Aging treatment regulation and control method for double gradient temperature control rolling of copper alloy strip for automobile connector

Abstract

The invention discloses an aging treatment regulation and control method for double gradient temperature control rolling of a copper alloy strip for an automobile connector, which comprises the following steps: primary gradient temperature control rolling: rolling an actually produced copper plate strip under room temperature and low temperature treatment conditions respectively, and ensuring that the total deformation is 85%; primary aging: setting out at the temperature of 420 DEG C, and keeping the temperature for 4 hours; secondary gradient temperature control rolling is conducted, specifically, single-pass rolling is conducted under the room-temperature and low-temperature treatment conditions, and the deformation amount is 50%; and secondary aging: setting out at the temperature of 420 DEG C, and keeping the temperature for 4 hours. According to the invention, a combined process of double gradient temperature control rolling and aging treatment is adopted, grain refinement and formation of dispersively distributed nano precipitates are promoted, and twin crystals are introduced. By means of the microstructure, the hardness of the material is improved, and good balance between the mechanical property and the conductivity is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of temperature-controlled rolling, and in particular to an aging treatment control method for double-gradient temperature-controlled rolling of a copper alloy strip for an automobile connector. Background Art

[0002] Copper and copper alloy materials are widely used in automobile manufacturing, transportation, electronic information and other fields due to their excellent mechanical properties, electrical conductivity and thermal conductivity. Especially in automotive connectors, they have become one of the key materials. However, with the rapid development of automobile electrification and intelligence, automotive connectors have higher requirements on the comprehensive performance of copper alloy strips for automotive connectors under harsh service conditions such as high voltage, high current and cyclic temperature rise. At present, the comprehensive performance of alloys is mainly improved by microalloying and optimizing the deformation heat treatment process to meet the growing performance requirements.

[0003] Microalloying optimizes the distribution and grain structure of the precipitated phase by adding trace elements (such as titanium, magnesium, etc.) to the alloy, thereby improving the hardness and conductivity of the alloy. However, the addition and distribution control of these trace elements are extremely important. Too much or too little trace elements may lead to unstable performance and affect the balance between conductivity and hardness. In addition, the microalloying process is complicated, and it is difficult to ensure the consistency of alloy composition and performance in large-scale production, which limits its application in new energy vehicle connectors.

[0004] The traditional thermomechanical treatment process mainly involves aging treatment after rolling deformation at room temperature. Although this method can improve the hardness of copper alloy strips, it is often difficult to maintain or improve the conductivity while increasing the hardness, which leads to a decrease in the conductivity of the material and makes it difficult to meet the high performance requirements of current automotive connectors. Therefore, how to maintain a certain conductivity while increasing the hardness of the alloy has become a key issue in solving the performance requirements of copper alloy strips for automotive connectors. Summary of the invention

[0005] The purpose of the present invention is to provide an aging treatment control method for dual gradient temperature controlled rolling of copper alloy strips for automotive connectors, the copper strips are subjected to low temperature rolling and aging treatment, and a nano twin structure is introduced by controlling the rolling temperature. Since the twin boundary not only has the strengthening effect of the traditional high-angle grain boundary, but also significantly reduces the resistance, the method can maintain a certain conductivity while improving the hardness of the alloy, thereby preparing a high-performance copper alloy strip suitable for automotive connectors, in order to solve the problems mentioned in the background technology. To achieve the above purpose, the present invention provides the following technical scheme: A method for aging treatment control of dual gradient temperature controlled rolling of copper alloy strips for automotive connectors, specifically comprising the following contents:

[0006] (1) Single gradient temperature controlled rolling: The copper sheet and strip produced in actual production are rolled at room temperature and low temperature treatment conditions, with a total deformation of 85%;

[0007] (2) Primary aging: 420℃, sample at temperature, holding time 4h;

[0008] (3) Secondary gradient temperature controlled rolling: single-pass rolling is carried out under room temperature and low temperature treatment conditions, with a deformation of 50%;

[0009] (4) Secondary aging: 420℃, sample at temperature, holding time 4h.

[0010] Preferably, in said (1), the copper plate and strip actually produced are rolled at room temperature and low temperature treatment conditions respectively, divided into 5 passes, and the deformation amount of each pass is 17%.

[0011] Preferably, before each low-temperature treatment rolling in (1), the copper plate and strip are immersed in liquid nitrogen for 30 minutes.

[0012] Preferably, the primary aging and the secondary aging are both carried out in a vacuum atmosphere tubular resistance furnace.

[0013] Technical effects and advantages of the present invention: The present invention adopts a combined process of dual gradient temperature-controlled rolling and aging treatment to promote grain refinement and the formation of dispersed nano-precipitates, and introduce twins. This microstructure improves the hardness of the material and achieves a good balance between mechanical properties and electrical conductivity. In addition, the process flow of the present invention has high controllability and can effectively optimize the comprehensive performance of copper alloy strips, thereby meeting the application requirements of automotive connectors for both hardness and conductivity; low-temperature rolling not only promotes the efficient accumulation of dislocations, thereby improving the strength of the material, but also generates a small amount of twin structures. Hardness is increased by the combined effects of twin interface strengthening, precipitation strengthening, grain boundary strengthening and dislocation strengthening. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of IACS conductivity under different conditions in the embodiment;

[0015] Figure 2 Schematic diagram of Vickers hardness under different conditions in the embodiment. DETAILED DESCRIPTION

[0016] In order to make the technical means for realizing the present invention, the creative features, the objectives and effects to be achieved easy to understand, the present invention is further explained below in conjunction with specific diagrams. In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, an integral connection or a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two components.

[0017] Example

[0018] A method for regulating and controlling aging treatment of double gradient temperature controlled rolling of copper alloy strip for automobile connectors, the specific steps are as follows:

[0019] (1) Single gradient temperature controlled rolling: For the 6.6 mm C18150 copper alloy sheet and strip produced in actual production, rolling was carried out at room temperature and low temperature treatment conditions, respectively, with a total of 5 passes, each pass deformation of 17%, and a total deformation of 85%. Before rolling, the copper sheet and strip were placed in liquid nitrogen for 30 minutes of low temperature treatment. After each rolling pass, the copper sheet and strip were immersed in liquid nitrogen for 30 minutes to prepare for the next rolling pass;

[0020] (2) Primary aging: 420℃, sample laying at temperature, holding time 4h, and primary aging is carried out in a vacuum atmosphere tubular resistance furnace;

[0021] (3) Secondary gradient temperature controlled rolling: The alloy after the primary rolling is subjected to single-pass rolling at room temperature and low temperature respectively, with a rolling deformation of 50%; before rolling, the copper sheet and strip are placed in liquid nitrogen for low temperature treatment for 30 minutes;

[0022] (4) Secondary aging: 420℃, sample at temperature, holding time 4h, and secondary aging is carried out in a vacuum atmosphere tubular resistance furnace.

[0023] Through the above treatment process, a copper alloy strip with a good combination of hardness and conductivity is finally obtained. Four different processes are used to manufacture copper alloy strips. The conditions of each step in the four processes are as follows: PathⅠ: room temperature rolling + primary aging + room temperature rolling + secondary aging; PathⅡ: room temperature rolling + primary aging + low temperature treatment rolling + secondary aging; PathIII: low temperature treatment rolling + primary aging + room temperature rolling + secondary aging; PathIV: low temperature treatment rolling + primary aging + low temperature treatment rolling + secondary aging.

[0024] The electrical conductivity and hardness of the C18150 copper alloy strips obtained by the four processes were measured in stages. The measurement results are shown in Tables 1 and 2.

[0025] Table 1

[0026]

[0027] Table 2

[0028] Hardness(HV) PathI PathII Path III Path IV Rolling I 138.1 138.1 144.8 144.8 Aging I 149.3 149.3 150.4 150.4 Rolling II 157.6 158.5 154.7 157.6 Aging II 147.6 151.7 1487 150.3

[0029] From Tables 1 and 2, we can get Figure 1 and 2 ,Depend on Figure 1 and 2 It can be seen from the IACS conductivity and Vickers hardness shown that after being treated by the method of the present invention, the hardness of the C18150 copper alloy strip is improved while maintaining high conductivity, and low-temperature treatment and rolling can inhibit the movement of dislocations, promote the formation of twins, and refine the grains, thereby optimizing the material structure, improving the hardness while maintaining a certain conductivity, and making the material hardness better than the material rolled at double room temperature.

[0030] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for regulating and controlling the aging treatment of a copper alloy strip for automobile connectors by double gradient temperature controlled rolling, characterized in that: Specifically include the following: (1) Single gradient temperature controlled rolling: The copper sheet and strip produced in actual production are rolled at room temperature and low temperature treatment conditions, with a total deformation of 85%; (2) Primary aging: 420℃, sample at temperature, holding time 4h; (3) Secondary gradient temperature controlled rolling: single-pass rolling is carried out under room temperature and low temperature treatment conditions, with a deformation of 50%; (4) Secondary aging: 420℃, sample at temperature, holding time 4h.

2. The aging treatment control method for dual gradient temperature controlled rolling of a copper alloy strip for automotive connectors according to claim 1 is characterized in that: In the above (1), the copper strip actually produced is rolled at room temperature and low temperature treatment conditions respectively, divided into 5 passes, and the deformation amount of each pass is 17%.

3. The aging treatment control method for dual gradient temperature controlled rolling of a copper alloy strip for automotive connectors according to claim 2, characterized in that: Before each low-temperature treatment rolling in (1), the copper plate and strip are immersed in liquid nitrogen for 30 minutes.

4. The aging treatment control method for dual gradient temperature controlled rolling of a copper alloy strip for automobile connectors according to claim 1, characterized in that: The primary aging and secondary aging are both carried out in a vacuum atmosphere tubular resistance furnace.

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