JP2007291518A - Cu-Fe-P-Mg BASED COPPER ALLOY, ITS PRODUCTION METHOD, AND CONDUCTIVE COMPONENT - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper alloy material for a conductive component combining electrical conductivity, strength, bending workability and press blanking property on high levels in a well balance. <P>SOLUTION: The copper alloy has a composition comprising, by mass, 0.15 to 0.7% Fe, 0.04 to 0.5% P and 0.01 to 0.5% Mg, and, if necessary, comprising ≤0.5% Sn, and the balance substantially Cu, and also satisfying 1.5≤Fe/P≤10, 0.5≤Mg/P≤7 and Fe+Mg≥0.25, and has a metallic structure with a mean crystal grain diameter of ≤20 μm, where an Fe-P based compound and an Mg-P based compound are present at a grain diameter of ≤1 μm in the matrix, also, the grains with a grain diameter of >0.2 to 1 μm in the Mg-P based compound are present by 0.3 to 10 pieces per 100 μm<SP>2</SP>, and, preferably, new recrystallization does not occur after final cold working. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a copper alloy suitable for current-carrying parts such as bus bars, connector terminals for automobiles, terminals for electric / electronic parts, etc., and particularly balances conductivity, strength, bending workability and press punchability at a high level. Further, the present invention relates to a Cu—Fe—P—Mg based copper alloy and a method for producing the same.

  Conventionally, brass having excellent strength, press punchability, and cost has been used for narrow bus bars such as a junction box for automobiles (hereinafter referred to as “J / B”). However, as the J / B becomes smaller and more dense, the current-carrying part of the bus bar becomes thinner, and brass has various problems such as generation of Joule heat due to low conductivity (about 28% IACS). Occurred.

  In order to cope with such a problem, an alloy having a conductivity of 45% IACS or more and a medium strength such as Cu-1Ni-0.5Sn-0.05P (C19020 alloy), Cu-0.7Mg-0. Copper alloys such as 005P (C18605 alloy) and Cu-2.2Fe-0.13Zn-0.03P (C19400 alloy) have been developed and used. In addition, high-conductivity type high-strength copper alloys as disclosed in Patent Documents 1 to 10 have been proposed.

Japanese Patent Laid-Open No. 10-130755 JP-A-11-343527 JP 2000-54043 A JP 2000-239812 A JP 61-221344 A JP 61-67738 A No. 2956696 Special table 2003-501554 gazette Japanese Patent Publication No. 6-35633 JP 11-256255 A

  However, in recent years, there has been a tendency for the number of circuits of electrical components to increase due to the reduction in weight and performance of automobiles, and a copper alloy having a conductivity of 65% IACS or more, preferably 70% IACS or more is desired for bus bars and connectors. . The existing copper alloys (C19020 alloy, C18605 alloy, C19400 alloy) have become unable to meet recent needs in terms of conductivity.

  In addition, for the purpose of reducing the cost, weight, and size of bus bars, the technology of eliminating relay terminals has become the mainstream. The relay terminal-less means that the relay terminal that has been used to connect the bus bar and the fuse is eliminated, and a new press-fitting female terminal function (tuning fork terminal) is provided on the bus bar side. In other words, this tuning fork terminal maintains the electrical connection by directly contacting the end face punched by the bus bar side press with the fuse, so the material used for the bus bar has the end face punched by the press. It is desired that the shape is stable and good. In this regard, the existing copper alloy and the copper alloys of Patent Documents 1 to 5 do not give sufficient consideration to press punchability (end face shape).

  Furthermore, due to demands for miniaturization and the like for current-carrying parts such as bus bars and connectors, excellent workability that can be processed into various shapes is required, and in particular, excellent bending workability is more important than ever. I came. The copper alloy of Patent Document 6 is intended to improve conductivity, increase strength, and improve shear workability by an alloy system in which Ni-P-based precipitates are produced, but it is not necessarily satisfactory with respect to bending workability. It is not a thing.

  Thus, it is difficult to obtain a copper alloy material for energized parts that has a high level of electrical conductivity, strength, bending workability, and press punchability. The present invention is to provide a new copper alloy material in which each of these characteristics is improved at the same time.

In order to achieve the above object, the copper alloy provided in the present invention is, in mass%, Fe: 0.15 to 0.7%, P: 0.04 to 0.5%, Mg: 0.01 to 0. 0.5%, if necessary, including Sn: 0.5% or less, with the balance being substantially Cu, and 1.5 ≦ Fe / P ≦ 10, 0.5 ≦ Mg / P ≦ 7, Fe + Mg ≧ A metal structure having a composition satisfying 0.25, and an Fe—P compound and a Mg—P compound containing particles having a particle size exceeding 0.2 μm in a matrix having a particle size of 1 μm or less. Have. Average crystal in which 0.3 to 10 particles having a particle diameter of more than 0.2 to 1.0 μm are present per 100 μm ² and no new recrystallization has occurred after the last cold working. What has a metal structure with a particle size of 30 micrometers or less becomes a suitable object. The average crystal grain size is more preferably 20 μm or less. Also, electrical conductivity of 70% IACS or higher, tensile strength of 400 N / mm ² or higher, bending workability that does not cause cracking when bending at a bending radius equal to the plate thickness, and press punching Those having a press punching property in which the aggression rate (described later) is 5% or less are suitable targets. This copper alloy has a bending process part and a press punching part, and is used suitably for the electricity supply components which use a press punching end surface for an electrical contact.

  Here, “the balance is substantially Cu” means that mixing of elements other than the above is allowed within a range that does not impair the effects of the present invention, and “consisting of the balance Cu and unavoidable impurities”. included. The “press punched end face” is a cross section formed by press punching.

The Fe-P-based compound is a precipitated phase that contains the largest amount of Fe and then contains a large amount of P, and is mainly composed of a compound of the composition formula Fe ₃ P or Fe ₂ P. The Mg—P-based compound is a precipitated phase containing the largest amount of Mg and then containing a large amount of P, and is mainly composed of a compound of the composition formula Mg ₃ P ₂ . These compounds can be identified by, for example, an analytical method (such as EDX) in which an electron beam is applied to the compound particles. The particle diameter of the compound can be determined, for example, by measuring the diameter (longest part) of each particle existing in the cross section etched after electropolishing on an SEM image. It can also be obtained from a TEM image instead of the SEM image. “A compound is present in a particle size range of 1 μm or less” means that the particle size of individual particles of the compound is in a range of 1 μm or less.

  As a method for producing such a copper alloy, a “casting process” in which a cooling rate of a cast slab in a 700 to 300 ° C. region is 30 to 200 ° C./min or more in a cooling process during casting, and a material center portion is 850 to 950. After the cast material is heated so that it is held in the ° C region for 0.5 h or more, hot rolling is started, the hot rolling final pass is terminated at 500 to 700 ° C, and then the average cooling rate in at least 500 to 300 ° C area is set. “Hot rolling process” that rapidly cools to a temperature range of 300 ° C. or less as 5 ° C./sec or more, and after cold rolling at a processing rate of 30% or more, hold at 400 to 600 ° C. for 1 h or more, and then from the holding temperature A manufacturing method having a “cold rolling → annealing step” for cooling at a cooling rate of up to 300 ° C. at 20 to 200 ° C./h is provided. In particular, after the “cold rolling → annealing step”, it further includes a “cold rolling → strain relief annealing step” of heating to a temperature range of 250 to 400 ° C. after performing cold rolling within a processing rate of 70% or less. Manufacturing methods can be employed.

According to the present invention, a copper alloy having a high conductivity of 65% IACS or more, or 70% IACS or more, a high strength of 400 N / mm ² or more, and stably improving bending workability and press punchability. Became available. Therefore, the present invention is extremely excellent as a current-carrying material for various electric / electronic parts such as automobile bus bars represented by J / B and terminals.

  According to the inventors' investigation, it has been found that the object of the present invention can be achieved in a Cu-Fe-P-Mg based copper alloy containing a proper amount of metal elements (Fe, Mg) forming a P compound in a Cu matrix. It was. Hereinafter, matters for specifying the present invention will be described.

[Chemical composition]
Fe is an element that contributes to strength improvement by forming a compound with P and precipitating it into the matrix. In order to sufficiently exhibit this effect, it is necessary to secure an Fe content of 0.15% by mass or more. However, excessive Fe content causes a decrease in bending workability and a decrease in electrical conductivity due to the coarsening of the Fe-P-based compound, so the upper limit of the Fe content is limited to 0.7% by mass. The Fe content is more preferably in the range of 0.2 to 0.5% by mass, and even more preferably 0.25 to 0.45% by mass.

  P generally contributes as a deoxidizer for copper alloys, but in the present invention, precipitation of Fe—P compounds and Mg—P compounds improves strength and press punchability. When the P content is less than 0.04% by mass, the effect of improving strength and punchability is not sufficiently exhibited. On the other hand, if it exceeds 0.5 mass%, hot cracking tends to occur. Therefore, the P content needs to be in the range of 0.04 to 0.5 mass%. An upper limit can be prescribed | regulated to less than 0.5 mass%. The P content is more preferably in the range of 0.05 to 0.3% by mass, and even more preferably 0.06 to 0.2% by mass.

  Furthermore, regarding the Fe and P contents, it is important to adjust the composition so that the Fe / P ratio (ratio by mass%) is 1.5 to 10. If the Fe / P ratio is less than 1.5, the solid solution amount of P increases and the electrical conductivity is likely to be insufficiently improved, and Mg consumed as the P consumed for the formation of the Fe-P compound decreases. -P-based compounds are likely to be coarsened and bending workability is liable to be lowered. On the other hand, if the Fe / P ratio exceeds 10, excessive solid solution Fe increases and the electrical conductivity tends to decrease. The Fe / P ratio is more preferably in the range of 1.5-5, more preferably in the range of 2-5, or even 2-4.

  Mg alone is an element that contributes to improving the strength of the copper alloy, but it alone does not have an effect of improving the press punchability. However, it has been found that when a compound with P is formed, the press punching property is remarkably improved. When the Mg content is less than 0.01% by mass, the amount of Mg—P compound produced is small, and the effect of improving the press punchability cannot be obtained sufficiently. On the other hand, excessive addition of Mg causes a significant decrease in electrical conductivity and a decrease in bending workability, and a special atmosphere control is required during casting, resulting in an increase in manufacturing cost. Therefore, the upper limit of the Mg content needs to be 0.5% by mass, and more preferably less than 0.5% by mass. The Mg content is more preferably in the range of 0.05 to 0.3% by mass, and even more preferably 0.06 to 0.25% by mass.

  Furthermore, regarding the contents of Mg and P, it is important to adjust the composition so that the Mg / P ratio (ratio by mass%) is 0.5 to 7. When the Mg / P ratio is less than 0.5, the solid solution amount of P increases and the conductivity decreases. On the other hand, if the Mg / P ratio becomes too large, the solid solution amount of Mg increases and the electrical conductivity decreases. The Mg / P ratio is more preferably in the range of 0.5-4, more preferably in the range of 0.5-4, or even more preferably in the range of 0.6-2.5.

  Regarding the total amount of Fe and Mg, it is important to adjust the composition so that Fe + Mg ≧ 0.25. If it is less than this, since the total amount of precipitated P precipitate is small, the strength and punchability tend to be lowered. It is more preferable to control to Fe + Mg ≧ 0.3.

  Sn dissolves in the matrix and contributes to improving the strength, and can be added as necessary. However, if Sn is added in excess of 0.5% by mass, the strength increases, but the electrical conductivity decreases remarkably. Therefore, when adding Sn, it carries out in the range of 0.5 mass% or less. It can also be specified to be less than 0.5% by mass. It is desirable to ensure an Sn content of 0.01% by mass or more in order to sufficiently bring out the strength improvement effect by the addition of Sn. The particularly preferred Sn content range is 0.03 to 0.3% by mass.

  In addition, it is desirable to reduce as much as possible the elements that dissolve in the Cu matrix and the elements that form the P compound. Specifically, Zn, Ti, Al, Ni, Si, B, As, Sb, Ag, Pb, Be, Zr, Cr, Mn, In, etc. that can be mixed in the copper alloy are the contents of individual elements. It is desirable to keep the content of 0.1% by mass or less, preferably less than 0.01% by mass, and the total content thereof is 0.2% by mass or less, preferably less than 0.1% by mass. Of these, regarding Ni, it is desirable to ensure the Mg content so that Mg / Ni ≧ 20 when the Ni content is 0.01% or more. Otherwise, P is consumed by the Ni—P-based compound, and there is a possibility that a sufficient amount of the Mg—P-based compound required in the present invention cannot be ensured.

[Metal structure]
Fe—P-based compounds contribute to strength improvement by being dispersed in the matrix. However, control of the particle size is important. As a result of various studies, if the cooling rate and superheating conditions of the casting-hot rolling process are not controlled, Fe-P compound particles having a particle size exceeding 1 μm are easily generated, resulting in a significant decrease in bending workability. Became clear. Moreover, such coarse particles do not contribute to the improvement of strength, and the production of Mg—P is suppressed by the consumption of P. Therefore, in the copper alloy of the present invention, it is important that the Fe—P-based compound is dispersed in a particle size range of 1 μm or less.

  The Mg—P compound is important for improving the press punchability in the present invention. Dispersion of the compound particles in the matrix reduces the aggression rate (described later) on the press punched surface, and the electrical connection of the part on the punched end surface is improved. Although the mechanism by which Mg-P-based compounds reduce the aggression rate has not been fully elucidated at present, Mg-P-based compound particles of an appropriate size are used as the starting point of breakage and the propagation path of cracks during press punching. As a result, it is assumed that the shape of the press punched surface is close to flat. Such a function cannot be found in the above-described Fe-P compounds.

Similar to the Fe-P compound, the Mg-P compound needs to have a particle size of 1 μm or less. The presence of larger particles is an adverse effect of bending workability. Further, it has been found that the presence of Mg—P compound particles having a particle size exceeding 0.2 μm is extremely effective for sufficiently exerting the effect of improving the press punchability. However, Mg-P compound particles having a particle size of 0.2 μm or less may be mixed. The amount of precipitation of the Mg—P-based compound is not limited as long as the amount of precipitation described below is 5% or less, but in order to obtain a high conductivity such as 65% IACS or more, or 75% IACS or more, The following precipitate size and amount are required. Specifically, the press punching property can be remarkably improved by forming a structure state in which 0.3 to 10 particles of Mg-P compound having a particle size exceeding 0.2 to 1 μm exist per 100 μm ^2. it can. If it is less than 0.3, improvement of the press punchability tends to be insufficient, and if it exceeds 10, the bending workability tends to deteriorate. More preferably, it exists in the range of 1 to 10 per 100 μm ² . Here, the number of Mg-P compound particles having a particle size exceeding 0.2 to 1 μm per 100 μm ² should be observed with the focus fixed at a magnification of 10,000 times by an electron microscope (SEM). Is calculated by counting the number of Mg-P compounds having a particle diameter of more than 0.2 to 1.0 μm and multiplying the number by “100 μm ² / total area of observation field”. Whether the observed particles are Mg-P compounds can be determined by increasing the magnification or by an analysis means (such as EDX) attached to the SEM. For the particle size, the major axis of the observed particle is read. The total area of the observation field is set to 250 μm ² or more.

It is desirable that the average crystal grain size of the matrix is adjusted to 30 μm or less in the stage after annealing accompanied by the last recrystallization. Preferably it is 20 micrometers or less. The value of the average crystal grain size at this stage is reflected almost as it is in the value of the average crystal grain size after finally performing cold rolling and strain relief annealing. If the average crystal grain size becomes too large, the bending workability tends to be lowered. Further, those that exhibit a metal structure that has not been recrystallized after being cold worked have particularly high strength. When it can be confirmed by observation with an optical microscope that the crystal grains extend in the processing direction, it is determined to exhibit a “cold-worked metal structure”. When the temperature of the stress relief annealing described later is too high, generation of new recrystallized grains is recognized in the “cold-worked metal structure” or the whole becomes a new recrystallized structure. In such a case, it is difficult to achieve high strength such as 400 N / mm ² or more due to softening.

[Production method]
The copper alloy of the present invention can be produced using, for example, the following general age-hardening type copper alloy production process.
“Melting → Casting → Hot rolling → (Cold rolling → Intermediate annealing) → Cold rolling → Annealing → Cold rolling → Strain relief annealing”
Depending on the target plate thickness and line configuration, the process of “cold rolling → intermediate annealing” can be inserted once or a plurality of times. Further, before cold rolling, steps such as chamfering, pickling and degreasing are performed as necessary.
However, in order to control the metal structure as described above, it is necessary to devise the manufacturing conditions as shown below after adjusting the alloy composition as described above.

  First, in the “casting process”, when cooling the cast slab (including various forms such as slab, billet, ingot), the cooling rate of the slab in the 700 to 300 ° C. region is set to 30 to 200 ° C./min. It is necessary to set it as the above, and it is desirable to set it as 30-150 degrees C / min. If the cooling rate at this stage is too slow, a particularly coarse Fe—P-based compound grows, and it becomes difficult to control the precipitation form with a particle size of 1 μm or less in a later step. As a result, it becomes difficult to stably improve the bending workability.

  In the “hot rolling step”, the cast material before hot rolling (the slab itself, or the slab cut into a predetermined size) has a material center in the range of 850 to 950 ° C., preferably in the range of 880 to 950 ° C. It is heated and held in a furnace so as to be held for 0.5 h or more, preferably 1 h or more. As a result, the precipitated phase generated during casting is re-dissolved and the structure is homogenized. If the heating is insufficient, the coarse Fe-P compound precipitated by casting does not re-dissolve, so P remains consumed in the Fe-P compound, and the Mg-P compound that contributes to punchability The amount of precipitation decreases. Then, after taking out material from a furnace, hot rolling is started and a hot rolling final pass is complete | finished at 500-700 degreeC. When the hot rolling temperature is lower than 500 ° C., formation of a coarse compound phase having a particle size exceeding 1 μm is not preferable. On the other hand, if the final pass is terminated at a temperature exceeding 700 ° C., a 0.2 to 1.0 μm Mg—P compound cannot be obtained, and sufficient punchability cannot be realized. More preferably, the hot rolling final pass temperature is 500 ° C. or higher and lower than 650 ° C. In order to prevent a decrease in material temperature between passes, it is advantageous to use a hot rolling mill having a facility for keeping or heating a plate being rolled. It is desirable to force quench the material as soon as possible after the final hot rolling pass. Specifically, a method of water-cooling on a roller table or immediately immersing the wound coil in water can be employed. Thus, it is important that the average cooling rate in the range of at least 500 to 300 ° C. is 5 ° C./sec or more and rapidly cooled to a temperature range of 300 ° C. or less. When the residence time in this temperature range becomes long, a coarse compound phase exceeding a particle size of 1 μm is formed.

  After hot rolling, an operation for removing the oxide scale on the surface is usually performed by chamfering or pickling. Then, after performing the process of "cold rolling-> intermediate annealing" once or several times as needed, an aging treatment is performed. However, applying an aging treatment to a material that has been cold-rolled at a processing rate of a certain level or more is extremely effective in obtaining a metal structure defined in the present invention. In this specification, this process is called “cold rolling → annealing process”.

  In the “cold rolling → annealing process”, the material is first subjected to cold rolling with a processing rate of 30% or more. Then, it hold | maintains at 400-600 degreeC for 1 hour or more, and after that, it anneals by cooling with the cooling rate from a holding temperature to 300 degreeC being 20-200 degreeC / h, and performs recrystallization and an aging treatment. If the above processing rate is less than 30%, recrystallization may not proceed sufficiently, and the crystal grain size of the matrix remains partially coarsened and tends to become a non-uniform crystal grain structure. May adversely affect the pressability and press punchability. Further, the formation of precipitation nuclei hardly occurs, which is disadvantageous in finely dispersing the Fe-P compound and the Mg-P compound. The upper limit of the processing rate in this cold rolling need not be specified, but usually good results are obtained within a processing rate range of 85% or less. Setting an excessively high processing rate increases the load on the rolling mill and the like, which is not desirable. In annealing, it is important to employ conditions such that the average crystal grain size of recrystallized grains is 20 μm or less. If the holding temperature is less than 400 ° C. or the holding time is less than 1 h, it is not preferable because securing the amount of precipitation and recrystallization are likely to be insufficient. A holding temperature exceeding 430 ° C. is particularly advantageous in realizing the precipitation form of the Mg—P compound for improving the press punchability. When the holding temperature is higher than 600 ° C., it is not preferable because the Fe—P compound and the Mg—P compound are not sufficiently precipitated and the crystal grains are likely to be coarsened. If the holding time is excessively long, the productivity is lowered. Usually, good results can be obtained by holding for about 1 to 6 hours. Also, if the cooling rate after heating is too fast, it will not be possible to secure a sufficient amount of precipitates, so it is desirable to set the cooling rate to at least 300 ° C to 200 ° C / h or less, and 150 ° C / h or less. More preferably, it is 120 ° C./h or less. However, excessively slowing the cooling rate leads to a decrease in manufacturability, so it may be 20 ° C./h or more, preferably 50 ° C./h or more.

  By adopting the manufacturing conditions as described above, a desired metal structure can be obtained. Thereafter, cold rolling can be performed for final plate thickness adjustment and further strength improvement. However, in that case, it is desirable to finally perform strain relief annealing. In this specification, this final cold rolling and strain relief annealing process is referred to as “cold rolling → strain relief annealing process”.

  In the “cold rolling → distortion annealing process”, it is desirable that the cold working rate is in the range of 70% or less. If an excessively high processing rate is set, the amount of strain in the material increases and bending workability decreases. However, it is preferable to secure a processing rate of 20% or more in order to obtain a sufficient strength improvement effect. The strain relief annealing is generally performed in a continuous annealing furnace or a batch annealing furnace. In either case, the material temperature is maintained at 250 to 400 ° C. When the holding temperature is lower than 250 ° C., the effect of removing the distortion cannot be obtained sufficiently, and it is difficult to improve the bending workability particularly when the cold working rate is high. If the holding temperature exceeds 400 ° C., the material tends to soften, which is not preferable. The holding time may be about 3 to 120 seconds in the case of continuous annealing and about 1 to 24 hours in the case of batch annealing. In the cooling process after annealing, it is not necessary to perform special quenching, and it may be cooled outside the furnace.

Copper alloys having the respective compositions shown in Table 1 were produced, and the influence of the alloy composition was examined.
Each alloy was melted in an Ar atmosphere using a high frequency melting furnace and cast into a carbon mold. In this case, it has been confirmed by experiments that the cooling rate of the central portion of the ingot in the 700 to 300 ° C. region is about 50 ° C./min. A cast material having a thickness of 30 mm, a width of 40 mm, and a length of 40 mm was cut out from the obtained ingot, extracted after holding it at 900 ° C. for 1 h, and subjected to hot rolling. In the case of a cast material of this size, the center of the material is held at least at 880 ° C. or more for 0.5 h by holding at 900 ° C. × 1 h. The final pass of hot rolling was finished at 700 to 500 ° C. to obtain a hot rolled sheet. After hot rolling, the hot rolled sheet was immediately immersed in water. At this time, at least 500 to 300 ° C. was passed at an average cooling rate of 5 ° C./sec or more. After removing the oxide on the surface of the hot-rolled sheet, it was cold-rolled at a processing rate of 74%, held at 500 ° C. for 2 h, then cooled to 300 ° C. in 2 h in the furnace, and taken out of the furnace. Further, after cold rolling at a processing rate of 47%, strain relief annealing was performed at 300 ° C. for 1 h to obtain a specimen having a thickness of 0.64 mm.

  Test pieces were prepared from the respective test materials, and the tensile strength, conductivity, bending workability, and egress rate were measured. Moreover, the structure of the test material was observed and the size of the precipitate was measured.

The tensile strength was measured according to JIS Z2241 using a tensile test piece parallel to the rolling direction.
The conductivity was measured according to JIS H0505.
The bending workability is determined by MBR / t (t is a plate) by performing a bending test in which the bending axis is parallel to the rolling direction (BW) by a W bending test method according to JBMA T307 (Japan Copper and Brass Association Standard). Thickness). If the MBR / t value is 1.0 or less, it is evaluated as having good bending workability as a material for energized parts, and if it is 0.5 or less, excellent bending workability that can withstand severe processing is obtained. It is evaluated to have.

The aggression rate is an index for evaluating press punchability. FIG. 1 illustrates a cross-sectional photograph of a press punched portion. The “Egret rate” is a value obtained by dividing the size (depth) A of the portion corresponding to the “fracture surface” formed on the press punched end face (left face in the part of FIG. 1) by the thickness t. It is displayed. In the press punching test for obtaining this value, a value obtained by punching under the condition of a clearance of 3 to 10% (for example, 8%) can be adopted. However,
Clearance = (Gap between punch and die) / (Material thickness) x 100
It is.
Here, the clearance is set to 8%, and the average value of a total of four locations measured at N = 2 for each of two locations in the direction perpendicular to the rolling direction of the punched surface punched by the circular punch is defined as the egress rate. did. If this aggression rate is 5% or less, it is evaluated that it has a good press punching property as a material for a current-carrying part that uses the punched end face for electrical contact, and it is particularly preferably 3% or less.

The average crystal grain size is determined by polishing and etching the sample surface after annealing (final annealing with recrystallization) applied to a material subjected to cold rolling with a processing rate of 74%, and then using an optical microscope. Obtained by observation. Specifically, three viewing fields of about 15300 μm ² were randomly selected and obtained by a cutting method, and the average value was used.
Regarding the precipitate, the material after strain relief annealing was identified by the EDX attached to the SEM, and the presence or absence of the Fe-P compound and the Mg-P compound was examined. As a result, it was confirmed that Fe-P-based compounds and Mg-P-based compounds existed in all Examples. Further, for each particle, the major axis was measured from the SEM image, and the value was taken as the particle size of the particle, and the presence or absence of particles exceeding 1 μm was examined. Three viewing fields are selected at random from an observation field of about 250 μm ² , and “None” is displayed when there is no particle having a particle diameter exceeding 1 μm in all fields of view, and the particle diameter exceeds 1 μm in any field of view. When particles exist, “present” is indicated. The Mg-P compounds were also examined for the presence of particles having a particle size exceeding 0.2 μm to 1 μm. When Mg—P compound particles having a particle size exceeding 0.2 μm to 1 μm are present in all of the three visual fields, “Yes” is displayed, and “None” is displayed in other cases. Further, in order to examine the precipitation state of the Mg—P compound in more detail, the number of Mg—P compounds having a particle size exceeding 0.2 μm to 1 μm per 100 μm ² was measured. Specifically, the surface of the material after strain relief annealing was observed by SEM at a magnification of 10,000 times. For any three fields of views, counts the number of focus than the particle size of 0.2 in a state in which fixed the Mg-P compounds of ～1Myuemu, the total number of the "unit area 100 [mu] m ^2/3-field total observation area 256. The number per 100 μm ² was calculated by multiplying by “92 μm ² ”.
These results are shown in Table 2.

As can be seen from Table 2, in the copper alloys of Examples 1 to 9 having the composition defined in the present invention, the tensile strength is 400 N / mm ² or more, the conductivity is 70% IACS or more, the bending workability MBR / t value is 0.00. A copper alloy having a strength of 5 or less and an egress rate of 5% or less and having a high level of balance between strength, conductivity, bending workability and press punching properties desired as a material for energized parts could be realized.

  On the other hand, in Comparative Example 1, since the Fe content was too high, a coarse Fe—P-based compound was precipitated and the bending workability was poor. In Comparative Example 2, the Fe content was small and the Fe / P ratio was too small, so that a coarse Mg-P compound was formed, and the bending workability was remarkably lowered. In Comparative Example 3, since the P content was too low, the precipitation of the P compound was insufficient, and the electrical conductivity was lowered due to the presence of excessive solid solution Fe and solid solution Mg. In Comparative Example 4, since Fe was not contained, the Mg-P compound was coarsened, and the bending workability was remarkably lowered. In Comparative Example 5, no Mg-P compound was present because Mg was not contained, and the aegle rate was high, resulting in poor press punchability. In Comparative Example 6, the Ni content was higher than 0.1%, so the conductivity was low, and the solid solution amount was increased, so that the bending workability was poor. In Comparative Example 7, the Mg content was higher than 0.5%, so the electrical conductivity was low, and the abundance of Mg—P compound of more than 0.2 to 1 μm was increased, resulting in poor bending workability. In Comparative Example 8, since the total amount of Mg + Fe was small, the strength was low, the aggression rate was high, and the press punchability was poor.

  Next, the influence of manufacturing conditions was examined using a copper alloy having the same composition as in Example 1. In Comparative Example 18, after the hot rolling, a process of “cold rolling at a processing rate of 74% → maintained at 380 ° C. for 5 hours → cooling at a predetermined speed → removing from the furnace” was performed two cycles. % Cold rolling → strain removal annealing held at 300 ° C. for 1 h ”is used as a test material having a thickness of 0.64 mm. Table 3 shows the production conditions of each alloy, and Table 4 shows the characteristics of the obtained materials.

  Examples 1, 10, and 11 are all manufactured under the manufacturing conditions within the scope of the present invention, and have high levels of strength, conductivity, bending workability, and press punchability that are desired as materials for current-carrying parts. A copper alloy with a good balance could be realized.

  On the other hand, in Comparative Example 9, the cooling rate of the ingot in the 700 to 300 ° C. region was controlled to be as low as 10 ° C./min in the “casting process”. When the ingot of the scale used in the experiment is normally cast, the cooling rate of 700 to 300 ° C. becomes 30 to 150 ° C./min (appropriate condition). Therefore, for the purpose of simulating a slow cooling rate when no special cooling was performed at the mass production site, the cooling rate was controlled to 10 ° C./min by cooling the ingot in the furnace using a siliconit furnace. . As a result, a coarse Fe—P compound having a particle size exceeding 1 μm was produced at the casting stage, and the bending workability was poor. In Comparative Example 10, water cooling was performed after casting, and the cooling rate at 700 to 300 ° C. was set to 300 ° C./min. Since the cooling was strong, cracks were confirmed on the surface and cross section of the ingot due to thermal shock, and the sheet passing after casting was stopped. In Comparative Example 11, the heating temperature in the “hot rolling process” was as low as 800 ° C., so that a coarse Fe—P-based compound remained and bending workability deteriorated. In Comparative Example 12, since the final pass temperature in the “hot rolling process” is as high as 800 ° C., Mg—P-based compound particles having a particle size of more than 0.2 μm and not more than 1 μm were not generated. Workability decreased. In Comparative Example 13, the cooling rate in the “hot rolling process” was as slow as 1 ° C./sec, so that the precipitates became coarse and the bending workability deteriorated. In Comparative Example 14, since the processing rate in the “cold rolling → annealing process” was as low as 20%, recrystallization did not occur during annealing, and a mixed grain structure in which the rolling structure remained was obtained. Decreased. In Comparative Example 15, since the temperature in aging annealing in “cold rolling → annealing process” is as high as 700 ° C., precipitation of Fe—P compounds and Mg—P compounds did not occur, and the crystal grains became coarse. The conductivity was low, and the bending workability and press workability were reduced. In Comparative Example 16, since the temperature in the aging annealing in the “cold rolling → annealing process” was as low as 350 ° C., precipitation of the Fe—P compound and the Mg—P compound was not sufficient, and recrystallization did not occur. , Conductivity and bending workability decreased. In Comparative Example 17, the relieving annealing temperature in the “cold rolling → distortion annealing process” was as high as 500 ° C., so that new recrystallization occurred, the material was softened, the strength was low, and the press punchability was lowered. In Comparative Example 18, since the hot rolling end temperature was as high as 720 ° C., an Mg—P compound of more than 0.2 to 1.0 μm was not obtained, and the press punching property was lowered.

The drawing substitute photograph which showed the cross section of the press punching part in order to demonstrate an egress rate.

Claims (9)

  In mass%, Fe: 0.15 to 0.7%, P: 0.04 to 0.5%, Mg: 0.01 to 0.5%, the balance being substantially Cu, and 1.5 ≦ Fe Mg-P having a composition satisfying / P ≦ 10, 0.5 ≦ Mg / P ≦ 7, and Fe + Mg ≧ 0.25, and including a Fe—P compound and particles having a particle size exceeding 0.2 μm in the matrix A copper alloy having a metallographic structure in which all of the compounds are present in a particle size of 1 μm or less. In mass%, Fe: 0.15 to 0.7%, P: 0.04 to 0.5%, Mg: 0.01 to 0.5%, the balance being substantially Cu, and 1.5 ≦ Fe / P ≦ 10, 0.5 ≦ Mg / P ≦ 7, Fe + Mg ≧ 0.25, and the Fe-P compound and Mg—P compound both have a particle size of 1 μm or less in the matrix. In addition, 0.3 to 10 particles having a particle diameter of more than 0.2 to 1 μm of the Mg-P compound exist per 100 μm ² , and new recrystallization has occurred after the last cold working. A copper alloy having a metal structure with no average crystal grain size of 30 μm or less.   Furthermore, the copper alloy of Claim 1 or 2 which has a composition containing Sn: 0.5% or less.   The copper alloy according to any one of claims 1 to 3, which has a metal structure in which new recrystallization does not occur after being cold worked.   The copper alloy according to any one of claims 1 to 4, which has a metal structure having an average crystal grain size of 20 µm or less. Conductivity of 70% IACS or more, tensile strength of 400 N / mm ² or more, bending workability that does not cause cracking when bending at 90 ° with a bending radius equal to the plate thickness, The copper alloy according to any one of claims 1 to 5, which has press punchability at a rate of 5% or less.   “Casting process” in which the cooling rate of the slab in the 700 to 300 ° C. range is 30 to 200 ° C./min or higher in the cooling process during casting, and the material center is held in the 850 to 950 ° C. range for 0.5 h or more. After the cast material is heated, hot rolling is started, the final hot rolling pass is terminated at 500 to 700 ° C., and then the average cooling rate of at least 500 to 300 ° C. is set to 5 ° C./sec or more and 300 ° C. or less. “Hot rolling process” that rapidly cools to a temperature range and after cold rolling with a processing rate of 30% or more, hold at 400 to 600 ° C. for 1 h or more, and then set the cooling rate from the holding temperature to 300 ° C. to 20 to 200 The manufacturing method of the copper alloy in any one of Claims 1-6 which has a "cold rolling-> annealing process" cooled as deg. C / h.   After the "cold rolling-> annealing process", the steel sheet further includes a "cold rolling-> strain relief annealing process" in which a cold rolling is performed within a processing rate of 70% or less and then heated to a range of 250 to 400 ° C. 8. A method for producing a copper alloy according to 7.   An energized component comprising the copper alloy according to claim 1, having a bent portion and a press punched portion, and utilizing the press punched end face for electrical contact.