JP4714943B2 - Method for producing precipitation hardening type copper alloy strip - Google Patents

Description

  The present invention relates to a method for producing a precipitation hardening type copper alloy strip.

  Conventionally, copper alloy strips have been widely used for current-carrying members such as terminals and connectors and mechanical parts because copper alloy-based materials have excellent mechanical strength, relatively good conductivity, and are inexpensive. It was. With the recent reduction in weight of automobiles and reduction in the thickness of electrical and electronic parts, the size of current-carrying members such as terminals has been reduced. As a result, the material for forming the current-carrying member is required to be compatible with applications that require mechanical strength at a level that is difficult to achieve with conventional copper alloy strips. For such applications, precipitation hardened copper alloy strips are often used to ensure the required mechanical strength. And the request | requirement with respect to a copper alloy strip provided with not only mechanical strength but favorable bending workability and favorable electrical conductivity is also increasing. That is, a method for producing a copper alloy strip having a good balance of mechanical strength, bending workability and electrical conductivity is required.

  As described above, for example, Patent Document 1 discloses a copper-nickel-phosphorous alloy as a copper alloy suitable for an energizing member. In Patent Document 1, by adding one or more of iron, chromium, manganese, and cobalt to a copper-nickel-phosphorous alloy, it has excellent migration resistance, high strength, and high conductivity. An energizing material having improved weldability, hot rollability, and heat-resistant peelability of solder plating or tin plating is disclosed without impairing the above. This copper-nickel-phosphorus alloy is excellent in precipitation hardening ability as a precipitation hardening type alloy and is said to have a conductivity of 30% IACS to 50% IACS. Then, according to the examples, a copper alloy ingot is cast, hot rolling is performed after chamfering, and then cold rolling and annealing pickling are repeated, and pickling is performed after final annealing at 450 ° C. for 10 hours. Cold rolling is performed at a processing rate of 20%.

  Patent Document 2 describes a copper alloy containing nickel and phosphorus as essential components, and has a high conductivity level of 70% IACS or higher, strength, bending workability, press punchability, and stress relaxation resistance. And a copper alloy material that simultaneously improves its anisotropy. In patent document 2, the method of recrystallizing only one part by the annealing before finishing which served as the aging precipitation process is taken. Further, in Patent Document 2, the aging precipitation treatment is performed once in the intermediate processing, and the recovery heat treatment is performed only once in principle for final annealing. Furthermore, the copper alloy of Patent Document 2 has an average aspect ratio (major axis / minor axis) A of 10 or more for crystal grains in a cross section parallel to the rolling direction and the plate thickness direction, and the maximum value Amax and the minimum value Amin of the aspect ratio. A plate material satisfying the ratio Amax / Amin of 1.0 to 3.0 can be manufactured.

  Patent Document 3 discloses a copper alloy suitable for a thin-walled current-carrying member and a bus bar, which simultaneously improves strength, conductivity, bending workability, and stress relaxation resistance. In Patent Document 3, for nickel-tin-phosphorous copper alloys, precipitates are uniformly generated by solution treatment / aging precipitation treatment with a low dislocation density, and the recrystallization temperature is not raised after the aging precipitation treatment. In addition, it is said that precipitates with high consistency are maintained in a fine and uniformly dispersed structure, and further strength improvement is obtained in combination with work hardening.

JP-A-4-231433 JP 2006-299409 A JP 2006-291356 A

However, even if the methods disclosed in Patent Documents 1 to 3 are used, it is difficult to obtain a copper alloy strip having a high level of characteristics in all of mechanical strength, bending workability, and conductivity. First, since the method disclosed in Patent Document 1 has a low cold rolling reduction rate of about 20%, the strength of the obtained copper alloy strip does not reach 500 N / mm ^{2 and} has a low level of mechanical strength. Only precipitation hardened copper alloy strips can be obtained.

And the method disclosed in Patent Document 2 is recrystallized only partly by annealing before finishing which also serves as aging precipitation treatment. However, this is a manufacturing method in which the aging precipitation treatment is performed only once in the intermediate process, and the recovery heat treatment is in principle only the final annealing. Therefore, the processing rate in the cold rolling before and after the annealing before finishing disclosed here is relatively low, and the aging precipitation treatment is performed for the first time in the heat treatment before finishing. As a result, even if the strength is high, it is about 500 N / mm ² , and only a precipitation hardening type copper alloy strip having insufficient mechanical strength can be obtained.

  In addition, the method disclosed in Patent Document 3 is a method in which a nickel-tin-phosphorous copper alloy is uniformly formed by solution treatment and aging precipitation treatment, and the temperature after the aging precipitation treatment is raised to the recrystallization temperature or higher. There is no method adopted. However, it is premised that the obtained copper alloy strip is set to production conditions that allow confirmation of the formation of a recrystallized structure of 3 μm to 30 μm. That is, when the method of Patent Document 3 is used, the recrystallized grains provided in the obtained copper alloy strip are relatively large, leading to a decrease in hardness. Therefore, the amount of tin added is increased to compensate for this decrease in hardness, but the strength improvement level is still insufficient. Furthermore, when the method disclosed in Patent Document 3 is adopted, in the composition of the obtained copper alloy strip, the electrical conductivity is lowered by increasing the amount of tin added, and the level is slightly cleared of 30% IACS which is a market requirement. It is usual to obtain copper alloy strips. Moreover, since the process which performs a solution treatment is employ | adopted, it is a manufacturing method with a big burden of an installation cost and a running cost.

  The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a method for producing a copper alloy strip excellent in total balance of mechanical strength, bending workability and conductivity. .

  Accordingly, the inventors have conceived that the above problem can be achieved by adopting a manufacturing method using a recovery phenomenon described below for a copper-nickel-phosphorous alloy.

The manufacturing method of the precipitation hardening type copper alloy strip according to the present invention includes 0.50% by mass to 1.50% by mass of nickel, 0.05% by mass to 0.20% by mass of phosphorus, and the remaining copper and inevitable impurities. A method for producing a copper alloy strip, comprising the following steps A to C, characterized by strengthening using a recovery phenomenon.

Step A: A step of subjecting a copper alloy ingot to hot rolling, and thereafter performing an aging precipitation treatment to obtain an aging precipitation-treated copper alloy strip.
Step B: The copper alloy strip subjected to the aging precipitation treatment obtained in Step A is subjected to intermediate processing including intermediate cold rolling applied at a processing rate of 50% to 90% and intermediate recovery heat treatment applied thereafter as a unit, and recovery heat treatment A process of obtaining a finished copper alloy strip.
Step C: Precipitation hardening type in which the recovery heat-treated copper alloy strip obtained in Step B is subjected to final cold rolling at a processing rate of 20% to 95% and then subjected to final recovery heat treatment to strengthen the recovery phenomenon. The process of obtaining a copper alloy strip.

In the method for producing a precipitation hardening type copper alloy strip according to the present invention, in the copper alloy strip, one or more of 0.04 mass% or less tin and 0.50 mass% or less zinc is further added. It is also preferable.

  In the method for producing a precipitation hardening type copper alloy strip according to the present invention, it is also preferable that the step B repeats the intermediate processing of one unit a plurality of times.

  In the method for producing a precipitation hardening type copper alloy strip according to the present invention, the step B includes at least one of the intermediate processing of the one unit based on the Vickers hardness of the copper alloy strip before the intermediate recovery heat treatment. It is also preferable that the decrease rate of the Vickers hardness of the copper alloy strip after the recovery heat treatment is 4% to 15%.

  In the method for producing a precipitation hardening type copper alloy strip according to the present invention, the step B includes subjecting the copper alloy strip subjected to the aging precipitation treatment before the intermediate processing to cold rolling at a processing rate of 50% to 90%, It is preferable to include a step of performing a secondary aging precipitation treatment in which a recrystallized structure appears to obtain a copper alloy strip that has undergone the secondary aging precipitation treatment.

  In the method for producing a precipitation hardening type copper alloy strip according to the present invention, the final recovery heat treatment in the step C is performed based on the Vickers hardness of the copper alloy strip before the final recovery heat treatment. It is also preferable that the decrease rate of the Vickers hardness is less than 4%.

  In the method for producing a precipitation hardening type copper alloy strip according to the present invention, the final recovery heat treatment in the step C is performed based on the Vickers hardness of the copper alloy strip before the final recovery heat treatment. It is also preferable that the decrease rate of the Vickers hardness is 4% to 15%.

In the method for producing a precipitation hardening type copper alloy strip according to the present invention, the tensile strength is 500 N / mm ² or more, the elongation is 5% or more, and the electrical conductivity is 50% IACS or more, bending workability and stress relaxation resistance. It is also preferable to produce a copper alloy strip having a good thickness.

Furthermore, in the manufacturing method of the precipitation hardening type copper alloy strip according to the present invention, nickel is added in an amount of 0.50% by mass to 1.50% by mass using the method for manufacturing a precipitation hardening type copper alloy strip according to any of the above. By using a copper alloy ingot containing 0.05 mass% to 0.20 mass% of phosphorus and having a Ni (mass%) / P (mass%) ratio value of 6 to 10, the tensile strength is 500 N / mm ² or more. It is also preferable to produce a copper alloy strip having good bending workability and stress relaxation resistance, having physical properties of elongation 5% or more and conductivity 65% IACS or more.

  The manufacturing method of the precipitation hardening type copper alloy strip according to the present invention includes a step of performing hot rolling on a copper-nickel-phosphorous copper alloy ingot and then aging precipitation treatment to obtain an aging precipitation treated copper alloy strip, aging precipitation A process for obtaining a recovered heat-treated copper alloy strip by subjecting the treated copper alloy strip to intermediate cold rolling and subsequent intermediate recovery heat treatment at a processing rate of 50% to 90% to obtain the recovered heat-treated copper alloy strip; It includes a step of applying the final cold rolling at a processing rate of 20% to 95% and then performing a final recovery heat treatment. If the method for producing a precipitation hardening type copper alloy strip according to the present invention is used, in the presence of precipitation particles formed by aging precipitation treatment, the recovery phenomenon is utilized after strengthening the mechanical strength by cold rolling, A copper alloy strip excellent in total balance of mechanical strength, bending workability, and conductivity can be produced.

  Hereinafter, although the form of the manufacturing method of the precipitation hardening type copper alloy strip which concerns on this invention is demonstrated, the manufacturing method of a general precipitation hardening type copper alloy strip is described before that.

  In a general precipitation hardening type copper alloy strip manufacturing process, after hot rolling, cold rolling and recrystallization annealing are performed one stage before or two stages before final thickness, followed by solution treatment. After the solution treatment, the aging precipitation treatment is performed as it is after the cold rolling or without the cold rolling. The final cold rolling is performed at a relatively low processing rate, and the product is finished by applying strain relief annealing. In such a process, a relatively high mechanical strength is achieved by the solution treatment and the aging precipitation treatment. However, if the work rate of the final cold rolling is further increased in order to further increase the mechanical strength, the elongation rate is lowered and the copper alloy strip having poor bending workability is obtained. And the crystal structure of the copper alloy strip obtained through a general manufacturing process is observed in a shape in which the recrystallized grains formed by solution treatment are somewhat flattened by cold rolling. That is, the crystal grain of the copper alloy strip which is a normal product is usually formed by solution treatment, contains many twins, and the crystal grain size is usually several tens of μm.

In contrast to the above general method for producing precipitation hardening type copper alloy strips, the method for producing precipitation hardening type copper alloy strips according to the present invention comprises 0.50% by mass to 1.50% by mass of nickel and 0.05% of phosphorus. The copper alloy strip containing the mass% to 0.20 mass% and comprising the remaining copper and inevitable impurities is strengthened. At this time, in the said copper alloy strip, 1 or more types may be further added among 0.04 mass% or less tin and 0.50 mass% or less zinc.

  If it is set as the said composition, it can suppress that a nickel- phosphorus compound precipitates by performing an aging precipitation process, and contributes to reinforcement | strengthening of mechanical strength, and recrystallization occurs simultaneously. Further, at this time, the amount of nickel-phosphorus solid solution is reduced, so that the conductivity is improved. However, if nickel whose content exceeds 1.5% by mass is added simultaneously with phosphorus, hot workability is lowered, and cracks are often generated during hot rolling, which is not preferable. On the other hand, if the nickel content is less than 0.5% by mass, it is difficult to obtain sufficient strength. Similarly, if the phosphorus content is less than 0.05% by mass, it is difficult to obtain sufficient strength, which is not preferable. On the other hand, if the phosphorus content exceeds 0.20% by mass, the conductivity tends to decrease, such being undesirable. Tin is effective for improving the strength and may be added arbitrarily. However, if the tin content exceeds 0.04% by mass, the electric conductivity tends to decrease, which is not preferable. Zinc has a property of preventing delamination of a film placed in a heated state after being subjected to soldering or tin plating, and may be optionally added when necessary. However, the effect of preventing delamination is saturated even if zinc is added in excess of 0.5 mass%. On the other hand, it tends to decrease the conductivity, which is not preferable.

Furthermore, the manufacturing method of the precipitation hardening type copper alloy strip according to the present invention includes 0.50% by mass to 1.50% by mass of nickel, 0.05% by mass to 0.20% by mass of phosphorus, and the remaining copper and inevitable. In the composition composed of impurities, it is suitable to select a copper alloy strip having a Ni (mass%) / P (mass%) value of 6 to 10. Here, it is not preferable that the value of Ni (mass%) / P (mass%) is less than 6, since the conductivity is lowered. On the other hand, when the value of Ni (mass%) / P (mass%) exceeds 10, both the strength and conductivity of the copper alloy strip tend to be low.

  In the method for producing a precipitation hardening type copper alloy according to the present invention, in addition to the above-mentioned additive components, at least one selected from chromium, boron, titanium, manganese, and magnesium is further added within a total range of 3% or less. You can also The addition of these components is effective for improving the mechanical strength. However, when adding one or more of these elements, it is added so that the total amount becomes 0.01% or more in order to fully exert its action. On the other hand, if the total addition amount exceeds 3%, hot workability and cold workability may be deteriorated, which is not preferable. Other elements other than those described above are preferably controlled to be less than 0.05% as impurities. However, in order to avoid sulfur becoming brittle copper alloy strips, sulfur is preferably controlled to 50 ppm or less.

  And the precipitation hardening type copper alloy strip strengthened using the recovery phenomenon can be manufactured by giving the process containing the process shown below with respect to the copper alloy provided with the said composition. Hereinafter, it demonstrates according to a process.

<Process A>
Step A is a step in which a copper alloy ingot is hot-rolled and then subjected to an aging precipitation treatment to obtain an aging precipitation-treated copper alloy strip. In step A, an aging precipitation treatment is performed immediately after hot rolling. That is, by performing the aging precipitation treatment immediately after the hot rolling, the nickel-phosphorus compound is uniformly deposited as a precipitate and exhibits a precipitation hardening phenomenon. And it becomes easy to aim at hardening of a copper alloy strip by a subsequent processing process. Further, since the precipitated particles suppress the movement of the crystal grain boundary, the generation of recrystallized grains is suppressed in Step B to be described later, thereby contributing to the generation of a fine recovery structure. Furthermore, if hot rolling is performed in step A, the cumulative working rate can be increased in cold rolling up to the final product thereafter. The fact that the cumulative processing rate of cold rolling is large is somewhat reduced because the intermediate processing includes a recovery heat treatment, but at the same time as the work hardening amount is increased, the cells generated during the cold rolling and further at the time of recovery are increased. Can be generated finely and densely. According to the production method of the present invention, normal recrystallization is not caused at all or only partly, so that the subgrain can be refined and kept in a homogenized state, and bending workability and extensibility are also good. Can be maintained.

  In hot rolling of a copper alloy ingot, first, the ingot is heated to 700 ° C. to 1000 ° C. and rolled. Since heating of the ingot before hot rolling also has an effect of dissolving nickel and phosphorus, it is more preferably set to 800 ° C to 950 ° C. By the way, if a manufacturing method is adopted in which a solution treatment is performed in order to dissolve nickel and phosphorus after hot rolling, followed by an aging precipitation treatment, an investment in equipment for installing special equipment is required. Further, the increase in energy cost due to the solution treatment is obvious, and there is a problem in economy, which is not preferable. In addition, when the manufacturing method which performs an aging precipitation process after hot rolling is employed, a small amount of coarse precipitates may be inevitably generated during hot rolling. However, if the precipitation hardening type copper alloy strip according to the present invention has a composition, the coarse precipitates are very small even if they are generated, and the mechanical properties are not affected. That is, in the process A according to the present invention, the effect equivalent to that of the solution treatment / aging precipitation treatment is obtained only by performing the aging precipitation treatment without performing the costly solution treatment.

<Process B>
Process B is subjected to intermediate processing including intermediate cold rolling applied at a processing rate of 50% to 90% and intermediate recovery heat treatment applied thereafter as a unit for the aging-precipitated copper alloy strip obtained in Process A for recovery. This is a step of obtaining a heat-treated copper alloy strip. As described above, in the process B, the intermediate recovery heat treatment and the intermediate cold rolling are performed in combination. Since the cold rolling applied here is a strong process, if the copper alloy strip is cold rolled, subgrains are generated finely and densely, and the copper alloy strip becomes hard. Here, the work-hardened copper alloy strip can be basically converted into a copper alloy strip having a giant crystal through three processes: a recovery process, a recrystallization process, and a process of growing crystal grains, if heated. . And in a general process, recrystallization annealing is performed. However, if heating is performed until the recrystallization process or the crystal grain growth process, the crystal grains become coarse and the hardness decreases. That is, since recrystallization annealing works in the direction of reducing the mechanical strength of the copper alloy strip, when cold rolling is performed on the copper alloy strip after the recrystallization annealing, the precipitation hardening type copper alloy of the present invention is intended. Achievement of mechanical strength enhancement becomes difficult.

  Therefore, in the manufacturing method according to the present invention, heat treatment is performed in the recovery process without causing normal recrystallization. If heat treatment in the recovery process is performed, edge cracking during cold rolling can be avoided. Here, the intermediate cold rolling at the processing rate of 50% to 90% and the intermediate recovery heat treatment to be performed thereafter are used as one unit of intermediate processing, even if cold rolling is performed at the processing rate of 50% to 90%. By performing the heat treatment, it is possible to perform cold rolling at the same level of processing rate next time, and it becomes possible to perform repeated operations.

  In the method for producing a precipitation hardening type copper alloy strip according to the present invention, the step B is performed at least once in one unit of intermediate processing based on the Vickers hardness of the copper alloy strip before the intermediate recovery heat treatment. The reduction rate of the Vickers hardness of the copper alloy strip after the recovery heat treatment is 4% to 15%. Based on the Vickers hardness of the copper alloy strip before the intermediate recovery heat treatment, if the decrease rate of the Vickers hardness of the copper alloy strip after the intermediate recovery heat treatment is 4% to 15%, recrystallization does not appear. And elongation rate can be secured in a well-balanced manner. In order to make the fine recovery structure appear in a preferable state, the processing rate of the intermediate cold rolling before the intermediate recovery heat treatment is preferably set to 50% or more in order to finely and densely distribute the subgrains. More preferably, the setting is 60% or more, and even more preferably a setting exceeding 80%. However, if it is applied at a processing rate exceeding 90%, it tends to be difficult to ensure bending workability even if a recovery heat treatment is performed, which is not preferable. The fine recovery structure generated in the copper alloy strip after the intermediate recovery heat treatment hardly disappears even by subsequent cold rolling, and the growth in the recovery heat treatment is small.

In addition, in the manufacturing method of the precipitation hardening type copper alloy strip according to the present invention, when it is desired to particularly increase the conductivity, in the step B, the copper alloy strip subjected to the aging precipitation treatment before the intermediate processing is processed at a processing rate of 50% to 50%. A step of performing cold rolling at 90% and then performing a secondary aging precipitation treatment in which a recrystallized structure partially appears to form a copper alloy strip that has been subjected to the secondary aging precipitation treatment may be employed. This secondary aging precipitation treatment is preferably a mixed structure of a recovery structure and a partial recrystallized structure, and Vickers hardness can be used as an alternative index for the formation of the mixed structure. At this time, if the Vickers hardness is 110 to 150, it can be said that a good mixed structure is provided. When the secondary aging precipitation treatment is performed excessively, complete recrystallization occurs, and the strength of the resulting copper alloy strip becomes less than 500 N / mm ² .

<Process C>
In step C, the copper alloy strip that has been subjected to the recovery heat treatment obtained in step B is finally cold-rolled at a processing rate of 20% to 95%, and then subjected to the final recovery heat treatment to reinforce the copper alloy strip using the recovery phenomenon. It is the process of obtaining. In step C, final cold rolling and final recovery heat treatment are performed. The processing rate of the final cold rolling applied to the intermediate recovery heat-treated copper alloy strip is preferably 20% or more in order to compensate for the strength reduction due to the previous intermediate recovery heat treatment. And the strength level of the copper alloy strip after cold rolling increases as the processing rate increases. However, if the processing rate of the final cold rolling exceeds 95%, it is not preferable because it becomes difficult to ensure the bending workability of the copper alloy no matter how the recovery heat treatment temperature is set. And the processing rate of the last cold rolling of the process C changes with whether priority is given to intensity | strength or workability and electrical conductivity as a characteristic of the copper alloy strip finally obtained. The processing rate of the final cold rolling depends on the properties of the intermediate recovery heat-treated copper alloy strip, but if strength is given priority, 40% to 95%, if workability and conductivity are given priority, before that When no recrystallization structure is generated by this heat treatment, it is preferably about 20% to 50%, and when partially recrystallized, it is preferably 40% to 85%. And the final recovery heat treatment is close to what is usually called low temperature annealing or strain relief annealing, with the aim of improving stress relaxation characteristics and spring limit values while suppressing the decrease in strength. . Then, the change in the Vickers hardness of the copper alloy strip in the final recovery heat treatment is set in a range of 3% increase to 3% decrease compared to before the final recovery heat treatment. However, priority can be given to securing the bending workability of the precipitation hardening type copper alloy strip by adopting a recovery heat treatment in which the decrease rate of the Vickers hardness is 4% to 15%. Note that low temperature annealing may be omitted if it is not necessary to improve the stress relaxation rate and the spring limit value depending on the application. For example, in the case of a thick plate thickness that is difficult to be continuously annealed, it is difficult to perform low-temperature annealing without applying a gusset, and thus low-temperature annealing may be omitted.

  As mentioned above, although the manufacturing method of the precipitation hardening type copper alloy strip which concerns on this invention has been described, a supplement is added below. The copper alloy raw material can be dissolved by a conventional method, and an antioxidant treatment may be performed if necessary. Ingot casting can be performed by die casting, continuous or semi-continuous casting. Hot rolling is performed by heating the ingot to 800 ° C. to 950 ° C. in order to aim at the effect of promoting solid solution. The aging precipitation treatment can be performed at 400 ° C. to 550 ° C. for 1 hour to 10 hours. The recovery heat treatment is preferably performed using continuous annealing equipment at a furnace temperature of 300 ° C. to 600 ° C. within 3 minutes of passing time, but using a batch furnace under conditions suitable for the specified reduction range of Vickers hardness. You may carry out.

  The properties of the copper alloy strips prepared in Examples and Comparative Examples were evaluated by taking up tensile strength and elongation, 0.2% proof stress, bending workability and conductivity. In the examples, stress relaxation resistance was also evaluated. The measurement method for each evaluation item is described below.

General physical properties: Tensile strength and elongation were measured according to JIS Z 2241 using a universal testing machine. The 0.2% yield strength was obtained from the SS curve obtained when measuring the tensile strength and the elongation. Vickers hardness was measured in accordance with JIS Z 2244. The conductivity was measured with a digital conductivity meter (Auto Sigma 3000) manufactured by Nippon Hocking.

Bending workability: The bending workability of copper alloy strips was evaluated by a W bending test in accordance with the technical standard JCBA-T307 of the Japan Copper and Brass Association. Specifically, the W-bending test was performed in both directions of Good Way in which the bending axis was taken in the direction perpendicular to the rolling direction and Bad Way in which the bending axis was taken in the direction parallel to the rolling direction. R / t, which is an index of bending workability, was calculated using the thickness t of the test piece. The criteria for determining whether or not the bending workability is good is that the value of R / t is 1.0 or less that can withstand general parts processing is “good” and 0.5 or less that can withstand fine processing is “excellent”. "

Stress relaxation resistance: The stress relaxation resistance of the copper alloy strip was measured in accordance with the technical standard JCBA-T309 of the Japan Copper and Brass Association. Specifically, a bending stress equivalent to 80% of the 0.2% proof stress included in the test piece was applied, and the stress relaxation rate after 150 ° C. × 1000 hours was evaluated. The stress relaxation resistance required in automotive terminal applications where the usage environment is severe is less than 30% in terms of the stress relaxation rate obtained by this evaluation method, but is generally allowed to be practically about 35%. .

  Hereinafter, the present invention will be described in more detail by comparing the examples of the present invention with comparative examples. Table 1 shown later shows the composition and processing steps related to the production conditions according to the present invention, and Table 2 shows various properties of the obtained precipitation hardening copper alloy strip.

  In Example 1, a copper alloy composition containing 1.00% by mass of nickel, 0.11% by mass of phosphorus, 0.03% by mass of tin, and 0.15% by mass of zinc was used. In preparing the sample, first, materials necessary for the above component adjustment are put into a high-frequency melting furnace, a charcoal cover is melted to form a molten metal, the molten metal is poured into a mold, cast, and a thickness of 30 mm. An ingot of 5 kg was prepared. And this ingot was heated to 900 degreeC, and it hot-rolled and obtained the copper alloy plate of thickness 13mm. Thereafter, the copper alloy sheet was subjected to an aging precipitation treatment at 460 ° C. for 2 hours to obtain an aging precipitation-treated copper alloy sheet. The surface of this aging-precipitated copper alloy plate was polished and then cold-rolled to obtain a copper alloy plate having a thickness of 1.80 mm. Then, the said copper alloy plate was heated at 460 degreeC, and the recovery heat processing was performed. The reduction rate of the Vickers hardness by the recovery heat treatment at this time was 4% based on the Vickers hardness of the copper alloy plate before the recovery heat treatment. Then, the copper alloy plate was cold-rolled at a processing rate of 82% to obtain a copper alloy plate having a thickness of 0.33 mm, and a recovery heat treatment was performed at 460 ° C. The reduction rate of the Vickers hardness by the recovery heat treatment at this time was 11% based on the Vickers hardness before the recovery heat treatment of the copper alloy plate. And this recovery heat-treated copper alloy plate was finally cold-rolled at a processing rate of 39% to obtain a copper alloy plate having a thickness of 0.20 mm, and a final recovery heat treatment was performed at 385 ° C. to obtain Sample A-1. The rate of decrease in Vickers hardness by this final recovery heat treatment was 1% based on the Vickers hardness of the copper alloy plate before the recovery heat treatment.

As shown in Table 2, the evaluation results of the sample A-1 are as follows: tensile strength is 618 N / mm ² , elongation is 9.3%, Vickers hardness is 197, 0.2% proof stress is 606 N / mm ² , The stress relaxation rate was 24% and the conductivity was 55.5% IACS. In the evaluation of bending workability, the minimum bending radius R at which no crack was generated in the W bending test was 0.05 mm or less on Good Way and 0.1 mm on Bad Way. Therefore, R / t, which is an index of bending workability, is 0.25 or less for Good Way and 0.50 for Bad Way.

  For Sample A-1, the crystal structure was confirmed with a magnification (× 20000) using a transmission electron microscope (hereinafter referred to as TEM). FIG. 1 shows a TEM observation image of Sample A-1 (0.2 mm final recovery processed product). In FIG. 1, subgrains and precipitated particles are observed. In addition, an OIM (Orientation Imaging Microscopy) map was observed for A-1 with EBSP at a magnification (× 1500). The results are shown in FIG. As can be seen from FIG. 2, a fine recovery structure is observed.

  In Example 2, it was set as the copper alloy composition which contains 0.91 mass% of nickel and 0.093 mass% of phosphorus. In preparing the sample, first, materials necessary for the above component adjustment are put into a high-frequency melting furnace, a charcoal cover is melted to form a molten metal, the molten metal is poured into a mold, cast, and a thickness of 30 mm. An ingot of 5 kg was prepared. And this ingot was heated to 900 degreeC, and it hot-rolled and obtained the copper alloy plate of thickness 13mm. Thereafter, the copper alloy plate was subjected to an aging precipitation treatment at 460 ° C. for 7 hours to obtain an aging precipitation-treated copper alloy plate. The surface of this aging-precipitated copper alloy plate was polished and then cold-rolled to obtain a copper alloy plate having a thickness of 1.80 mm. Then, the said copper alloy plate was heated at 460 degreeC, and the recovery heat processing was performed. The reduction rate of the Vickers hardness by the recovery heat treatment at this time was 2% based on the Vickers hardness before the recovery heat treatment of the copper alloy sheet. Then, the copper alloy sheet was cold-rolled again at a processing rate of 82% to obtain a copper alloy sheet having a thickness of 0.33 mm, and a recovery heat treatment was performed at 460 ° C. At this time, the decreasing rate of the Vickers hardness after the recovery heat treatment was 10% based on the Vickers hardness before the recovery heat treatment of the copper alloy sheet. Further, this recovery heat-treated copper alloy plate was finally cold-rolled at a processing rate of 39% to obtain a copper alloy plate having a thickness of 0.20 mm, and a final recovery heat treatment at 380 ° C. was performed to obtain Sample A-2. . At this time, the decrease rate of the Vickers hardness by the final recovery heat treatment was set to 2% based on the Vickers hardness before the recovery heat treatment of the copper alloy sheet.

As shown in Table 2, the evaluation results of the sample A-2 are as follows: tensile strength is 599 N / mm ² , elongation is 5.4%, Vickers hardness is 187, 0.2% proof stress is 585 N / mm ² , The stress relaxation rate was 25% and the conductivity was 58.7% IACS. In the evaluation of bending workability, the minimum bending radius R at which no crack was generated in the W bending test was 0.05 mm or less on Good Way and 0.1 mm on Bad Way. Therefore, R / t, which is an index of bending workability, is 0.25 or less for Good Way and 0.50 for Bad Way.

  In Example 3, it was set as the copper alloy composition which contains 0.91 mass% of nickel, 0.098 mass% of phosphorus, 0.04 mass% of tin, and 0.11 mass% of zinc. In preparing the sample, first, materials necessary for the above component adjustment were put into a gas furnace and melted to form a molten metal, and this molten metal was used to create a 3500 kg ingot having a thickness of 160 mm using a vertical semi-continuous casting machine. . Then, this ingot was heated to 860 ° C. and hot-rolled to obtain a copper alloy strip having a thickness of 13 mm. Thereafter, the copper alloy strip was subjected to an aging precipitation treatment at 460 ° C. for 4 hours to obtain an aging precipitation-treated copper alloy strip. Both sides of this aging-precipitated copper alloy strip were chamfered by 0.5 mm each and subjected to cold rolling to obtain a copper alloy strip having a thickness of 1.80 mm. Then, the copper alloy plate extracted from the copper alloy strip was heated at 460 ° C. and subjected to recovery heat treatment. The reduction rate of the Vickers hardness by the recovery heat treatment at this time was 4% based on the Vickers hardness of the copper alloy plate before the recovery heat treatment. Further, the copper alloy plate was subjected to final cold rolling at a processing rate of 88% to obtain a copper alloy plate having a thickness of 0.21 mm, and a final recovery heat treatment was performed at 460 ° C. to obtain Sample A-3. The rate of decrease in Vickers hardness by this final recovery heat treatment was 0.5% based on the Vickers hardness of the copper alloy plate before the recovery heat treatment.

As shown in Table 2, the evaluation results of Sample A-3 are as follows: tensile strength is 634 N / mm ² , elongation is 8.6%, Vickers hardness is 205, 0.2% proof stress is 617 N / mm ² , The stress relaxation rate was 18% and the conductivity was 55.4% IACS. In the evaluation of bending workability, the minimum bending radius R at which no crack was generated in the W bending test was 0.05 mm for Good Way and 0.2 mm for Bad Way. Therefore, R / t, which is an index of bending workability, is 0.24 for Good Way and 0.95 for Bad Way.

  In Example 4, a test copper alloy sheet was sampled from the cold-rolled copper alloy strip having a thickness of 1.8 mm manufactured in Example 3 to obtain a starting material. The copper alloy sheet was further subjected to secondary aging precipitation treatment at 460 ° C. for 2 hours. Then, this secondary aging precipitation-treated copper alloy plate was cold-rolled at a working rate of 80% to obtain a copper alloy plate having a thickness of 0.36 mm, and a recovery heat treatment was performed at 460 ° C. The reduction rate of the Vickers hardness by the recovery heat treatment at this time was 6% based on the Vickers hardness of the copper alloy plate before the recovery heat treatment. Further, this recovery heat-treated copper alloy plate was finally cold-rolled at a processing rate of 44% to obtain a copper alloy plate having a thickness of 0.20 mm, and a final recovery heat treatment at 440 ° C. was performed to obtain Sample A-4. . The reduction rate of the Vickers hardness by this final recovery heat treatment was 4% based on the Vickers hardness before the recovery heat treatment of the copper alloy sheet.

As shown in Table 2, the evaluation results of the sample A-4 are as follows. Tensile strength is 550 N / mm ² , elongation is 8.6%, Vickers hardness is 159, 0.2% proof stress is 524 N / mm ² , The stress relaxation rate was 24% and the conductivity was 66.8% IACS. In the evaluation of bending workability, the minimum bending radius R at which no crack was generated in the W bending test was 0.05 mm for Good Way and 0.1 mm for Bad Way. Therefore, R / t, which is an index of bending workability, is 0.25 for Good Way and 0.50 for Bad Way.

  In Example 5, a copper alloy ingot containing 0.79% by mass of nickel, 0.11% by mass of phosphorus, 0.03% by mass of tin, and 0.14% by mass of zinc was prepared in the same manner as in Example 1. I got it. The ingot was heated to 860 ° C. and hot-rolled to obtain a copper alloy plate having a thickness of 12 mm. Thereafter, the copper alloy sheet was subjected to aging precipitation treatment at 430 ° C. for 3 hours. Further, after the sample was polished, cold rolling with a processing rate of 78% was added. The sample after the cold rolling had a Vickers hardness of 177. The sample was further subjected to an aging precipitation treatment at 430 ° C. for 3 hours. The Vickers hardness of the sample after this aging treatment was 126, and it was confirmed that recrystallized grains were scattered in the crystal structure. Further, the sample after the aging treatment was subjected to cold rolling at a processing rate of 62%, and further subjected to a recovery heat treatment at a temperature of 380 ° C. This recovery heat treatment increased the Vickers hardness by 1%. The final sample thus obtained has a thickness of 1.0 mm.

<Contrast between Examples>
Here, examples are compared with reference to the data in Table 2.

Comparison between Sample A-1 and Sample A-2: Sample A-1 and Sample A-2 differ in alloy composition and aging precipitation treatment time. The mechanical strength of Sample A-1 is higher than that of Sample A-2. However, Sample A-2 shows a higher conductivity than Sample A-1.

  Thus, it is thought that the electrical conductivity of sample A-2 is high because the aging precipitation treatment time is long. Moreover, it is thought that the tensile strength of A-1 is large is an effect including an appropriate amount of tin.

  Furthermore, in order to facilitate understanding of the background from which the physical properties of Sample A-1 were obtained, the tensile strength, elongation, Vickers hardness, 0.2% yield strength, electrical conductivity from intermediate cold rolling to final recovery heat treatment The characteristic transition with respect to rate is shown in Table 3. By the recovery heat treatment, the tensile strength decreases, the elongation increases, and the conductivity increases. The tensile strength after the final recovery heat treatment is greater than the tensile strength after the intermediate recovery heat treatment. From the transition of the physical properties, it is clear that the mechanical strength of the precipitation hardening type copper alloy strip can be enhanced by utilizing the recovery phenomenon.

Comparison between sample A-3 and other example samples: The tensile strength of sample A-3 is the largest among the samples of the examples. This is because the processing rate of the final cold rolling is high.

Comparison of Sample A-4 and Sample A-5 with Samples of Other Examples: Sample A-4 and Sample A-5 have particularly high electrical conductivity but low tensile strength. This is because the aging treatment is performed twice. Here, the reason why the conductivity of Sample A-5 is the highest is considered to be that the value of Ni (mass%) / P (mass%) is appropriate. That is, the value of Ni (mass%) / P (mass%) of sample A-5 is 7.2, whereas Ni (mass%) / P (mass%) of sample A-1 to sample A-4. ) Is between 9.1 and 9.8.

  Furthermore, the stress relaxation rate is 24% for sample A-1, 25% for sample A-2, 18% for sample A-3, 24% for sample A-4, 31% for sample A-5, and good characteristics. Is shown. Thus, in the copper alloy strip obtained using the manufacturing method according to the present invention, since the precipitated particles are uniformly dispersed, the stress relaxation rate is usually 35% or less. In addition, regarding the bending workability, Bad Way bending R / t, Sample A-1 is 0.50, Sample A-2 is 0.50, Sample A-3 is 0.95, and Sample A-4 is 0.4. The sample A-3 having a Vickers hardness of 205 and the sample A-5 having a large sample thickness are slightly inferior, but are generally good.

Comparative example

[Comparative Example 1]
Sample B-1 prepared in Comparative Example 1 had a copper alloy composition containing 1.90% by mass of nickel, 0.098% by mass of phosphorus, 0.04% by mass of tin, and 0.11% by mass of zinc. In preparing the sample, first, materials necessary for the above component adjustment are put into a high-frequency melting furnace, a charcoal cover is melted to form a molten metal, the molten metal is poured into a mold, cast, and a thickness of 30 mm. An ingot of 5 kg was prepared. However, since this crack was generated when this ingot was heated to 900 ° C. and the thickness was changed to 13 mm by hot rolling, the subsequent test was stopped.

[Comparative Example 2]
In Comparative Example 2, the hot-rolled copper alloy plate prepared in Example 3 was used as a starting material. Thereafter, the copper alloy plate was cold-rolled to obtain a copper alloy plate having a thickness of 1.80 mm. This copper alloy plate was heated at 460 ° C. and subjected to recovery heat treatment. The reduction rate of the Vickers hardness by the recovery heat treatment at this time was 4% based on the Vickers hardness of the copper alloy plate before the recovery heat treatment. Further, this recovery heat-treated copper alloy sheet was cold-rolled to a thickness of 0.60 mm at a processing rate of 67%, subjected to solution treatment at 850 ° C., and subjected to aging precipitation at 460 ° C. for 4 hours. Further thereafter, this aging precipitation-treated copper alloy plate was cold-rolled to a thickness of 0.45 mm at a working rate of 25%, and subjected to a recovery heat treatment at 380 ° C. to obtain a sample B-2. Note that the temperature is set so that the decrease rate of the Vickers hardness before and after the recovery heat treatment by the recovery heat treatment at this time is approximately −1%.

As shown in Table 2, the evaluation results of the sample B-2 are as follows. The tensile strength is 441 N / mm ² , the elongation is 3.0%, the Vickers hardness is 152, the 0.2% proof stress is 426 N / mm ² , The conductivity was 61.8% IACS. In the evaluation of bending workability, the minimum bending radius R at which no crack was generated in the W bending test was 0.30 mm for Good Way and 0.20 mm for Bad Way. Accordingly, R / t, which is an index of bending workability, is 0.67 for Good Way and 0.44 for Bad Way.

[Comparative Example 3]
In Comparative Example 3, similar to Comparative Example 2, the hot-rolled copper alloy plate having a thickness of 13 mm prepared in Example 3 was used as a starting material. And after cold-rolling this copper alloy plate to thickness 2.50mm, the solution treatment was performed at 790 degreeC, and the aging precipitation process was performed at 430 degreeC for 16 hours. Further thereafter, this aging-precipitated copper alloy plate was cold-rolled to a thickness of 0.75 mm at a processing rate of 70% and subjected to a recovery heat treatment at 460 ° C. At this time, the decreasing rate of the Vickers hardness after the recovery heat treatment was 3% on the basis of the Vickers hardness before the recovery heat treatment of the copper alloy sheet. Further, the copper alloy plate after the recovery heat treatment was cold-rolled at a working rate of 47% to a thickness of 0.40 mm, and the recovery heat treatment was performed at 460 ° C. At this time, the decreasing rate of the Vickers hardness after the recovery heat treatment was 2% on the basis of the Vickers hardness before the recovery heat treatment of the copper alloy sheet. Further, this recovery heat-treated copper alloy sheet was cold-rolled to a thickness of 0.20 mm at a processing rate of 50%, heated at 385 ° C., and subjected to recovery heat treatment to obtain Sample B-3. The temperature is set so that the rate of decrease in Vickers hardness before and after the recovery heat treatment by the recovery heat treatment at this time is approximately −3%.

As shown in Table 2, the evaluation results of Sample B-3 are as follows: tensile strength is 612 N / mm ² , elongation is 4.4%, Vickers hardness is 198, 0.2% proof stress is 601 N / mm ² , The conductivity was 58.6% IACS. In the evaluation of bending workability, the minimum bending radius R at which no crack was generated in the W bending test was 0.05 mm or less on Good Way, and exceeded 0.20 mm on Bad Way. Therefore, R / t, which is an index of bending workability, is 0.25 or less for Good Way and is over 1.00 for Bad Way.

<Contrast between Example and Comparative Example>
Sample B-1 was cracked when subjected to hot rolling, and characteristic data could not be obtained. This crack is considered to be caused by the generation of a low melting point compound containing nickel and phosphorus when the nickel content increases.

  Hereinafter, comparison will be made with reference to Table 2.

  Comparison between Sample B-2 and Sample of Example: Sample B-2 was manufactured in accordance with the manufacturing process of a normal aging precipitation alloy after the second cold rolling, but this is still a normal solution. The working rate in the final cold rolling after the aging / aging precipitation treatment is slightly increased. Although the conductivity of Sample B-2 is high, the tensile strength is small and the elongation is low. However, the bending workability of Sample B-2 is R / t of 0.67, and excellent bending workability is not obtained despite the low mechanical strength. It cannot be said that it is a copper alloy strip having a balance of.

  Comparison between Sample B-3 and Sample of Example: Sample B-3 was subjected to intermediate and final recovery heat treatment three times in total, and the decrease rate of Vickers hardness by recovery heat treatment was less than 4% in all cases. Yes, the processing rate in cold rolling before recovery heat treatment is all low. For this reason, compared with the sample of an Example, it is thought that the effect which can satisfy the elongation rate and bending workability is not acquired. Further, the bending workability of Sample B-3 is clearly inferior to that of the sample of Example, where R / t exceeds 1.0.

  Table 4 shows the changes in physical properties when subjected to normal solution treatment / aging precipitation treatment for reference. As is apparent from Table 4, the tensile strength after the solution treatment / aging precipitation treatment does not show a satisfactory value. From this result, for the copper alloy strip having the same alloy composition as the precipitation hardening type copper alloy strip according to the present invention, the purpose of strengthening the mechanical strength is achieved even if the aging precipitation phenomenon is used as usual. It can be seen that it is difficult to obtain necessary and sufficient characteristics.

  The manufacturing method of the precipitation hardening type copper alloy strip according to the present invention includes a step of performing hot rolling on a copper-nickel-phosphorous copper alloy ingot and then aging precipitation treatment to obtain an aging precipitation treated copper alloy strip, aging precipitation A process for obtaining a recovered heat-treated copper alloy strip by subjecting the treated copper alloy strip to intermediate cold rolling and subsequent intermediate recovery heat treatment at a processing rate of 50% to 90% to obtain the recovered heat-treated copper alloy strip; It includes a step of applying the final cold rolling at a processing rate of 20% to 95% and then performing a final recovery heat treatment. Therefore, if the precipitation hardening type copper alloy strip manufacturing method according to the present invention is used, the recovery phenomenon is utilized after strengthening the mechanical strength by cold rolling in the presence of precipitation particles formed by aging precipitation treatment. Therefore, it is possible to produce a copper alloy strip excellent in the total balance of mechanical strength, bending workability, and conductivity. Further, the electrical conductivity can be further improved by adding an aging precipitation treatment to the intermediate processing.

  Therefore, if the manufacturing method according to the present invention is adopted, a total balance of tensile strength, elongation rate, conductivity, bending workability, etc. is required, connector-terminal of automobile, terminal of electric / electronic component, relay It is possible to provide copper alloy strips applied to current-carrying members such as switches and sockets with high quality without significant cost increase.

It is a TEM observation photograph (x20000) of sample A-1 surface concerning this invention. It is an EBSP observation photograph (x1500) of sample A-1 surface concerning this invention.

Claims (9)

A method for producing a copper alloy strip containing 0.50% to 1.50% by mass of nickel, 0.05% to 0.20% by mass of phosphorus, and the balance copper and inevitable impurities, comprising the following step A A process for producing a precipitation-hardening type copper alloy strip characterized by strengthening using a recovery phenomenon, which includes a step C.
Step A: A step of subjecting a copper alloy ingot to hot rolling, and thereafter performing an aging precipitation treatment to obtain an aging precipitation-treated copper alloy strip.
Step B: The copper alloy strip subjected to the aging precipitation treatment obtained in Step A is subjected to intermediate processing including intermediate cold rolling applied at a processing rate of 50% to 90% and intermediate recovery heat treatment applied thereafter as a unit, and recovery heat treatment A process of obtaining a finished copper alloy strip.
Step C: Precipitation hardening type in which the recovery heat-treated copper alloy strip obtained in Step B is subjected to final cold rolling at a processing rate of 20% to 95% and then subjected to final recovery heat treatment to strengthen the recovery phenomenon. The process of obtaining a copper alloy strip. The precipitation hardening type copper alloy strip according to claim 1, wherein one or more of 0.04 mass% tin and 0.50 mass % zinc are further added to the copper alloy strip. Manufacturing method. The said process B is a manufacturing method of the precipitation hardening type copper alloy strip of Claim 1 or Claim 2 which repeats said 1 unit of intermediate | middle process in multiple times. In the step B, at least one time of the intermediate processing of one unit is based on the Vickers hardness of the copper alloy strip before the intermediate recovery heat treatment, and the decrease rate of the Vickers hardness of the copper alloy strip after the intermediate recovery heat treatment is 4 method for manufacturing a precipitation hardening copper alloy strips according to% to 15% and der Ru any of claims 1 to 3 which. In the step B, the copper alloy strip subjected to the aging precipitation treatment before the intermediate working is cold-rolled at a working rate of 50% to 90%, and then a secondary aging precipitation treatment in which a recrystallized structure partially appears is performed. The manufacturing method of the precipitation hardening type copper alloy strip in any one of Claims 1-3 which includes the process made into the secondary aging precipitation-treated copper alloy strip . The final recovery heat treatment in the step C is based on the Vickers hardness of the copper alloy strip before the final recovery heat treatment, and the decrease rate of the Vickers hardness of the copper alloy strip after the final recovery heat treatment is less than 4%. The manufacturing method of the precipitation hardening type copper alloy strip in any one of Claims 1-5 . The final recovery heat treatment in the step C is based on the Vickers hardness of the copper alloy strip before the final recovery heat treatment, and the decrease rate of the Vickers hardness of the copper alloy strip after the final recovery heat treatment is 4% to 15%. The manufacturing method of the precipitation hardening type copper alloy strip in any one of Claims 1-5 . A copper alloy strip having a tensile strength of 500 N / mm ² or more, an elongation of 5% or more, and an electrical conductivity of 50% IACS or more and having good bending workability and stress relaxation resistance is produced. The manufacturing method of the precipitation hardening type copper alloy strip in any one of Claim 7 . In the manufacturing method of the precipitation hardening type copper alloy strip in any one of Claims 1-3, Claim 5-5 ,
A copper alloy containing 0.50% to 1.50% by mass of nickel, 0.05% to 0.20% by mass of phosphorus, and a Ni (mass%) / P (mass%) ratio of 6 to 10 By using an ingot,
Precipitation hardening type characterized by producing a copper alloy strip with good bending workability and stress relaxation resistance, having a tensile strength of 500 N / mm ² or more, an elongation of 5% or more, and a conductivity of 65% or more IACS. A method for producing a copper alloy strip.

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