JPH05214465A - Metallic sheet minimal in anisotropy of characteristic and excellent in spring limit value and strength and its production - Google Patents

Abstract

PURPOSE:To obtain a metallic sheet minimal in the anisotropy of characteristics and excellent in spring limit value and strength. CONSTITUTION:A molten alloy having a composition consisting of 20-85% Cu, 0.0005-1.0% Co, 0.005-3.5% Ti, 0.1-10% Cr, 0.001-1.5% Mo, and the balance Fe is cast at >=100 deg.C/sec solidification cooling rate, which is subjected to primary cold rolling at >=50%, to annealing, to secondary cold rolling at 5-70%, and then to ageing treatment. By this method, the metallic sheet in which the aspect ratio of crystalline grain is regulated to <=20% can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin metal sheet having a small spring having a small anisotropy of characteristics (difference in characteristics between the rolling direction and the direction perpendicular to the rolling direction) and excellent strength.

[0002]

2. Description of the Related Art As a thin metal material plate of this type, for example, a Cu material of C1720-P of JIS standard for a spring material is used.
1.81Be-0.05Fe alloy, JP-A-1-1627
Cu-Ti (2.5-5.
0) Although there are alloys such as weight%, they do not have both a small characteristic anisotropy and an excellent spring limit value.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a metal thin plate having both a small characteristic anisotropy and an excellent spring limit value, and a method of manufacturing the metal thin plate at low cost. The purpose is to do.

[0004]

In order to achieve the above object, the present invention has the following constitution. That is, the feature of the present invention is, by weight, Cu: 20 to 85%, C
o: 0.0005 to 1.0%, Ti: 0.005 to 3.
5%, Cr: 0.1-10%, Mo: 0.001-1.
A molten metal containing 5% and the balance being unavoidable impurities and Fe is cast into a metal plate having a plate thickness of 0.5 to 8 mm at a solidification cooling rate of 100 to 50000 ° C./sec, and the metal plate has a reduction ratio of 50. ~ 95% primary cold rolling, then 450 ~
After annealing in the temperature range of 1000 ° C, secondary cold rolling is performed at a reduction rate of 5 to 70%, and then aging treatment is performed in the temperature range of 150 to 650 ° C. The purpose of the present invention is to obtain a thin metal plate that has low elasticity, is excellent in spring limit value and strength, and has high conductivity and high Young's modulus.

[0005]

[Function] The reason for limiting the present constituent requirements will be described below. First,
The reasons for limiting the chemical composition of the alloy are as follows. In order to improve the spring limit value / strength and Young's modulus, the higher the Cu content is, the more preferable. In addition, the Cu content is controlled to meet the purpose of electric conductivity required as a practical thin metal plate. It is desirable to obtain a balance between the electrical conductivity to be achieved and the spring limit value / strength and Young's modulus. Figure 1 shows the Cu content
As shown in the above, if it is less than 20% by weight, the electrical conductivity practically required for these applications cannot be obtained and only the effect on the spring limit value, strength and Young's modulus is obtained, so this is the lower limit. Further, the upper limit is set to 85% by weight, when the total content other than Cu, mainly Fe, is less than 15% by weight, an excellent balance between the spring limit value / strength and Young's modulus, which is the characteristic of the present alloy, can be obtained. Because it will disappear. Therefore, the Cu content is 15 to 85
The range is wt%.

Next, Co is specified to 0.0005 to 1.0% by weight. If it is less than 0.0005%, it has little effect on the spring limit value / strength, and if it exceeds 1.0% by weight, the spring limit value. This is because the effect on strength is saturated and the cost increases. Further, the Ti content is specified to be 0.005 to 3.5% by weight when the content is less than 0.005%, the effect on the conductivity is small, and when it exceeds 3.5% by weight, the effect on the conductivity is saturated and casting and cooling are performed. This is because the productivity such as hot working is hindered. Cr
To 0.1 to 10% by weight, and Mo to 0.001 to
The content of Mo is 0.001 in order to improve the crevice corrosion resistance of the final product by the combined effect of Cr and Mo without deteriorating the solder / Ag plating property. If it is less than weight%, the effect on crevice corrosion is small, and if it exceeds 1.5% by weight, the effect on crevice corrosion is saturated and the cost increases. When the Cr content is specified to be 6 to 13.5% by weight ratio with respect to the Fe content, the corrosion resistance of the raw material can be further improved by the combined effect with Mo. That is, if it is less than 6%, the effect is insufficient, and if it exceeds 13.5%, the effect on the corrosion resistance is saturated and the solder / Ag plating property is deteriorated, so this range is set.

Further, it is necessary to improve casting structure control, spring limit value / strength improvement, workability, various plating properties, and solder weather resistance (long-time heat peelability at 150 ° C. for 1000 hours or more after soldering). In addition, Zr, Si,
Al, Ni, Zn, Sn, Nb, P, La, Ce, Y,
One or more of V, Ca, Be, Mg and Hf are added in a total amount of 0.005 to 8% by weight, and one or two of C and B are added in a total amount of 0.005 to 2% by weight.

In particular, in the case where the weight ratio of the Cr content to the Fe content exceeds 6% and the Mo content exceeds 0.01%, the above-mentioned respective components are added within the range of 0.005% by weight or more, By a rapid solidification method such as a twin roll casting method described below, it is possible to obtain a cast structure in which the Fe phase containing Cr and Mo and the Cu phase of the present invention are uniformly finely dispersed. After heat treatment, 10 in the thickness direction
It is important for obtaining a metallographic structure having crystal grains with a size of μm or less.

The material of the present invention has an aspect ratio of 20.
The following are mandatory requirements. The aspect ratio is represented by the ratio of the crystal structure length in the rolling direction to the crystal structure length in the plate thickness direction. As shown in FIG. 3, when the aspect ratio becomes 20 or less, the characteristic anisotropy index (%), that is, the spring limit value , Strength, number of times of repeated bending, and conductivity are represented by (characteristic value in rolling direction-characteristic value in direction orthogonal to rolling) /
The value obtained by introducing into the formula of characteristic value in rolling direction x 100 (%) is summed, and the value obtained by making this sum value 1/4 is 5%.
Below, the difference between the respective characteristic values in the rolling direction and the direction orthogonal to the rolling becomes extremely small.

By virtue of the above components and aspect ratio, the present invention can provide a material having a small characteristic anisotropy and an excellent spring limit value, strength and electric conductivity. Next, a method for manufacturing the metal plate of the present invention will be described. Molten metal having the above-mentioned chemical composition is injected into a pool of a twin-roll type casting device which is, for example, a rapid solidification method, and the molten metal is rapidly cooled by rotating a cooling roll to obtain a plate having a thickness of 0.5 to 8 mm. Cast a metal plate. The solidification cooling rate at this time is 100-
It is important to set it to 50,000 ° C./second.

The relationship between the solidification cooling rate of the molten metal and the crystal grain size after working / heat treatment is as shown in FIG. The crystal grain size was obtained by the ASTM cutting method. As shown in FIG. 2, when the melt solidification cooling rate is increased, the size of the crystal structure becomes finer. After processing and heat treatment in this process, Fe
In order to obtain an isotropic structure of 10 μm or less for both the Cu phase and the Cu phase, it is necessary to set the solidification cooling rate of the melt to 100 ° C./sec or more. At this time, the Fe phase containing Cr and Mo and the C phase are added.
A structure in which the u phase is uniformly dispersed is obtained. Further, as other effects, it is possible to obtain the effect of shortening the aging time by improving the spring limit value / strength by improving the supersaturation degree of Cu in the Fe phase and the Fe in the Cu phase during solidification cooling and the aging acceleration effect.

Subsequently, primary cold rolling is carried out with a rolling reduction of 50 to 95%. This is to get the required plate thickness and 50
This is because by carrying out the primary cold rolling of not less than%, the workability such as bendability is repeatedly given by the subsequent annealing treatment. The annealing at that time is the temperature required for recovery / recrystallization due to the working strain accumulated in the primary cold rolling in both the slow heating / slow cooling type (BAF type) and the rapid heating type (continuous annealing type). That is, 450-1
It is performed in the temperature range of 000 ° C. Then carry out secondary cold rolling 5
After carrying out in the range of 70%, an aging treatment is carried out by holding at a temperature of 150 to 650 ° C. for 10 to 500 minutes.

As a result of the above processes, the aspart ratio is 20.
The following structure can be obtained, which makes it possible to manufacture a material having small characteristic anisotropy and excellent spring limit value, strength and conductivity. Here, the aging treatment is essential in the manufacturing process in order to improve the spring limit value / strength and electric conductivity, and an appropriate temperature should be selected depending on the chemical composition and the previous process conditions. As the condition, due to the relationship between the aging condition and the spring limit value / strength and conductivity, if the temperature is too low, strain will occur around the precipitate and the conductivity and elongation will decrease. Costs increase due to restrictions and manufacturing efficiency. If the temperature is too high, precipitates will decrease and high spring limit value and strength cannot be obtained.
The aging treatment at 0 to 650 ° C for 10 to 500 minutes is a suitable condition.

The metal plate is processed into a coil shape or a slit shape, and then plated with Ni, Cu, Ag, Au or the like, or alloy plating thereof, solder, Sn plating and the like. Alternatively, the metal plate is processed as a spring component in advance and then the plating process is performed. In either case, plating is performed under the following conditions. For plating, the base plate is subjected to electrolytic or immersion degreasing using an alkaline degreasing agent, and after the surface is activated by pickling, electrical or immersion plating is performed using a desired metal bath or alloy bath.

The thickness of the plating layer is usually 0.01 to 10 μm.
The range is about 0.20 to 5.0 μm in terms of adhesion, thickness uniformity, solder weather resistance and economy. When the thickness is 0.20 μm or less, the solder weather resistance (a phenomenon in which the solder is peeled off by heating at 150 ° C. for 1000 hours or 1500 hours at a low temperature for a long time) and the presence of pinholes deteriorate reliability. On the other hand, if it exceeds 5.0 μm, the adhesion and the uniformity of thickness are deteriorated.

[0016]

Examples (Example 1) Alloys in the component ranges of the present invention (test materials A to F and Q to HH) and alloys in the component ranges of the comparative examples (test materials G to P) shown in Table 1 are respectively shown. The molten metal was poured into the pool of the twin roll casting machine, and a metal plate having a plate thickness of 2.2 mm was cast at a solidification cooling rate of 3.2 × 10 ² ° C./sec.

[0017]

[Table 1]

Next, as a countermeasure against cracking during cold rolling, the obtained metal sheet was soft annealed at 800 ° C. for 1 hour, and then surface-ground to a sheet thickness of 2.1 mm to obtain 85% primary cold rolling. It was rolled. Subsequently, annealing was performed at 750 ° C. for 3 hours, then secondary cold rolling of 25% was performed, and then aging treatment was performed at 480 ° C. for 3 hours. The material properties of the metal thin plate thus obtained are shown in sample numbers 1 to 34 of Table 2. In addition,
Sample Nos. 35 and 36 in Table 2 are the test materials B and D of the present invention having a plate thickness of 10.degree. C. at a solidification cooling rate of 10.degree.
A 0 mm metal plate was cast by a horizontal continuous casting machine.
As a comparative example, Be-Cu, Cu-Ti, phosphor bronze or CDA195 was used as a comparative alloy and cast by the above casting method of the present invention.

The aspect ratio of the thin metal plate is Sample No. 1
-6, 17-34, the range is 5.3-13.5%, and sample numbers 7-16, 35, 36 and Be-Cu, C
u-Ti, phosphor bronze, and CDA195, 5.3 to 13.
It was in the range of 5%. The spring limit values in Tables 2 and 3 were measured by the moment method, the strength was determined by the JIS13B tensile test (pulling speed: 10 mm / min), the Young's modulus was determined by the resonance method, and the conductivity was determined by the 4-terminal method.
As corrosion resistance, crevice corrosion is 0.125 mm plate thickness including cut surface, 10 mm width, 30 mm length sample is sandwiched between polycarbonate resin and salt water spray test is carried out for 96 hours according to JIS-Z2371. Judgment was made based on the area ratio of red rust generation, and normal corrosion resistance was carried out by the above method in the bare state of the material.

Regarding the solder wettability in terms of plating characteristics, a wetted area ratio of 95% or more was passed. The heat resistance of Ag plating is about 0.3 μm after Cu strike plating.
g was plated at about 3 μm, and then heated at 430 ° C. for 3 minutes in the atmosphere, and judged by occurrence of swelling on the plated surface. Manufacturability includes nozzle clogging during casting and cold workability (2.0 mm
From 0.1 to 0.125 mm without intermediate annealing and cold working within 15 passes, cracks at the edge and center)
It was judged by. Further, the cost evaluation was judged to be good when 1.3 times or less of the average raw material price when Co and Mo were not added. In the table, the characteristics of Be-Cu alloy, Cu-Ti alloy and phosphor bronze are also added for comparison.

Here, Sample No. 7 is a case where the added amount of Cu is 20% by weight or less, and has a conductivity as low as that of phosphor bronze. In addition, Sample No. 8 has a low Young's modulus because the amount of addition of elements such as Fe that effectively acts on Young's modulus is small when the amount of Cu added is 85% by weight or more, and Sample No. 9 has a Co addition amount of 0.0005% by weight. %, The spring limit value and strength are low. In addition, sample No. 10 has a high cost because the amount of Co added is large. Sample No. 11 has a low Ti content of 0.005% or less and thus has low conductivity. Sample No. 12 has a Ti content of 3.5.
%, The productivity is poor. Sample No. 13 has a low Mo content because of low Mo, and Sample No. 14 has a high cost. Sample No. 15 has low corrosion resistance due to low Cr content, and Sample No. 16 has poor solder wettability and heat resistance against Ag plating. It is apparent that sample Nos. 35 and 36 have a low spring limit value and strength and are excellent in the characteristics of the present invention when the solidification cooling rate of the molten metal is small outside the range of the present invention.

[0022]

[Table 2]

[0023]

[Table 3]

(Example 2) Alloys in the component ranges of the present invention shown in Table 1 and test materials B and Q were respectively poured into the pool of a twin roll casting machine in a molten state at 3.2 x 10 ² ° C. A metal plate having a plate thickness of 2.2 mm was cast at a solidification cooling rate of 1 / sec. This metal plate has a temperature of 800 ° C as a measure against cracks during primary cold rolling.
After 1 hour of softening and annealing, the surface is ground after considering the reduction ratio so that the plate thickness after the primary cold rolling becomes 0.15 mm, and then the primary cold rolling is performed with the reduction ratios of 35, 55 and 90.
It was carried out at 3 levels of%. After that, these metal sheets were annealed at 750 ° C. for 3 hours, and then subjected to secondary cold rolling for 3 hours.
The plate thickness is 0.1 at 5 levels of 8, 25, 55 and 65%.
46, 0.138, 0.120, 0.068 and 0.0
It was a 53 mm thin metal plate. Then 480 ℃ to the metal sheet
Aged for 3 hours.

Table 4 shows the material characteristics of the above-mentioned thin metal plate.
The evaluation was performed in the same manner as in Example 1 by measuring the spring limit value / strength and conductivity in parallel with the rolling direction, and the workability was based on contact bending. Those with a lower primary cold rolling rate than the following results,
If the secondary cold rolling rate exceeds 70%, the workability is poor,
Further, it was found that those having a secondary cold rolling rate of less than 5% had low conductivity.

In the sample numbers, the aspect ratio of the present invention example was in the range of 5.3 to 13.5%, and that of the comparative example was in the range of 5.3 to 13.5%.

[0027]

[Table 4]

Example 3 The surface-ground metal plate of Example 2 was subjected to primary cold rolling at three levels of reduction ratios of 30, 60 and 90%, and this metal plate was annealed under the following conditions. (1) After heating at a heating rate of 50 ° C./hour in a BAF type annealing furnace, A: 550 ° C. × 3 hours, B: 750 ° C. × 3 hours, C: 9
Three types of retention were carried out at 50 ° C. for 3 hours, and then cooled to 100 ° C. at a cooling rate of 50 ° C./hour.

(2) After heating at a heating rate of 10 ° C./S in a continuous annealing furnace, two types of holding were performed: D: 750 ° C. × 60 seconds, E: 950 ° C. × 60 seconds, and then air-cooled to room temperature. .. Next, each of the metal plates is subjected to secondary cold rolling at a rolling rate of 10, 25, 60 or 75%, and an aspect ratio of 1.5 to 2 is obtained.
Spring limit value, repeated bending (90
(.Degree.) And electrical conductivity were obtained in the directions parallel to the rolling direction (L) and perpendicular to the rolling direction (C). Table 5
It shows in Table 7. For the evaluation of the aspect ratio, the average value of the crystal structure length ratios in the rolling direction and the plate thickness direction in 10 fields of view was used by observing the structure 100 times in the plate thickness 1/4 layer in the rolling direction cross section with an optical microscope. I was there. For the characteristic evaluation, the spring limit value / strength and conductivity were measured in the same manner as in Example 1, and the repeated bending was performed at a reciprocating bending number of 90 ° (the absolute value of the bending number was not corrected for each plate thickness). Yes From the following results, it is clear that by setting the aspect ratio to 20 or less by this method, it is possible to provide a material having a small characteristic anisotropy, an excellent spring limit value and strength, and excellent repetitive bendability and conductivity. Is.

[0030]

[Table 5]

[0031]

[Table 6]

[0032]

[Table 7]

[0033]

As described above, the present invention, as a spring material, has a small characteristic anisotropy, is excellent in the spring limit value, strength and conductivity, and has both a high Young's modulus and a high reliability, which has been impossible in the past. The material has a great industrial effect.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a Cu content and a spring limit value, strength and conductivity.

FIG. 2 is a diagram showing a relationship between a solidification cooling rate of molten metal and a grain size number.

FIG. 3 is a diagram showing a relationship between an aspect ratio and a characteristic anisotropy index.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuji Uemori 20-1 Shintomi, Futtsu City, Chiba Prefecture Nippon Steel Co., Ltd. Technology Development Division (72) Inventor Toshiaki Mizoguchi 20-1 Shintomi, Futtsu City, Chiba Prefecture Steel Engineering Co., Ltd.

Claims (8)

[Claims] 1. By weight%, Cu: 20-85%, Co:
0.0005-1.0%, Ti: 0.005-3.5
%, Cr: 0.1 to 10%, Mo: 0.001 to 1.5
%, With the balance being unavoidable impurities and Fe, and having an aspect ratio of the crystal grains of 20 or less, a metal having excellent spring limit value and strength with small characteristic anisotropy Thin plate. 2. The thin metal sheet according to claim 1, wherein the weight ratio of the Cr content to the Fe content is 6.0 to 13.5%. 3. Zr, Si, A as an alloy component
l, Ni, Zn, Sn, Nb, P, La, Ce, Y,
A total of 0.005 to 8% by weight of one or more of V, Ca, Be, Mg and Hf, and 0.005 to 2% by weight of one or two of C and B. The thin metal plate according to 1 or 2. 4. Ni, Cu, A on the surface of the thin metal plate
The metal thin plate according to claim 1, 2 or 3, wherein the metal plating of g or Au or an alloy thereof, solder or Sn plating is applied in a single layer or a multilayer of 0.01 to 10 µm. 5. By weight%, Cu: 20-85%, Co:
0.0005-1.0%, Ti: 0.005-3.5
%, Cr: 0.1 to 10%, Mo: 0.001 to 1.5
%, With the balance being inevitable impurities and Fe, cast at a solidification cooling rate of 100 to 50000 ° C./sec into a metal plate having a plate thickness of 0.5 to 8 mm, and the metal plate having a reduction ratio of 50 to Primary cold rolling at 95%, then 450-100
A spring limit with small characteristic anisotropy, characterized in that after annealing in the temperature range of 0 ° C, secondary cold rolling is performed at a reduction rate of 5 to 70%, and then aging treatment is performed in the temperature range of 150 to 650 ° C. A method for manufacturing a thin metal plate having excellent value and strength. 6. The method according to claim 5, wherein the weight ratio of the Cr content to the Fe content is 6.0 to 13.5%. 7. An alloy component further comprising Zr, Si, A
l, Ni, Zn, Sn, Nb, P, La, Ce, Y,
A total of 0.005 to 8% by weight of one or more of V, Ca, Be, Mg and Hf, and 0.005 to 2% by weight of one or two of C and B. The manufacturing method according to 5 or 6. 8. After the aging treatment, a metal plating of Ni, Cu, Ag or Au or their alloys, solder or Sn plating on the surface of the thin metal plate is applied in a thickness of 0.01 to 10 μm.
8. The method according to claim 5, 6 or 7, wherein the single layer or multiple layers are used.