Copper alloy strip and preparation method thereof

Abstract

The invention relates to a copper alloy strip and a preparation method thereof, and belongs to the technical field of copper alloys. The chemical components of the copper alloy strip are Ti, Co, Mo, Cr, Nb and Cu. Wherein the content of Ti ranges from 3.5% to 3.6% by mass, the content of Co ranges from 0.05% to 0.08% by mass, the content of Mo ranges from 0.1% to 0.15% by mass, the content of Cr ranges from 0.15% to 0.2% by mass, the content of Nb ranges from 0.02% to 0.05% by mass, and the balance is Cu. According to the copper alloy strip, the tensile strength is larger than or equal to 1400 MPa, the electric conductivity is larger than or equal to 12% IACS, and the residual stress is smaller than or equal to 50 MPa.

Description

Technical Field

[0001] The present application relates to the technical field of copper alloys, and in particular to a copper alloy strip and a preparation method thereof. Background Art

[0002] High-strength and high-conductivity copper alloy strips are mainly used to make elastic electronic components, especially high-strength and high-conductivity copper alloy strips with low residual stress are widely used in etching high-precision electronic communication components.

[0003] High-strength elastic copper alloys are widely used in the field of elastic components. With the acceleration of informatization and automation, the integration of electronic components is high, and elastic copper alloy components tend to be miniaturized, ultra-thin and special-shaped. Therefore, higher requirements are put forward for the mechanical properties, conductivity and residual stress of copper alloys. At present, copper alloy strips with tensile strength of more than 1000MPa mainly include Cu-Be, Cu-Ni-Sn and Cu-Ti alloys. Due to environmental protection and processing cost reasons, Cu-Ti alloy is the most promising material to replace Cu-Be and Cu-Ni-Sn, but the strength of Cu-Ti alloy prepared by conventional methods is relatively low, and it is difficult to make the tensile strength reach more than 1400MPa. Therefore, there is an urgent need for a copper alloy with ultra-high strength, low residual stress and high conductivity. Summary of the invention

[0004] The present application provides a copper alloy strip and a preparation method thereof to solve the following technical problem: how to improve the strength of the copper alloy strip.

[0005] In a first aspect, an embodiment of the present application provides a copper alloy strip, wherein the chemical composition of the copper alloy strip is: Ti, Co, Mo, Cr, Nb, and Cu; wherein, in terms of mass fraction,

[0006] The content of Ti is 3.5% to 3.6%, the content of Co is 0.05% to 0.08%, the content of Mo is 0.1% to 0.15%, the content of Cr is 0.15% to 0.2%, the content of Nb is 0.02% to 0.05%, and the rest is Cu.

[0007] Optionally, in terms of mass fraction, the chemical composition of the copper alloy strip includes 3.5% Ti, 0.08% Co, 0.15% Mo, 0.2% Cr, 0.05% Nb, and the remainder Cu.

[0008] Optionally, the copper alloy strip meets the following indicators:

[0009] The tensile strength is ≥1400MPa, the electrical conductivity is ≥12%IACS, and the residual stress is ≤50MPa.

[0010] In a second aspect, an embodiment of the present application provides a method for preparing the copper alloy strip according to any one of the first aspects, the method comprising:

[0011] The alloy ingot is hot-rolled and air-cooled in sequence to obtain a hot-rolled plate having a second phase;

[0012] The hot-rolled sheet is sequentially cold-rolled and solution-heat-treated to obtain a strip having an average grain size of 0.8 μm to 1 μm;

[0013] The strip is subjected to multiple cold rolling-aging heat treatments to obtain a copper alloy strip.

[0014] Optionally, the hot rolling includes heating and rolling; wherein,

[0015] The heating temperature is 870°C to 890°C; and / or,

[0016] The final rolling temperature is ≥700℃.

[0017] Optionally, the cold rolling deformation is 50% to 70%; and / or,

[0018] The temperature of the solution heat treatment is 900°C to 940°C.

[0019] Optionally, the strip is subjected to multiple cold rolling-aging heat treatments to obtain a copper alloy strip, comprising:

[0020] The strip is sequentially subjected to a first cold rolling-aging heat treatment, a second cold rolling-aging heat treatment and a third cold rolling-aging heat treatment to obtain a copper alloy strip.

[0021] Optionally, in the first cold rolling-aging heat treatment, the deformation amount of cold rolling is 50% to 70%, and the temperature of aging heat treatment is 350°C to 390°C.

[0022] Optionally, in the second cold rolling-aging heat treatment, the deformation amount of cold rolling is 60% to 70%, and the temperature of aging heat treatment is 280°C to 300°C.

[0023] Optionally, in the third cold rolling-aging heat treatment, the deformation amount of cold rolling is 40% to 50%, and the temperature of the aging heat treatment is 280°C to 300°C.

[0024] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0025] The copper alloy strip provided in the embodiment of the present application includes chemical components Ti, Co, Mo, Cr, Nb, and Cu; the content of Ti is 3.5% to 3.6%, forming a dispersed second phase in the copper alloy strip, which plays a precipitation strengthening role; the content of Co is 0.05% to 0.08%, which can refine the grain size of the copper alloy strip and play a fine grain strengthening role; the content of Mo is 0.1% to 0.15%, the content of Cr is 0.15% to 0.2%, and the content of Nb is 0.02% to 0.05%, which can synergistically promote the precipitation of the second phase of the copper alloy strip, play a precipitation strengthening role, and provide conditions for the large-scale value-added of dislocations and the formation of twins in the copper alloy strip. Therefore, by rationally designing the contents of Ti, Co, Mo, Cr, and Nb, the strength of the copper alloy strip is fully improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 A schematic flow chart of a method for preparing a copper alloy strip provided in an embodiment of the present application;

[0029] Figure 2 A microstructure diagram of a copper alloy strip after hot rolling and air cooling in a method for preparing the copper alloy strip provided in Example 1 of the present application;

[0030] Figure 3 A microstructure diagram after solution heat treatment in a method for preparing a copper alloy strip provided in Example 1 of the present application;

[0031] Figure 4 A microstructure diagram of a copper alloy strip after hot rolling and air cooling in a method for preparing the copper alloy strip provided in Example 2 of the present application;

[0032] Figure 5 A microstructure diagram after solution heat treatment in a method for preparing a copper alloy strip provided in Example 2 of the present application;

[0033] Figure 6 A microstructure diagram of a copper alloy strip after hot rolling and air cooling in a method for preparing the copper alloy strip provided in Example 3 of the present application;

[0034] Figure 7This is a microstructure diagram of a copper alloy strip after solution heat treatment in a preparation method provided in Example 3 of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0036] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0037] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0038] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0039] In a first aspect, an embodiment of the present application provides a copper alloy strip, wherein the chemical composition of the copper alloy strip is: Ti, Co, Mo, Cr, Nb, and Cu; wherein, in terms of mass fraction,

[0040] The content of Ti is 3.5% to 3.6%, the content of Co is 0.05% to 0.08%, the content of Mo is 0.1% to 0.15%, the content of Cr is 0.15% to 0.2%, the content of Nb is 0.02% to 0.05%, and the rest is Cu.

[0041] The chemical composition of the copper alloy strip is Ti, Co, Mo, Cr, Nb and the basic component Cu. The Ti content can be 3.5% to 3.6%, which plays a precipitation strengthening role by forming a dispersed second phase. This strengthening mechanism is based on the second phase hindering dislocation movement, thereby improving the strength of the alloy. The Co content can be 0.05% to 0.08%, and its role is to refine the grain size. Fine grain strengthening is because small grains can increase the grain boundary area, and the grain boundary has a hindering effect on deformation, thereby improving the strength and toughness of the alloy. The Mo content can be 0.1% to 0.15%, the Cr content can be 0.15% to 0.2%, and the Nb content can be 0.02% to 0.05%. These three elements synergistically promote the precipitation of the second phase during air cooling after hot rolling, and together with the Co element, provide conditions for obtaining ultrafine grains in subsequent solid solution treatment. At the same time, the dislocation density can be increased and twin deformation can occur during the cold rolling process. The dislocation value increase can increase the interaction between dislocations and improve the strength of the alloy; and the formation of twins will also have an important impact on the properties of the alloy, such as improving strength and plasticity. "Second phase" refers to the second phase rich in Mo, Cr and Nb.

[0042] The range of Ti content ensures the number and distribution of the precipitated second phase, and the appropriate content can ensure the maximization of the dispersion strengthening effect. If the Ti content is lower than 3.5%, the density of the dispersed second phase will be too low, and the strengthening effect will be insufficient; if the Ti content is higher than 3.6%, it will cause the segregation of solidification elements and affect the strengthening effect. The contents of Co, Cr and Nb ensure the conductivity of the copper alloy to a certain extent. The content ranges of Mo, Cr and Nb cooperate with each other to promote the precipitation of the second phase and the formation of dislocations and twins. The synergy between them is achieved by affecting the thermodynamic and kinetic processes of the alloy, such as changing the precipitation temperature, speed and morphology of the second phase. The copper alloy strip fully improves the strength of the alloy through the comprehensive application of multiple strengthening mechanisms (precipitation strengthening, fine grain strengthening, etc.). Precipitation strengthening is mainly achieved by the Ti-containing precipitation phase, and fine grain strengthening is completed by the synergistic effect of Co and the second phases containing Mo, Cr and Nb. These strengthening mechanisms complement each other, so that the alloy is strengthened at different scales.

[0043] Exemplarily, the Ti content can be 3.5%, 3.52%, 3.54%, 3.56%, 3.58%, 3.6%, etc.; the Co content can be 0.05%, 0.06%, 0.07%, 0.08%, etc.; the Mo content can be 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, etc.; the Cr content can be 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, etc.; the Nb content can be 0.02%, 0.03%, 0.04%, 0.05%, etc.

[0044] In some embodiments, the chemical composition of the copper alloy strip is, by mass fraction, 3.5% Ti, 0.08% Co, 0.15% Mo, 0.2% Cr, 0.05% Nb, and the rest is Cu.

[0045] For example, the chemical composition of the copper alloy strip may include 3.5% Ti, 0.08% Co, 0.15% Mo, 0.2% Cr, and 0.05% Nb, and a tensile strength of 1460 MPa, a conductivity of 14% IACS, and a residual stress of 43 MPa may be achieved.

[0046] In some embodiments, the copper alloy strip satisfies the following indicators simultaneously:

[0047] The tensile strength is ≥1400MPa, the electrical conductivity is ≥12%IACS, and the residual stress is ≤50MPa.

[0048] The copper alloy strip provided in the embodiment of the present application can achieve a tensile strength of more than 1400 MPa and a conductivity of more than 12% IACS, while the residual stress is less than 50 MPa, that is, a high-strength and high-conductivity copper alloy strip with low residual stress, which can be fully used in etching high-precision electronic communication components.

[0049] In a second aspect, an embodiment of the present application provides a method for preparing the copper alloy strip according to any one of the first aspects, Figure 1 A schematic diagram of a process for preparing a copper alloy strip provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0050] S1, hot rolling and air cooling the alloy ingot in sequence to obtain a hot rolled plate having a second phase;

[0051] The alloy ingot is hot rolled to plastically deform the ingot at high temperature. This process can break the coarse original grains of the ingot, improve the uniformity of the ingot structure, and create conditions for the subsequent precipitation of the second phase. Through hot rolling, the dislocation density inside the alloy increases, and the energy generated by the deformation contributes to the nucleation of the second phase. For example, for the copper alloy strip, during the hot rolling process, elements such as Ti, Mo, Cr, and Nb may begin to gradually form a dispersed second phase, laying the foundation for the subsequent strengthening effect. After hot rolling, air cooling is carried out, and the composite precipitation of Cr, Nb and Mo is achieved during the air cooling process, which can achieve the control of ultrafine grains during the recrystallization process and contribute to the final strengthening effect. In addition, the alloy ingot is obtained by vacuum induction melting.

[0052] In some embodiments, the hot rolling includes heating and rolling; wherein,

[0053] The heating temperature is 870°C to 890°C; and / or,

[0054] The final rolling temperature is ≥700℃.

[0055] The heating temperature can be 870°C to 890°C to refine the as-cast structure, further form a second phase during air cooling, and provide conditions for subsequent solid solution to obtain ultrafine grains. Exemplarily, the heating temperature can be 870°C, 875°C, 880°C, 885°C, 890°C, etc., and the corresponding holding time is 30min to 40min. The final rolling temperature of the rolling can be ≥700°C to achieve full refinement and uniformity of the as-cast structure. If the final rolling temperature is lower than 700°C, rolling cracking may occur and the structure is difficult to refine. Exemplarily, the final rolling temperature of the rolling can be 700°C, 710°C, 720°C, 730°C, 740°C, etc.

[0056] S2, sequentially cold rolling and solution heat treating the hot-rolled sheet to obtain a strip having an average grain size of 0.8 μm to 1 μm;

[0057] The hot-rolled plate is cold-rolled, and the rolling force further deforms the plate, reducing the thickness. At the same time, the grains are further elongated and broken, and the dislocation density is greatly increased. This process improves the strength and hardness of the plate, but it also causes work hardening and reduces the plasticity of the material. The structure of the plate after cold rolling is in a highly distorted state, preparing for solution heat treatment. Solution heat treatment allows the solute atoms (such as Co, Cr, Nb, etc.) in the alloy to fully dissolve into the matrix (copper) to form a uniform solid solution. This process eliminates work hardening, restores the plasticity of the material, and creates conditions for the uniform precipitation of the second phase during subsequent aging treatment. Finally, a strip with an average grain size of 0.8μm to 1μm is obtained. The fine grain size is beneficial to improving the comprehensive properties of the material, such as strength and toughness.

[0058] In some embodiments, the cold rolling deformation is 50% to 70%; and / or,

[0059] The temperature of the solution heat treatment is 900°C to 940°C.

[0060] The deformation of cold rolling can be 50% to 70%, ensuring that the subsequent solution treatment undergoes recrystallization to obtain an ultrafine grain structure (0.8 μm to 1 μm). For example, the deformation of cold rolling can be 50%, 55%, 60%, 65%, 70%, etc.; the temperature of the solution heat treatment can be 900°C to 940°C to achieve an ultrafine grain structure of the strip and provide a fine grain strengthening effect. For example, the temperature of the solution heat treatment can be 900°C, 910°C, 920°C, 930°C, 940°C, etc., and the corresponding holding time can be 35 to 45 seconds.

[0061] S3, subjecting the strip to multiple cold rolling-aging heat treatments to obtain a copper alloy strip.

[0062] The strip is subjected to multiple cold rolling, and each cold rolling further increases the deformation degree of the plate, so that the dislocation density continues to increase, providing more nucleation positions for the precipitation of the second phase during aging treatment. At the same time, multiple cold rolling can further refine the grains and improve the uniformity of the sheet's structure. Aging heat treatment causes the solute atoms in the solid solution to precipitate in the form of a second phase. In the copper alloy strip, after multiple cold rolling and aging treatment, the Ti element will form a strengthening phase, which plays a precipitation strengthening role, and Co and Mo, Cr, Nb, etc. help to refine the grains and further strengthen the material. Through multiple cold rolling-aging heat treatment cycles, the size, quantity and distribution of the second phase are continuously adjusted and optimized, and finally the copper alloy strip has an ultrafine crystal matrix combined with a high-density precipitation phase, which has a good strengthening effect and can also ensure a certain electrical conductivity.

[0063] In some embodiments, the strip is subjected to multiple cold rolling-aging heat treatments to obtain a copper alloy strip, comprising:

[0064] The strip is sequentially subjected to a first cold rolling-aging heat treatment, a second cold rolling-aging heat treatment and a third cold rolling-aging heat treatment to obtain a copper alloy strip.

[0065] In some embodiments, in the first cold rolling-aging heat treatment, the deformation amount of cold rolling is 50% to 70%, and the temperature of aging heat treatment is 350°C to 390°C.

[0066] In the first cold rolling-aging heat treatment, the cold rolling deformation can be 50% to 70%, forming a large number of microscopic defects such as dislocations, providing nucleation conditions for the subsequent aging to form dispersed precipitates; the aging heat treatment temperature can be 350°C to 390°C, promoting the formation of the second phase and obtaining a strengthening effect. Exemplarily, in the first cold rolling-aging heat treatment, the cold rolling deformation can be 50%, 55%, 60%, 65%, 70%, etc.; the aging heat treatment temperature can be 350°C, 360°C, 370°C, 380°C, 390°C, etc., and the corresponding holding time can be 12h.

[0067] In some embodiments, in the second cold rolling-aging heat treatment, the deformation amount of cold rolling is 60% to 70%, and the temperature of aging heat treatment is 280°C to 300°C.

[0068] In the second cold rolling-aging heat treatment, the cold rolling deformation can be 60% to 70%, forming a large number of microscopic defects such as dislocations, providing nucleation conditions for the subsequent aging to form dispersed precipitates; the aging heat treatment temperature is 280°C to 300°C, which promotes the formation of the second phase and obtains a strengthening effect. Exemplarily, in the second cold rolling-aging heat treatment, the cold rolling deformation can be 60%, 62%, 64%, 66%, 68%, 70%, etc.; the aging heat treatment temperature can be 280°C, 290°C, 300°C, etc., and the corresponding holding time can be 10h to 24h.

[0069] In some embodiments, in the third cold rolling-aging heat treatment, the deformation amount of cold rolling is 40% to 50%, and the temperature of aging heat treatment is 280°C to 300°C.

[0070] In the third cold rolling-aging heat treatment, the cold rolling deformation can be 40% to 50%, forming a large number of microscopic defects such as dislocations, providing nucleation conditions for the subsequent aging to form dispersed precipitates; the temperature of the aging heat treatment can be 280°C to 300°C, and low-temperature aging can further promote the precipitation of the second phase, improve the conductivity, and play a recovery role, thereby reducing the residual stress. In the temperature range of 280°C to 300°C, the strength and residual stress can be balanced. Exemplarily, in the third cold rolling-aging heat treatment, the cold rolling deformation can be 40%, 42%, 44%, 46%, 48%, 50%, etc.; the temperature of the aging heat treatment can be 280°C, 290°C, 300°C, etc., and the corresponding holding time is 10h to 24h.

[0071] In summary, Ti, as the main additive element, forms a dispersed second phase during the subsequent aging treatment, which plays a role in precipitation strengthening; Co can refine the grain size after solid solution, and finally achieve fine grain strengthening; Mo, Cr and Nb can precipitate the second phase in air cooling after hot rolling, providing conditions for the large-scale value-added of dislocations and the formation of twins in the subsequent deformation process. On the basis of the above chemical composition, a part of the second phase is first precipitated by hot rolling and air cooling, and after cold rolling and solid solution, it plays a pinning role on the grain boundary to form an ultrafine grain structure. Combined with subsequent multiple deformation and aging treatment, multiple strengthening mechanisms such as fine grain strengthening, precipitation strengthening and dislocation strengthening can be achieved to synergistically improve the strength. Among them, multiple cold rolling and aging treatment can use dislocations as the preferred nucleation position for precipitation, achieve more sufficient precipitation, improve strength and ensure a certain conductivity. In addition, multiple low-temperature aging can gradually achieve stress relief and obtain strips with low residual stress.

[0072] The preparation method of the copper alloy strip is implemented based on the above-mentioned copper alloy strip. The specific chemical composition of the copper alloy strip can refer to the above-mentioned embodiment. Since the copper alloy strip adopts part or all of the technical solutions of the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0073] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for the unrecorded specific conditions in the following examples are usually measured according to national standards. If there is no corresponding national standard, then carry out according to general international standards, normal conditions or according to the conditions recommended by the manufacturer.

[0074] Example 1

[0075] A copper alloy strip has the following chemical components: Ti, Co, Mo, Cr, Nb, and the rest is Cu and inevitable impurities; wherein, by mass fraction, Ti: 3.5%, Co: 0.08%, Mo: 0.15%, Cr: 0.2%, and Nb: 0.05%.

[0076] A method for preparing a copper alloy strip, comprising:

[0077] The alloy ingot is hot rolled and air cooled in sequence to obtain a hot rolled plate with a second phase; specifically, the alloy ingot is hot rolled, and the hot rolling includes heating and rolling, the heating temperature is 870°C, the heat preservation is 40 minutes, and the final rolling temperature of the rolling is 720°C;

[0078] The hot-rolled sheet is sequentially cold-rolled and solution-heat treated to obtain a strip having an average grain size of 0.8 μm to 1 μm; wherein the cold-rolling deformation is 50% and the solution-heat treatment is carried out at 900° C. for 35 seconds;

[0079] The strip is subjected to multiple cold rolling-aging heat treatments to obtain a copper alloy strip. Specifically, the strip is subjected to the first cold rolling-aging heat treatment, the second cold rolling-aging heat treatment and the third cold rolling-aging heat treatment in sequence to obtain a copper alloy strip; wherein, the first cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 50%; then the strip is kept at 350°C for 12 hours for aging heat treatment; the second cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 60%; then the strip is kept at 280°C for 10 hours for aging heat treatment; the third cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 40%; then the strip is kept at 280°C for 10 hours for aging heat treatment.

[0080] Example 2

[0081] A copper alloy strip has the following chemical components: Ti, Co, Mo, Cr, Nb, and the rest is Cu and inevitable impurities; wherein, by mass fraction, Ti: 3.55%, Co: 0.05%, Mo: 0.1%, Cr: 0.15%, and Nb: 0.02%.

[0082] A method for preparing a copper alloy strip, comprising:

[0083] The alloy ingot is hot rolled and air cooled in sequence to obtain a hot rolled plate with a second phase; specifically, the alloy ingot is hot rolled, the hot rolling includes heating and rolling, the heating temperature is 880°C, the heat preservation is 40 minutes, and the final rolling temperature of the rolling is 720°C;

[0084] The hot-rolled sheet is sequentially cold-rolled and solution-heat treated to obtain a strip having an average grain size of 0.8 μm to 1 μm; wherein the cold-rolling deformation is 55% and the solution-heat treatment is carried out at 920° C. for 40 seconds;

[0085] The strip is subjected to multiple cold rolling-aging heat treatments to obtain a copper alloy strip. Specifically, the strip is subjected to the first cold rolling-aging heat treatment, the second cold rolling-aging heat treatment and the third cold rolling-aging heat treatment in sequence to obtain a copper alloy strip; wherein, the first cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 60%; then the strip is kept at 370°C for 12 hours for aging heat treatment; the second cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 66%; then the strip is kept at 300°C for 24 hours for aging heat treatment; the third cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 45%; then the strip is kept at 290°C for 20 hours for aging heat treatment.

[0086] Example 3

[0087] A copper alloy strip has the following chemical components: Ti, Co, Mo, Cr, Nb, and the rest is Cu and inevitable impurities; wherein, by mass fraction, Ti: 3.6%, Co: 0.06%, Mo: 0.12%, Cr: 0.18%, and Nb: 0.03%.

[0088] A method for preparing a copper alloy strip, comprising:

[0089] The alloy ingot is hot rolled and air cooled in sequence to obtain a hot rolled plate with a second phase; specifically, the alloy ingot is hot rolled, and the hot rolling includes heating and rolling, the heating temperature is 890°C, the heat preservation is 30 minutes, and the final rolling temperature of the rolling is 720°C;

[0090] The hot-rolled sheet is sequentially cold-rolled and solution-heat treated to obtain a strip having an average grain size of 0.8 μm to 1 μm; wherein the cold-rolling deformation is 60% and the solution-heat treatment is carried out at 940° C. for 45 seconds;

[0091] The strip is subjected to multiple cold rolling-aging heat treatments to obtain a copper alloy strip. Specifically, the strip is subjected to the first cold rolling-aging heat treatment, the second cold rolling-aging heat treatment and the third cold rolling-aging heat treatment in sequence to obtain a copper alloy strip; wherein, the first cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 70%; then the strip is kept at 390°C for 12 hours for aging heat treatment; the second cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 70%; then the strip is kept at 300°C for 24 hours for aging heat treatment; the third cold rolling-aging heat treatment: the strip is cold rolled with a cold rolling deformation of 50%; then the strip is kept at 280°C for 24 hours for aging heat treatment.

[0092] The performance indicators of the copper alloy strips prepared in Examples 1 to 3 were tested. Please refer to Table 1 for the performance indicators of the copper alloy strips.

[0093] Table 1 Performance indicators of copper alloy strip

[0094] Serial number Tensile strength MPa Electrical conductivity %IACS Residual stress MPa Example 1 1460 14 43 Example 2 1420 14 45 Example 3 1432 14 40

[0095] It can be seen from Table 1 that the copper alloy strip provided in the embodiment of the present application can simultaneously meet the following requirements: the tensile strength is

[0096] ≥1400MPa, electrical conductivity is ≥12%IACS, and residual stress is ≤50MPa. Figure 2 This is a microstructure diagram of a copper alloy strip after hot rolling and air cooling in a preparation method of Example 1 of the present application; see Figure 2 , indicating the formation of a dispersed second phase; Figure 3 This is a microstructure diagram after solution heat treatment in a method for preparing a copper alloy strip provided in Example 1 of the present application; see Figure 3 , indicating that an ultrafine-grained structure is obtained, with an average grain size of about 1 μm. Figure 4 This is a microstructure diagram of a copper alloy strip after hot rolling and air cooling in a method for preparing the copper alloy strip provided in Example 2 of the present application; see Figure 4 , indicating the formation of a dispersed second phase; Figure 5 This is a microstructure diagram after solution heat treatment in a method for preparing a copper alloy strip provided in Example 2 of the present application; see Figure 5 , indicating that an ultrafine-grained structure is obtained, with an average grain size of about 1 μm. Figure 6 This is a microstructure diagram of a copper alloy strip after hot rolling and air cooling in a method for preparing the copper alloy strip provided in Example 3 of the present application; see Figure 6 , indicating the formation of a dispersed second phase; Figure 7 This is a microstructure diagram of a copper alloy strip after solution heat treatment in a method for preparing the copper alloy strip provided in Example 3 of the present application. Figure 7 , indicating that an ultrafine-grained structure is obtained, with an average grain size of about 1 μm.

[0097] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:

[0098] (1) The copper alloy strip provided in the embodiment of the present application achieves a tensile strength of more than 1400 MPa, a conductivity of more than 12% IACS, and a residual stress of less than 50 MPa;

[0099] (2) Ti, as the main added element, forms a dispersed second phase during the subsequent aging treatment, which plays a precipitation strengthening role. When the alloying elements Cr and Mo are added together, the solid solubility of these two elements in copper is extremely low. Combined with a trace amount of Nb element, a second phase with a certain number density will be formed during the air cooling process after hot rolling, which will affect the dislocation density and the number of twin boundaries during the cold rolling process, and contribute to the strengthening effect of the final strip. The synergistic effect of the trace addition of Co and the hot rolling precipitation phase can refine the grain size of the solution treatment. The average grain size can be refined to 0.8μm to 1μm, which can improve the strength, plasticity and toughness of the alloy;

[0100] (3) The composite precipitation of Cr, Nb and Mo in the hot-rolled plate during air cooling can achieve the control of ultrafine grains in the recrystallization process and contribute to the final strengthening effect. The composite precipitation combined with ultrafine grains can not only obtain a higher dislocation density in the subsequent cold rolling process, but also retain more dislocations and other defects while fully precipitating them during the subsequent multiple low-temperature aging heat treatments, thereby maximizing the effects of precipitation strengthening and dislocation strengthening. At the same time, it can also significantly reduce the residual stress of the alloy while maintaining the plate shape of the strip.

[0101] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A copper alloy strip, the chemical composition of which is: Ti, Co, Mo, Cr, Nb, and Cu; wherein: In terms of mass fraction, The content of Ti is 3.5% to 3.6%, the content of Co is 0.05% to 0.08%, the content of Mo is 0.1% to 0.15%, the content of Cr is 0.15% to 0.2%, the content of Nb is 0.02% to 0.05%, and the rest is Cu.

2. The copper alloy strip according to claim 1, characterized in that: In terms of mass fraction, the chemical composition of the copper alloy strip includes 3.5% Ti, 0.08% Co, 0.15% Mo, 0.2% Cr, 0.05% Nb, and the rest Cu.

3. The copper alloy strip according to claim 1 or 2, characterized in that: The copper alloy strip meets the following indicators: The tensile strength is ≥1400MPa, the electrical conductivity is ≥12%IACS, and the residual stress is ≤50MPa.

4. A method for preparing the copper alloy strip according to any one of claims 1 to 3, the method comprising: The alloy ingot is hot-rolled and air-cooled in sequence to obtain a hot-rolled plate having a second phase; The hot-rolled sheet is sequentially cold-rolled and solution-heat-treated to obtain a strip having an average grain size of 0.8 μm to 1 μm; The strip is subjected to multiple cold rolling-aging heat treatments to obtain a copper alloy strip.

5. The method according to claim 4, characterized in that The hot rolling includes heating and rolling; wherein, The heating temperature is 870°C to 890°C; and / or, The final rolling temperature is ≥700℃.

6. The method according to claim 4, characterized in that The cold rolling deformation is 50% to 70%; and / or, The temperature of the solution heat treatment is 900°C to 940°C.

7. The method according to claim 4, characterized in that The strip is subjected to multiple cold rolling-aging heat treatments to obtain a copper alloy strip, comprising: The strip is sequentially subjected to a first cold rolling-aging heat treatment, a second cold rolling-aging heat treatment and a third cold rolling-aging heat treatment to obtain a copper alloy strip.

8. The method according to claim 7, characterized in that In the first cold rolling-aging heat treatment, the deformation amount of cold rolling is 50% to 70%, and the temperature of aging heat treatment is 350°C to 390°C.

9. The method according to claim 7, characterized in that: In the second cold rolling-aging heat treatment, the deformation amount of cold rolling is 60% to 70%, and the temperature of aging heat treatment is 280°C to 300°C.

10. The method according to claim 7, characterized in that In the third cold rolling-aging heat treatment, the deformation amount of cold rolling is 40% to 50%, and the temperature of aging heat treatment is 280°C to 300°C.

Images