improve the strength through high deformation rate.

[0053] S7, Low-temperature annealing

[0054] Low-temperature annealing is performed under an inert gas protective atmosphere. The annealing temperature is 230–300℃, with a heating time of 30–60 minutes from room temperature to this temperature and a holding time of 180–360 minutes. Low-temperature annealing serves two purposes: first, it eliminates residual stress, which negatively impacts subsequent drawing and straightening processes; second, it eliminates phase transformation stress, which can lead to spontaneous cracking of the bar stock. If the annealing temperature is too low, stress elimination will be incomplete; if the annealing temperature is too high, reaching the medium-temperature annealing temperature, it can easily lead to the growth of precipitates, reducing precipitation strengthening and machinability; if the low-temperature annealing time is less than 180 minutes, stress elimination will be incomplete; if the low-temperature annealing time is too long, the production cycle will be prolonged. Limiting the heating time is crucial; if it is less than 30 minutes, the heating rate will be too fast, potentially exceeding the set temperature; if the heating time exceeds 60 minutes, the heating rate will be too slow, resulting in a longer actual annealing time for the billet.

[0055] S8, Joint Pull

[0056] The wire rod is processed into finished bars with specifications of φ3~8.6mm×2000~3000mm through an integrated process of drawing, polishing, straightening, cutting and flattening on the combined drawing unit.

[0057] S9. Finished Product Inspection

[0058] After the above-mentioned special cold deformation and heat treatment processes, the microstructure of the silicon bronze rod is as follows: the size of the Ni2Si phase is less than 200 μm, the size of the Fe3Si phase is less than 100 μm, the size of the Mn2Si particles is less than 3 μm, and the area ratio of the Mn2Si phase is 4-8%; including <111> Directional fiber texture and <100> Directional fiber texture, <111> The area ratio of directional fiber texture is 60% to 80%. <100> The area ratio of directional fiber texture is 10% to 20%.

[0059] The properties of silicon bronze bars are as follows: tensile strength Rm≥900Mpa, elongation A%≥4, yield strength ratio of 0.8~0.9, straightness≤0.3mm / m, and machinability index ≥60% compared with leaded brass HPb63-3. Machinability index = cutting force of silicon bronze bar / cutting force of HPb63-3 ×100%.

[0060] The technical solution and effects of the present invention will be illustrated below with specific embodiments.

[0061] Example 1

[0062] A silicon bronze rod with a diameter of φ6mm is prepared by the following method:

[0063] 1) Smelting: Mix the required ingredients and then smelt them in an induction furnace at a temperature of 1150-1200℃. After all the metal has melted and the composition has been tested and found to be qualified, keep it at the temperature.

[0064] 2) Horizontal continuous casting: The billet specification is Φ14mm, the casting temperature is 1180~1220℃, the inlet temperature of the cooling water in the crystallizer is 18~20℃, the cooling water pressure is 0.3~0.4Mpa, and the outlet temperature is 22~26℃; the traction parameters are as follows: traction speed is 0.5m / min, traction pitch is 6mm, the first reverse thrust length is 0.6mm, the second reverse thrust length is 0.06mm, and the duty cycle is 25%.

[0065] 3) High-temperature annealing: The annealing temperature is 700℃, the time to rise from room temperature to this temperature is 60 minutes, and the holding time is 150 minutes.

[0066] 4) Wire rod stretching: Φ14mm billet is continuously stretched to φ8.8mm, with a total machining rate of 60.5%.

[0067] 5) Medium-temperature annealing: The φ8.8mm wire rod adopts a two-stage annealing process. The first-stage annealing temperature is 400℃, the time from room temperature to this temperature is 35min, and the holding time is 180min; the second-stage annealing temperature is 540℃, the time from room temperature to this temperature is 45min, and the holding time is 90min.

[0068] 6) Drawing with a minimum allowable diameter: The annealed φ8.8mm wire rod is continuously drawn to a minimum allowable diameter of φ6.5mm, with a processing rate of 45.4%.

[0069] 7) Low-temperature annealing: The φ6.5mm wire rod is annealed at a low temperature under an inert gas protective atmosphere. The low-temperature annealing temperature is 280℃, the time to rise from room temperature to this temperature is 30min, and the holding time is 240min.

[0070] 8) Combined drawing: φ6.5mm wire rods are processed into φ6.5mm×2500mm bars through an integrated process of drawing, polishing, straightening, cutting and flattening on a combined drawing unit.

[0071] 9) Finished product inspection. Its metallographic structure photograph (500X) is as follows: Figure 1 As shown.

[0072] Example 2

[0073] A silicon bronze rod with a diameter of φ8mm is prepared by the following method:

[0074] 1) Smelting: Mix the required ingredients and then smelt them in an induction furnace at a temperature of 1130-1220℃. After all the metal has melted and the composition has been tested and found to be qualified, keep it at the temperature.

[0075] 2) Horizontal continuous casting: The billet specification is Φ20mm, the casting temperature is 1200~1250℃, the inlet temperature of the cooling water in the crystallizer is 22~25℃, the cooling water pressure is 0.35~0.42Mpa, and the outlet temperature is 26~30℃; the traction parameters are as follows: traction speed is 0.32m / min, traction pitch is 4.8mm, the first reverse thrust length is 0.35mm, the second reverse thrust length is 0.03mm, and the duty cycle is 30%.

[0076] 3) High-temperature annealing: The annealing temperature is 750℃, the time to rise from room temperature to this temperature is 80 minutes, and the holding time is 120 minutes.

[0077] 4) Wire rod stretching: Φ18mm billet is continuously stretched to φ12mm, with a total machining rate of 55.6%.

[0078] 5) Medium-temperature annealing: The φ12mm wire rod adopts a two-stage annealing process. The first-stage annealing temperature is 450℃, the time from room temperature to this temperature is 60min, and the holding time is 150min; the second-stage annealing temperature is 570℃, the time from room temperature to this temperature is 60min, and the holding time is 90min.

[0079] 6) Drawing with a blank: The annealed φ12mm wire rod is continuously drawn to the blank specification of φ8.6mm, with a processing rate of 48.6%.

[0080] 7) Low-temperature annealing: The φ8.6mm wire rod is annealed at a low temperature under an inert gas protective atmosphere. The low-temperature annealing temperature is 300℃, the time to rise from room temperature to this temperature is 40min, and the holding time is 210min.

[0081] 8) Combined drawing: φ8.6mm wire rods are processed into φ8.6mm×2500mm bars through an integrated process of drawing, polishing, straightening, cutting and flattening on a combined drawing unit.

[0082] 9) Finished product inspection.

[0083] Example 3

[0084] A silicon bronze rod with a diameter of φ4mm is prepared by the following method:

[0085] 1) Smelting: Mix the required ingredients and then smelt them in an induction furnace at a temperature of 1140-1260℃. After all the metal has melted and the composition has been tested and found to be qualified, keep it at the temperature.

[0086] 2) Horizontal continuous casting: The billet specification is Φ10mm, the casting temperature is 1190~1240℃, the inlet temperature of the cooling water in the crystallizer is 25~28℃, the cooling water pressure is 0.4~0.5Mpa, and the outlet temperature is 28~32℃; the traction parameters are as follows: traction speed is 0.6m / min, traction pitch is 8mm, the first reverse thrust length is 0.8mm, the second reverse thrust length is 0.08mm, and the duty cycle is 35%.

[0087] 3) High-temperature annealing: The annealing temperature is 700℃, the time to rise from room temperature to this temperature is 50 minutes, and the holding time is 150 minutes.

[0088] 4) Wire rod stretching: Φ10mm billet is continuously stretched to φ6.5mm, with a total machining rate of 57.8%.

[0089] 5) Medium-temperature annealing: The φ6.5mm wire rod adopts a two-stage annealing process. The first-stage annealing temperature is 420℃, the time from room temperature to this temperature is 50min, and the holding time is 200min; the second-stage annealing temperature is 540℃, the time from room temperature to this temperature is 45min, and the holding time is 100min.

[0090] 6) Drawing with a minimum allowable diameter: The annealed φ6.5mm wire rod is continuously drawn to a minimum allowable diameter of φ4.4mm, with a processing rate of 54.2%.

[0091] 7) Low-temperature annealing: The φ4.4mm wire rod is annealed at a low temperature under an inert gas protective atmosphere. The low-temperature annealing temperature is 230℃, the time to rise from room temperature to this temperature is 30min, and the holding time is 360min.

[0092] 8) Combined drawing: φ4.4mm wire rods are processed into φ4mm×2500mm bars through an integrated process of drawing, polishing, straightening, cutting and flattening on a combined drawing unit.

[0093] 9) Finished product inspection.

[0094] Comparative Example 1

[0095] The difference between Comparative Example 1 and Example 1 is that the Si content is 2.32 wt%, while the remaining alloy composition and preparation method are the same as in Example 1. Comparative Example 1 is used to illustrate the effect of Si content below 2.5 wt% on the mechanical properties of silicon bronze.

[0096] Comparative Example 2

[0097] The difference between Comparative Example 2 and Example 1 is that the Mn content is 0.84 wt%, while the remaining alloy composition and preparation method are the same as in Example 1. Comparative Example 2 is used to illustrate the effect of Mn content below 1.0 wt% on the mechanical and machinability of silicon bronze.

[0098] Comparative Example 3

[0099] The difference between Comparative Example 3 and Example 1 is that the Ni content is 0.046 wt%, while the remaining alloy composition and preparation method are the same as in Example 1. Comparative Example 3 is used to illustrate the effect of not adding Ni on the mechanical properties of silicon bronze.

[0100] Comparative Example 4

[0101] The difference between Comparative Example 4 and Example 1 is that the Fe content is 0.027 wt%, while the remaining alloy composition and preparation method are the same as in Example 1. Comparative Example 4 is used to illustrate the effect of not adding Fe on the mechanical properties of silicon bronze.

[0102] Comparative Example 5

[0103] The difference between Comparative Example 5 and Example 1 is that the billet in Comparative Example 5 is directly coiled and stretched without high-temperature annealing, while the alloy composition and other steps are the same as in Example 1. Comparative Example 5 is used to illustrate the effect of the high-temperature annealing step on the mechanical and machinability of silicon bronze.

[0104] Comparative Example 6

[0105] The difference between Comparative Example 6 and Example 1 is that the intermediate-temperature annealing step only involves the first stage of annealing, while the alloy composition and other steps are the same as in Example 1. Comparative Example 6 is used to illustrate the effect of the staged intermediate-temperature annealing step on the mechanical and machinability of silicon bronze.

[0106] Comparative Example 7

[0107] The difference between Comparative Example 7 and Example 1 is that the intermediate-temperature annealing step only involves the second stage of annealing, while the alloy composition and other steps are the same as in Example 1. Comparative Example 7 is used to illustrate the effect of the staged intermediate-temperature annealing step on the mechanical and machinability of silicon bronze.

[0108] Comparative Example 8

[0109] The difference between Comparative Example 8 and Example 1 is that the finishing process in Comparative Example 8 had a finishing rate of 34.6%, while the alloy composition and other steps were the same as in Example 1. Comparative Example 8 is used to illustrate the effect of a finishing rate of less than 40% on the mechanical and machinability of silicon bronze.

[0110] Comparative Example 9

[0111] The difference between Comparative Example 9 and Example 1 is that the finishing process in Comparative Example 9 had a finishing rate of 61.2%, while the alloy composition and other steps were the same as in Example 1. Comparative Example 9 is used to illustrate the effect of a finishing rate higher than 55% on the mechanical and machinability properties of silicon bronze.

[0112] Comparative Example 10

[0113] The difference between Comparative Example 10 and Example 1 is that low-temperature annealing is not performed before the combined drawing in the preparation method, while the alloy composition and other steps are the same as in Example 1. Comparative Example 10 is used to illustrate the effect of the low-temperature annealing step on the mechanical and machinability of silicon bronze.

[0114] Comparative Example 11

[0115] Comparative Example 11 is a finished QSi3-1 φ6mm×2500mm bar purchased from the market, and its metallographic structure photograph (500X) is as follows. Figure 1 As shown.

[0116] The alloy compositions of the three examples and eleven comparative examples are shown in Table 2 below.

[0117] Table 2 Chemical composition of each example and comparative example

[0118]

[0119]

[0120] The tensile strength, yield strength, elongation, machinability index, and straightness of the three examples and eleven comparative examples were tested, and the results are recorded in Table 3. The test methods are as follows:

[0121] Tensile strength, yield strength and elongation: tested in accordance with GB / T228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature".

[0122] Cutting performance index: The cutting force is calculated based on the cutting force of the cutting force tester and compared with that of leaded brass HPb63-3. Then, the cutting performance index is obtained according to the formula: Cutting performance index = Cutting force of silicon bronze bar / Cutting force of HPb63-3 × 100%.

[0123] Straightness: Tested in accordance with GB / T26303.2-2010 "Methods for Dimensional Inspection of Copper and Copper Alloy Processed Materials Part 2: Bars, Wires and Profiles".

[0124] Table 3 Mechanical and cutting properties of each embodiment and comparative example

[0125]

[0126]

[0127] The phase size, area ratio, and texture area ratio of the three examples and 11 comparative examples were tested and the results are recorded in Table 4. The test method was to observe and measure using a scanning electron microscope backscattered electron diffraction device (EBSD).

[0128] Table 4 Microstructure of each embodiment and comparative example

[0129]

[0130]

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon bronze rod, characterized in that, Containing the following elements and mass percentages: Si: 2.5–3.8 wt%, Mn: 1.0–1.8 wt%, Ni: 0.5–2.0 wt%, Fe: 0.01–0.3 wt%, Zn: 0.01–0.5 wt%, with the balance being Cu and unavoidable impurities. The microstructure of the cross-section of the silicon bronze rod includes α phase, Ni₂Si phase, Fe₃Si phase, and Mn₂Si phase, with the Mn₂Si phase accounting for 4%–8% of the area; the Ni₂Si phase has a size less than 200 μm, the Fe₃Si phase has a size less than 100 μm, and the Mn₂Si phase has a size less than 3 μm; the silicon bronze rod comprises… <111> Directional fiber texture and <100> Directional fiber texture, the <111> The directional fiber texture area accounts for 60% to 80%, the aforementioned <100> The area ratio of directional fiber texture is 10% to 20%.

2. The silicon bronze rod according to claim 1, characterized in that, The silicon bronze rod has a tensile strength ≥900MPa, a yield strength ratio of 0.8~0.9, and a straightness ≤0.3mm / m.

3. The silicon bronze rod according to claim 1, characterized in that, The cutting performance index of the silicon bronze rod is ≥60% compared with that of leaded brass HPb63-3. The cutting performance index is calculated as: (Cutting force of silicon bronze rod / Cutting force of HPb63-3) × 100%.

4. A method for preparing silicon bronze rods as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Smelting: Mixing materials according to the required composition and melting all the metal; S2, Horizontal Continuous Casting; S3. High-temperature annealing: The annealing temperature is 630-750℃, and the holding time is 60-180min; S4, Circular stretching; S5. Medium-temperature annealing: A two-stage annealing process is adopted. The first-stage annealing temperature is 360-450℃ and the holding time is 120-240min. The second-stage annealing temperature is 480-570℃ and the holding time is 60-120min. S6, Leave a bottom stretch; S7. Low-temperature annealing: Low-temperature annealing is carried out under an inert gas protective atmosphere. The low-temperature annealing temperature is 230-300℃ and the holding time is 180-360min. S8, Joint Pull-up.

5. The method for preparing silicon bronze rods according to claim 4, characterized in that, In step S2, a pull-stop-reverse traction process is adopted. The casting temperature is 1150-1250℃, the inlet temperature of the cooling water in the crystallizer is 15-30℃, the cooling water pressure is 0.2-0.6MPa, the outlet temperature is 20-40℃, the traction speed is 0.4-1.5m / min, the traction pitch is 2-15mm, the first reverse thrust length is 0.1-1.5mm, and the second reverse thrust length is 0.01-0.2mm.

6. The method for preparing silicon bronze rods according to claim 5, characterized in that, Step S4 specifically includes continuously stretching the billet to an intermediate specification wire blank on a wire drawing machine, with a processing rate of 50% to 70%.

7. The method for preparing silicon bronze rods according to claim 6, characterized in that, Step S6 specifically includes stretching the wire blank to the specified size in a wire drawing machine, with a processing rate of 40% to 55%.

8. The method for preparing silicon bronze rods according to claim 7, characterized in that, Step S8 specifically includes the process of drawing, polishing, straightening, cutting, and flattening the wire rod into finished bar stock on a combined drawing unit.

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