JP2007107087A - Copper alloy plate having excellent stress relaxation resistance, and process for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Cu-Ni-Sn-P-based alloy having high stress relaxation resistance in an orthogonal direction to the rolling direction, and jointly having high strength, high electrical conductivity and excellent bending workability. <P>SOLUTION: In the Cu-Ni-Sn-P-based alloy, when a solution obtained by dissolving the copper alloy by an extraction residue method under specified conditions is subjected to suction filtration by a filter having an opening size of 0.1 μm, the content of Ni in the extraction residue after extraction separation on the filter is not more than 40% in terms of the proportion to the content of Ni in the copper alloy. Thus, Ni compounds with a coarse size of >0.1 μm are suppressed, and further, Ni compounds with a fine size of ≤0.1 μm are increased so as to improve its stress relaxation resistance in an orthogonal direction to the rolling direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a copper alloy plate excellent in stress relaxation resistance and a manufacturing method thereof, and more particularly to a copper alloy plate excellent in stress relaxation resistance suitable for connection parts such as automobile terminals and connectors and a manufacturing method thereof.

  In recent years, connecting parts such as automobile terminals and connectors are required to have a performance capable of ensuring reliability in a high temperature environment such as an engine room. One of the most important characteristics in reliability under this high temperature environment is a contact fitting force maintaining characteristic, so-called stress relaxation resistance characteristic. That is, when a steady displacement is applied to a spring-shaped component made of a copper alloy, for example, when a tab of a male terminal is fitted with a spring-shaped contact of a female terminal, these connecting components are like an engine room. If the contact fitting force is maintained under a high temperature environment, the contact fitting force is lost with time, and the stress relaxation resistance is a resistance characteristic against this.

  Conventionally, Cu-Ni-Si alloys, Cu-Ti alloys, Cu-Be alloys, and the like are widely known as copper alloys having excellent stress relaxation resistance. Since these all contain strong oxidizing elements (Si, Ti, Be, etc.), they cannot be melted in a large-scale melting furnace with a wide opening to the atmosphere, and high costs can be avoided in terms of productivity. Absent.

  On the other hand, a Cu—Ni—Sn—P alloy having a relatively small amount of additive element can be so-called shaft furnace ingot, and can be greatly reduced in cost because of its high productivity. For this Cu—Ni—Sn—P alloy, various measures for improving the stress relaxation resistance have been proposed.

  For example, Patent Document 1 below discloses a method for producing a copper-based alloy for connectors having excellent stress relaxation resistance. This manufacturing method is a Cu-Ni-Sn-P alloy in which Ni-P intermetallic compounds are uniformly and finely dispersed in a matrix to improve electrical conductivity and at the same time improve stress relaxation resistance and the like. According to the same document, in order to obtain desired characteristics, the cooling start and end temperature of the hot rolling, the cooling rate thereof, and further the heat treatment of 5 to 720 minutes applied during the subsequent cold rolling process. It is necessary to strictly control the temperature and time.

In Patent Documents 2 and 3 below, as a Cu—Ni—Sn—P alloy having excellent stress relaxation resistance and a method for producing the same, a solid content in which precipitation of Ni—P compounds is suppressed by reducing the P content as much as possible. It is disclosed that a molten copper alloy is used. According to this, there is an advantage that it can be manufactured by an extremely short annealing heat treatment without requiring an advanced heat treatment technique.
Japanese Patent No. 2844120 JP-A-11-293367 JP 2002-294368 A

  In the JASO-C400 standard of the Japan Society for Automotive Engineers, regarding the stress relaxation resistance, the stress relaxation rate after holding at 150 ° C. × 1000 hr is defined as 15% or less. 1A and 1B show a stress relaxation resistance test apparatus. Using this test apparatus, one end of the test piece 1 cut into a strip shape is fixed to the rigid body test stand 2 and the other end is lifted and bent in a cantilever manner (warping magnitude d). After holding for a period of time, unloading is performed at room temperature, and the magnitude of warpage (permanent strain) after unloading is obtained as δ. The stress relaxation rate (RS) is represented by RS = (δ / d) × 100.

  The stress relaxation rate of the copper alloy plate has anisotropy, and takes different values depending on which direction the longitudinal direction of the test piece is oriented with respect to the rolling direction of the copper alloy plate. Generally, the stress relaxation rate is smaller in the direction parallel to the rolling direction than in the direction perpendicular to the rolling direction. However, in the JASO standard, there is no provision for this direction. Therefore, conventionally, it is sufficient that a stress relaxation rate of 15% or less is achieved in either the direction parallel to or perpendicular to the rolling direction. Has been. However, in recent years, it has been desirable for copper alloy sheets to have high stress relaxation resistance in a direction perpendicular to the rolling direction.

  FIG. 2 shows a cross-sectional structure of a typical box connector (female terminal 3). In FIG. 2, the pressing piece 5 is cantilevered by the upper holder portion 4, and when the male terminal 6 is inserted, the pressing piece 5 is elastically deformed, and the male terminal 6 is fixed by the reaction force. In FIG. 2, 7 is a wire connecting portion, and 8 is a fixing tongue piece. Here, when the female terminal 3 is manufactured by pressing a copper alloy plate, the female terminal 3 is cut so that the longitudinal direction of the female terminal 3 (longitudinal direction of the pressing piece 5) is perpendicular to the rolling direction. The pressing piece 5 is required to have particularly high stress relaxation resistance for bending (elastic deformation) in the length direction of the pressing piece 5. Therefore, the copper alloy sheet is required to have high stress relaxation resistance in a direction perpendicular to the rolling direction.

  In contrast, in the solid solution type copper alloys disclosed in Patent Documents 2 and 3, high stress relaxation resistance with a stress relaxation rate of 15% or less is substantially achieved in the direction parallel to the rolling direction. However, it has not yet been achieved in the perpendicular direction.

  For this reason, a high stress relaxation property with a stress relaxation rate of 15% or less is required from the user side in a direction perpendicular to the rolling direction, rather than a direction parallel to the rolling direction, with respect to this type of solid solution type copper alloy. It has become.

  In view of these points, an object of the present invention is to achieve a high stress relaxation resistance with a stress relaxation rate of 15% or less in a direction perpendicular to the rolling direction for a Cu-Ni-Sn-P alloy. .

In order to achieve this object, the gist of the copper alloy excellent in stress relaxation resistance of the present invention is mass%, Ni: 0.1 to 3.0%, Sn: 0.01 to 3.0%, P : A copper alloy containing 0.01 to 0.3% each and consisting of the remainder copper and inevitable impurities, in the extraction residue extracted and separated on a filter having an opening size of 0.1 μm by the following extraction residue method The following Ni amount is set to 40% or less in terms of the Ni content in the copper alloy.
Here, in the extraction residue method, 10 g of the copper alloy was immersed in 300 ml of a 10% by mass ammonium acetate concentration methanol solution, and the copper alloy was used as an anode, while platinum was used as a cathode, and a current density of 10 mmA. a constant current electrolysis at / cm ^2, which the solution obtained by dissolving the copper alloy, and suction filtered through a polycarbonate membrane filter having an opening size 0.1 [mu] m, the undissolved substances residue is separated and extracted on the filter And
The amount of Ni in the extraction residue is obtained by dissolving the undissolved residue on the filter with a solution in which aqua regia and water are mixed at a ratio of 1: 1, and then analyzing by ICP emission spectroscopy. Shall.

  Furthermore, the summary of the method for producing a copper alloy sheet excellent in stress relaxation resistance according to the present invention for achieving the above object is a method for producing a copper alloy sheet of a preferred embodiment described above or below, When obtaining a copper alloy sheet by casting, hot rolling, cold rolling, and finish annealing of the alloy, the time required from the completion of addition of the alloy element in the copper alloy melting furnace to the start of casting is set within 1200 seconds. The required time from extracting the ingot from the heating furnace to the end of hot rolling is 1200 seconds or less.

  According to the present invention, in a Cu—Ni—Sn—P based copper alloy, it is possible to achieve high stress relaxation resistance with a stress relaxation rate of 15% or less in a direction perpendicular to the rolling direction. Moreover, it is possible to obtain a copper alloy having excellent characteristics for terminals and connectors, such as excellent bending characteristics, electrical conductivity (about 30% IACS or more) and strength (yield strength of about 480 MPa or more).

  In the solid solution type copper alloy in which precipitation of the conventional Ni—P compound described above is suppressed, the present inventors have a high stress relaxation resistance with a stress relaxation rate of 15% or less in a direction parallel to the rolling direction. The reason why it was achieved but not yet achieved in the perpendicular direction was examined.

  As a result, if coarse Ni oxides, crystallized substances and precipitates of a certain size or larger are suppressed, a high stress relaxation resistance with a stress relaxation rate of 15% or less is achieved in a direction perpendicular to the rolling direction. I found out.

  That is, the coarse Ni oxides, crystallized substances, and precipitates of a certain size or more correspond to the amount of Ni in the extraction residue extracted and separated on the filter having a mesh size of 0.1 μm in the above-mentioned summary of the present invention. To do. If the amount of Ni in this extraction residue is suppressed to 40% or less as a percentage of the Ni content in the copper alloy as in the gist of the present invention, a high stress relaxation resistance with a stress relaxation rate of 15% or less is obtained in the rolling direction. Is achieved in a direction perpendicular to. At the same time, bending properties, conductivity and strength can be improved.

  In addition, if Ni compounds (Ni products) such as coarse Ni oxides, crystallized substances, and precipitates having a certain size exceeding 0.1 μm are suppressed in this way, on the other hand, 0.1 μm or less. This leads to ensuring the amount of fine Ni compounds (including fine Ni clusters below the nano level) and the like, and the solid solution amount of Ni. The Ni cluster is a group of atoms before crystallization at the atomic structure level.

  The stress relaxation resistance in the direction perpendicular to the rolling direction cannot be improved only by uniform fine dispersion of the Ni-P intermetallic compound in the Cu-Ni-Sn-P alloy matrix as in Patent Document 1 described above. Therefore, it is necessary to secure the fine Ni compound amount of 0.1 μm or less and the solid solution amount of Ni. However, these fine Ni compounds of 0.1 μm or less and the solid solution amount of Ni cannot be directly measured.

  On the other hand, in the present invention, by suppressing the coarse Ni compound exceeding 0.1 μm, the amount of fine Ni compound of 0.1 μm or less and the solid solution amount of Ni are indirectly secured. Is characteristic.

  In the present invention, in order to suppress the coarse Ni compound exceeding 0.1 μm and to secure a fine Ni compound amount of 0.1 μm or less and a solid solution amount of Ni, production conditions different from those of the conventional method are used. Necessary. That is, as described in the summary of the method for producing a copper alloy sheet of the present invention, when the copper alloy sheet is obtained by casting, hot rolling, cold rolling, and finish annealing of the copper alloy, the addition of the alloy element in the copper alloy melting furnace is completed. It is necessary to shorten the time from the start of casting to the start of casting, and further from the extraction of the ingot from the ingot heating furnace to the end of hot rolling.

  In a general manufacturing process of this kind of copper alloy sheet, these required times tend to be long. For this reason, most of the added Ni content is taken up by oxides, crystallized substances generated during melting and casting, and coarse precipitates generated from the soaking of the ingot to the end of hot rolling, The amount of fine Ni compound of 0.1 μm or less to be generated according to the added Ni content and the solid solution amount of Ni are unexpectedly reduced.

  Usually, in a general manufacturing process of this kind of copper alloy sheet, a final (product) sheet is obtained by repeating hot rolling and cold rolling and annealing. Control the amount of fine Ni compound and the solid solution amount of Ni of 1 μm or less. At that time, the diffusion of alloy elements such as Ni into the moderately dispersed intermetallic compound stabilizes the solid solution amount of Ni and the precipitation amount of fine products, thereby improving the mechanical properties such as strength level. Try to control.

  However, in these general manufacturing processes, as described above, the amount of fine Ni compounds of 0.1 μm or less and the absolute amount of Ni solid solution is reduced in the preceding process. Even when trying to precipitate a large amount of the fine product due to cold rolling conditions and annealing conditions after rolling, the absolute amount of fine Ni compound or Ni solid solution of 0.1 μm or less is insufficient, and strength and stress relaxation resistance It was difficult to improve the characteristics.

  Furthermore, when there are many coarse oxides, crystallized substances, and precipitates (Ni compounds), the fine products precipitated in the cold rolling and annealing processes are trapped in the coarse products and become independent in the matrix. And there are fewer and fewer fine products present. For this reason, in the general manufacturing method described above, sufficient strength and excellent stress relaxation resistance could not be obtained for a large amount of Ni added.

  On the other hand, in the present invention, by suppressing the coarse Ni compound exceeding 0.1 μm, the necessary (useful) fine Ni compound amount of 0.1 μm or less and the solid solution amount of Ni can be secured. . As a result, high stress relaxation resistance with a stress relaxation rate of 15% or less is achieved in a direction perpendicular to the rolling direction. At the same time, bending properties, conductivity and strength can be improved.

(Copper alloy component composition)
First, the component composition of the copper alloy of the present invention will be described below. In the present invention, based on the premise of the component composition of the copper alloy, as described above, a shaft furnace ingot is possible, and a Cu—Ni—Sn—P-based alloy that can be significantly reduced in cost because of its high productivity. .

  And, in order to improve the stress relaxation properties in the direction perpendicular to the rolling direction, which are required as connecting parts such as automobile terminals and connectors, at the same time, in order to improve bending properties, conductivity and strength, basically , Ni: 0.1 to 3.0%, Sn: 0.01 to 3.0%, P: 0.01 to 0.3%, respectively, and a copper alloy composed of the remaining copper and inevitable impurities . In addition,% display of content of each element means the mass% altogether. The reasons for addition and suppression of alloy elements of copper alloy will be described below.

(Ni)
Ni is an element necessary for forming fine precipitates with P and improving strength and stress relaxation resistance. When the content is less than 0.1%, the amount of fine Ni compound of 0.1 μm or less and the absolute amount of solid solution of Ni are insufficient even by the optimum production method of the present invention. For this reason, in order to exhibit the effect of Ni effectively, containing 0.1% or more is required.

  However, if the content exceeds 3.0%, compounds such as Ni oxides, crystallization products, and precipitates become coarse, or coarse Ni compounds increase, and the amount of Ni in the extraction residue is increased. It cannot be 40% or less in terms of the Ni content in the copper alloy. As a result, the amount of fine Ni compound and the solid solution amount of Ni of 0.1 μm or less are reduced. Moreover, since these coarsened Ni compounds serve as starting points for fracture, not only strength and stress relaxation resistance but also bending workability are deteriorated. Therefore, the Ni content is in the range of 0.1 to 3.0%. Preferably, it is 0.3 to 2.0% of range.

(Sn)
Sn is dissolved in the copper alloy to improve the strength. Furthermore, Sn-based precipitates suppress softening due to recrystallization during annealing. However, in order to positively produce Sn-based precipitates in the copper alloy according to the present invention, annealing at a higher temperature is required. However, if the Sn content is less than 0.1%, The softening due to crystals cannot be suppressed, and the strength decreases. Therefore, if the Sn content is less than 0.1%, it is necessary to increase the strength by increasing the rolling reduction of the final cold rolling after annealing. In this case, there is a slight decrease in conductivity and stress relaxation resistance. However, if the Sn content is less than 0.01%, Sn is too small, and even if the final cold rolling reduction after annealing is increased, the strength is too low, and the balance of these properties does not reach the desired level. On the other hand, if it exceeds 3.0%, the conductivity is lowered, and 30% IACS or more cannot be achieved. Therefore, the Sn content is in the range of 0.01 to 3.0%, preferably in the range of 0.1 to 2.0%, and more preferably in the range of 0.3 to 2.0%.

(P)
P is an element necessary for forming fine precipitates with Ni and improving strength and stress relaxation resistance. If the content is less than 0.01%, the P-based fine precipitate particles are insufficient, so the content must be 0.01% or more. However, when it exceeds 0.3% and contains excessively, the Ni-P intermetallic compound precipitation particle | grains will coarsen and not only the intensity | strength and stress relaxation characteristics but hot workability will also fall. Therefore, the P content is in the range of 0.01 to 0.3%. Preferably, it is set as 0.02 to 0.2% of range.

(Fe, Zn, Mn, Si, Mg)
Fe, Zn, Mn, Si, and Mg are easily mixed from a melting raw material such as scrap. Although these elements have their respective effects, they generally lower the electrical conductivity. Moreover, when content increases, it will become difficult to agglomerate with a shaft furnace. Therefore, when obtaining a conductivity of 30% IACS or more, Fe: 0.5% or less, Zn: 1% or less, Mn: 0.1% or less, Si: 0.1% or less, Mg: 0 3% or less. In other words, in this invention, content below these upper limits is permitted.

  Fe raises the recrystallization temperature of a copper alloy like Sn. However, if it exceeds 0.5%, the conductivity decreases and 30% IACS cannot be achieved. Preferably, it is 0.3% or less.

  Zn prevents peeling of tin plating. However, if it exceeds 1%, the conductivity decreases and 30% IACS cannot be achieved. Moreover, when ingot-making with a shaft furnace, 0.05% or less is desirable. And if it is a temperature range (about 150-180 degreeC) used as a terminal for motor vehicles, even if it contains 0.05% or less, there exists an effect which can prevent peeling of tin plating.

  Mn and Si have an effect as a deoxidizer. However, if it exceeds 0.1%, the conductivity decreases and 30% IACS cannot be achieved. Further, when ingot forming is performed in a shaft furnace, it is further preferable to set Mn: 0.001% or less and Si: 0.002% or less.

  Mg has the effect of improving the stress relaxation resistance. However, if it exceeds 0.3%, the conductivity decreases and 30% IACS cannot be achieved. Moreover, when ingot-making with a shaft furnace, 0.001% or less is desirable.

(Ca, Zr, Ag, Cr, Cd, Be, Ti, Co, Au, Pt)
The copper alloy of the present invention further allows Ca, Zr, Ag, Cr, Cd, Be, Ti, Co, Au, and Pt to be contained in a total of 1.0% or less of these elements. These elements have an effect of preventing coarsening of crystal grains. However, when the total of these elements exceeds 1.0%, the conductivity is lowered and 30% IACS cannot be achieved. Moreover, it becomes difficult to ingot in a shaft furnace.

  In addition, Hf, Th, Li, Na, K, Sr, Pd, W, S, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B Misch metal is an impurity, and the total of these elements is limited to 0.1% or less.

(Extraction residue regulations)
In the present invention, as described above, coarse Ni oxides, crystallized substances and precipitates (Ni compounds) exceeding a certain size of 0.1 μm are suppressed, and high stress relaxation resistance with a stress relaxation rate of 15% or less is achieved. Achieved in a direction perpendicular to the rolling direction.
In the present invention, the amount of coarse Ni compound of a certain size or more is defined as the amount of Ni in the extraction residue extracted and separated on a filter having an opening size of 0.1 μm. And the amount of Ni (the amount of coarse Ni compound) in this extraction residue is regulated to 40% or less as a percentage of the Ni content in the copper alloy.

  Thus, if the amount of coarse Ni compound having a certain size or more is suppressed, the effect of suppressing these coarse Ni compounds, the amount of fine Ni compound of 0.1 μm or less, and the effect of ensuring the solid solution amount of Ni are obtained. Arise. As a result, high stress relaxation resistance with a stress relaxation rate of 15% or less is achieved in a direction perpendicular to the rolling direction. At the same time, bending properties, conductivity and strength can be improved.

  When the ratio of the Ni content in the extraction residue to the Ni content in the copper alloy exceeds 40%, the amount of the coarse compound increases. Further, according to this, the amount of fine Ni compound of 0.1 μm or less and the solid solution amount of Ni are insufficient. For this reason, the stress relaxation property and strength in the direction perpendicular to the rolling direction are reduced. At the same time, since the coarse compound serves as a starting point of fracture, bending workability also decreases.

(Extraction residue method)
The extraction residue method defined in the present invention defines specific measurement conditions in order to provide reproducibility in measurement. That is, 10 g of the copper alloy is immersed in 300 ml of a 10% by mass ammonium acetate methanol solution, and the copper alloy is used as an anode, while platinum is used as a cathode and constant current electrolysis is performed at a current density of 10 mmA / cm ^2. I do. Thus, the solution in which the copper alloy is dissolved is suction filtered through a polycarbonate membrane filter having an opening size of 0.1 μm, and undissolved residue is separated and extracted on the filter. The filter aperture size of 0.1 μm is the smallest filter aperture size at present.

  In the solution in which the copper alloy is dissolved, Ni previously dissolved in the copper matrix is dissolved, and a coarse Ni compound exceeding 0.1 μm and a fine Ni compound not exceeding 0.1 μm are dissolved. Without being distributed. For this reason, the undissolved residue separated and extracted on the filter having an aperture size of 0.1 μm is only a coarse Ni compound exceeding 0.1 μm. On the other hand, Ni dissolved in advance and a fine Ni compound of 0.1 μm or less permeate the filter together with the solution.

(Ni amount in extraction residue)
The amount of Ni in the separated and extracted residue is analyzed by ICP emission spectroscopy after dissolving the undissolved residue on the filter with a solution in which aqua regia and water are mixed at a ratio of 1: 1. To ask for.

(Copper alloy manufacturing method)
Next, the manufacturing method of this invention copper alloy is demonstrated below. The copper alloy of the present invention can be produced by a conventional method. That is, a final (product) plate is obtained by casting a molten copper alloy with an adjusted composition, ingot chamfering, soaking, hot rolling, and repeating cold rolling and annealing. The mechanical properties such as the strength level are also controlled by controlling the precipitation of fine products of 0.1 μm or less mainly by cold rolling conditions and annealing conditions.

  However, as an optimal manufacturing method for manufacturing the copper alloy sheet of the present invention, when obtaining a copper alloy sheet by copper alloy casting, hot rolling, cold rolling, annealing, the alloy elements in the copper alloy melting furnace The required time from the completion of addition to the start of casting is set to 1200 seconds or less, and further, the required time from the extraction of the ingot from the ingot heating furnace to the end of hot rolling is set to 1200 seconds or less.

  In the present invention, in order to suppress the coarse Ni compound exceeding 0.1 μm and to secure a fine Ni compound amount of 0.1 μm or less and a solid solution amount of Ni, in this way, a copper alloy melting furnace Therefore, it is necessary to shorten the time from the completion of the addition of the alloy element to the start of casting, and further from the extraction of the ingot from the ingot heating furnace to the end of hot rolling.

  In a general manufacturing process of this kind of copper alloy sheet, these required times tend to be long. For this reason, most of the added Ni content is taken up and added to oxides, crystals, and coarse precipitates generated from the soaking of the ingot to the end of hot rolling. Depending on the Ni content, the amount of fine Ni compounds of 0.1 μm or less and the solid solution amount of Ni are reduced.

  Therefore, even if it is attempted to control the amount of fine Ni compound of 0.1 μm or less or the solid solution amount of Ni mainly by cold rolling conditions and annealing conditions in the latter stage, in the above-mentioned process, fine Ni compounds of 0.1 μm or less The absolute amount of the compound amount and the solid solution amount of Ni is reduced. Furthermore, when there are many coarse Ni compounds, the fine products precipitated in the cold rolling and annealing processes are trapped by the coarse products, and the fine products that exist independently in the matrix become more and less. . For this reason, in the general manufacturing method described above, sufficient strength and excellent stress relaxation resistance could not be obtained for a large amount of Ni added.

  For this reason, in this invention, a coarse Ni compound is suppressed more upstream in the said manufacturing process. Specifically, in order to suppress particularly large Ni compounds, (1) time management from the completion of addition of alloy elements in the melting furnace to the start of casting, and (2) from the extraction of the ingot from the heating furnace to the end of hot rolling Time management is important.

  First, melting and casting itself can be performed by a normal method such as continuous casting or semi-continuous casting. However, in the time management from the completion of addition of the alloy element in the melting furnace (1) to the start of casting, the casting is performed within 1200 seconds, preferably within 1100 seconds after completion of the addition of the element in the melting furnace, It is desirable that the cooling / solidification rate is 0.1 ° C./second or more, preferably 0.2 ° C./second or more.

  Thereby, generation | occurrence | production, growth, and coarsening of the oxide and crystallized substance containing Ni can be suppressed, and these can be disperse | distributed finely. From the viewpoint of suppressing the formation of oxides containing Ni, it is more preferable to perform vacuum melting / casting or melting / casting in an atmosphere having a low oxygen partial pressure.

  Conventionally, casting is started because it is necessary to reliably dissolve the mother alloy such as Cu-P containing the additive element, and to uniformly disperse the dissolved additive element in the molten metal and to perform reanalysis after the raw material is added. It took about 1500 seconds or more to complete. However, it has been found that if it takes a long time to cast in this way, the production and coarsening of oxides containing Ni are promoted and the yield of additive elements is reduced.

  In order to avoid the formation and coarsening of the oxide containing Ni, the time required from the completion of the addition of the alloy element in the melting furnace to the start of casting as described above is 1200 when manufacturing the copper alloy of the present invention. The time is shortened to be within seconds, preferably within 1100 seconds. Such shortening of the time to casting can be achieved by predicting the composition after the raw material addition based on past melting results and shortening the time required for reanalysis.

  Next, in the time management from the extraction of the ingot from the heating furnace (2) to the end of hot rolling, after the ingot is heated in the heating furnace, the ingot taken out from the furnace waits for the start of hot rolling. Time arises. However, in order to produce a copper alloy that suppresses the coarsening of the Ni compound of the present invention, the time from the melting to the start of casting and the cooling / solidification rate are controlled and the ingot is extracted from the heating furnace. It is recommended to control the required (total elapsed time) until the end of hot rolling to 1200 seconds or less, preferably 1100 seconds or less.

  Conventionally, it has not been studied to manage the time from the extraction of the heating furnace to the end of the hot rolling, and it is accompanied by the transportation from the heating furnace to the hot rolling line and the enlargement of the slab aimed at improving the productivity. It has been common to spend more than 1500 seconds by extending the hot rolling time. However, it has been found that when such time is required, Ni-based coarse precipitates are deposited during that time, and Ni and P are precipitated with crystallized substances and oxides generated during dissolution and casting as nuclei. . When these coarse precipitate particles increase, the amount of Ni residue increases excessively, so that the strength and stress relaxation resistance decrease.

  In order to avoid such actions as reduction of solute Ni and coarsening of Ni compounds, the total required time from extraction in the furnace to the end of hot rolling is positively produced as described above in the production of the alloy of the present invention. Are managed within 1200 seconds. Such time management can be achieved by quickly transporting the ingot from the heating furnace to the hot rolling line, avoiding the use of large slabs that increase the hot rolling time, and dare to use small slabs. .

  About hot rolling, what is necessary is just to follow a usual method, the entrance temperature of hot rolling is about 600-1000 degreeC, and end temperature shall be about 600-850 degreeC. After hot rolling, it is cooled with water or allowed to cool.

  Thereafter, cold rolling and annealing are performed to obtain a copper alloy plate having a product thickness. Annealing and cold rolling may be repeated depending on the final (product) plate thickness. In the cold rough rolling, the processing rate is selected so that a processing rate of about 30 to 80% is obtained in the final finish rolling. An intermediate recrystallization annealing can be appropriately interposed during the cold rough rolling.

  The finish annealing for the copper alloy sheet after the cold rough rolling may be continuous annealing or batch annealing. However, in order to increase the precipitation amount of the fine Ni—P intermetallic compound, the holding temperature is inevitably increased during continuous annealing (short time) and the holding temperature is decreased during batch annealing (long time). In this respect, as a measure of the processing temperature (substance temperature) and the holding time, 500 to 800 ° C. × 10 to 60 seconds are preferable for continuous annealing, and 300 to 600 ° C. × 2 to 20 hours are preferable for batch annealing (long time). In addition, after this finish annealing, it is desirable to rapidly cool at a cooling rate of 10 ° C./second or more.

  The strain relief annealing or the stabilization annealing after the final finish cold rolling is desirably performed at an actual temperature of 250 to 450 ° C. × 20 to 40 seconds. This is because the distortion introduced in the final finish rolling is removed, the material is not softened, and the strength is hardly lowered.

  Examples of the present invention will be described below. Various copper alloy thin plates of Cu—Ni—Sn—P based alloys having different Ni compound states in the structure were produced, and properties such as strength, conductivity, and stress relaxation resistance were evaluated.

  Specifically, after each copper alloy having the chemical composition shown in Table 1 was melted in a coreless furnace, it was ingoted by a semi-continuous casting method, and the ingot was 70 mm thick × 200 mm wide × 500 mm long. Got. These ingots were commonly rolled under the following conditions to produce a copper alloy sheet. The surface of each ingot was chamfered and heated, and then hot-rolled to form a plate having a thickness of 16 mm, and rapidly cooled into water from a temperature of 650 ° C. or higher.

  After removing the oxide scale, this plate was subjected to cold rolling → continuous annealing → cold rolling → strain relief annealing to produce a copper alloy thin plate. That is, the plate after primary cold rolling (rough cold rolling, intermediate cold rolling) is face-faced, and the final annealing is performed by continuous annealing at a solid temperature of 660 ° C. for 20 seconds. Finish cold rolling was performed at 50%. However, only Invention Example 16 and Comparative Example 19 in Table 2 have a Sn content of less than 0.1% and cannot suppress softening due to annealing (recrystallization during annealing), resulting in reduced strength. The reduction in cold rolling was relatively high at 80% to improve the strength. Thereafter, low temperature strain relief annealing at an actual temperature of 400 ° C. × 20 seconds was performed to obtain a copper alloy thin plate having a thickness of 0.25 mm.

  At this time, as shown in Table 2, the time required from the completion of addition of the alloy element in the melting furnace to the start of casting (in Table 2, described as the time required until the start of casting), the cooling solidification rate at the time of casting, and the heating furnace extraction The state of the Ni compound in the copper alloy sheet structure was controlled by variously changing the temperature, the end temperature of the hot rolling, and the required time from the heating furnace extraction to the end of the hot rolling (in Table 2, the time required to complete the hot rolling). .

  From each copper alloy thin plate thus obtained, 10 g of a test piece for extraction residue measurement was collected, and the amount of Ni contained in the extraction residue extracted and separated by a mesh having a mesh size of 0.1 μm was obtained by the method described above. The above-mentioned ICP emission spectroscopic analysis method was used. And the ratio (%) with respect to Ni content of the said copper alloy was calculated | required. These results are shown in Table 2.

  In each example, a sample was cut out from each obtained copper alloy plate and subjected to a tensile test, conductivity measurement, stress relaxation rate measurement, and bending test. These results are also shown in Table 2.

(Tensile test)
A test piece was collected from the copper alloy thin plate, and a JIS No. 5 tensile test piece was prepared by machining so that the longitudinal direction of the test piece was perpendicular to the rolling direction of the plate. Then, mechanical characteristics were measured with a 5882 type Instron universal testing machine under the conditions of room temperature, a test speed of 10.0 mm / min, and GL = 50 mm. The proof stress is a tensile strength corresponding to a permanent elongation of 0.2%.

(Conductivity measurement)
A sample was taken from the copper alloy thin plate and the conductivity was measured. The electrical conductivity of the copper alloy sheet sample is a double-bridge type in accordance with the nonferrous metal material conductivity measurement method specified in JIS-H0505 by processing a strip-shaped test piece of width 10 mm x length 300 mm by milling. The electrical resistance was measured with a resistance measuring device, and the conductivity was calculated by the average cross section method.

(Stress relaxation characteristics)
The stress relaxation rate in the direction perpendicular to the rolling direction of the copper alloy sheet was measured, and the stress relaxation resistance property in this direction was evaluated. Specifically, a test piece was taken from the copper alloy thin plate and measured using the cantilever method shown in FIG. A strip-shaped test piece 1 having a width of 10 mm (with the length direction perpendicular to the rolling direction of the plate material) is cut out, one end thereof is fixed to the rigid body test stand 2, and the span length L of the test piece 1 is d. A deflection amount having a size of (= 10 mm) is given. At this time, L is determined so that a surface stress corresponding to 80% of the material yield strength is applied to the material. This is held in an oven at 180 ° C. for 30 hours and then taken out. The permanent strain δ when the deflection d is removed is measured, and the stress relaxation rate (RS) is calculated by RS = (δ / d) × 100. In addition, holding | maintenance of 180 degreeC x 30 hours is equivalent to holding | maintenance of about 150 degreeC x 1000 hours, when it calculates with a Larson Miller parameter.

(Evaluation test for bending workability)
The bending test of the copper alloy sheet sample was performed according to the Japan Copper and Brass Association technical standard. The plate material was cut into a width of 10 mm and a length of 30 mm, bent in a Good Way (bending axis perpendicular to the rolling direction) with a bending radius of 0.5 mm, and visually observed for cracks in the bent portion with a 50 × optical microscope. The thing without a crack was evaluated as (circle), and the thing which a crack produced evaluated as x.

  As is apparent from Table 2, Invention Examples 1 to 16 which are copper alloys (alloy numbers 1 to 13) within the composition of the present invention in Table 1 have a required time of 1200 from the completion of addition of the alloy element in the melting furnace to the start of casting. The cooling solidification rate at the time of casting is 0.5 ° C./second or more, and the required time from the furnace extraction to the start of hot rolling is within 1200 seconds. Moreover, both the heating furnace extraction temperature and the hot rolling end temperature are appropriate.

  For this reason, Invention Examples 1 to 16 in Table 2 are set to 0.1 μm so that the ratio of the Ni content in the extraction residue extracted and separated by the above-described extraction residue method to the alloy Ni content is 80% or less. Coarse Ni compounds such as oxides, crystallized substances, and precipitates are suppressed. Therefore, it is presumed that the amount of fine Ni compound of 0.1 μm or less (including fine Ni clusters of nano level or less) and the like, and the solid solution amount of Ni can be secured.

  As a result, Invention Examples 1 to 16 can achieve high stress relaxation resistance with a stress relaxation rate of 15% or less in the direction perpendicular to the rolling direction. In addition, it has excellent characteristics for terminals and connectors, such as excellent bending characteristics and strength.

  However, in the comparison among Invention Examples 1 to 6 in Table 2, the time required from the completion of addition of the alloy element in the melting furnace to the start of casting is relatively long Inventive Examples 2 and 6, from extraction of the heating furnace to the start of hot rolling Inventive Examples 3 and 4 that require a relatively long time are relatively low in stress relaxation resistance compared to Inventive Examples 1 and 5 in which these are relatively short.

  Among Invention Examples 1 to 16 in Table 2, Invention Examples 9 to 15 (alloy numbers 6 to 12 in Table 1) in which the amount of other elements exceeds the above-described preferable upper limit, the conductivity is Invention Examples 1 to 8. It is lower than

  In Invention Examples 9 to 13, Fe, Zn, Mn, Si, and Mg are higher than the above-described preferable upper limit as shown in Alloy Nos. 6 to 10 in Table 1.

  In invention example 14, the total of elements of Ca, Zr, Ag, Cr, Cd, Be, Ti, Co, Au, and Pt exceeded the preferable upper limit of 1.0% by mass as described in alloy number 11 in Table 1. Is expensive.

  Invention Example 15 includes Hf, Th, Li, Na, K, Sr, Pd, W, S, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te , B, and misch metal are higher than the preferable upper limit of 0.1% by mass as shown in Alloy No. 12 in Table 1.

  On the other hand, in Invention Example 16, as in Alloy 13 in Table 1, the Sn content was as low as less than 0.1%, and the reduction ratio of the finish cold rolling was relatively high as described above to improve the strength. Due to the softening by annealing, the strength is relatively low compared to other invention examples.

On the other hand, although Comparative Examples 23-26 of Table 2 are the copper alloys (alloy number 1) in this invention composition of Table 1, manufacturing conditions remove | deviate from the preferable range, respectively.
In Comparative Examples 23 and 24, the time required from the completion of addition of the alloy element in the melting furnace to the start of casting exceeds 1200 seconds and is too long. In Comparative Examples 25 and 26, the time required from extraction in the heating furnace to the start of hot rolling exceeds 1200 seconds and is too long.

  For this reason, in Comparative Examples 23 to 26 in Table 2, the ratio of the amount of Ni in the extraction residue extracted and separated by the extraction residue method described above to the alloy Ni content exceeds 40%, and exceeds 0.1 μm. There are too many Ni compounds such as coarse Ni oxides, crystallized substances, and precipitates, which are not suppressed. Therefore, it is estimated that the amount of fine Ni compound or the like of 0.1 μm or less and the solid solution amount of Ni cannot be secured.

  As a result, Comparative Examples 23 to 26 have remarkably low stress relaxation resistance in the direction perpendicular to the rolling direction as compared with the inventive examples.

  Comparative Examples 17 to 22 in Table 2 use copper alloys outside the composition of the present invention of Alloy Nos. 14 to 19 in Table 1. For this reason, although the manufacturing conditions are within the preferable range, any of the ratio of Ni content in the extraction residue to the alloy Ni content, stress relaxation resistance, bending characteristics, conductivity, and strength is an example of the invention. Is significantly inferior to

  In the copper alloy of Comparative Example 17, the Ni content deviates from the lower limit (alloy number 14 in Table 1). For this reason, strength and stress relaxation resistance are low.

  In the copper alloy of Comparative Example 18, the Ni content deviates from the upper limit (Alloy No. 15 in Table 1). For this reason, strength, stress relaxation resistance, and bending workability are low.

  In the copper alloy of Comparative Example 19, the Sn content deviates from the lower limit (alloy number 16 in Table 1). For this reason, in Comparative Example 19, the reduction ratio of the finish cold rolling was relatively increased as described above to improve the strength, but the strength was too low due to the softening by annealing.

  In the copper alloy of Comparative Example 20, the Sn content is higher than the upper limit (Alloy No. 17 in Table 1). For this reason, electrical conductivity is low.

  In the copper alloy of Comparative Example 21, the P content deviates from the lower limit (alloy number 18 in Table 1). For this reason, strength and stress relaxation resistance are low.

  In the copper alloy of Comparative Example 22, the P content deviates from the upper limit (alloy number 19 in Table 1). For this reason, strength, stress relaxation resistance, and bending workability are low.

  From the above results, the component composition of the copper alloy sheet of the present invention, the structure, in order to improve the stress relaxation resistance and bending workability in the direction perpendicular to the rolling direction, with high strength and high conductivity, Furthermore, the significance of preferable manufacturing conditions for obtaining the structure is supported.

  As described above, according to the present invention, the Cu—Ni—Sn—P system has high stress relaxation resistance in the direction perpendicular to the rolling direction, and has high strength, high conductivity, and excellent bending workability. Alloys can be provided. As a result, it can be applied to applications requiring stress relaxation resistance in a direction perpendicular to the rolling direction, particularly for connecting parts such as automobile terminals and connectors.

It is sectional drawing explaining the stress relaxation test of a copper alloy plate. It is sectional drawing which shows the structure of a box-type connector.

Claims (5)

In mass%, Ni: 0.1-3.0%, Sn: 0.01-3.0%, P: 0.01-0.3%, respectively, the balance copper and copper consisting of inevitable impurities The following Ni content in an extraction residue extracted and separated on a filter having an aperture size of 0.1 μm by the following extraction residue method is 40% or less in proportion to the Ni content in the copper alloy. A copper alloy with excellent stress relaxation resistance.
Here, in the extraction residue method, 10 g of the copper alloy was immersed in 300 ml of a 10% by mass ammonium acetate concentration methanol solution, and the copper alloy was used as an anode, while platinum was used as a cathode, and a current density of 10 mmA. a constant current electrolysis at / cm ^2, which the solution obtained by dissolving the copper alloy, and suction filtered through a polycarbonate membrane filter having an opening size 0.1 [mu] m, the undissolved substances residue is separated and extracted on the filter And
The amount of Ni in the extraction residue is obtained by dissolving the undissolved residue on the filter with a solution in which aqua regia and water are mixed at a ratio of 1: 1, and then analyzing by ICP emission spectroscopy. Shall.   The copper alloy is further mass% Fe: 0.5% or less, Zn: 1% or less, Mn: 0.1% or less, Si: 0.1% or less, Mg: 0.3% or less. A copper alloy having excellent stress relaxation resistance according to claim 1.   The copper alloy further contains Ca, Zr, Ag, Cr, Cd, Be, Ti, Co, Au, and Pt in a total amount of these elements of 1.0% by mass or less. Copper alloy with excellent stress relaxation resistance described in 1.   The copper alloy is Hf, Th, Li, Na, K, Sr, Pd, W, S, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te. The copper alloy excellent in stress relaxation resistance according to claim 1, wherein the content of B, B, and Misch metal is 0.1% by mass or less in total of these elements.   A method for producing a copper alloy plate according to any one of claims 1 to 4, wherein the copper alloy plate is obtained by casting, hot rolling, cold rolling, and finish annealing of the copper alloy. Stress relaxation to reduce the time required from the completion of addition of the alloy element to the start of casting within 1200 seconds, and further to the time required for hot rolling after the ingot is extracted from the ingot heating furnace to 1200 seconds or less A method for producing a copper alloy sheet having excellent characteristics.

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