Free-cutting tellurium brass

Abstract

According to the free-cutting tellurium brass, components and a treatment process of copper alloy are designed in the scheme, tellurium is matched with elements such as zirconium and tin, so that the copper alloy has good mechanical and machining performance, and the mechanical performance, cutting performance and the like of the copper alloy are further improved through subsequent treatment procedures such as continuous extrusion and cold deformation.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to free-cutting tellurium brass. Background Art

[0002] Tellurium brass is a high-conductivity, free-cutting copper alloy with good corrosion resistance, electrical ablation resistance, and hot and cold processing properties. It can be used for forging, casting, stamping, and molding, and is widely used in electronics, electrical appliances, railway transportation, connectors, and other fields. However, since the second phase Cu2Te is relatively soft and has little effect on hindering the movement of dislocations, the mechanical properties of tellurium copper cannot meet the demand. For this reason, the market often uses a large amount of components that enhance mechanical properties to be added to copper. Although this improves the mechanical properties, such as tensile strength, it can easily lead to a decrease in cutting performance and needs to be improved. Summary of the invention

[0003] To solve at least one of the above technical defects, the present invention provides the following technical solutions:

[0004] This application document discloses a free-cutting tellurium brass, comprising the following preparation steps:

[0005] First, the predetermined raw materials are melted and cast, and the component proportions are detected before casting as follows: 58-68wt% copper, 0.05-0.07wt% tellurium, 0.001-0.005wt% zirconium, 0.08-0.15wt% tin, 0.06-0.12wt% iron, 0.0001-0.0006wt% boron, 0.0001-0.0006wt% phosphorus, 0.05-0.07wt% nickel, 0.005-0.008% lanthanum, and the balance is zinc and unavoidable impurities;

[0006] Second, the cast rod is continuously extruded;

[0007] Third, cold deformation treatment is performed on the cast rod after continuous extrusion treatment;

[0008] Fourth, the bar formed after cold deformation is annealed.

[0009] In this scheme, the composition and processing technology of the copper alloy are designed. The copper alloy has good mechanical and processing properties through the combination of tellurium with zirconium, tin and other elements. The mechanical properties and cutting performance of the copper alloy are further improved through subsequent continuous extrusion, cold deformation and other processing procedures.

[0010] Further, the raw material is melted and the molten metal is cast to form a cast rod with a diameter of 11-14 mm, and the cast rod with a diameter of 11-14 mm is extruded into a rod with a mass of 7-9 mm in a continuous extrusion process.

[0011] Furthermore, during the continuous extrusion process, the speed of the extrusion wheel is 5.0-6.5 rpm, which helps to promote the spheroidization of the second phase particles and the grain refinement of the alloy, thereby improving the mechanical properties and electrical conductivity of the alloy.

[0012] Furthermore, during the cold deformation process, the cold deformation amount is 70-90%; during the annealing process, the annealing temperature is 350-420°C and the time is 2-5h. Annealing at this temperature helps to reduce dislocation density, vacancies, bond deformation defects, etc., and helps to improve conductivity.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The present invention designs a tellurium brass alloy, which has good cutting performance while maintaining high conductivity and high strength. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with specific embodiments.

[0016] Example 1

[0017] A free-cutting tellurium brass comprises the following preparation steps:

[0018] First, the furnace temperature is raised to 1000°C, the prepared raw materials are added for smelting, and samples are taken for testing. The component proportions are adjusted as follows: 60wt% copper, 0.05wt% tellurium, 0.003wt% zirconium, 0.08wt% tin, 0.08wt% iron, 0.0003wt% boron, 0.0002wt% phosphorus, 0.05wt% nickel, 0.005% lanthanum, and the remainder is zinc and inevitable impurities. The cast rod is cast by a continuous casting process, and the diameter of the cast rod is 12mm.

[0019] Second, the cast rod is subjected to continuous extrusion treatment. The temperature of the cast rod is preheated to 400°C, and then extruded. The extrusion wheel speed is 6 rpm, and the extrusion process is stopped when the cast rod forms a rod body with a diameter of 8 mm.

[0020] Third, the cast rod after continuous extrusion treatment is subjected to cold deformation treatment, and the cast rod is formed into a rod body with a diameter of 3.0 mm by drawing.

[0021] Fourth, the bar formed after cold deformation treatment is annealed at a temperature of 400°C for 3 hours.

[0022] Example 2

[0023] A free-cutting tellurium brass comprises the following preparation steps:

[0024] Second, the furnace temperature is raised to 1030°C, the prepared raw materials are added for smelting, and samples are taken for testing. The component proportions are adjusted as follows: 62wt% copper, 0.06wt% tellurium, 0.002wt% zirconium, 0.09wt% tin, 0.09wt% iron, 0.0004wt% boron, 0.0003wt% phosphorus, 0.06wt% nickel, 0.006% lanthanum, and the remainder is zinc and unavoidable impurities. The cast rods are cast by a continuous casting process, and the diameter of the cast rods is 11mm.

[0025] Second, the cast rod is subjected to continuous extrusion treatment. The temperature of the cast rod is preheated to 400° C., and then extruded. The extrusion wheel speed is 5.5 rpm, and the extrusion process is stopped after the cast rod forms a rod body with a diameter of 7 mm.

[0026] Third, the cast rod after continuous extrusion treatment is subjected to cold deformation treatment, and the cast rod is formed into a rod body with a diameter of 3.0 mm by drawing.

[0027] Fourth, the bar formed after cold deformation treatment is annealed at a temperature of 410°C for 2.5 hours.

[0028] Example 3

[0029] A free-cutting tellurium brass comprises the following preparation steps:

[0030] Third, the furnace temperature is raised to 1000°C, the prepared raw materials are added for smelting, sampling is carried out, and the component proportions are adjusted as follows: 65wt% copper, 0.06wt% tellurium, 0.004wt% zirconium, 0.10wt% tin, 0.09wt% iron, 0.0005wt% boron, 0.0003wt% phosphorus, 0.06wt% nickel, 0.007% lanthanum, and the remainder is zinc and inevitable impurities. The cast rod is cast by a continuous casting process, and the diameter of the cast rod is 14mm.

[0031] Second, the cast rod is subjected to continuous extrusion treatment. The temperature of the cast rod is preheated to 400° C., and then extruded. The extrusion wheel speed is 6.5 rpm, and the extrusion process is stopped when the cast rod forms a rod body with a diameter of 9 mm.

[0032] Third, the cast rod after continuous extrusion treatment is subjected to cold deformation treatment, and the cast rod is formed into a rod body with a diameter of 3.0 mm by drawing.

[0033] Fourth, the bar formed after cold deformation treatment is annealed at a temperature of 420°C for 2 hours.

[0034] Comparative Example 1

[0035] Compared with Example 3, there is no cold deformation treatment process in this example.

[0036] The copper alloy prepared as above was tested for performance, wherein the cutting performance was tested in accordance with the nonferrous industry standard YS / T648-2007, and the corresponding classification was determined according to the cutting morphology, as shown in Table 1.

[0037] Table 1

[0038] tensile strength Cutting shape Example 1 575MPa Category I Example 2 589MPa Category I Example 3 584MPa Category I Comparative Example 1 427MPa Category 3

[0039] It can be seen that under the limited component ratio of this scheme, cold deformation treatment can effectively improve the tensile strength of copper alloy. The reason is that cold drawing deformation increases the dislocation density in the alloy, increases dislocation entanglement, and some fine second phases are distributed on the dislocation lines and the matrix. At the same time, the grains are elongated during cold drawing deformation, and along a certain direction, the grains present typical fibrous stripes. The second phase is distributed along the deformation direction during cold deformation, presenting strips and bands, with large size and large area distributed along the grain boundaries, which correspondingly improves the cutting performance.

[0040] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A free-cutting tellurium brass, characterized in that: The method comprises the following preparation steps: First, the predetermined raw materials are melted and cast, and the component proportions are detected before casting as follows: 58-68wt% copper, 0.05-0.07wt% tellurium, 0.001-0.005wt% zirconium, 0.08-0.15wt% tin, 0.06-0.12wt% iron, 0.0001-0.0006wt% boron, 0.0001-0.0006wt% phosphorus, 0.05-0.07wt% nickel, 0.005-0.008% lanthanum, and the balance is zinc and unavoidable impurities; Second, the cast rod is continuously extruded; Third, cold deformation treatment is performed on the cast rod after continuous extrusion treatment; Fourth, the bar formed after cold deformation is annealed.

2. The free-cutting tellurium brass according to claim 1, characterized in that: The raw material is melted and the molten metal is cast into a cast rod with a diameter of 11-14 mm, and the cast rod with a diameter of 11-14 mm is extruded into a rod with a mass of 7-9 mm in a continuous extrusion process.

3. The free-cutting tellurium brass according to claim 2, characterized in that: The speed of the extrusion wheel during the continuous extrusion process was 5.0-6.5 rpm.

4. The free-cutting tellurium brass according to claim 1, characterized in that: During the cold deformation process, the cold deformation amount is 70-90%; during the annealing process, the annealing temperature is 350-420°C and the time is 2-5h.