Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
  • H01B1/026—Alloys based on copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/02—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working in inert or controlled atmosphere or vacuum

Definitions

• the present invention is related to a titanium copper for electronic components which is suitable for electronic components, particularly connectors, battery terminals, jacks, relays, switches, autofocus camera modules, lead frames, and a method for manufacturing the titanium copper.
• titanium copper has a relatively high strength and is excellent in stress relaxation characteristics among copper alloys. Therefore, titanium copper has been used for a long time as a material for signal terminals, whose strength is particularly required.
• Titanium copper is an age hardening type copper alloy.
• a supersaturated solid solution of Ti which is a solute atom
• heat treatment for a relatively long time at a low temperature is performed from this state, a modulation structure, in which the Ti concentration in the parent phase fluctuates periodically, develops and results into improvement of strengthen, because of spinodal decomposition.
• the problem is that the strength and the bending workability are contradictory properties. That is, if the strength is increased, the bending workability is impaired, and on the contrary, when emphasis is placed on the bending workability, the desired strength can not be obtained.
• Patent Document 1 JP2013-100586A discloses a titanium copper comprising Ti of 1.5 to 5.0 mass%, and the rest consisting of copper and inevitable impurities, having a tensile strength of 800 MPa or more, wherein when an EBSD measurement is carried out parallel to the plate thickness direction at the central portion in the plate thickness direction which is a cross sectional position of 45 to 55% with respect to the thickness, and when the crystal orientation is analyzed, the area ratio of Cube orientation ⁇ 001 ⁇ ⁇ 100> Is 5% or more, the area ratio of Brass orientation ⁇ 110 ⁇ ⁇ 112> is 40% or less, and the area ratio of Copper orientation ⁇ 112 ⁇ ⁇ 111> is 20% or less. According to this disclosure, by controlling the crystal orientation inside the copper alloy plate in this way, it is possible to obtain sufficient bending workability for notch bending.
• Patent Document 2 discloses a copper alloy sheet material containing 1.0 to 5.0 mass% of Ti and the rest consisting of copper and inevitable impurities, wherein in the crystal orientation analysis by EBSD measurement, the copper alloy sheet material is characterized in that the area ratio of the Cube orientation ⁇ 001 ⁇ ⁇ 100> is 5 to 50%. According to the disclosure, there is a correlation between the Cube orientation accumulation ratio and the bending workability, and by controlling this, a copper alloy sheet material having excellent bending workability and excellent strength can be obtained.
• Patent Document 3 JP2015-190044A discloses that, at the stage before finish cold rolling, by controlling the ratio of the maximum side average crystal grain size / average grain size to be smaller than a certain level, and by reducing the number density of coarse second phase particles, the level of the bending workability of the copper alloy sheet material can be improved and variations can be reduced.
• Patent Document 4 JP2004-052008A discloses a titanium copper alloy material comprising Ti of 1.0 to 5.0 mass% and the rest consisting of copper and inevitable impurities, characterized in that the value of the ratio of (the deviation of crystal grain size) / (the average crystal grain size) is 0.60 or less, and the mechanical properties such as bending workability and stress relaxation property of the titanium copper alloy material are uniform and good.
• US2010/0139822 and EP A 2196548 each propose a Cu-Ti-based copper alloy sheet material and method of manufacturing same.
• the inventors of the present invention conducted extensive research and discovered findings that, in order to improve the bending workability of titanium copper for electronic components to which beating process is applied, it is important to simultaneously control its work-hardening exponent, and the relation of the X-ray diffraction integrated intensity I ⁇ 200 ⁇ from the ⁇ 200 ⁇ crystal face on the surface of the titanium copper and the X-ray diffraction integrated intensity I 0 ⁇ 200 ⁇ of a pure copper standard powder.
• the inventors also discovered finding that, to realize the control described above, when manufacturing a titanium copper by hot rolling an ingot of titanium copper, followed by a step of cold rolling and a final solution heat treatment, it is necessary to make the minimum working ratio per pass and the total working degree in the step of cold rolling within a certain range, while setting the rate of temperature rise and the heating temperature in the step of final solution heat treatment in a certain rage.
• the present invention is accomplished based on the above findings.
• bending workability of titanium copper for electronic components can be improved, and a titanium copper for electronic components, which has excellent bending workability even when subjected to beating process, as well as a method for manufacturing the same, can be provided.
• the Ti concentration is set to 2.0 to 4.5 mass%.
• Ti is solidified in the Cu matrix by solution treatment, and fine precipitates are dispersed in the alloy by aging treatment, thereby increasing strength and conductivity.
• the Ti concentration is less than 2.0 mass%, precipitation of precipitates becomes insufficient and desired strength can not be obtained.
• the Ti concentration exceeds 4.5% by mass, the processability is deteriorated, and the material is easily broken during rolling.
• the preferable Ti concentration is 2.5 to 3.5 mass%.
• one or more third element(s) selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si can be contained, and thereby the strength can be further improved.
• these third elements can be contained in a total amount of 0 to 0.5 mass%. In view of the balance between strength and workability, it is preferable to contain one or more of the above elements in a total amount of 0.1 to 0.4 mass%.
• Zr, P, B, V, Mg and Si in an amount of 0.01 to 0.15 mass%, Fe, Co, Ni, Cr, Mo, Nb and Mn in an amount of 0.01 to 0.3 mass%, and Zn in an amount of 0.1 to 0.5 mass%, may be contained.
• n is called work-hardening exponent (referred to as Hajime Sudo: Material Test Method, Uchida Rokakuho Publishing Co. LTD, (1976), p. 34 ), and takes the value 0 ⁇ n ⁇ 1.
• the true strain at the maximum load point is set as the work-hardening exponent (n value) (referred to as Hajime Sudo: Material Test Method, Uchida Rokakuho Publishing Co. LTD, (1976), p. 35 ).
• n value work-hardening exponent
• a tensile test in the rolling parallel direction can be carried out in accordance with JIS Z 2241 (2011) in the same manner as the measurement of 0.2% yield strength, which will be described hereinafter, to obtain a stress-strain curve.
• the true strain ⁇ t can be calculated by substituting the nominal strain ⁇ at the maximum load point read from the obtained stress-strain curve into the following formula (2).
• ⁇ t ln 1 + ⁇
• the n value In order to obtain a titanium copper excellent in bending workability, it is important to set the n value within a predetermined range. Titanium copper is work hardened by beating, and the strength is increased. At this time, since the strength is in a trade-off relationship with the bending workability, the bending workability deteriorates due to the increase in strength. In order to suppress the increase in strength due to beating process, it is preferable to make the work-hardening index small. Specifically, the work-hardening exponent (n value) in the direction parallel to the rolling direction should be 0.05 to 0.25. The n value is preferably 0.08 to 0.22, more preferably 0.11 to 0.19.
• the X-ray diffraction integrated intensity I ⁇ 200 ⁇ from the ⁇ 200 ⁇ crystal face on the surface of the titanium copper and the X-ray diffraction integrated intensity I 0 ⁇ 200 ⁇ of a pure copper standard powder satisfy the relation: 0.15 ⁇ I ⁇ 200 ⁇ / I 0 ⁇ 200 ⁇ ⁇ 0.70. This is because if the ratio of I ⁇ 200 ⁇ / I 0 ⁇ 200 ⁇ is too large, the strain of each crystal grain becomes nonuniform and the bending workability deteriorates.
• the ratio of I ⁇ 200 ⁇ / I 0 (200) is preferably 0.25 or more and 0.60 or less, more preferably 0.30 or more and 0.50 or less.
• the X-ray diffraction integrated intensity can be measured by using a predetermined X-ray diffraction apparatus.
• the titanium copper according to the present invention can have excellent bending workability.
• the average roughness Ra of the outer peripheral surface of the bent portion is 1.0 ⁇ m or less.
• the average roughness Ra is calculated according to JIS-B 0601 (2013). The fact that the average roughness of the bent portion is small even after the bending means that harmful cracks which may cause breakage are difficult to occur in the bent portion.
• the average roughness Ra of the surface of the titanium copper according to the present invention before the bending test is 0.2 ⁇ m or less.
• the working ratio which simulates a beating process, is based on the following equation.
• T 0 is the thickness of the ingot before the cold rolling and T is the thickness of the ingot at the end of the cold rolling.
• Working Ratio % T 0 ⁇ T / T 0 ⁇ 100
• titanium copper it is preferable to control the average crystal grain size in the rolled surface within the range of 2 to 30 ⁇ m, more preferably in the range of 2 to 15 ⁇ m, and still more preferably in the range of 2 to 10 ⁇ m.
• the average crystal grain size means the average crystal grain size obtained by analyzing the crystal orientation in the EBSD (Electron Back Scatter Diffraction) measurement on the rolled surface, using analysis software attached to EBSD (e.g. OIM Analysis provided by TSL Solutions Co., Ltd.), wherein the average crystal grain size is calculated when an orientation difference of 5° or more is defined as a grain boundary.
• EBSD Electro Back Scatter Diffraction
• 0.2% yield strength in a direction parallel to the rolling direction may be 800 MPa or more.
• the 0.2% yield strength of titanium copper according to the present invention may be 850 MPa or more in a preferred embodiment, 900 MPa or more in a further preferred embodiment, and 950 MPa or more in a further preferred embodiment.
• the upper limit of the 0.2% yield strength is not particularly restricted from the viewpoint of the strength intended by the present invention, but since it is troublesome and expensive, the 0.2% yield strength of titanium copper according to the present invention is generally 1300 MPa or less, typically 1200 MPa or less, more typically 1100 MPa or less.
• the 0.2% yield strength in the direction parallel to the rolling direction is measured in accordance with JIS-Z 2241 (2011) (method for metal material tensile test).
• the thickness can be 1.0 mm or less. In a typical embodiment, the thickness can be 0.02 to 0.8 mm, and in an more typical embodiment, the thickness can be 0.05 to 0.5 mm.
• Titanium copper according to the present invention can be processed into various copper elongation products such as plates, strips, pipes, rods and wires.
• the titanium copper according to the present invention is preferably used as a conductive material or a spring material in electronic components such as a switch, a connector, an autofocus camera module, a jack, a terminal (in particular, a battery terminal), a relay and the like, although its application is not limited.
• electronic components can be used, for example, as in-vehicle parts or parts for electrical and electronic equipment.
• Preparation of ingot by melting and casting is basically carried out in vacuum or in an inert gas atmosphere. If undissolved residues of the added element(s) is present during dissolution, it does not work effectively for improving the strength. Therefore, in order to eliminate undissolved residues, for third elements having a high melting point such as Fe or Cr, after add the element, it is necessary to sufficiently stir it, and to maintain a certain period of time. On the other hand, since Ti is relatively soluble in Cu, it may be added after dissolution of the third element(s). Therefore, it is desirable to at first add one or more elements selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si in total of 0 to 0. 5 mass%, and then add Ti to a concentration of 2.0 to 4.5 mass%, so as to produce an ingot.
• the working ratio of the cold rolling is typically 30% or more.
• annealing can then be carried out.
• the annealing conditions are typically 900 ° C. and 1 to 5 minutes.
• the cold rolling and the annealing can be repeated as necessary.
• the reason for preliminarily performing solution heat treatment is to reduce the burden on the final solution treatment. That is, in the final solution heat treatment, since the second phase particles are already solutionized, heat treatment for solid solution of the second phase particles is not necessary, and it is only necessary to maintain this state and further cause recrystallization, so that a slight heat treatment is sufficient.
• the first solution heat treatment may be performed at a heating temperature of 850 to 900 °C for 2 to 10 minutes. It is also preferable to make the heating rate and the cooling rate at that time as high as possible and to prevent precipitation of the second phase particles during this process. Note that the first solution heat treatment may not be performed.
• the minimum working ratio per pass is less than 10%, it becomes difficult to control the area ratio of I ⁇ 200 ⁇ / I 0 ⁇ 200 ⁇ of finally obtained titanium copper to 0.70 or less, whereas if the minimum working ratio per pass exceeds 30%, the material breaks and the production becomes difficult. From this viewpoint, the minimum working ratio per pass is preferably 13 to 27%, more preferably 16 to 24%.
• the total working degree ⁇ is less than 3.0, it becomes difficult to control the ratio of I ⁇ 200 ⁇ / I 0 ⁇ 200 ⁇ of finally obtained titanium copper to 0.15 or more, whereas when the total processing degree ⁇ is 5 .0 or more, it also becomes difficult to control the area ratio of I ⁇ 200 ⁇ / I 0 ⁇ 200 ⁇ of finally obtained titanium copper to 0.70 or less.
• the total working degree ⁇ is preferably 3.3 to 4.7, more preferably 3.6 to 4.4.
• the working ratio per pass can be obtained from the following equation.
• T 0 is the thickness of the ingot before the cold rolling and T is the thickness of the ingot at the end of the cold rolling.
• Working Ratio % T 0 ⁇ T / T 0 ⁇ 100
• the heating temperature is set close to the solid solubility limit of the second phase particle composition.
• the heating temperature (° C.) is set to (52 ⁇ X + 610) to (52 ⁇ X + 680).
• the heating temperature is lower than 52 ⁇ X + 610, recrystallization becomes insufficient, and when the heating temperature exceeds 52 ⁇ X + 680, the crystal grain size becomes coarse, and the bending workability of finally obtained titanium copper is remarkably deteriorated.
• the heating time is, for example, 30 seconds to 10 minutes, and typically 1 minute to 8 minutes.
• the heating time is, for example, 30 seconds to 10 minutes, and typically 1 minute to 8 minutes.
• the final solution heat treatment is followed by the final cold rolling.
• the strength can be increased by the final cold rolling, in order to obtain bending workability as intended in the present invention, it is desirable set to the reduction ratio to 5 to 50%, preferably to 20 to 40%.
• the final cold rolling is followed by aging treatment. It is preferable to heat at a material temperature of 300 to 500 °C for 1 to 50 hours, more preferably at a material temperature of 350 to 450 °C for 10 to 30 hours.
• the aging treatment is preferably performed in an inert atmosphere such as Ar, N 2 , H 2 or the like in order to suppress the generation of the oxide film.
• the method comprises:
• steps such as grinding, polishing, shot-blast acid washing and the like for removing oxide scales on the surface can be appropriately performed between the above steps.
• Alloys containing the alloy components shown in Table 1 and the rest consisting of copper and inevitable impurities were used as an experimental materials and effects of the alloy components, the production conditions for cold rolling and subsequent final solution heat treatment on the 0.2% yield strength, the work-hardening exponent, the ratio of I ⁇ 200 ⁇ / I 0 ⁇ 200 ⁇ , and the bending workability after rolling were investigated.
• hot rolling was performed at 900 to 950 °C to obtain a hot rolled sheet having a thickness of 15 mm.
• cold rolling and annealing were repeated to obtain strip thicknesses (0.3 to 3.3 mm), and a first solution heat treatment was performed on the stripes.
• the conditions of the first solution heat treatment were heating at 850 °C for 10 minutes and then water cooling.
• intermediate cold rolling was carried out under the conditions shown in Table 1, then inserted into an annealing furnace which is capable of rapid heating, and the final solution treatment was performed, followed by water cooling.
• the heating conditions at this time were set as shown in Table 1.
• JIS 13B test piece was prepared and the 0.2% yield strength in the direction parallel to the rolling direction was measured using a tensile tester according to the above measuring method.
• a tensile test in a direction parallel to the rolling direction was performed to obtain a stress-strain curve, and the n value was obtained by the above-described method.
• a cold rolling with a working ratio of 10%, which simulates a beating process, was conducted, and subsequently a W bending test was performed in the Badway direction at r/t 1.0 in accordance with JIS-H 3130 (2012) after the cold rolling.
• the outer peripheral surface of the bent portion of this test piece was observed.
• the outer peripheral surface of the bent portion was photographed using a confocal microscope HD100 manufactured by Lasertec Corporation, and the average roughness Ra (according to JIS-B 0601: 2013) was measured using the attached software and compared.
• the surface of the sample before bending was observed with a confocal microscope, irregularities were not confirmed, and the average roughness Ra was 0.2 ⁇ m or less in each case.
• Comparative Example 1 since the minimum working ratio per pass was too low, the ratio of I ⁇ 200 ⁇ / I 0 ⁇ 200 ⁇ was outside the range of the present invention, and the bending workability was inferior to the Examples.

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