US20020090315A1

US20020090315A1 - Titanium-copper alloy material, and heat-treating or hot-rolling method of titanium-copper alloy

Info

Publication number: US20020090315A1
Application number: US09/984,039
Authority: US
Inventors: Michiharu Yamamoto
Original assignee: Individual
Current assignee: Nippon Mining Holdings Inc
Priority date: 2000-04-27
Filing date: 2001-10-26
Publication date: 2002-07-11

Abstract

Spinodal decomposition of Cu alloy, which contains from 0.5 to less than 5.0% of Ti, is suppressed and a low hardness dispersion of Hv 40 or less is obtained over a sheet surface. In addition, an isotropy in terms of tensile strength in the vertical direction over the sheet surface is improved such that it is 50N/mm²or less. In the hot-rolling of the alloy, it is cooled at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of between 773K (500° C.) and 573K (300° C.).

Description

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a titanium-copper material, which contains not less than 0.5 mass % and less than 5.0 mass % of Ti, the balance being Cu and unavoidable impurities, which is homogeneously annealed and cooled so as not to cause spinodal decomposition and hence material hardening during the cooling after the solution treatment.

The present invention also relates to a hot-rolling method and a heat treating method of the titanium-copper alloy, for generating the above properties.

Furthermore, the present invention relates to a wrought titanium-copper alloy having improved homogeneity and bending property, consisting of not less than 0.5 mass % and less than 5.0 mass % of Ti, the balance being Cu and unavoidable impurities.

The present invention also relates to a method for producing wrought titanium-copper alloy having reduced anisotropy and improved bending property, by means of subjecting an ingot to rolling, solution and aging treatments.

2. Description of Related Art

The copper alloy, which contains Ti (hereinafter referred to as “the titanium-copper alloy”) is an aging precipitation type copper alloy. Since the strength and stress-relaxation property are remarkable material properties of the titanium-copper alloy, it is broadly used in the field of electronic parts, terminals and connectors. The titanium-copper alloy is melted and cast into an ingot, followed by hot-rolling, cold-rolling, heat-treatment and the like. Surface treatment such as plating may be applied on several materials. The properties and shape of the titanium-copper alloy material are thus adjusted to the predetermined ones. It is then formed into the parts.

It is believed that: Ti is contained in titanium-copper alloy as the super-saturated solid solution; and, the aging hardening occurs when Ti is isolated from the super-saturated solid solution and forms an intermediate Cu ₃Ti phase. The titanium-copper alloy is also characterized by higher heat resistance and improved stress relaxation property as compared with the high-strength beryllium-copper. Therefore, a blanked and bent sheet and strip of the titanium-copper is broadly used for electronic parts, terminals and connectors.

The formability and material properties of the wrought titanium-copper largely vary depending upon the production conditions, particularly the solution and aging conditions. Spinodal decomposition may occur depending upon the conditions of the solution treatment. In the spinodal decomposition, precipitation from the super-saturated solid solution occurs without formation of nuclei. When there is fluctuation in the solute concentration of the material, the free energy of the system becomes lower than that of the super-saturation solid solution. As a result, phase decomposition proceeds spontaneously without the formation of critical nuclei. In other words, when a small concentration variation once occurs in the material, a larger concentration variation is successively induced. Finally, the material is decomposed into two phases. This decomposition occurs abruptly. The spinodal decomposition largely changes the properties of the material.

If the spinodal decomposition can be suppressed in the post-cooling step after the hot-rolling and solution treating steps, not only is the subsequent working facilitated, but also the dispersion of material properties is lessened. As a result, the quality is stabilized. The post-cooling condition after the solution-treatment of the titanium-copper alloy must, therefore, be so adjusted that the dispersion of material properties is lessened and, further, the subsequent working can be facilitated.

Furthermore, the anisotropy of the aged titanium-copper alloy must be lessened and the bending property must be improved from the viewpoint of forming the alloy into parts.

Hardness of the hot-rolled or solution-treated titanium-copper usually lies in the range of Hv 80 to 300 and is largely dependent upon the composition and cooling speed. Heretofore, when the hot-rolled or solution-treated titanium-copper alloy is rapidly cooled, since the temperature and cooling speed vary within the alloy, spinodal decomposition locally occurs. As a result, the hardness and properties so largely vary that the quality and the subsequent working become unstable. For example, the hardness dispersion of a strip may amount to Hv 100 or more depending upon the heat treating conditions, and in the worst case to approximately ±50% of the average value.

It seems possible to lessen the hardness dispersion by means of various methods such as {circle over (1)} keeping the finishing temperature of hot-rolling and the final material temperature after the solution treatment at a constant level, and {circle over (2)} keeping the post cooling condition after the hot-rolling and the solution treatment at a constant level. It is, however, difficult to completely lessen the hardness dispersion and to attain stable quality by these methods, because the spinodal decomposition has the characteristics as described above.

The conventional rolled titanium-copper material has such anisotropy that the difference is tensile strength in the parallel and perpendicular directions to the rolling direction amounts to not less than 100 N/mm ². It has, however, not been elucidated which production factor mast significantly influences the anisotropy.

SUMMARY OF INVENTION

The present invention is based on the recognition of the above facts and provides a homogeneous titanium-copper alloy material, the post forming of which is facilitated.

The present invention also provides a heat-treating method and hot-rolling method of the titanium-copper alloy, which can suppress the spinodal decomposition and hence the dispersion of properties of the material. The quality of the titanium-copper alloy is, therefore, stabilized. The post-aging hardness becomes constant and the post formability is facilitated. As a result, the advantages attained are improvement of the dimension accuracy of the product, and, further, a product having complicated shape can be shaped.

It was discovered as a result of researches and experiments by the present inventors that the conditions of solution heat-treatment and the grain size of the material as solution-treated significantly affect the properties of the material treated subsequently. The present invention is based on this recognition and provides a wrought titanium-copper material having reduced anisotropy and improved bending formability required for the manufacturing of parts.

In accordance with the present invention, there is provided the following material and methods.

(1) Hot-rolled titanium-copper alloy material having solution-treated temper, characterized in that it contains not less than 0.5 mass % and less than 5.0 mass % of Ti, the balance being essentially Cu and unavoidable impurities, and has a hardness difference between the maximum value and the minimum value amounting to Hv 40 or less.

(2) Hot-rolled titanium-copper alloy material having solution-treated temper according to (1), characterized in that it is hot-rolled at a temperature not less than 873K (600° C.) and rolling-finished at a temperature not less than 773K (500° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of between 773K (500° C.) and 573K (300° C.).

(3) Hot-rolled titanium-copper alloy material having solution-treated temper, according to (1), characterized in that it is solution-treated by heating at a temperature of not less than 873K (600° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of between 773K (500° C.) and 573K (300° C.).

(4) Cold-rolled titanium-copper alloy material having solution-treated temper, characterized in that it contains not less than 0.5 mass % and less than 5.0 mass % of Ti, the balance being essentially Cu and unavoidable impurities, and has a hardness difference between the maximum value and the minimum value amounting to Hv 40 or less.

(5) Cold-rolled titanium-copper alloy material having solution-treated temper according to (4), characterized in that it is solution-treated by heating at a temperature of not less than 873K (600° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of between 773K (500° C.) and 573K (300° C.).

(6) Titanium-copper alloy material according to (1), (2), (3), (4) or (5) in the form of a sheet, wherein hardness difference of Hv 40 or less is satisfied over a sheet surface area of 0.27 m ².

(7) Titanium-copper alloy material according to (6), wherein the hardness is from Hv 80 to 300.

(8) Titanium-copper alloy material according to (7), wherein the hardness difference is Hv 30 or less.

(9) Wrought titanium-copper alloy material having improved bending formability, produced by rolling, solution treatment and aging, characterized in that: it contains not less than 0.5 mass % and less than 5.0% of Ti, the balance being essentially Cu and unavoidable impurities; the grain size is not less than 0.005 mm and less than 0.035 mm directly after the final solution-treatment; the tensile strength under the wrought state is not less than 800 N/mm ²; and the anisotropy in terms of tensile-strength difference between that parallel to the rolling direction and perpendicular to the rolling direction is not more than 50 N/mm², preferably not more than 30N/mm².

(10) Heat-treating method of titanium-copper alloy, which contains not less than 0.5 mass % and less than 5.0% of Ti, the balance being essentially Cu and unavoidable impurities, by means of solution-treatment and aging, characterized in that it is solution-treated by heating at a temperature of not less than 873K (600° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of between 773K (500° C.) and 573K (300° C.).

(11) Heat-treating method of titanium-copper alloy according to (10), wherein the solution-treatment is carried out in an induction heating apparatus.

(12) Heat treating method of titanium-copper alloy, which contains not less than 0.5 mass % and less than 5.0 mass % of Ti, the balance being Cu and unavoidable impurities, characterized in that it is hot-rolled at a temperature not less than 873K (600° C.) and finished at a temperature not less than 773K (500° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second in a temperature range of at least between 773K (500° C.) and 573K (300° C.).

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph indicating the relationship between the hardness of 3.0 mass % Ti—Cu (sheet thickness—0.3 mm) and various starting temperatures of water cooling (cooling speed—1000° C./sec or more). [0031]
FIG. 2 is a graph indicating the relationship between the hardness of 3.0 mass % Ti—Cu (sheet thickness—0.3 mm) and the speed of cooling changed by means of various cooling media, from the starting temperature of 780° C.[0032]

DESCRIPTION OF PREFERRED EMBODIMENTS

The titanium-copper according to the present invention, contains as the basic components, not less than 0.5 mass % and less than 5.0 mass % of Ti. When the Ti additive content is less than 0.5 mass %, properties such as the strength are poor. On the other hand, when the Ti additive content is 5.0 mass % or more, the material is excessively hardened such that good workability can not be attained. The same effects as described hereinabove can also be expected by adding 1.0 mass % or less of Cr, Zr, Ni, Fe and the like. The balance is Cu and the unavoidable impurities. [0033]
The titanium-copper alloy materials (1) and (4) according to the present invention has hardness difference between the maximum and minimum values of not more than Hv 40, preferably not more than Hv 30. Taking a sample and measuring the hardness as stipulated under JIS and the like, the difference between the maximum hardness and minimum hardness is obtained. The titanium-copper alloy material herein is the product obtained by the aforementioned method, and its temper state is hot- or cold-rolled and solution-treated. The titanium-copper alloy material herein has not yet been subjected to forming as a final product and is, for example, one piece of material, such as one coil, one strip, one wire, one sheet or a lot consisting of cut coil pieces and the like for the subsequent forming. The hardness dispersion is the difference between the maximum and minimum values. The average hardness is, for example, Hv 190. The hardness dispersion may amount to Hv 60 in conventional material. When this material is cut into pieces for forming, i.e., a work piece, the hardness disperses in a range of from Hv=230−170. It is, therefore, very difficult to obtain flat material having homogeneous formability. Contrary to this, the material according to the present invention has considerably reduced dispersion of hardness attributable to fluctuation in the Ti concentration in the solution-treated structure. The material according to the present invention is, therefore, easy to form. [0034]
The present inventors measured the hardness of a number of materials and discovered that satisfactory homogeneity over the entire material is ensured provided that the hardness dispersion over a sheet specimen of approximately 0.27 m[0035] ²satisfies Hv≦40.
A heat-treating method for forming such homogeneous structure is described hereinafter. [0036]
When the heating temperature of titanium-copper is less than 873K (600° C.), since no recrystallization occurs, heat treatment has no effect to adjust the temper state. The heating temperature is, therefore, not less than 873K (600° C.). When the heating is completed, the cooling is carried out. During the cooling, rapid cooling is carried out at least in a range of from 773K (500° C.) to 573K (300° C.). The starting temperature of rapid cooling is not less than 773K (500° C.) for the following reasons. In the ordinary heat treatment, a continuous plant is used. Various fundamental tests in a continuous plant revealed that one of the most major reasons for the dispersion of the properties is the temperature of the material which is being rapidly cooled, for example water-cooled, from the heat-treating temperature. [0037]
As is shown in FIG. 1, a critical point is reached at approximately 863K (590° C.) in the graph indicating the relationship between the hardness and the starting temperature of rapid cooling. The rapid cooling starting at a temperature of not more than 773K (500° C.) cannot impede advancement of the spinodal decomposition and hence local dispersion of the properties. A preferable starting temperature of rapid cooling is not less than 863K (590° C.). After completion of heating the material, rapid cooling should, therefore, be carried out as soon as possible. Since it is difficult by means of a conventional gas-heating furnace and electric resistance heating furnace to effectively heat a sheet or a strip, while maintaining high productivity, an induction heating furnace, which enables rapid heating and cooling, should be used. A continuous treatment is carried out to effectively treat the material. Material with stable properties can thereby obtained. [0038]
As shown in FIG. 2, there is also a critical point at approximately 200K (200° C.)/sec in the relationship between the cooling speed and hardness. The rapid cooling speed is, therefore, not less than 200K (200° C.)/sec. The properties of the material are largely influenced by the rapid cooling speed. When the rapid cooling speed is less than 200K (200° C.)/sec, spinodal decomposition takes place and the formability in the subsequent steps is drastically impaired. The cooling speed is dependent upon the sheet thickness and conveying speed of a sheet. The required cooling speed can be fully attained by means of using an adequate amount of water. In addition, the rapid cooling is continued until the temperature reaches lower than 573K (300° C.), because, if the rapid cooling stops at this temperature or higher, disadvantageously spinodal decomposition occurs during subsequent cooling and the material strength is disadvantageously increased. [0039]
Post-aging tensile strength of less than 800N/mm[0040] ²is unsatisfactory. When anisotropy in terms of the difference in the tensile strength between the directions parallel and perpendicular to the rolling direction exceeds 50N/mm², the anisotropy is so serious as to impair the bending formability. The material according to the present invention exhibits, therefore, 800N/mm²of the post-aging tensile strength and 50N/mm²of the anisotropy in terms of the difference in the tensile strength between the directions parallel and perpendicular to the rolling direction. Such strength and isotropy are not attained in the conventional material and are attributable to the grain size in the intermediate step, i.e., the grain size directly after the final solution treatment. Incidentally, the treatments in the subsequent steps exert influence upon the intermediate grain size such that the final grain size is coarser or finer than the intermediate grain size. However, influence of final grain size upon the anisotropy is slight.
The grain size of the titanium-copper alloy directly after the final solution treatment is not less than 0.005 mm and less than 0.035 mm. When the grain size is less than 0.005 mm, the material is locally uncrystallized and structure control becomes difficult. Furthermore, the influence of the preceding working such as cold-rolling remains so that the formability of the wrought material becomes unsatisfactory. On the other hand, when the grain size is 0.035 mm or more, the anisotropy becomes so large that the bending formability required in the forming of parts is seriously impaired. [0041]
The solution treatment is carried out in a continuous heat treatment. In order to obtain the grain size in the range of from 0.005 mm to less than 0.035 mm by the continuous heat treatment, the conditions of solution heat treatment are preferably set as follows. The heating temperature is not less than 923K (650° C.) and less than 1123K (850° C.). The heating time is not less than 10 seconds and less than 300 seconds. The speed of subsequent cooling speed is not less than 200K (200° C.)/second. When the heating temperature is less than 923K (650° C.), the grain size mentioned above cannot be obtained even by heating for 300 seconds or more. On the other hand, when the heating temperature is more than 1123K (850° C.), grain growth immediately occurs upon elevation up to this temperature. It is, therefore, difficult to control the grain size of the material within the above-described range. The cooling speed after the solution treatment is not less than 200K/second, because spinodal decomposition occurs and the material is hardened at a cooling rate less than 200K/second. Cooling speed of not less than 200K/second is attained by means of water-cooling and atomized gas-water cooling. The present invention is hereinafter described with reference to the examples. [0042]

EXAMPLES

Example 1

Titanium-copper alloys, which contain a specified mass % of Ti shown in Table 1, were used as the samples. The predetermined components were blended and melted in a vacuum melting-furnace to provide the titanium-copper alloys. The melt was cast into an ingot to provide a 3.5 kg ingot (30 mmt×80 mmw×150 mml). The riser portion of the ingot was cut off and subjected to scalping and milling of the edges in the transversal direction (10 mm at both edges). The scalped ingot was soaking-annealed in air at 1123K (850° C.) for 1 hour. Hot rolling was then carried out to reduce the thickness from 27 mm to a predetermined thickness usually 8 mm thickness (8 mmt×70 mmw×562.5 mml). During the rolling, the surface temperature of the material was measured by a two-color type radiation thermometer. When the temperature of the material was lowered to a predetermined temperature, water cooling was carried out. Hardness of the material was then measured (referred to as the test {circle over (1)}). Cooling speed of the material was adjusted by means of adjusting the thickness of the material and the amount of cooling water. The cooling speed was preliminarily determined by means of a thermo couple, which was inserted into the material to obtain the cooling speed under various heat-treating conditions. [0043]

TABLE 1

Components (mass %)

Ti Cu

1 Tinanium-Copper {circle over (1)} 1.5 Balance

2 Titanium-Copper {circle over (2)} 3.0 Balance

3 Titanium-Copper {circle over (3)} 4.5 Balance

Comparative

4 Titanium-Copper {circle over (4)} 0.4 Balance

5 Titanium-Copper {circle over (5)} 6.0 Balance
The solution treatment was carried out at 1173K (900° C.) for 1 hour. The scalping and milling of the edges in the transversal direction (0.5 mm at both edges) were again carried out. Cold rolling was then carried out to reduce thickness from 7.5 mm to 1.0 mm of thickness (1.0 mmt×65 mmw×4210 mml, approximately 0.27 m[0044] ²of the surface area of a sheet). Then, heating was carried out at a predetermined temperature for 5 minutes, and cooling was carried out under various cooling conditions, using a Greeble testing device. This method can arbitrarily change the heating and cooling speeds, and can investigate the high-temperature properties under a specified heat-treating condition. Hardness on optional five locations of a rolled sheet was measured. Cold rolling was then carried out to reduce the sheet thickness to a predetermined thickness. Influence of heat-treating conditions upon the properties and formability of the material was evaluated (referred to as the test {circle over (2)}). A contact type thermo-couple was inserted into a heat-treated portion of the material to continuously measure the material temperature during the heat-treating. Various cooling speeds were attained by adjusting the amount of water and gas flow rate of water cooling, gas-water atomized cooling, and air cooling.
Table 2 shows the results of the test {circle over (1)}, in which the samples were hot-rolled, and cooled under various conditions, and then subjected to the hardness measurement. A micro Vickers hardness tester (300 g of load) was used to measure the hardness of optional five locations of a sample. The hardness and the difference in hardness were evaluated. Although the hardness dispersion of Sample Nos. 16 and 17 presents no problem at all, since the Ti content is less than 0.5 mass %, the material strength ([0045] Hv 200 or more) as the final required property cannot be obtained after the cold rolling and aging treatment.

Table 3 shows the results of the test {circle over (2)}. In this test, 1.0-mm thick cold-rolled sheets were heated at a predetermined temperature for 5 minutes, followed by cooling under various cooling conditions. Further working was carried out to reduce the thickness to a predetermined thickness. Occurrence of edge cracks during the cold rolling at 70% of draft was observed to evaluate the cold-rolling workability of the samples. The cast and heat-treated materials according to the present invention exhibit slight dispersion of the properties and have improved formability because of low hardness. The titanium-copper alloy of stable quality could therefore be produced.

TABLE 2


Hardness of Hot-Rolled Copper Alloys Cooled under Specified Conditions

		Cooling	Material
Starting	Starting	Spend in	Temperature at
Temperature	Temperature	Rapid	the End of	Hardness (Hv)
of Cooling	of Rapid	Cooling	Rapid Cooling	Evaluation of
(°C.)	Cooling (°C.)	(°C./sec)	(°C.)	Material

1	Titanium-Copper	800	700	220	100	80˜100
	{circle over (1)}
2	Titanium-Copper	700	650	250	150	90˜110
	{circle over (1)}
3	Titanium-Copper	800	700	250	100	100˜120
	{circle over (2)}
4	Titanium-Copper	800	650	250	100	100˜120
	{circle over (2)}
5	Titanium-Copper	800	600	220	250	105˜135
	{circle over (2)}
6	Titanium-Copper	750	600	250	100	100˜120
	{circle over (2)}
7	Titanium-Copper	650	550	250	200	110˜150
	{circle over (2)}
8	Titanium-Copper	800	600	220	150	115˜145
	{circle over (3)}
9	Titanium-Copper	750	600	220	100	115˜145
	{circle over (3)}
10	Titanium-Copper	650	550	220	200	120˜160
	{circle over (3)}

Comparative

11	Titanium-Copper	800	450	220	100	110˜190
	{circle over (1)}
12	Titanium-Copper	550	500	220	100	130˜230
	{circle over (2)}
13	Titanium Copper	800	450	220	100	130˜230
	{circle over (2)}
14	Titanium-Copper	800	600	100	100	210˜290
	{circle over (2)}
15	Titanium-Copper	800	600	220	400	200˜300
	{circle over (3)}
16	Titanium-Copper	800	600	220	150	80˜100
	{circle over (4)}
17	Titanium-Copper	550	500	220	100	140˜160
	{circle over (4)}

18	Titanium-Copper	Hot-Rolling Cracks Generate
	{circle over (5)}

TABLE 3


Hardness of Hot-Rolled Copper Alloys Cooled under Specified Conditions

			Material
			Tempera-	Hardness (Hv) of
		Cooling	ture at the	Material & Evaluation
Starting	Starting	Speed in	End of	of Formability in Final
Temperature	Temperature	Rapid	Rapid	Stages

of Cooling	of Rapid	Cooling	Cooling	Hardness
(°C.)	Cooling (°C.)	(°C./sec)	(°C.)	(HV)	Formability

1	Titanium	750	700	1000	50	80˜100	good
	Copper{circle over (1)}
2	Titanium	700	650	800	100	90˜110	good
	Copper{circle over (1)}
3	Titanium	800	700	1000	100	110˜130	good
	Copper{circle over (2)}
4	Titanium	800	650	1000	100	110˜130	good
	Copper{circle over (2)}
5	Titanium	800	600	1000	250	85˜115	good
	Copper{circle over (2)}
6	Titanium	750	600	800	100	100˜120	good
	Copper{circle over (2)}
7	Titanium	650	550	800	200	100˜140	good
	Copper{circle over (2)}
8	Titanium	800	600	800	150	115˜145	good
	Copper{circle over (3)}
9	Titanium	750	650	1000	100	115˜445	good
	Copper{circle over (3)}
10	Titanium	650	550	800	200	110˜150	good
	Copper{circle over (3)}

Comparative

11	Titanium	800	450	1000	100	110˜190	generation
	Copper{circle over (1)}						of cracks
12	Titanium	550	500	100	100	110˜210	generation
	Copper{circle over (1)}						of cracks
13	Titanium	800	450	1000	100	150˜210	generation
	Copper{circle over (2)}						of cracks
14	Titanium	800	550	100	100	200˜260	generation
	Copper{circle over (2)}						of cracks
15	Titanium	800	600	300	400	2O0˜280	generation
	Copper{circle over (2)}						of cracks
16	Titanium	800	600	220	400	200˜300	generation
	Copper{circle over (3)}						of cracks
17	Titanium	700	450	1000	50	220˜320	generation
	Copper{circle over (3)}						of cracks
18	Titanium	800	600	100	50	220˜300	generation
	Copper{circle over (3)}						of cracks

Example 2

A 3.5 kg titanium-copper alloy ingots (30 mmt×120 mmw×100 mml) having the components blended as shown in Table 1 were hot-rolled under the same process and conditions as in Example 1 to produce an 8-mm thick sheet. [0048]
Although the titanium-copper alloy {circle over (4)} was subjected to the production process until the final aging, the required properties, i.e., 800 N/mm[0049] ²or more of tensile strength and 2% or more of elongation, were not obtained. Cracks were generated during the hot-rolling of the comparative titanium-copper alloy {circle over (5)}, the subsequent working of which was therefore impossible.
The solution-treatment was carried out at 1173K (900° C.) for 1 hour. The scalping was then again carried out. The cold-rolling was carried out to reduce thickness from 7.5 mm to 1.0 mm. Then, the final solution-treatment was carried out at a predetermined temperature under various conditions using a Greeble testing device, which can optionally change the heating and cooling speeds. The grain size of the wrought copper alloy was then evaluated in accordance with the testing method of grain size (JIS H0501). The cold-rolling to reduce the material thickness to 0.3 mm and then the aging at 673K (400° C.) for 4 hours were applied to the cold reduced material. A contact type thermo-couple was inserted into a heat-treated portion of the material to continuously measure the material temperature during the heat-treating condition. Various cooling speeds were attained by adjusting the amount of water and gas flow rate of water cooling, gas-water atomized cooling, and air cooling. Tensile test specimens were taken from the material in the directions parallel and perpendicular to the rolling direction to investigate the anisotropy. The cyclic bending test was also carried out to investigate the bending property. [0050]
Table 4 shows the conditions of the final heat-treatment. Table 5 shows the result of the tensile test and the cyclic bending test. The average value of N=3 was measured in the tensile testing method. In the cyclic bending test, 90° bending around the bending radius of R=0.3 mm (sheet thickness—0.3 mm) was continued until fracture occurred. In Table 4, the “fracture” indicates that which occurred at one bending. [0051]

As is apparent from Table 5, the method according to the present invention attains the production of copper alloy having reduced anisotropy and improved cyclic bending formability.

TABLE 4


Hardness of Hot-Rslled Copper
Alloys Cooled under Specified Conditions

		Cooling Speed	Grain-Size
Heating		in Rapid	after
Temperature	Heating	Cooling	Solution
K (°C.)	Time (sec)	(°C./sec)	Treatment

1	Titanium	1023(750)	20	1000	10
	Copper{circle over (1)}
2	Titanium	973(700)	120	800	10
	Copper{circle over (1)}
3	Titanium	1073(800)	100	1000	20
	Copper{circle over (2)}
4	Titanium	1073(800)	15	1000	10
	Copper{circle over (2)}
5	Titanium	1073(800)	120	1000	30
	Copper{circle over (2)}
6	Titanium	1023(750)	30	800	10
	Copper{circle over (2)}
7	Titanium	953(680)	250	800	10
	Copper{circle over (2)}
8	Titanium	1073(800)	60	800	20
	Copper{circle over (3)}
9	Titanium	1023(750)	100	1000	20
	Copper{circle over (3)}
10	Titanium	953(680)	250	800	10
	Copper{circle over (3)}
11	Titanium	973(700)	200	1000	5
	Copper{circle over (2)}

Comparative

12	Titanium	873(600)	200	1000	5<
	Copper{circle over (1)}
13	Titanium	893(620)	250	800	5<
	Copper{circle over (2)}
14	Titanium	1173(900)	120	1000	40
	Copper{circle over (2)}
15	Titanium	1073(800)	600	800	40
	Copper{circle over (3)}

TABLE 5


Tensile Test and Cyclic Bending Test

	Grain Size	Tensile Strength
	after Heat	(N/mm²)	90°Cyclic Bending

Treatment

Perpen-

(Number)

	(μm)	Parallel	dicular	Parallel	Perpendicular

1	Titanium	10	870	890	3	2
	Copper{circle over (1)}
2	Titanium	10	920	930	3	2
	Copper{circle over (1)}
3	Titanium	20	900	910	4	3
	Copper{circle over (2)}
4	Titanium	10	910	920	3	2
	Copper{circle over (2)}
5	Titanium	30	880	900	4	4
	Copper{circle over (2)}
6	Titanium	10	960	970	3	2
	Copper{circle over (2)}
7	Titanium	10	920	940	3	2
	Copper{circle over (2)}
8	Titanium	20	980	1000	3	2
	Copper{circle over (3)}
9	Titanium	20	1000	1030	1	1
	Copper{circle over (3)}
10	Titanium	10	1050	1070	1	1
	Copper{circle over (3)}
11	Titanium	5	1010	1050	1	1
	Copper{circle over (2)}

Comparative

12	Titanium	5<	930	990	1	Rupture
	Copper{circle over (1)}
13	Titanium	5<	970	1030	1	Rupture
	Copper{circle over (2)}
14	Titanium	40	870	940	2	Rupture
	Copper{circle over (2)}
15	Titanium	40	950	1020	1	Rupture
	Copper{circle over (3)}

Claims

1. Hot-rolled titanium-copper alloy material having solution-treated temper, characterized in that it contains not less than 0.5 mass % and less than 5.0 mass % of Ti, the balance being essentially Cu and unavoidable impurities, and has a hardness difference between the maximum value and the minimum value amounting to Hv 40 or less.

2. Hot-rolled titanium-copper alloy material having solution-treated temper, according to claim 1, characterized in that it is hot-rolled at a temperature not less than 873K (600° C.) and rolling-finished at a temperature not less than 773K (500° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of between 773K (500° C.) and 573K (300° C.).

3. Hot-rolled titanium-copper alloy material having solution-treated temper, according to claim 1, characterized in that it is solution-treated by heating at a temperature of not less than 873K (600° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of between 773K (500° C.) and 573K(300° C.).

4. Cold-rolled titanium-copper alloy material having solution-treated temper, characterized in that it contains not less than 0.5 mass % and less than 5.0 mass % of Ti, the balance being essentially Cu and unavoidable impurities, and has a hardness difference between the maximum value and the minimum value amounting to Hv 40 or less.

5. Cold-rolled titanium-copper alloy material having solution-treated temper, according to claim 4, characterized in that it is solution-treated by heating at a temperature of not less than 873K (600° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of at least between 773K (500° C.) and 573K (500° C.).

6. Titanium-copper alloy material according to claim 1, 2, 3, 4 or 5 in the form of a sheet, wherein hardness difference of Hv 40 or less is satisfied over a sheet surface area of 0.27 m².

7. Titanium-copper alloy material according to claim 6, wherein the hardness is from Hv 80 to 300.

8. Titanium-copper alloy material according to claim 7, wherein the hardness difference is Hv 30 or less.

9. Wrought titanium-copper alloy material having improved bending property, produced by rolling, solution-treatment and aging, characterized in that: it contains not less than 0.5 mass % and less than 5.0% of Ti, the balance being essentially Cu and unavoidable impurities; the grain size is not less than 0.005 mm and less than 0.035 mm directly after the final solution-treatment; the tensile strength under the wrought state is 800 N/mm²; and the anisotropy in terms of tensile-strength difference between that in the parallel and perpendicular directions is not more than 50 N/mm².

10. Wrought titanium-copper alloy material having improved formability, according to claim 9, characterized in that the anisotropy is not more than 30N/mm².

11. Heat-treating method of titanium-copper alloy, which contains not less than 0.5 mass % and less than 5.0% of Ti, the balance being essentially Cu and unavoidable impurities, by means of solution-treatment and aging, characterized in that it is solution-treated by heating at a temperature of not less than 873K (600° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of between 773K (500° C.) and 573K (300° C.).

12. Heat-treating method of titanium-copper alloy according to claim 11, wherein the solution treatment is carried out in an induction heating apparatus.

13. Heat-treating method of titanium-copper alloy, which contains not less than 0.5 mass % and less than 5.0 mass % of Ti, the balance being Cu and unavoidable impurities, characterized in that it is hot-rolled at a temperature not less than 873K (600° C.) and finished at a temperature not less than 773K (500° C.), followed by cooling at a cooling speed of not less than 200K (200° C.)/second at least in a temperature range of at least between 773K (500° C.) and 573K (300° C.).