Copper-nickel-silicon alloy strip for connector and production method thereof

Abstract

The invention discloses a copper-nickel-silicon alloy strip for a connector and a production method thereof. The chemical composition and weight percentage of the copper-nickel-silicon alloy strip for the connector are: Ni 1.5-3.0%, Si 0.30-0.75%, Mg 0.01-0.05%, P≤0.03%, Zn 0.05-0.20%, wherein Ni / Si=4.1-4.4, and the balance is copper and inevitable impurities; by controlling the Ni / Si ratio and adopting the strengthening combination mode of cold working-solid solution treatment-aging treatment-cold working for production, the composite strengthening effect of aging strengthening and cold deformation strengthening is achieved, and the simultaneous improvement of mechanical properties and electrical properties is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of copper alloy strips, and in particular relates to a copper-nickel-silicon alloy strip for connectors and a production method thereof. Background Art

[0002] Connectors are essential components for current and signal transmission and exchange in electronic system equipment. Connectors are electronic devices that transmit and exchange current or optical signals between electronic system equipment. They can connect different systems into a whole through the transmission of current or optical signals, and prevent signal distortion or energy loss between systems. They are essential basic components for the entire system. Depending on the medium transmitted by the connector, connectors can be mainly divided into three categories: electrical connectors, microwave radio frequency connectors, and optical connectors. Downstream application areas include automotive, communications, consumer electronics, industry, rail transit, military, and aerospace.

[0003] At present, the number of vehicle connectors required for a single ordinary vehicle model is about 600-1000. As the degree of electrification and intelligence of automobiles deepens, users have higher requirements for the comfort and intelligence of driving. The number of signal connectors has increased significantly, and the demand for high-speed connectors will also usher in an explosion. As the leading new energy vehicle companies begin to deploy 800V fast charging technology, the high voltage of new energy vehicles means that higher requirements are placed on the performance of copper alloy materials used in automotive connectors.

[0004] To ensure the reliability and durability of the connector, high-performance connector copper-based materials are required to have high strength and high conductivity. However, the traditional Cu-Ni-Si alloy copper strip undergoes a heat treatment production process, resulting in uneven structure and large grain size, which leads to poor conductivity of the alloy and affects the subsequent use of the product. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a copper-nickel-silicon alloy strip for connectors and a production method thereof. By controlling the Ni / Si ratio and adopting a strengthening combination of cold working-solution treatment-aging treatment-cold working for production, the composite strengthening effect of aging strengthening and cold deformation strengthening is achieved, and the simultaneous improvement of mechanical properties and electrical properties is realized.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The invention provides a copper-nickel-silicon alloy strip for a connector. The chemical composition and weight percentage of the copper-nickel-silicon alloy strip for the connector are: Ni 1.5-3.0%, Si 0.30-0.75%, Mg 0.01-0.05%, P≤0.03%, Zn 0.05-0.20%, wherein Ni / Si=4.1-4.4, and the balance is copper and unavoidable impurities.

[0008] The copper-nickel-silicon alloy strip for the connector has a tensile strength of 580-650 MPa, a yield strength of 540-600 MPa, a hardness of 180-200 HV, a conductivity of 50-60% IACS, and an elongation of ≥8%.

[0009] The present invention also provides a production method of the copper-nickel-silicon alloy strip for the connector, which comprises the following steps: smelting → casting → sawing → heating in a walking furnace → hot rolling → online quenching → milling → rough rolling → thick shearing → thick strip cleaning → pre-finishing rolling → solution treatment at 790-810°C for 20-25s → aging treatment at 460-480°C for 5.5-6.5h → cleaning and grinding → finishing rolling → stress relief annealing → cleaning → bending and leveling → slitting.

[0010] The hot rolling starting temperature is 870-1000°C, and the final rolling temperature is 840-870°C.

[0011] The hot rolling reduction ratio is 90 to 95%.

[0012] The reduction ratio of the rough rolling is 90 to 95%.

[0013] The reduction ratio of the pre-finish rolling is 50-55%.

[0014] The reduction ratio of the finish rolling is 35 to 45%.

[0015] The stress relief annealing conditions are: annealing temperature 540-560° C., annealing speed 55-65 m / min.

[0016] The control and functions of the components in the copper-nickel-silicon alloy strip for connectors provided by the present invention are as follows:

[0017] Cu-Ni-Si alloy is a typical aging-strengthening alloy. When it is heat-treated under appropriate conditions, Ni and Si can be precipitated from the copper matrix to form nano-scale intermetallic compounds (second phases). This second phase interacts with dislocations and hinders the movement of dislocations, thereby improving the strength of the material. At the same time, since the alloy elements are precipitated from the Cu matrix, the number of solute atoms in the copper matrix that scatter electrons is reduced, thereby improving the electrical conductivity; during the aging treatment, Ni and Si can form two compounds, δNi2Si and βNi3Si, and the strengthening effect of δNi2Si is better than that of βNi3Si. Therefore, in order to obtain the strengthening phase δNi2Si to obtain the maximum strengthening effect, the present invention controls Ni / Si to 4.1-4.4 when designing the alloy composition. Within this ratio, Ni and Si can generate a large amount of Ni2Si second phases in the copper matrix, thereby producing a very strong dispersion strengthening effect and greatly improving the mechanical properties of the copper alloy.

[0018] Mg: It can not only remove oxygen and sulfur in the melt, but also form compounds with phosphorus to further strengthen the alloy. Mg also has the effect of slowing down the aging rate and improving the alloy's resistance to high-temperature softening. However, Mg will reduce the electrical conductivity and deteriorate the brazing wettability. Therefore, the present invention controls the Mg element content to 0.01-0.05%.

[0019] P: It is usually used to remove oxygen from copper alloy melts. Adding P to the melt can also improve fluidity. However, the addition of P should not be too much. The remaining P element will be dissolved in the Cu matrix as an impurity, causing additional electron scattering, seriously reducing the conductivity, and excessive P and Cu will also form a low-melting-point Cu3P eutectic phase. Cracking is likely to occur during hot rolling, so the present invention controls P≤0.03%.

[0020] Zn: during brazing, it can diffuse to the surface to form a Zn-rich layer, blocking the diffusion of Sn in the brazing material to form brittle Cu3Sn, and improving the anti-stripping ability of the brazing joint. However, Zn will reduce the electrical conductivity, so the present invention controls Zn to 0.05-0.20%.

[0021] In the production method of the copper-nickel-silicon alloy strip for connectors provided by the present invention, a strengthening combination of cold working-solution treatment-aging treatment-cold working is adopted for production. The copper-nickel-silicon alloy strip after hot rolling is subjected to rough rolling and pre-finishing cold rolling, and then subjected to solution treatment at 790-810°C for 20-25s and aging treatment at 460-480°C for 5.5-6.5h, and then subjected to cold working. A large amount of fine δNi2Si strengthening phase will precipitate in the copper matrix. With the precipitation of the δNi2Si strengthening phase, the lattice distortion caused by the solute atoms is greatly reduced, thereby reducing the scattering effect of the solute atoms on the electrons, so that the conductivity can be greatly improved; and the recrystallized structure in the hot-rolled state will gradually plastically deform to a fibrous structure along the rolling direction, greatly improving the hardness of the copper-nickel-silicon alloy strip.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The copper-nickel-silicon alloy strip provided by the present invention can obtain fine alloy structure grains and uniform nano-scale precipitation strengthening phase Ni2Si, complete the composite strengthening effect of aging strengthening and cold deformation strengthening, and achieve simultaneous improvement of mechanical properties and electrical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 TEM image of the copper-nickel-silicon alloy strip in Example 3;

[0025] Figure 2 This is the EDS image of the copper-nickel-silicon alloy strip in Example 3. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the embodiments.

[0027] The copper-nickel-silicon alloy strip for connectors provided by the present invention has the following chemical composition and weight percentage: Ni 1.5-3.0%, Si 0.30-0.75%, Mg 0.01-0.05%, P≤0.03%, Zn 0.05-0.20%, wherein Ni / Si=4.2-4.4, and the balance is copper and unavoidable impurities.

[0028] The production method of the copper-nickel-silicon alloy strip for connectors comprises the following steps: smelting → casting → sawing → heating in a stepping furnace → hot rolling → milling → rough rolling → thick shearing → thick strip cleaning → pre-finishing rolling → solution treatment at 790-810° C. for 20-25 seconds → aging treatment at 460-480° C. for 5.5-6.5 hours → cleaning and grinding → finishing rolling → stress relief annealing → cleaning → bending and leveling → slitting;

[0029] The hot rolling starting temperature is 870-1000°C, and the final rolling temperature is 840-870°C.

[0030] The hot rolling reduction ratio is 90 to 95%.

[0031] The reduction ratio of the rough rolling is 90 to 95%.

[0032] The reduction ratio of the pre-finish rolling is 50-55%.

[0033] The reduction ratio of the finish rolling is 35 to 45%.

[0034] The present invention is described in detail below with reference to the embodiments.

[0035] The chemical composition and weight percentage of the copper-nickel-silicon alloy strips in various embodiments and comparative examples are shown in Table 1, and the remainder is copper and unavoidable impurities.

[0036] Table 1

[0037]

[0038] The production process parameters of the copper-nickel-silicon alloy strip in each embodiment and comparative example are shown in Table 2.

[0039] Table 2

[0040]

[0041]

[0042] The properties of the copper-nickel-silicon alloy strips in the embodiments and comparative examples are shown in Table 3.

[0043] Table 3

[0044]

[0045] The TEM image of the copper-nickel-silicon alloy strip in Example 3 is as follows: Figure 1 As shown, EDS diagram is as follows Figure 2 shown.

[0046] The detailed description of a copper-nickel-silicon alloy strip for a connector and a production method thereof with reference to the above-mentioned embodiments is illustrative rather than restrictive, and several embodiments may be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A copper-nickel-silicon alloy strip for a connector, characterized in that: The chemical composition and weight percentage of the copper-nickel-silicon alloy strip for the connector are: Ni 1.5-3.0%, Si 0.30-0.75%, Mg 0.01-0.05%, P≤0.03%, Zn0.05-0.20%, wherein Ni / Si=4.1-4.4, and the balance is copper and unavoidable impurities.

2. The copper-nickel-silicon alloy strip for connector according to claim 1, characterized in that: The copper-nickel-silicon alloy strip for the connector has a tensile strength of 580-650 MPa, a yield strength of 540-600 MPa, a hardness of 180-200 HV, a conductivity of 50-60% IACS, and an elongation of ≥8%.

3. The method for producing a copper-nickel-silicon alloy strip for a connector according to claim 1 or 2, characterized in that: The production method comprises the following steps: smelting→casting→sawing→walking furnace heating→hot rolling→milling→rough rolling→thick shearing→thick strip cleaning→pre-finishing rolling→solution treatment at 790-810°C for 20-25s→aging treatment at 460-480°C for 5.5-6.5h→cleaning and grinding→finishing rolling→stress relief annealing→cleaning→stretching, bending and leveling→slitting.

4. The production method according to claim 3, characterized in that: The hot rolling starting temperature is 870-1000°C, and the final rolling temperature is 840-870°C.

5. The production method according to claim 3, characterized in that: The hot rolling reduction ratio is 90 to 95%.

6. The production method according to claim 3, characterized in that: The reduction ratio of the rough rolling is 90 to 95%.

7. The production method according to claim 3, characterized in that: The reduction ratio of the pre-finish rolling is 50-55%.

8. The production method according to claim 3, characterized in that: The reduction ratio of the finish rolling is 35 to 45%.

9. The production method according to claim 3, characterized in that: The stress relief annealing conditions are: annealing temperature 540-560° C., annealing speed 55-65 m / min.

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