RU2795791C2 - Titanium-copper material, method for producing titanium-copper material and electronic component - Google Patents

Abstract

FIELD: titanium-copper materials.

SUBSTANCE: invention can be used for the manufacture of electronic components such as connectors, battery clips, plugs, relays, switches, auto focus video camera modules, etc. Titanium-copper material contains from 2.0 to 4.5 wt.% Ti, at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si, in total from 0 to 0.5 wt.%, the rest is copper and unavoidable impurities, where the surface area of crystal grains, characterized by a GOS parameter in the range from 2 to 6°, ranges from 60 to 90%, provided that the orientation difference of 5° and more, when analyzing the orientation of crystals by the EBSD method for the surface subjected to rolling, and the surface area of crystal grains, characterized by a Schmid factor of 0.35 or less, is in the range from 5 to 20%.

EFFECT: improving the material resistance to stress relaxation.

6 cl, 18 ex, 1 tbl, 2 dwg

Description

The field of technology to which the invention belongs

The present invention relates to a titanium-copper material, a method for producing a titanium-copper material, and an electronic component. For example, the present invention relates to a titanium-copper material, a titanium-copper material production method, and an electronic component using the titanium-copper material, which are suitable for use in electronic components such as connectors, battery clamps, plugs, relays, switches, modules. video cameras with auto focus and lead frames.

State of the art

Recently, the evolving miniaturization of electronic components, such as lead frames and connectors used in electrical/electronic devices and on-board components, causes a noticeable trend towards narrowing the pitch and reducing the height of the copper alloy element forming the electronic component. The smaller connector has a narrower pin width resulting in a smaller shape, so the copper alloy element used is required to show high strength in order to obtain the desired spring characteristics. In this regard, among the copper alloys, a titanium-containing copper alloy (hereinafter referred to as "titanium-copper material") has a relatively high strength and the best stress relaxation resistance. Therefore, titanium-copper material has traditionally been used as an element for a signal system element.

Among various copper alloys, in terms of stress relaxation resistance, titanium-copper material is a PH copper alloy which is characterized by having a good balance between strength and bending workability and, in addition, exhibits particularly well improved performance. Therefore, developments have been made to improve properties such as bending strength and machinability while maintaining the stress relaxation resistance of the titanium-copper alloy.

Japanese Patent Application Publication No. 2014-185370 A (Patent Document 1) describes a Cu-Ti based copper alloy sheet having improved bending workability while maintaining high strength, and having improved fatigue load resistance while maintaining good relaxation resistance. stresses, where the copper alloy is characterized by a composition containing from 2.0 to 5.0 wt.% Ti, from 0 to 1.5 wt.% Ni, from 0 to 1.0 wt.% Co, from 0 to 0.5 wt.% Fe, 0 to 1.2 wt.% Sn, 0 to 2.0 wt.% Zn, 0 to 1.0 wt.% Mg, 0 to 1.0 wt.% Zr, from 0 to 1.0 wt.% Al, 0 to 1.0 wt.% Si, 0 to 0.1 wt.% P, 0 to 0.05 wt.% B, 0 to 1.0 wt. .% Cr, 0 to 1.0 wt.% Mn and 0 to 1.0 wt.% V, while the total content of Sn, Zn, Mg, Zr, Al, Si, P, B, Cr, Mn and V among these elements is 3.0% or less, and the rest are Cu and inevitable impurities, and the copper alloy sheet has a metal structure, in which the maximum width of grain boundary reaction precipitates is 500 nm or less, and the density of granular precipitates having a diameter of 100 nm or more is 10 ⁵ /mm ² or less in a cross section perpendicular to the thickness direction.

Japanese Patent Application Publication No. 2010-126777 A (Patent Document 2) describes a copper alloy sheet having improved bending workability while maintaining high strength, wherein the copper alloy sheet has a composition containing 1.2 to 5.0 mass .% Ti, the rest are Cu and inevitable impurities, where the average crystal grain size is in the range of 5 to 25 μm, and the ratio (maximum crystal grain size - minimum crystal grain size) / average crystal grain size is 0.20 or less , in which the maximum crystal grain size is the maximum value of the average values of the crystal grain sizes in the respective areas from a plurality of areas characterized by the same profile and sizes, which are randomly selected on the surface of the sheet, the minimum crystal grain size is the minimum value of the number of average crystal grain sizes in the respective regions, and the average crystal grain size is the average of the average crystal grain sizes in the respective regions, and where the copper alloy sheet has a crystal orientation satisfying the relation I{420}/I ₀ {420} > 1.0, in which I{420} is the X-ray diffraction intensity for the {420} crystallographic plane on the surface of the copper alloy sheet, and I ₀ {420} is the X-ray diffraction intensity for the {420} crystallographic plane of the powdered reference material pure copper.

Japanese Patent Application Publication No. 2008-308734 A (Patent Document 3) discloses a copper alloy sheet material having improved bending workability and improved stress relaxation resistance as well as improved springback, wherein the copper alloy sheet is characterized by a composition containing from 1.0 to 5.0 wt.% Ti, the rest are Cu and inevitable impurities, and where the copper alloy sheet has a crystal orientation that satisfies the ratio I{420}/I ₀ {420} > 1.0, and is characterized by an average the size of crystalline grains in the range from 10 to 60 microns.

Japanese Patent Application Publication No. H07-258803 A (Patent Document 4) describes a method for producing a high-strength copper alloy having improved strength and improved bending workability by adjusting the production steps from a solubilizing treatment to a cold rolling step, the method including subjecting the copper alloy to containing from 0.01 to 4.0% Ti, and the rest of Cu and inevitable impurities, processing carried out in the following order: for 240 seconds and an average size of crystalline grains of not more than 20 microns; (2) the first cold rolling, carried out at a reduction ratio of less than 80%; (3) a second solubilization treatment carried out under heat treatment conditions at a temperature of 800° C. or more for 240 seconds and an average grain size in the range of 1 to 20 μm or less; (4) a second cold rolling performed at a reduction ratio of 50% or less; and (5) aging treatment at a temperature in the range of 300 to 700°C for a period of time in the range of 1 hour to less than 15 hours.

List of citations

Patent Literature Sources

Patent Document 1: Japanese Patent Application Publication No. 2014-185370 A

Patent Document 2: Japanese Patent Application Publication No. 2010-126777 A.

Patent Document 3: Japanese Patent Application Publication No. 2008-308734 A

Patent Document 4: Japanese Patent Application Publication No. H07-258803 A

The essence of the invention

Technical problem

Recently, electronic devices have been required to demonstrate increased reliability in addition to increased functionality, and the demonstration of increased reliability is also required of electronic components used for electronic devices. In particular, heat resistance is one of the important indicators that is required to demonstrate a higher level than in the prior art. The titanium-copper material is known to have a relatively better resistance to stress relaxation. However, the titanium-copper alloys disclosed in Patent Documents 1 to 4 still cannot achieve sufficient stress relaxation resistance, and thus there is a need to further improve the stress relaxation resistance.

In view of the above problems, the present disclosure provides a titanium-copper material having improved stress relaxation resistance, a method for manufacturing the titanium-copper material, and an electronic component using the titanium-copper material.

Solution

As found by the inventor of the present invention, as a result of intensive research aimed at solving the above problems, a titanium-copper material, which, respectively, has a grain orientation spread (GOS) for crystal grains, calculated as a result of measurement using the reflected electron diffraction method ( EBSD) in relation to the surface subjected to rolling, their surface area ratio and the surface area ratio of crystal grains, characterized by a certain value of the Schmid factor, are within predetermined ranges, is characterized by improved resistance to stress relaxation.

In one aspect, the titanium-copper material according to one embodiment of the present invention contains from 2.0 to 4.5 wt.% Ti and a total amount in the range from 0 to 0.5 wt.% of at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si as the third element, the rest is copper and unavoidable impurities, where the proportion surface area of crystal grains having a GOS (texture scattering) parameter in the range of 2 to 6°, when an orientation difference of 5° or more is considered as a crystal grain boundary when analyzing crystal orientation by measuring the EBSD surface of a rolled surface, is in the range of 60 to 90%, and the surface area ratio of crystal grains having a Schmid factor of 0.35 or less is in the range of 5 to 20%.

In one aspect, a method for producing a titanium-copper material according to one embodiment of the present invention comprises casting an ingot of a titanium-copper material containing 2.0 to 4.5 wt% Ti and a total amount ranging from 0 to 0.5 wt.%, at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si, as the third element, the rest is copper and inevitable impurities, hot rolling of the cast ingot; and then carrying out a cold rolling step and a subsequent final solubilizing treatment step, where the hot rolling step includes processing the ingot such that the compressive strain per pass is in the range of 0.15 to 0.30 and the maximum strain rate at a temperature of 700 to 900°C is in the range from 2.0 to 6.0/sec, and where the stage of the final solutory processing includes processing at a heating temperature (°C) in the range from 52 × X + 610 to 52 × X + 680, where X represents the added amount (wt.%) Ti, during the holding time in the range from 5 to 60 seconds.

Advantageous effects of the invention

According to the present invention, it is possible to provide a titanium-copper material having improved stress relaxation resistance, a titanium-copper material production method, and an electronic component using the titanium-copper material.

Brief description of the drawings

Fig. 1 is a picture for explaining the principle of measurement with respect to the degree of stress relaxation.

Fig. 2 is a picture for explaining the principle of measurement with respect to the degree of stress relaxation.

Description of Preferred Embodiments

(Ti concentration)

The titanium-copper material according to one embodiment of the present invention has a Ti concentration in the range of 2.0 to 4.5% by weight. The titanium-copper material is characterized by increased strength and increased electrical conductivity as a result of the dissolution of Ti in the Cu matrix during the solubilization treatment and as a result of dispersion in the alloy of fine precipitates during the aging treatment.

In the case of a Ti concentration of less than 2.0 wt.%, the deposition of precipitates will become insufficient, and any desired strength cannot be obtained. In the case of a Ti concentration of more than 4.5 mass%, workability deteriorates and the material is easily cracked during rolling. From the point of view of the balance between strength and workability, the preferred concentration of Ti is in the range of 2.5 to 3.5 mass%.

(Third element)

The titanium-copper material according to one embodiment of the present invention contains at least one of the third elements selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si, whereby the strength can be further improved. However, if the total concentration of the third elements is more than 0.5 mass%, workability deteriorates and the material is easily cracked during rolling. Therefore, these third elements may be contained in a total amount in the range of 0 to 0.5 mass%, and considering the balance between strength and machinability, the titanium-copper material preferably contains one or more of the above elements in a total amount in the range of 0.1 up to 0.4 wt.%. With regard to each added element, the titanium-copper material contains 0.01 to 0.15 wt.% each of Zr, P, B, V, Mg and Si, and 0.01 to 0.3 wt.% each from Fe, Co, Ni, Cr, Mo, Nb and Mn, and from 0.01 to 0.5 wt% Zn.

(Spread of grain orientations (GOS))

The titanium-copper material according to one embodiment of the present invention is characterized in that the grain orientation spread (GOS) quantifying the average crystal grain orientation difference is controlled within a certain range. More specifically, the surface area ratio of crystal grains having a GOS parameter in the range of 2 to 6° is in the range of 60 to 90%. The GOS parameter within the above range means the formation of fine precipitates in the crystal grains, thereby making it possible to improve the stress relaxation resistance.

If the surface area ratio of crystal grains having a GOS parameter in the range of 2° to 6° is less than 60%, the formation of fine precipitates will be insufficient and the stress relaxation resistance will not improve. On the other hand, if the surface area ratio of crystal grains having a GOS value in the range of 2 to 6° is more than 90%, the formation of coarse precipitates will increase, so that the stress relaxation resistance will not improve. The surface area ratio of crystal grains having a GOS value in the range of 2 to 6° is preferably in the range of 65 to 85%, and more preferably 70 to 80%.

As used herein, the term "GOS" refers to the average value of the orientation difference between all image elements within each crystal grain in the case where an orientation difference of 5° or more is considered as a crystal grain boundary, when analyzing the orientation of crystals by EBSD (Electron Reflected Diffraction) method on a rolled surface using analysis software (eg, OIM Analysis available from TSL Solutions, Inc.) supplied with the EBSD method. "GOS" is determined by calculating the average value of the orientation difference between image elements within the crystal grains and all remaining image elements for all crystal grains.

In this embodiment, the following conditions are used for measurement using the EBSD method:

(a) Conditions in the SEM method (scanning electron microscope)

- Conditions for the beam: accelerating voltage 15 kV and electric irradiation current 5×10 ^{- 8} A;

- Working distance: 25 mm;

- Field of observation: 150 µm × 150 µm;

- Observation surface: surface subjected to rolling;

- Pre-treatment of the observation surface: the structure is allowed to appear by electrochemical polishing in a solution of 67% phosphoric acid + 10% sulfuric acid + water under conditions at 15 V for 60 seconds.

(b) Conditions in the EBSD method

- Measurement program: OIM database;

- Data analysis program: OIM Analysis (version 5.3); And

- Step width: 0.25 µm.

(Schmid factor)

For the titanium-copper material of the present invention, the proportion of the surface area of crystal grains having a Schmid factor of 0.35 or less is controlled at a value level in the range of 5 to 20%. When the surface area ratio of crystal grains having a Schmid factor of 0.35 or less is in the range of 5 to 20%, and the surface area ratio of crystal grains having a GOS parameter is in the range of 2 to 6°, toughness can be improved. to the stress relaxation of the titanium-copper material of the present invention.

The shear stress τ required for the occurrence of shear deformation in the material can be expressed as τ = σ cos ϕ cos λ. In this case, σ is the tensile stress, ϕ is the angle between the tensile axis and the sliding direction, and the cos ϕ cos λ part is the Schmid factor. The Schmid factor takes a value in the range from 0 to 0.5 and represents the ease of deformation. That is, the Schmid factor means that with a smaller value, deformation will be difficult, and with a larger value, deformation will be easy. In the case where the surface area ratio of crystal grains having a Schmid factor of 0.35 or less is more than 20%, the stress resistance will increase and deformation will tend to accumulate. As a result, the stress relaxation resistance will not improve. Although the stress relaxation resistance improves as the proportion of the surface area of crystal grains having a Schmid factor of 0.35 or less decreases, controlling the surface area of crystal grains having a Schmid factor of 0.35 or less to a value of less than 5% in a fully recrystallized state is difficult in practice. From this point of view, the surface area ratio of crystal grains having a Schmid factor of 0.35 or less is preferably 6 to 18%, and more preferably 7 to 16%.

In the present embodiment, the term "Schmid factor" refers to the result calculated for individual crystal grains when an orientation difference of 5° or more is considered as a crystal grain boundary when analyzing crystal orientation by measuring using the EBSD (reflected electron diffraction) method for rolled surface using the analysis software (eg, OIM Analysis available from TSL Solutions, Inc.) supplied with the EBSD method. For measurement using the EBSD method, the following conditions are used:

(a) Conditions in the SEM method

- Conditions for the beam: accelerating voltage 15 kV and electric irradiation current 5×10 ^{- 8} A;

- Working distance: 25 mm;

- Field of observation: 150 µm × 150 µm;

- Observation surface: surface subjected to rolling;

- Pre-treatment of the observation surface: the structure is allowed to appear by electrochemical polishing in a solution of 67% phosphoric acid + 10% sulfuric acid + water under conditions at 15 V for 60 seconds.

(resistance to stress relaxation)

The titanium-copper material of one embodiment of the present invention may have improved stress relaxation resistance. In one embodiment, the material has a degree of stress relaxation equal to 10% or less after keeping the titanium-copper material at 300°C for 10 hours.

(Average crystal grain size)

In one embodiment of the titanium-copper alloy of the present invention, from the viewpoint of improving strength, bending workability and fatigue performance while achieving good balance, it is preferable to control the average crystal grain size on the surface subjected to rolling in the range of 2 to 30 µm, more preferably in the range of 2 to 15 µm, and even more preferably in the range of 2 to 10 µm.

The term “average crystal grain size” refers to the average crystal grain size in the case where an orientation difference of 5° or more is considered as a crystal grain boundary by analyzing the crystal orientation using the EBSD (electron reflected diffraction) method for a rolled surface using analysis software (for example, OIM Analysis, available from TSL Solutions) accompanying the EBSD method, as in the case of the average crystal grain size, to calculate the coefficient of crystal grain size variation in accordance with the above description of the invention.

(0.2% yield strength)

In one embodiment, the titanium-copper material according to an embodiment of the present invention can reach 0.2% yield strength of 800 MPa or more in a direction parallel to the rolling direction. The 0.2% yield strength of the titanium-copper material of the present invention is 850 MPa or more in one preferred embodiment, 900 MPa or more in one more preferred embodiment, and 950 MPa or more in another even more preferred embodiment. .

From the point of view of the target strength of the present invention, the upper limit value of 0.2% yield strength is not particularly limited. However, for labor costs and production costs, the upper limit value is usually 1200 MPa or less, and more often 1100 MPa or less.

In the present invention, the 0.2% yield strength of the titanium-copper material in the direction parallel to the rolling direction is measured in accordance with JIS-Z2241 (2011) (Tensile test method for metallic material).

(Thickness of titanium copper material)

In one embodiment, the titanium-copper material of the present invention may have a thickness of 1.0 mm or less, in one typical embodiment it may have a thickness in the range of 0.02 to 0.8 mm, and in one more in a typical embodiment, it may have a thickness in the range of 0.05 to 0.5 mm.

(Applicability)

The titanium copper material of the present invention can be processed into various copper products such as plates, strips, tubes, rods and wires. The titanium-copper material of the present invention can preferably be used as a conductive or spring material in electronic parts, including but not limited to: switches, connectors, auto focus video camera modules, plugs, clips (in particular, battery clamps) and relay. These electronic components can be used, for example, as on-board components or components for electrical/electronic devices.

(Mode of production)

Herein, a method for producing a titanium-copper material according to one embodiment of the present invention includes casting an ingot of a titanium-copper material containing 2.0 to 4.5 mass% Ti and a total amount ranging from 0 to 0.5 wt.%, at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si, as the third element, the rest is copper and inevitable impurities, hot rolling of the cast ingot; thereafter, a cold rolling step and a subsequent final solubilizing treatment step are carried out. Below in the present document will be successively described for each stage suitable for use example of the production of titanium-copper material corresponding to this variant of implementation.

<Ingot Production>

Ingot production by melting and casting is generally carried out in a vacuum or an inert gas atmosphere. If the added element remains in an unmelted state during melting, it does not have an effective effect on improving strength. Therefore, in order to avoid unmelted residues of third elements having a high melting point, such as Fe or Cr, after the addition of the element, it is necessary to carry out sufficient stirring, and then holding for a certain period of time. On the other hand, since the element Ti is relatively soluble in Cu, it can be added after melting the third element. Therefore, in order to produce an ingot, at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si is added to Cu, so that their total amount is in the range from 0 to 0.5 wt.%, and then Ti is added so as to include it in an amount in the range from 2.0 to 4.5 wt.%.

<Homogenizing annealing and hot rolling>

Due to the fact that the hardening materials of segregation and crystallization obtained during the production of the ingot are brittle, it is desirable to ensure their maximum dissolution in the initial phase in order to make them smaller, and to the maximum extent possible to eliminate them by homogenizing annealing. This is due to the effectiveness of preventing the occurrence of cracks due to bending. More specifically, after the ingot production step, it is preferable to perform homogenizing annealing by heating to a temperature in the range of 900 to 970° C. for 3 to 24 hours, and then hot rolling is preferred. In order to prevent liquid metal embrittlement, a temperature of 960° C. or less is preferred before and during hot rolling, and preferably a temperature of 800° C. or more, when passing from the original thickness to an overall reduction ratio of 80%.

In the present embodiment, the compression strain per pass is in the range of 0.15 to 0.30, and the maximum strain rate at a temperature in the range of 700 to 900°C is in the range of 2.0 to 6.0/s, and in in one preferred embodiment, from 3.0 to 5.0/sec. This may allow control of the GOS parameter and the Schmid factor within the above ranges. The compressive strain per pass can be calculated by dividing the compressive strain η = ln {(cross-sectional area before hot rolling)/(cross-sectional area after hot rolling)} by the total number of hot rolling passes. In addition, the strain rate ε (/sec) is calculated based on the following equation (1):

[Equation 1]

(1)

(1)

where H ₀ is the sheet thickness (mm) on the inlet side, n is the rotation speed (rpm) of the sheet roll, R is the radius (mm) of the sheet roll, and r' is the reduction ratio ((sheet thickness on the side entry) – (sheet thickness on exit side) / sheet thickness on entry side).

<Cold rolling and annealing>

After hot rolling, cold rolling is carried out. The reduction ratio in cold rolling is typically 60% or more. The reduction ratio per pass can be obtained according to the following equation (2), where T ₀ is the thickness of the ingot before rolling per pass, and T is the thickness of the ingot after rolling is completed per pass.

Reduction ratio (%) = {(T ₀ - T) / T ₀ } × 100 ⋅⋅⋅ (2)

After that, annealing can be carried out. Annealing is usually carried out at 900° C. for 1 to 5 minutes. Cold rolling and annealing can be repeated as needed.

<First Solution Treatment>

The first solubilizing treatment is preferably carried out after repeated cold rolling and annealing if necessary. In this case, the reason for carrying out the solubilization treatment beforehand is to reduce the load on the final solubilization treatment. That is, in the final solubilization treatment, it is not a heat treatment to dissolve the grains of the second phase, since dissolution has already been achieved, thus it is sufficient to cause recrystallization while maintaining this state, and thus light heat treatment can be carried out. More specifically, the first solubilization treatment may be carried out at a heating temperature in the range of 850 to 900° C. for 2 to 10 minutes. In this case, it is preferable to increase the heating rate and the cooling rate as much as possible so that the grains of the second phase do not form precipitates. As it should be noted, the first solubilization treatment may not be carried out.

<Intermediate rolling>

After that, an intermediate rolling is carried out. The reduction ratio for intermediate rolling is generally 60% or more.

<Final Sollution Treatment>

In the final solubilizing treatment, complete dissolution of the precipitates is desirable. However, if heating is carried out at an elevated temperature, up to the complete exclusion of precipitates, the crystalline grains will tend to coarsen. Therefore, the heating temperature is close to the solubility limit in the solid solution of the second phase grain composition. More specifically, when the added amount (wt%) of Ti is denoted by X, the heating temperature (°C) is in the range of 52×X+610 to 52×X+680.

If the heating temperature is less than 52×X+610, it will cause no recrystallization, and if the heating temperature is more than 52×X+680, the crystal grain size will coarsen. In both cases, eventually the strength of the titanium-copper material decreases.

The GOS parameter and the Schmid factor can be adjusted by adjusting the heating time in the final solubilization treatment. The heating time may range, for example, from 5 to 60 seconds, and typically from 20 to 45 seconds.

<Fine Cold Rolling>

The final solubilizing treatment is followed by finishing cold rolling. Finishing cold rolling can increase strength. In order to obtain good stress relaxation resistance, the reduction ratio is preferably in the range of 5 to 50%, and more preferably 20 to 40%.

<Aging Treatment>

After finishing cold rolling, aging treatment is carried out. It is preferably carried out by heating at a material temperature in the range of 300 to 500°C for 1 to 50 hours, and more preferably heating at a material temperature in the range of 350 to 450°C for 10 to 30 hours. The aging treatment is preferably carried out in an inert atmosphere such as Ar, N ₂ and H ₂ in order to suppress the formation of an oxide film.

Summarizing the above, it can be said that the production method of titanium-copper material according to the embodiment of the present invention includes:

the step of casting an ingot from a titanium-copper material containing from 2.0 to 4.5 wt.% Ti and a total amount in the range from 0 to 0.5 wt.% of at least one element selected from the group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si as the third element, the rest are copper and unavoidable impurities;

a hot rolling step for processing the cast ingot such that the compression strain per pass is in the range of 0.15 to 0.30 and the maximum strain rate at a temperature in the range of 700 to 900°C is in the range of 2.0 to 6 .0/sec; And

a final solubilization treatment for treating the ingot at a heating temperature (°C) in the range of 52×X+610 to 52×X+680 with a holding time in the range of 5 to 50 seconds, where X is the added amount (wt%) of Ti .

A person skilled in the art will understand that between the above steps, steps such as grinding, polishing and shot blasting to remove oxide scale on the surface may be performed.

Examples

The following are examples of the present invention together with comparative examples, these examples are provided for a better understanding of the present invention and its advantages and are not intended to limit the invention.

Each alloy, which contains the components shown in Table 1 and the remainder being copper and unavoidable impurities, was used as an experimental material to investigate the effect of alloy manufacturing conditions, hot rolling, and final solubilization treatment on 0.2% yield strength, average crystal grain size, GOS parameter, Schmid factor and resistance to stress relaxation.

First, 2.5 kg of electrolytic copper was melted in a vacuum melting furnace, and every third element was added at the proportion of each component in the mixture, which is shown in Table 1, and then Ti was added at the proportion of the component in the mixture, which is shown in Table 1. After holding for a time after adding enough added elements to ensure no unmelted residue, the melt was fed into the mold under an Ar atmosphere to produce ingots of approximately 2 kg each.

The ingot was subjected to homogenizing annealing at 950°C for 3 hours, followed by hot rolling at a temperature in the range of 900 to 950°C to obtain a hot-rolled sheet having a thickness of 10 mm. After the dross was removed by turning, cold rolling and annealing were repeated to obtain a 2.0 mm thick raw strip, and a first solubilization treatment of the raw strip was carried out. The first solutory treatment was carried out by heating at 850° C. for 10 minutes and then cooling in water. After that, intermediate cold rolling was carried out, followed by a final solubilization treatment and subsequent cooling in water. Following this, after removing the scale by pickling, finishing cold rolling was carried out at a reduction ratio of 25% to obtain a sheet thickness of 0.1 mm, and finally, aging treatment was carried out at 400° C. for 15 hours to obtain each of the examples and comparatives. examples.

To obtain samples, the following evaluations were carried out.

(0.2% yield strength)

Each sample was prepared in accordance with JIS 13B, and using the tensile test apparatus in accordance with the above measurement method, 0.2% yield strength in the direction parallel to the rolling direction was measured.

(Average crystal grain size)

After polishing and pickling the sheet surface (rolled surface) for each sample, the average crystal grain size was measured by analyzing the orientation of the crystals using the EBSD (Electron Reflected Diffraction) method (for example, the OSL Analysis product available from TSL Solutions), using the software analysis software attached to the EBSD method, and the difference in orientations of 5° or more was considered as the boundary of crystal grains.

(GOS)

The sheet surface (rolled surface) of each sample was polished and then pickled, and the sample was subjected to crystal orientation analysis by measurement using the EBSD method. Analysis software (e.g., OIM Analysis, available from TSL Solutions) was used to show the average value of the orientation difference between all image elements in each crystal grain, assuming that an orientation difference of 5° or more was considered as the crystal grain boundary. , and calculated the average value of the orientation difference between the image elements in the crystal grains and all the remaining image elements, for all crystal grains in order to calculate the average value.

(Schmid factor)

The sheet surface (rolled surface) of each sample was polished and then pickled, and the sample was subjected to crystal orientation analysis by measurement using the EBSD method. Analysis software (eg, OIM Analysis, available from TSL Solutions) was used to calculate the Schmid factor for individual crystal grains, assuming an orientation difference of 5° or more as the grain boundary.

(resistance to stress relaxation)

Measured the degree of stress relaxation after keeping each sample at 300°C for 10 hours. Each strip sample having a width of 10 mm and a length of 100 mm was selected so that the longitudinal direction of the sample was parallel to the rolling direction. As shown in FIG. 1, a deviation y ₀ was applied to the sample at position l = 50 mm as the operating point to apply a stress (s) corresponding to 80% of the 0.2% yield strength in the rolling direction. The y value of ₀ was determined using the following equation:

y ₀ = (2 / 3)⋅l ² ⋅s/(E⋅t), in which:

E is Young's modulus in the rolling direction, and t is the sample thickness. After heating at 300°C for 10 hours, the load was removed and as shown in FIG. 2, the amount of irreversible deformation (height) y was measured to calculate the degree of stress relaxation {[y (mm) / y ₀ (mm)] × 100 (%)}.

In the case of a stress relaxation degree of 10% or less, the stress relaxation resistance was considered as good (o).

In each of Examples 1 to 18, the degree of stress relaxation after being kept at 300° C. for 10 hours was 10% or less, indicating improved stress relaxation resistance.

On the other hand, in Comparative Example 1, the compressive deformation per pass was too small, so that fine precipitates were not sufficiently obtained, and the surface area ratio of crystal grains having a GOS parameter in the range of 2 to 6° was less than 60%. , as a result of which, in comparison with Examples 1 to 18, improved stress relaxation resistance could not be obtained.

In Comparative Example 2, the compressive deformation per pass was too large, and the profile during rolling was unsatisfactory, so that production was not possible. In each of Comparative Examples 3 and 4, the maximum strain rate at a temperature in the range of 700 to 900°C was inadequate, so that the surface area ratio of crystal grains having a Schmid factor of 0.35 or less was increased, and compared with Inventive examples 1 to 18 could not be obtained improved resistance to stress relaxation.

In Comparative Example 5, the final solubilization treatment temperature was too low, so that improved stress relaxation resistance could not be obtained compared to Examples 1 to 18. In Comparative Example 6, the final solubilization treatment temperature was too high, so that the surface area ratio of crystal grains having a GOS value in the range of 2 to 6° was more than 90%, and compared to Examples 1 to 18, could not be obtained. improved resistance to stress relaxation.

In Comparative Example 7, the holding time of the final solubilization treatment was too short, so that the size of the crystal grains was of the mixed grain type, the proportion of the surface area of the crystal grains having a GOS parameter in the range of 2 to 6° was less than 60%, and the proportion the surface area of crystal grains having a Schmid factor of 0.35 or less was reduced, whereby, compared with Examples 1 to 18, improved stress relaxation resistance could not be obtained. In Comparative Example 8, the holding time in the final solubilization treatment was too long, the size of the crystal grains coarsened, and the surface area ratio of the crystal grains having a GOS value in the range of 2 to 6° was more than 90%, resulting in comparison with the examples 1 to 18, improved stress relaxation resistance could not be obtained.

Comparative Examples 9 to 11 show cases in which the added amount of titanium or the third element was inadequate. In Comparative Example 9, the amount of added element was too large, so that cracking occurred during hot rolling, and thus production was not possible. In Comparative Example 10, the added amount of Ti was too small, so that the surface area ratio of crystal grains having a Schmid factor of 0.35 or less was increased, so that improved toughness could not be obtained compared with Examples 1 to 18. to stress relaxation. In Comparative Example 11, the added amount of Ti was too large, so that cracking occurred during hot rolling, making production impossible.

Claims (8)

1. Titanium-copper material that contains 2.0 to 4.5 wt.% Ti and a total amount of 0 to 0.5 wt.% of at least one element selected from the group consisting of Fe, Co, Ni , Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si as the third element, and the rest are copper and unavoidable impurities, with the surface area fraction of crystal grains characterized by GOS parameter, orientation spread grains, in the range from 2 to 6°, is 60-90%, provided that the difference in orientations, which is 5° or more, is taken as the boundary of crystal grains, when analyzing the orientation of crystals using the EBSD method for a surface subjected to rolling, and the surface area ratio of crystal grains having a Schmid factor of 0.35 or less is in the range of 5 to 20%. 2. Titanium-copper material according to claim. 1, which has a degree of stress relaxation of 10% or less after keeping the titanium-copper material at 300°C for 10 hours. 3. The titanium-copper material according to claim 1 or 2, wherein, when analyzing the crystal orientation using the EBSD method for the surface subjected to rolling, the average crystal grain size is in the range of 2 to 30 µm, provided that, as a crystal grain boundary, accept an orientation difference of 5° or more. 4. Titanium-copper material according to any one of paragraphs. 1-3, which has a 0.2% proof yield strength in the direction parallel to the rolling direction of 800 MPa or more when subjected to a tensile test according to JIS-Z2241 (2011). 5. Electronic component containing titanium-copper material according to any one of paragraphs. 1-4. 6. Method for the production of titanium-copper material according to any one of paragraphs. 1-4, which includes casting an ingot of a titanium-copper material containing from 2.0 to 4.5 wt.% Ti, and a total amount of from 0 to 0.5 wt.%, at least one element selected from group consisting of Fe, Co, Ni, Cr, Zn, Zr, P, B, Mo, V, Nb, Mn, Mg and Si as the third element, and the rest are copper and inevitable impurities, hot rolling cast ingot ; then carrying out a cold rolling step and a subsequent final solubilizing treatment step, wherein the hot rolling step includes processing the ingot such that the compression strain per pass is in the range of 0.15 to 0.30 and the maximum strain rate at a temperature in the range of 700 to 900°C is in the range of 2.0 to 6 ,0/sec, and a final solubilizing treatment step that includes treatment at a heating temperature, °C, in the range of 52 x X + 610 to 52 x X + 680, where X is the added amount, wt.%, Ti, for a holding time of 5 to 60 seconds.

Images