A high-flatness copper-nickel-tin-zinc alloy and its preparation method

Abstract

This invention provides a high-flatness copper-nickel-tin-zinc alloy and its preparation method, belonging to the field of copper alloy manufacturing technology. The high-flatness copper-nickel-tin-zinc alloy provided by this invention, by mass percentage, comprises the following chemical composition: Ni: 0.2-3.0%, Sn: 0.2-2.0%, Zn: 0.05-0.2%, Fe: 0.01-0.1%, P: 0.02-0.08%, Nb: 0.05-0.28%, Ta: 0.05-0.2%, La: 0.02-0.1%, and the balance Cu. The results of the examples show that the copper-nickel-tin-zinc alloy of this invention has a tensile strength >600 MPa and an elongation A... 11.3 The heat shrinkage rate is 5-7%, the hardness is >180HV, the conductivity is ≥40%IACS, the bending rate is 7-8mm / m, the flatness is ≤0.05mm, and the heat shrinkage rate is ≤0.006%.

Description

Technical Field

[0001] This invention relates to the field of copper alloy manufacturing technology, and in particular to a high-flatness copper-nickel-tin-zinc alloy and its preparation method. Background Technology

[0002] C19025 (NB109) copper alloy has the following characteristics: 1. High strength: H-state strength can reach over 540 MPa; 2. Conductivity reaches over 40% IACS; 3. Excellent stress relief rate, which is 1 / 4 to 1 / 10 of phosphor bronze or brass, and has good machinability. Therefore, C19025 copper alloy is particularly suitable for the miniaturization and lightweighting of electrical and electronic components, making it a highly reliable and low-cost alloy. However, the EH-state C19025 copper alloy usually relies on high-rate rolling to harden it to the target state during processing. However, high-rate rolling, due to the increased number of rolling passes and material hardening, will affect the strip shape. Since the strip shape requirements are extremely high during stamping, uneven strip shape can easily lead to the scrapping of parts after stamping due to shape deformation, thus significantly increasing costs.

[0003] Therefore, providing a copper-nickel-tin-zinc alloy with high flatness that does not deform after stamping has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a high-flatness copper-nickel-tin-zinc alloy and its preparation method. The high-flatness copper-nickel-tin-zinc alloy provided by this invention has excellent mechanical and electrical properties, as well as high flatness and no deformation after stamping.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a high-flatness copper-nickel-tin-zinc alloy, comprising the following chemical composition by mass percentage: Ni: 0.2-3.0%, Sn: 0.2-2.0%, Zn: 0.05-0.2%, Fe: 0.01-0.1%, P: 0.02-0.08%, Nb: 0.05-0.28%, Ta: 0.05-0.2%, La: 0.02-0.1%, and the balance Cu.

[0007] Preferably, by mass percentage, it comprises the following chemical components: Ni: 0.5–2.5%, Sn: 0.5–1.5%, Zn: 0.1–0.15%, Fe: 0.05–0.1%, P: 0.02–0.05%, Nb: 0.08–0.25%, Ta: 0.1–0.15%, La: 0.02–0.05%, and the balance Cu.

[0008] Preferably, by mass percentage, it comprises the following chemical components: Ni: 0.5–2.0%, Sn: 1.0–1.2%, Zn: 0.1–0.13%, Fe: 0.05–0.08%, P: 0.02–0.04%, Nb: 0.08–0.20%, Ta: 0.1–0.12%, La: 0.03–0.05%, and the balance Cu.

[0009] This invention provides a method for preparing the high-flatness copper-nickel-tin-zinc alloy described in the above technical solution, comprising the following steps:

[0010] (1) The alloy raw materials are smelted and horizontally continuously cast in sequence to obtain a billet;

[0011] (2) The billet obtained in step (1) is subjected to a first bell annealing to obtain a first annealed strip;

[0012] (3) The first annealed strip obtained in step (2) is subjected to initial rolling to obtain initial rolled strip;

[0013] (4) The initial rolled strip obtained in step (3) is subjected to a second bell annealing to obtain a second annealed strip;

[0014] (5) The second annealed strip obtained in step (4) is pre-rolled to obtain a pre-rolled strip; the total deformation of the pre-rolling is 60-70%;

[0015] (6) The pre-rolled strip obtained in step (5) is subjected to a first continuous annealing and a first tensile bending straightening to obtain a third annealed strip;

[0016] (7) The strip obtained in step (6) is subjected to finish rolling to obtain a finish rolled strip; the total deformation of the finish rolling is 50-60%;

[0017] (8) The fine-rolled strip obtained in step (7) is subjected to aging heat treatment to obtain heat-treated strip;

[0018] (9) The heat-treated strip obtained in step (8) is subjected to a second tensile bending and straightening and high-tension continuous annealing to obtain a high-flatness copper-nickel-tin-zinc alloy.

[0019] Preferably, the temperature of the first bell annealing in step (2) is 540-680°C, and the holding time of the first bell annealing is 5-12 hours.

[0020] Preferably, the total deformation of the initial rolling in step (3) is 80-90%.

[0021] Preferably, the temperature of the second bell annealing in step (4) is 500-600°C, and the holding time of the second bell annealing is 5-12 hours.

[0022] Preferably, the temperature of the first continuous annealing in step (6) is 680-800℃, and the speed of the first continuous annealing is 10-50m / min.

[0023] Preferably, the temperature of the aging heat treatment in step (8) is 280-360°C, and the holding time of the aging heat treatment is 5-12 hours.

[0024] Preferably, in step (9), the temperature of the high-tension continuous annealing is 300–400°C, the speed of the high-tension continuous annealing is 40–60 m / min, and the tension of the high-tension continuous annealing is 45–65 N / mm. 2 .

[0025] This invention provides a high-flatness copper-nickel-tin-zinc alloy, comprising the following chemical composition by mass percentage: Ni: 0.2-3.0%, Sn: 0.2-2.0%, Zn: 0.05-0.2%, Fe: 0.01-0.1%, P: 0.02-0.08%, Nb: 0.05-0.28%, Ta: 0.05-0.2%, La: 0.02-0.1%, and the balance Cu. The high-flatness copper-nickel-tin-zinc alloy provided by this invention uses copper as the base element. The added nickel and copper can form an infinitely solid solution, and the addition of nickel can improve the alloy's strength and corrosion resistance. Tin, as a microalloying element, can both increase the solid solution effect and reduce the grain size, while suppressing discontinuous precipitation, thus improving the alloy's strength without compromising its conductivity. Zinc has a strong solid solution strengthening effect, and its addition can improve the strength, hardness, and corrosion resistance of the copper-nickel-tin-zinc alloy. By adding a small amount of iron to the copper alloy, the nucleation and growth of discontinuous precipitates in the alloy can be suppressed, significantly improving the alloy's strength and plasticity. Elements such as Nb, Ta, and La can form high-melting-point compounds with impurities such as lead and bismuth in the copper alloy, which are distributed inside the grains, increasing the softening temperature of copper and refining the grains, thereby improving mechanical properties. The results of the embodiments show that the high-flatness copper-nickel-tin-zinc alloy provided by this invention has a tensile strength >600MPa and an elongation A 11.3 The heat shrinkage rate is 5-7%, the hardness is >180HV, the conductivity is ≥40%IACS, the bending rate is 7-8mm / m, the flatness is ≤0.05mm, and the heat shrinkage rate is ≤0.006%. Detailed Implementation

[0026] This invention provides a high-flatness copper-nickel-tin-zinc alloy, comprising the following chemical composition by mass percentage: Ni: 0.2-3.0%, Sn: 0.2-2.0%, Zn: 0.05-0.2%, Fe: 0.01-0.1%, P: 0.02-0.08%, Nb: 0.05-0.28%, Ta: 0.05-0.2%, La: 0.02-0.1%, and the balance Cu.

[0027] The high-flatness copper-nickel-tin-zinc alloy provided by this invention, by weight percentage, comprises Ni: 0.2-3.0%, preferably 0.5-2.5%, and more preferably 0.5-2.0%. In this invention, nickel and copper can form an infinitely solid solution, and the addition of nickel can improve the alloy's strength and corrosion resistance.

[0028] The high-flatness copper-nickel-tin-zinc alloy provided by the present invention comprises Sn: 0.2-2.0%, preferably 0.5-1.5%, and more preferably 1.0-1.2% by mass percentage. In the present invention, Sn, as a microalloying element, can both increase the solid solution effect and reduce the grain size, while suppressing discontinuous precipitation, thereby improving the strength of the alloy without impairing its conductivity.

[0029] The high-flatness copper-nickel-tin-zinc alloy provided by this invention comprises Zn: 0.05-0.2%, preferably 0.1-0.15%, and more preferably 0.1-0.13% by mass percentage. In this invention, zinc has a strong solid solution strengthening effect, and the addition of zinc can improve the strength, hardness, and corrosion resistance of the copper-nickel-tin-zinc alloy.

[0030] The high-flatness copper-nickel-tin-zinc alloy provided by this invention, by weight percentage, comprises Fe: 0.01-0.1%, preferably 0.05-0.1%, and more preferably 0.05-0.08%. By adding a small amount of iron to the copper alloy, this invention can suppress the nucleation and growth of discontinuous precipitates in the alloy, significantly improving the alloy's strength and plasticity. However, when the iron content is high, it reduces the alloy's plasticity, making it difficult to process. Therefore, its content is controlled within the range of 0.01-0.1%.

[0031] The high-flatness copper-nickel-tin-zinc alloy provided by this invention, by mass percentage, comprises P: 0.02-0.08%, preferably 0.02-0.05%, and more preferably 0.02-0.04%. In this invention, P is usually an impurity element that reduces the mechanical properties of the copper-nickel-tin-zinc alloy, therefore its content needs to be strictly controlled.

[0032] The high-flatness copper-nickel-tin-zinc alloy provided by this invention, by mass percentage, comprises Nb: 0.05–0.28%, preferably 0.08–0.25%, and more preferably 0.08–0.20%. In this invention, Nb can form high-melting-point compounds with impurity elements such as lead and bismuth in the copper alloy, which are distributed within the grains, increasing the softening temperature of copper, refining the grains, and improving mechanical properties.

[0033] The high-flatness copper-nickel-tin-zinc alloy provided by this invention, by mass percentage, comprises Ta: 0.05-0.2%, preferably 0.1-0.15%, and more preferably 0.1-0.12%. In this invention, Ta can form high-melting-point compounds with impurity elements such as lead and bismuth in the copper alloy, which are distributed inside the grains, increasing the softening temperature of copper, refining the grains, and improving mechanical properties.

[0034] The high-flatness copper-nickel-tin-zinc alloy provided by this invention, by mass percentage, comprises La: 0.02-0.1%, preferably 0.02-0.05%, and more preferably 0.03-0.05%. In this invention, La can form high-melting-point compounds with impurity elements such as lead and bismuth in the copper alloy, which are distributed inside the grains, increasing the softening temperature of copper, refining the grains, and improving mechanical properties.

[0035] The high-flatness copper-nickel-tin-zinc alloy provided by this invention comprises the balance Cu by weight percentage. In this invention, the copper element is the base element of the alloy.

[0036] The high-flatness copper-nickel-tin-zinc alloy provided by this invention uses copper as the base element. The added nickel and copper can form an infinitely solid solution, and the addition of nickel can improve the alloy's strength and corrosion resistance. Sn, as a microalloying element, can both increase the solid solution effect and reduce the grain size, while suppressing discontinuous precipitation, thereby improving the alloy's strength without compromising its conductivity. Zinc has a strong solid solution strengthening effect, and the addition of zinc improves the strength, hardness, and corrosion resistance of the copper-nickel-tin-zinc alloy. By adding a small amount of iron to the copper alloy, the nucleation and growth of discontinuous precipitates in the alloy can be suppressed, significantly improving the alloy's strength and plasticity. Nb, Ta, and La can form high-melting-point compounds with impurities such as lead and bismuth in the copper alloy, which are distributed inside the grains, increasing the softening temperature of copper, refining the grains, and improving mechanical properties.

[0037] This invention provides a method for preparing the high-flatness copper-nickel-tin-zinc alloy described in the above technical solution, comprising the following steps:

[0038] (1) The alloy raw materials are smelted and horizontally continuously cast in sequence to obtain a billet;

[0039] (2) The billet obtained in step (1) is subjected to a first bell annealing to obtain a first annealed strip;

[0040] (3) The first annealed strip obtained in step (2) is subjected to initial rolling to obtain initial rolled strip;

[0041] (4) The initial rolled strip obtained in step (3) is subjected to a second bell annealing to obtain a second annealed strip;

[0042] (5) The second annealed strip obtained in step (4) is pre-rolled to obtain a pre-rolled strip; the total deformation of the pre-rolling is 60-70%;

[0043] (6) The pre-rolled strip obtained in step (5) is subjected to a first continuous annealing and a first tensile bending straightening to obtain a third annealed strip;

[0044] (7) The strip obtained in step (6) is subjected to finish rolling to obtain a finish rolled strip; the total deformation of the finish rolling is 50-60%;

[0045] (8) The fine-rolled strip obtained in step (7) is subjected to aging heat treatment to obtain heat-treated strip;

[0046] (9) The heat-treated strip obtained in step (8) is subjected to a second tensile bending and straightening and high-tension continuous annealing to obtain a high-flatness copper-nickel-tin-zinc alloy.

[0047] This invention involves sequentially melting and horizontally casting alloy raw materials to obtain a cast billet.

[0048] This invention does not specifically limit the type of alloy raw material; commercially available products or recycled waste well-known to those skilled in the art can be used. In this invention, the recycled waste preferably includes milling and rolling waste generated during the preparation of copper-nickel-tin-zinc alloys; the amount of recycled waste is preferably more than 50 wt% of the total alloy raw material. This invention uses recycled waste as alloy raw material because the recycled waste consists of milling and rolling waste generated during the preparation of copper-nickel-tin-zinc alloys, and its composition is controllable. This not only ensures that the chemical composition of the copper-nickel-tin-zinc alloy meets the requirements but also enables the reuse of waste, saving significant production costs.

[0049] In this invention, the smelting is preferably carried out using a power frequency induction furnace. This invention does not impose any specific limitations on the model of the power frequency induction furnace; any power frequency induction furnace well-known to those skilled in the art can be used. This invention also does not impose any specific limitations on the specific operation and process parameters of the smelting; these can be determined based on the technical knowledge of those skilled in the art.

[0050] After smelting, the present invention preferably performs chemical composition testing on the smelted product. The specific operation of the chemical composition testing is not particularly limited in the present invention; methods well known to those skilled in the art can be used. In the present invention, when the chemical composition of the smelted product does not meet the requirements for the chemical composition of the copper-nickel-tin-zinc alloy, the present invention preferably adjusts the chemical composition of the smelted product. By testing the composition of the alloy melt, the present invention can ensure that the chemical composition of the copper-nickel-tin-zinc alloy does not deviate from expectations.

[0051] In this invention, the casting temperature during horizontal continuous casting is preferably 1150–1230°C, more preferably 1180–1220°C; the traction rate of the horizontal continuous casting is preferably 140–170 mm / min, more preferably 150–160 mm / min. This invention does not impose any special limitation on the traction rate of the horizontal continuous casting; it can be determined based on the technical knowledge of those skilled in the art.

[0052] After obtaining the cast billet, the present invention performs a first bell annealing on the cast billet to obtain a first annealed strip.

[0053] In this invention, the temperature of the first bell annealing is preferably 540–680°C, more preferably 560–650°C, and even more preferably 600–620°C; the holding time of the first bell annealing is preferably 5–12 h, more preferably 6–10 h, and even more preferably 8–10 h. In this invention, the atmosphere for the first bell annealing is preferably a mixture of hydrogen and nitrogen; the volume fraction of hydrogen in the mixture is preferably 45–65%, more preferably 50%; and the volume fraction of nitrogen in the mixture is preferably 35–55%, more preferably 50%. By performing the first bell annealing, this invention can reduce elemental segregation inside the billet, improve the plasticity of the billet, and facilitate subsequent rolling.

[0054] After the first bell jar annealing, the product of the first bell jar annealing is preferably milled; the milling amount of the upper and lower milling surfaces is preferably 0.8 to 1.2 mm independently, more preferably 1 mm. This invention, through milling, can remove the oxide layer on the surface of the cast billet, thereby avoiding the negative impact of oxygen on the properties of the copper alloy.

[0055] After obtaining the first annealed strip, the present invention performs initial rolling on the first annealed strip to obtain the initial rolled strip.

[0056] In this invention, the total deformation of the initial rolling is preferably 80-90%, more preferably 85-90%; the deformation per pass of the initial rolling is preferably 15-25%, more preferably 15-20%. Through initial rolling, this invention can reduce the size of the annealed strip and sheet, and also break up coarse grains in the cast billet, thereby eliminating structural defects.

[0057] After obtaining the initial rolled strip, the present invention performs a second bell annealing on the initial rolled strip to obtain a second annealed strip.

[0058] In this invention, the temperature of the second bell annealing is preferably 500–600°C, more preferably 520–580°C, and even more preferably 550°C; the holding time of the second bell annealing is preferably 5–12 h, more preferably 6–10 h, and even more preferably 8–10 h. In this invention, the atmosphere for the second bell annealing is preferably a mixture of hydrogen and nitrogen; the volume fraction of hydrogen in the mixture is preferably 45–65%, more preferably 50%; and the volume fraction of nitrogen in the mixture is preferably 35–55%, more preferably 50%. By performing a second bell annealing, this invention can, on the one hand, remove the stress generated during the initial rolling process, and on the other hand, transform the processed microstructure of the material into a recrystallized microstructure, while simultaneously improving the plasticity of the material to facilitate subsequent rolling.

[0059] After the second bell jar annealing, the product after the second bell jar annealing is preferably subjected to sulfuric acid washing, water washing, and passivating agent washing in sequence. In this invention, the mass concentration of the sulfuric acid solution used for the sulfuric acid washing is preferably 16-19%, more preferably 17.5%; the passivating agent used for the passivating agent washing is preferably an aqueous solution of benzotriazole; the mass concentration of the aqueous solution of benzotriazole is preferably 0.05-0.14%, more preferably 0.1%. This invention does not have a specific limitation on the specific number of sulfuric acid washing, water washing, and passivating agent washing, which can be determined based on the technical knowledge of those skilled in the art. This invention uses sulfuric acid washing to remove the oxide layer on the surface of copper-nickel-tin-zinc alloy strip, water washing to remove residual sulfuric acid solution, and passivating agent washing to passivate the surface of the cupronickel strip, preventing oxidation of the copper-nickel-tin-zinc alloy strip.

[0060] After obtaining the second annealed strip, the present invention pre-rolls the second annealed strip to obtain a pre-rolled strip.

[0061] In this invention, the total deformation of the pre-finishing rolling is 60-70%; the deformation per pass of the pre-finishing rolling is preferably 20-30%. Through pre-finishing rolling, this invention enables the copper-nickel-tin-zinc alloy strip to achieve the required product dimensions, while simultaneously improving the uniformity of the microstructure of the copper-nickel-tin-zinc alloy and further enhancing its mechanical properties.

[0062] After obtaining the pre-rolled strip, the present invention performs a first continuous annealing and a first tensile bending straightening on the pre-rolled strip to obtain a third annealed strip.

[0063] In this invention, the temperature of the first continuous annealing is preferably 680–800°C, more preferably 700–750°C; the speed of the first continuous annealing is preferably 10–50 m / min, more preferably 20–40 m / min, and even more preferably 30 m / min. This invention, through continuous annealing, can soften the copper alloy, facilitating subsequent rolling, and also achieve more uniform grain size while removing residual internal stress.

[0064] The present invention does not have any special limitations on the specific operation of the first bending correction, and the bending correction operation known to those skilled in the art can be used.

[0065] After obtaining the third annealed strip, the present invention performs precision rolling on the third annealed strip to obtain precision rolled strip.

[0066] In this invention, the total deformation of the finishing mill is 50-60%; the deformation per pass of the finishing mill is preferably 15-30%.

[0067] After obtaining the precision-rolled strip, the present invention performs aging heat treatment on the precision-rolled strip to obtain heat-treated strip.

[0068] In this invention, the temperature of the aging heat treatment is preferably 280-360°C, more preferably 300-350°C; the holding time of the aging heat treatment is preferably 5-12 hours, more preferably 6-10 hours, and even more preferably 8-10 hours.

[0069] After the aging heat treatment is completed, the product of the aging heat treatment is preferably subjected to sulfuric acid washing, water washing, and passivating agent washing in sequence. In this invention, the operation of sulfuric acid washing, water washing, and passivating agent washing, as well as the reagents used and their functions, are the same as those of the aforementioned sulfuric acid washing, water washing, and passivating agent washing, and will not be repeated here.

[0070] After obtaining the heat-treated strip, the present invention performs a second tensile bending straightening and high-tension continuous annealing on the heat-treated strip to obtain a high-flatness copper-nickel-tin-zinc alloy.

[0071] The present invention does not have any special limitations on the specific operation of the second bending correction, and the bending correction operation known to those skilled in the art can be used.

[0072] In this invention, the temperature of the high-tension continuous annealing is preferably 300–400°C, more preferably 320–380°C, and even more preferably 350°C; the speed of the high-tension continuous annealing is preferably 40–60 m / min, more preferably 45–55 m / min, and even more preferably 50 m / min; the tension of the high-tension continuous annealing is preferably 45–65 N / mm. 2 More preferably, it is 50–60 N / mm 2Further preferably 55 N / mm 2 This invention removes residual internal stress in copper alloys by performing tensile bending straightening followed by high-tension continuous annealing, thus preventing deformation of the copper alloy strip under stress and obtaining a copper-nickel-tin-zinc alloy with high flatness.

[0073] This invention eliminates the double-sided wavy shape caused by thinning by adding a tension straightening process before finishing rolling. This adjusts the shape of the strip after the previous process, ensuring a flat strip before finishing rolling. In the previous process, residual internal stresses not eliminated by bell-type furnace annealing and tension straightening are not easily apparent before slitting. While the strip may appear flat, the shear stress and narrowing width after slitting cause a redistribution of residual stress, resulting in an uneven strip shape after slitting. To avoid this problem, this invention adds a continuous air-cushion furnace annealing process at the end of the preparation method. Through high-tension rapid annealing, residual internal stresses are completely eliminated without affecting the properties of the copper alloy, thus preventing any impact on the strip shape during slitting.

[0074] The preparation method provided by this invention is simple. By optimizing the heat treatment and rolling process of copper-nickel-tin-zinc alloy, the internal stress of the copper alloy is eliminated. No new equipment is required, the production cost is low, and it is suitable for large-scale industrial application.

[0075] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0076] Example 1

[0077] A high-flatness copper-nickel-tin-zinc alloy, by mass percentage, is composed of the following chemical composition: Ni: 1.2%, Sn: 1.1%, Zn: 0.1%, Fe: 0.03%, P: 0.03%, Nb: 0.25%, Ta: 0.1%, La: 0.05%, and balance Cu.

[0078] The preparation method of the high-flatness copper-nickel-tin-zinc alloy specifically includes the following steps:

[0079] (1) The alloy raw materials are melted and horizontally continuously cast in sequence to obtain a billet; the casting temperature during the horizontal continuous casting is 1220℃ and the traction rate of the horizontal continuous casting is 150mm / min.

[0080] (2) The billet obtained in step (1) is subjected to a first bell annealing, and then milled to obtain a first annealed strip; the temperature of the first bell annealing is 600℃; the holding time of the first bell annealing is 10h; the atmosphere of the first bell annealing is a mixed atmosphere of hydrogen and nitrogen, in which the volume fraction of hydrogen is 50% and the volume fraction of nitrogen is 50%; the upper and lower milling amounts of the milled surface are 1mm each.

[0081] (3) The first annealed strip obtained in step (2) is subjected to initial rolling to obtain initial rolled strip; the total deformation of the initial rolling is 90%; the single-pass deformation of the initial rolling is 15%;

[0082] (4) The initial rolled strip obtained in step (3) is subjected to a second bell annealing, followed by sulfuric acid washing, water washing, and passivating agent washing to obtain the second annealed strip; the temperature of the second bell annealing is 550℃, and the holding time of the second bell annealing is 10h; the atmosphere of the second bell annealing is a mixed atmosphere of hydrogen and nitrogen, in which the volume fraction of hydrogen is 50% and the volume fraction of nitrogen is 50%; the sulfuric acid solution used for the sulfuric acid washing has a mass concentration of 17.5%; the passivating agent used for the passivating agent washing is an aqueous solution of benzotriazole; the mass concentration of the aqueous solution of benzotriazole is 0.1%;

[0083] (5) The second annealed strip obtained in step (4) is pre-rolled to obtain a pre-rolled strip; the total deformation of the pre-rolling is 60%; the deformation per pass of the pre-rolling is 20%;

[0084] (6) The pre-rolled strip obtained in step (5) is subjected to a first continuous annealing and a first tensile bending straightening to obtain a third annealed strip; the temperature of the first continuous annealing is 750℃ and the speed of the first continuous annealing is 30m / min.

[0085] (7) The strip obtained in step (6) is precision rolled to obtain a precision rolled strip; the total deformation of the precision rolling is 60%, and the deformation per pass of the precision rolling is 15%.

[0086] (8) The finely rolled strip obtained in step (7) is subjected to aging heat treatment, and then subjected to sulfuric acid washing, water washing and passivating agent washing in sequence to obtain heat-treated strip; the temperature of the aging heat treatment is 350℃; the holding time of the aging heat treatment is 10h; the mass concentration of the sulfuric acid solution used in the sulfuric acid washing is 17.5%; the passivating agent used in the passivating agent washing is benzotriazole aqueous solution; the mass concentration of the benzotriazole aqueous solution is 0.1%;

[0087] (9) The heat-treated strip obtained in step (8) is subjected to a second tensile bending straightening and high-tension continuous annealing to obtain a high-flatness copper-nickel-tin-zinc alloy; the temperature of the high-tension continuous annealing is 350℃; the speed of the high-tension continuous annealing is 50m / min; and the tension of the high-tension continuous annealing is 55N / mm. 2 .

[0088] Example 2

[0089] A high-flatness copper-nickel-tin-zinc alloy, by mass percentage, is composed of the following chemical composition: Ni: 1.5%, Sn: 1.0%, Zn: 0.05%, Fe: 0.02%, P: 0.04%, Nb: 0.28%, Ta: 0.2%, La: 0.05%, and balance Cu;

[0090] The preparation method is the same as in Example 1.

[0091] Example 3

[0092] A high-flatness copper-nickel-tin-zinc alloy, by mass percentage, is composed of the following chemical composition: Ni: 1.0%, Sn: 0.9%, Zn: 0.16%, Fe: 0.03%, P: 0.04%, Nb: 0.15%, Ta: 0.18%, La: 0.03%, and balance Cu;

[0093] The preparation method is the same as in Example 1.

[0094] Comparative Example 1

[0095] A copper-nickel-tin-zinc alloy, by mass percentage, comprises the following chemical composition: Ni: 1.0%, Sn: 1.5%, Zn: 0.1%, Fe: 0.03%, P: 0.03%, and balance Cu;

[0096] The preparation method is the same as in Example 1.

[0097] Comparative Example 2

[0098] A copper-nickel-tin-zinc alloy, by mass percentage, is composed of the following chemical composition: Ni: 2.0%, Sn: 0.5%, Zn: 0.05%, Fe: 0.02%, P: 0.04%, Nb: 0.28%, and the balance Cu.

[0099] Comparative Example 3

[0100] A copper-nickel-tin-zinc alloy, by mass percentage, is composed of the following chemical composition: Ni: 2.0%, Sn: 0.5%, Zn: 0.05%, Fe: 0.02%, P: 0.04%, La: 0.05%, and the balance Cu.

[0101] The properties of the high-flatness copper-nickel-tin-zinc alloys prepared in Examples 1-3 were tested, and the results are shown in Table 1:

[0102] Table 1. Properties of the high-flatness copper-nickel-tin-zinc alloys prepared in Examples 1-3

[0103]

[0104]

[0105] The test method for tensile strength is GB / T 34505-2017, "Tension Test at Room Temperature".

[0106] The specific test method for hardness is: GB / T4340.1-2009 Vickers hardness test for metallic materials;

[0107] The test method for elongation is GB / T 34505-2017, Tensile testing at room temperature.

[0108] The test method for conductivity is: YS / T 478-2005 Conductivity Eddy Current Test Method;

[0109] The flatness test method is: GB / T 26303.3-2010 Inspection Methods for Dimensions of Copper and Copper Alloy Processed Materials Part 3: Sheet and Strip Materials;

[0110] As can be seen from Table 1, the high-flatness copper-nickel-tin-zinc alloy provided by this invention has a tensile strength > 600 MPa and an elongation A 11.3 The properties of the copper-nickel-tin-zinc alloy provided by this invention are as follows: 5-7% mechanical properties, hardness >180HV, conductivity ≥40%IACS, bending strength 7-8mm / m, and flatness ≤0.05mm.

[0111] The thermal shrinkage rates of the high-flatness copper-nickel-tin-zinc alloys prepared in Examples 1-3 and the copper-nickel-tin-zinc alloy provided in Comparative Example 1 were tested. The test method was as follows: the length of the copper-nickel-tin-zinc alloy was 180 mm, and it was baked at a high temperature of 500±10℃ for 1 min. The thermal shrinkage rate was calculated and had to be <0.011%. The calculation formula is shown in Equation I.

[0112] Heat shrinkage rate = (180-L1) / 180*100% Equation I

[0113] In Formula I, L1 is the length of the copper-nickel-tin-zinc alloy after baking.

[0114] The results of the thermal shrinkage rates of the copper-nickel-tin-zinc alloys provided in Examples 1-3 and Comparative Example 1 are shown in Table 2:

[0115] Table 2 shows the thermal shrinkage rates of the copper-nickel-tin-zinc alloys provided in Examples 1-3 and Comparative Example 1.

[0116]

[0117]

[0118] As can be seen from Table 2, the copper-nickel-tin-zinc alloy provided by the present invention has a lower shrinkage rate and higher flatness after heat treatment.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-flatness copper-nickel-tin-zinc alloy, comprising the following chemical composition by mass percentage: Ni: 0.2~3.0%, Sn: 0.2~2.0%, Zn: 0.05~0.2%, Fe: 0.01~0.1%, P: 0.02~0.08%, Nb: 0.05~0.28%, Ta: 0.05~0.2%, La: 0.02~0.1% and balance Cu; The preparation method of the high-flatness copper-nickel-tin-zinc alloy includes the following steps: (1) The alloy raw materials are smelted and horizontally continuously cast in sequence to obtain a billet; (2) The billet obtained in step (1) is subjected to a first bell annealing to obtain a first annealed strip; (3) The first annealed strip obtained in step (2) is subjected to initial rolling to obtain the initial rolled strip; (4) The initial rolled strip obtained in step (3) is subjected to a second bell annealing to obtain a second annealed strip; (5) The second annealed strip obtained in step (4) is pre-rolled to obtain a pre-rolled strip; the total deformation of the pre-rolling is 60-70%; (6) The pre-rolled strip obtained in step (5) is subjected to a first continuous annealing and a first tensile bending straightening to obtain a third annealed strip; (7) The strip obtained in step (6) is subjected to finish rolling to obtain a finish-rolled strip; the total deformation of the finish rolling is 50-60%; (8) The fine-rolled strip obtained in step (7) is subjected to aging heat treatment to obtain heat-treated strip; (9) The heat-treated strip obtained in step (8) is subjected to a second tensile bending straightening and high-tension continuous annealing to obtain a high-flatness copper-nickel-tin-zinc alloy. In step (9), the temperature of the high-tension continuous annealing is 300~400℃, the speed of the high-tension continuous annealing is 40~60m / min, and the tension of the high-tension continuous annealing is 45~65N / mm. 2 .

2. The high-flatness copper-nickel-tin-zinc alloy according to claim 1, characterized in that, By mass percentage, it includes the following chemical composition: Ni: 0.5~2.5%, Sn: 0.5~1.5%, Zn: 0.1~0.15%, Fe: 0.05~0.1%, P: 0.02~0.05%, Nb: 0.08~0.25%, Ta: 0.1~0.15%, La: 0.02~0.05%, and the balance Cu.

3. The high-flatness copper-nickel-tin-zinc alloy according to claim 1, characterized in that, The chemical composition, by mass percentage, includes the following: Ni: 0.5-2.0%, Sn: 1.0-1.2%, Zn: 0.1-0.13%, Fe: 0.05-0.08%, P: 0.02-0.04%, Nb: 0.08-0.20%, Ta: 0.1-0.12%, La: 0.03-0.05%, and the balance Cu.

4. A method for preparing the high-flatness copper-nickel-tin-zinc alloy according to any one of claims 1 to 3, comprising the following steps: (1) The alloy raw materials are smelted and horizontally continuously cast in sequence to obtain a billet; (2) The billet obtained in step (1) is subjected to a first bell annealing to obtain a first annealed strip; (3) The first annealed strip obtained in step (2) is subjected to initial rolling to obtain the initial rolled strip; (4) The initial rolled strip obtained in step (3) is subjected to a second bell annealing to obtain a second annealed strip; (5) The second annealed strip obtained in step (4) is pre-rolled to obtain a pre-rolled strip; the total deformation of the pre-rolling is 60-70%; (6) The pre-rolled strip obtained in step (5) is subjected to a first continuous annealing and a first tensile bending straightening to obtain a third annealed strip; (7) The strip obtained in step (6) is subjected to finish rolling to obtain a finish-rolled strip; the total deformation of the finish rolling is 50-60%; (8) The fine-rolled strip obtained in step (7) is subjected to aging heat treatment to obtain heat-treated strip; (9) The heat-treated strip obtained in step (8) is subjected to a second tensile bending straightening and high-tension continuous annealing to obtain a high-flatness copper-nickel-tin-zinc alloy. In step (9), the temperature of the high-tension continuous annealing is 300~400℃, the speed of the high-tension continuous annealing is 40~60m / min, and the tension of the high-tension continuous annealing is 45~65N / mm. 2 .

5. The preparation method according to claim 4, characterized in that, In step (2), the temperature of the first bell annealing is 540~680℃, and the holding time of the first bell annealing is 5~12h.

6. The preparation method according to claim 4, characterized in that, The total deformation of the initial rolling in step (3) is 80-90%.

7. The preparation method according to claim 4, characterized in that, In step (4), the temperature of the second bell annealing is 500~600℃, and the holding time of the second bell annealing is 5~12h.

8. The preparation method according to claim 4, characterized in that, In step (6), the temperature of the first continuous annealing is 680~800℃, and the speed of the first continuous annealing is 10~50m / min.

9. The preparation method according to claim 4, characterized in that, The temperature of the aging heat treatment in step (8) is 280~360℃, and the holding time of the aging heat treatment is 5~12h.

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