High-strength low-concentration copper-chromium-zirconium alloy with excellent bending machinability and manufacturing method thereof

Abstract

The invention provides a high-strength low-concentration copper-chromium-zirconium alloy with excellent bending processability and a manufacturing method thereof. The high-strength low-concentration copper-chromium-zirconium alloy comprises the following components: 0.4-1.5% of Cr, 0.05-0.15% of Zr and the balance of copper and inevitable impurities. Compared with the prior art, only one-time solution treatment is carried out after hot rolling, that is, cold rolling with the machining rate reaching 90% or above is carried out after hot rolling, and then solution treatment is carried out. The average crystal grain size at the time can be adjusted to 5-20 microns, then cold rolling aging treatment is performed again, and final cold rolling and low-temperature heat treatment are performed for manufacturing, so that a high-strength and low-concentration copper-chromium-zirconium product with excellent strength and bending processability can be manufactured, the tensile strength of the product is greater than or equal to 600 MPa, and the tensile strength is greater than or equal to 100 MPa. And no crack is generated under the condition that the bending radius is equal to the plate thickness in a 90-degree bending test.

Description

Technical Field

[0001] The invention belongs to the technical field of copper alloys, and in particular relates to a high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability and a manufacturing method thereof. Background Art

[0002] As miniaturized and high-density mobile electronic devices, such as smartphones, are increasingly developed, copper alloy materials used as connectors and other electronic components are also becoming thinner and lighter, requiring higher strength and excellent bending processability. However, the tensile strength of copper-chromium-zirconium products currently manufactured is generally between 500 and 580 MPa, or the bending performance is unqualified when the strength reaches 600 MPa.

[0003] Copper-chromium-zirconium alloy has high strength and excellent high-temperature stress relaxation properties among copper alloys. Copper-chromium-zirconium is a typical age-hardening alloy. Through high-temperature solution treatment, a supersaturated solid solution of Cr and Zr as solute atoms is formed. Moreover, starting from this state, through a long period of aging treatment, nano-scale strengthening phase particles will be precipitated during the process. The strengthening phase particles can strengthen the alloy and make the strength greater than 600MPa; at the same time, the precipitation of Cr and Zr elements leads to a reduction in the number of solute atoms in the copper matrix, which can improve the electrical conductivity of the alloy.

[0004] The patent with publication number CN 115369281 A published on November 22, 2022, discloses a high-strength and high-conductivity chromium-zirconium-copper alloy and its preparation method, the composition of which is: 0.6-1.0% Cr element, 0.05-0.12% Zr element, 0.02-0.06% Si element, 0.02-0.06% Fe element, 0.05-0.15% Nb element, 0.05-0.15% Ti element, 0.05-0.15% Ag element, and the balance of Cu element. This technical solution combines high-melting-point metal elements by smelting and casting, effectively utilizes the strengthening phase formed between Cu, Cr, Zr, Nb, Si, Ti, Ag and Fe elements, fully improves the strength of the chromium-zirconium-copper alloy, and does not significantly affect the conductivity of the alloy; the strength and conductivity of the alloy ingot can be further enhanced through post-processing, and the alloy ingot can be effectively processed into a chromium-zirconium-copper alloy product with both high strength and high conductivity. However, the bending performance of the product is not disclosed.

[0005] Copper-chromium-zirconium alloys also have a conflicting relationship between strength and bendability, just like other copper alloys. Improving strength will impair bendability, and if bendability is emphasized, the desired strength will inevitably be reduced.

[0006] Therefore, it is necessary to provide a copper-chromium-zirconium alloy with excellent bending workability and high strength. Summary of the invention

[0007] The present invention provides a high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability and a manufacturing method thereof. By controlling the processing rate of a single cold rolling to be above 90%, Cr and Zr can be fully dissolved in a parent phase through a single solution treatment to obtain an average grain size of 5 to 20 μm, and a copper-chromium-zirconium product with a tensile strength of ≥600 MPa is produced. In a 90° bending test, no cracks are generated when the bending radius is equal to the plate thickness. The copper-chromium-zirconium product also has good electrical and thermal conductivity, and an electrical conductivity of ≥85 IACS%.

[0008] The specific technical solutions of the present invention are as follows:

[0009] A high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability, comprising the following components in percentage by mass:

[0010] Cr0.4~1.5%, Zr0.05~0.15%, the balance includes copper and inevitable impurities.

[0011] Preferably, the Cr content in the high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability is 0.6-1.1%.

[0012] Preferably, other elements may be added as needed, and the other elements may be one or more of Fe, Co, B, Sn, Ni, Si, Al, and Mg, and the total amount of the other elements does not exceed 0.15%.

[0013] The content of the unavoidable impurities is not more than 0.25%;

[0014] The copper-chromium-zirconium alloy with excellent bending workability, high strength and low concentration is a copper-chromium-zirconium strip, and the thickness of the copper-chromium-zirconium strip is less than 0.8 mm.

[0015] The tensile strength of the high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability is ≥600 MPa, and no cracks are generated when the bending radius is equal to the plate thickness during a 90° bending test; and the electrical conductivity is ≥85 IACS%.

[0016] The present invention provides a high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability and a manufacturing method thereof, comprising the following process flow:

[0017] Smelting → casting → homogenization → hot rolling → primary cold rolling → online solution treatment → secondary cold rolling → aging treatment → final cold rolling → low-temperature heat treatment of finished products;

[0018] The homogenization treatment has a heating temperature of 900 to 1000° C. and a heat preservation time of 2 to 12 hours.

[0019] The hot rolling starts at a temperature of 900 to 980° C. and ends at a temperature of 750° C. or higher. After the hot rolling, water cooling and quenching are performed.

[0020] The processing rate of the primary cold rolling is 90% or more, preferably 92 to 98%.

[0021] The cold rolling uses a reversible cold rolling mill with a diameter of 100 mm to 180 mm. Such a rolling mill can achieve high-pressure rolling of hard materials.

[0022] In the online solution treatment, the heating temperature is maintained at 900-1050°C and the conveyor speed is 5-80m / min, so that the concentrations of Cr, Zr, α phase and α+Cr reach a temperature above the boundary line, and the temperature is cooled to below 400°C at a rate greater than 100°C / s to fully dissolve Cr in the parent phase to obtain an average grain size of 5-20μm.

[0023] Preferably, when the Cr content in the high-strength and low-concentration copper-chromium-zirconium alloy with excellent bending workability is 0.6-1.1%, the heating temperature during the online solution treatment is maintained at 960-1050°C.

[0024] The aging treatment temperature is 400-500°C and the holding time is 5-10 hours;

[0025] The final cold rolling has a processing rate of 25 to 40%.

[0026] The low-temperature heat treatment temperature of the finished product is 200-360° C., and the heat preservation time is 4-8 hours.

[0027] Compared with the prior art, if the Cr content in the present invention does not reach 0.4%, although the conductivity is improved, sufficient strength cannot be obtained. On the contrary, if the Cr content exceeds 1.5%, the bending processability is easily reduced due to the formation of coarse precipitates. Considering both strength and bending processability, the present invention controls the Cr content to 0.4-1.5%, preferably 0.6-1.1%, and Zr 0.05-0.15%, both of which are relatively low in concentration; in the manufacturing method of the copper-chromium-zirconium with excellent bending processability and high strength provided by the present invention, by making the cold rolling processing rate before solution treatment reach a large deformation of more than 90%, Cr and Zr are fully dissolved in the parent phase during solution treatment, so that a copper-chromium-zirconium alloy with good bending processability can be finally obtained. The present invention only performs one online solution treatment after hot rolling, that is, cold rolling with a processing rate of more than 90% is performed after hot rolling, and then online solution treatment is performed. At this time, the average grain size can be adjusted to 5 to 20 μm, followed by cold rolling and aging treatment, and finally cold rolling and low-temperature heat treatment to produce a high-strength, low-concentration copper-chromium-zirconium alloy product with excellent strength and bending workability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the grain diagram of copper, chromium, and zirconium after solution treatment in Example 1. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1-Example 3

[0031] A high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability, Cr0.9%, Zr0.11%, and the balance being copper and inevitable impurities.

[0032] Comparative Example 1-Comparative Example 3

[0033] A high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability, Cr0.9%, Zr0.11%, and the balance being copper and inevitable impurities.

[0034] The content of copper-chromium-zirconium alloy in each embodiment and comparative example is the same.

[0035] The production of the above embodiments is carried out according to the following process flow:

[0036] Smelting → casting → homogenization → hot rolling → primary cold rolling → online solution treatment → secondary cold rolling → aging treatment → final cold rolling → low-temperature heat treatment of finished products;

[0037] The homogenization treatment has a heating temperature of 900 to 1000° C. and a heat preservation time of 2 to 12 hours.

[0038] The hot rolling starts at a temperature of 900 to 980° C. and ends at a temperature of 750° C. or higher. After the hot rolling, online water cooling and quenching are performed.

[0039] The processing rate of the primary cold rolling is 90% or more, preferably 92 to 98%.

[0040] The cold rolling uses a reversible cold rolling mill with a diameter of 100 mm to 180 mm. Such a rolling mill can achieve high-pressure rolling of hard materials.

[0041] In the online solution treatment, the heating temperature is maintained at 900-1050°C and the belt speed is 5-80m / min, so that the concentration of Cr, Zr, α phase and α+Cr reaches a temperature above the boundary line, and the temperature is cooled at a speed greater than 100°C / s to below 400°C, so that Cr is fully dissolved in the parent phase to obtain an average grain size of 5-20μm.

[0042] Preferably, when the Cr content in the high-strength and low-concentration copper-chromium-zirconium alloy with excellent bending workability is 0.4-1.0%, the heating temperature during the online solution treatment is maintained at 960-1050°C.

[0043] The aging treatment temperature is 400-500°C and the holding time is 5-10 hours;

[0044] The final cold rolling has a processing rate of 25 to 40%.

[0045] The low-temperature heat treatment temperature of the finished product is 200-360°C, and the insulation time is 4-8 hours.

[0046] The main process parameters of each embodiment are shown in Table 1.

[0047] Table 1 Main process parameters of each embodiment

[0049]

[0050]

[0051] The production process parameters of copper-chromium-zirconium in each comparative example are shown in Table 2, and the process is smelting→casting→homogenization treatment→hot rolling→one cold rolling→aging treatment→final cold rolling→low-temperature heat treatment of finished product.

[0052] Table 2 Main process parameters of comparative production

[0053]

[0054] The average grain size of each example and comparative example was measured by the intercept method, that is, the grain size of a cross section perpendicular to the rolling direction.

[0055] Table 3 Dimensions and properties of the products of each embodiment and comparative example

[0056]

[0057]

[0058] From the above results, it can be seen that the tensile strength of the copper-chromium-zirconium produced in Examples 1-3 exceeds 600 MPa, and the bending processability is also good. In the bending test, no cracks are generated when the bending radius is equal to the plate thickness, and the bending performance is qualified. The bending performance of the comparative examples 1-3 is also qualified, but the tensile strength is generally low.

[0059] The underlined data above do not meet the requirements of the present invention.

[0060] In summary, according to the present invention, a copper-chromium-zirconium alloy strip having the same or higher strength and bendability as conventional copper-chromium-zirconium can be manufactured through an economical manufacturing process that only performs a single solution treatment.

[0061] The description of the above embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability, characterized in that: The high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability comprises the following components in percentage by mass: Cr0.4~1.5%, Zr0.05~0.15%, the balance includes copper and inevitable impurities.

2. The high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability according to claim 1, characterized in that: The high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability has a tensile strength of ≥600 MPa, and does not generate cracks when the bending radius is equal to the plate thickness during a 90° bending test; and has an electrical conductivity of ≥85 IACS%.

3. A method for producing the high-strength, low-concentration copper-chromium-zirconium alloy with excellent bending workability according to any one of claims 1 to 2, characterized in that: The manufacturing method comprises the following process flow: Smelting → casting → homogenization treatment → hot rolling → primary cold rolling → online solution treatment → secondary cold rolling → aging treatment → final cold rolling → low-temperature heat treatment of finished product.

4. The manufacturing method according to claim 3, characterized in that: The homogenization treatment has a heating temperature of 900 to 1000° C. and a heat preservation time of 2 to 12 hours.

5. The manufacturing method according to claim 3, characterized in that: The hot rolling starts at a temperature of 900-980°C, ends at a temperature of more than 750°C, and is quenched and cooled online.

6. The manufacturing method according to claim 3, characterized in that: The processing rate of the primary cold rolling reaches more than 90%.

7. The manufacturing method according to claim 3, characterized in that: In the online solution treatment, the heating temperature during the solution treatment is maintained at 900-1050° C., the belt speed is 5-80 m / min, and the cooling is performed at a speed greater than 100° C. / s.

8. The manufacturing method according to claim 3, characterized in that: The aging treatment has an aging treatment temperature of 400 to 500° C. and a heat preservation time of 5 to 10 hours.

9. The manufacturing method according to claim 3, characterized in that: The final cold rolling has a cold rolling processing rate of 25 to 40%.

10. The manufacturing method according to claim 3, characterized in that: The low-temperature heat treatment temperature of the finished product is 200-360°C, and the insulation time is 4-8 hours.

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