CN1688732B - Age hardening copper base alloy and its preparing process - Google Patents

Abstract

An age-hardening copper-based alloy and method of making for the manufacture of commercial strip products in the form of strip, plate, wire, foil, tubing, powder or castings for applications requiring high yield strength and adequate electrical conductivity. The alloy is particularly suitable for use in circuit connectors and interconnect connectors. The alloy contains Cu-Ti-X, wherein X is selected from Ni, Fe, Sn, P, Al, Zn, Si, Pb, Be, Mn, Mg, Ag, As, Sb, Zr, B, Cr and Co and their combination. The alloy is capable of providing excellent yield strength in combination with electrical conductivity and excellent stress relaxation resistance. Yield strength of at least 724MPa (105ksi) and conductivity of at least 50% IACS.

Description

Age Hardening Copper-Based Alloy and Its Preparation Process

The invention relates to an age-hardening copper-based alloy and a process for preparing commercially available products from the alloy. More specifically, a process comprising solution annealing and at least one aging anneal during the process is used to process 0.35-5% by weight titanium copper alloy to finished dimensions. The conductivity of the obtained product is higher than 50% IACS, and the yield strength is higher than 724 MPa (105 ksi).

Throughout this patent application, unless otherwise stated, all compositions are in % by weight and all mechanical and electrical experiments were performed at room temperature (nominally 22°C). The word "about" means ± 10%, as in copper base the word "base" means that the alloy contains at least 50% by weight of the specified base element. The term "rolling" is intended to include drawing or drawing or any other form of cold working such as is used in the manufacture and processing of wire, rod or tube.

Many different types of circuit connectors are made from copper-based alloys. For circuit connectors, important properties include yield strength, bend formability, stress relaxation resistance, modulus of elasticity, ultimate tensile strength, and electrical conductivity.

The target values for these properties and their relative importance depend on the intended use of the product fabricated from the copper alloy. The following performance descriptions are general for many intended applications, however, for automotive hood applications, the target values are specific.

Yield strength is the stress at which a material exhibits a specific deviation from the proportional relationship between stress and strain, typically 0.2%. This is a marker of stress when plastic deformation is the dominant form relative to elastic deformation. Ideally, the copper alloy used as the connector has a yield strength of at least 724 MPa.

Stress relaxation becomes apparent when applied stress is applied to the metal strip in service, for example when the strip is loaded after being bent into a connector. Metals react by creating equal and opposite internal stresses. If the metal is held in a strained position, the internal stress decreases as a function of time and temperature. This phenomenon occurs due to the transformation of elastic strain in metals into plastic or permanent strain by microplastic flow.

Copper-based circuit connectors must maintain above critical contact force conditions on their mating components for extended periods of time to obtain a good electrical connection. Stress relaxation reduces the contact force below the critical load, resulting in an open circuit. For copper alloys for connector applications, it is desirable to retain at least 95% of the original stress when exposed to 105°C for 1000 hours, and to retain at least 85% of the initial stress when exposed to 150°C for 1000 hours .

The modulus of elasticity, also known as Young's modulus, is a measure of the rigidity or rigidity of a metal, which is the ratio of the stress in the elastic region to the corresponding strain. Since the modulus of elasticity is a measure of the stiffness of a material, it is desirable to have a high modulus on the order of 140 GPa ( ^20x103 ksi).

Bendability determines the minimum bend radius (MBR), which determines how severe a bend can be made without cracking along the outside diameter of the bent metal strip. MBR is an important property for connectors to be formed into different shapes and bends with various angles.

Bend formability can be expressed as MBR/t, where t is the metal strip thickness. MBR/t is the ratio of the minimum radius of curvature of the mandrel around which the bent metal strip will not fail to the strip thickness. The "mandrel" test is described in detail in ASTM (American Society for Testing and Materials) No. E290-92 entitled Standard Test Method for Semi-Guided Bend Test for Ductility of Metallic Materials .

Ideally, the MBR/t is substantially isotropic, with similar values in the "good direction" where the bending axis is perpendicular to the rolling direction of the metal strip, and in the "bad direction" where the bending axis is parallel to the rolling direction of the metal strip. value. Desirably the MBR/t has a value of about 1.5 or less for a 90° bend and about 2 or less for a 180° bend.

Alternatively, the bend formability at 90° bending can be evaluated by using a test block with a V-groove and a punch with a working surface of the required radius. In the "V-block" method, the copper alloy strip in the condition to be tested is placed between the test block and a punch which, when driven into the groove, creates the desired degree of curvature in the strip.

Related to the "V-block" method is the 180° "forming punch" method, in which a punch with a cylindrical working surface is used to bend the copper alloy strip 180°.

Both the "V-Block" and "Forming Punch" methods are specified in ASTM No. B820-98 entitled Standard Test Method for Bend Test for Formability of Copper Alloy Spring Material .

Both methods give quantifiable results on bend properties for a given metal sample, and either method can be used to determine relative bend properties.

Ultimate tensile strength is the ratio of the maximum load that a strip can sustain before it fails during a tensile test to the initial cross-sectional area of the strip. Ideally, the ultimate tensile strength is about 760MPa.

Conductivity is represented by %IACS (International Annealed Copper Standard), where the conductivity of unalloyed copper at 20°C is defined as 100%IACS.

Among various documents, US Pat. Nos. 4,601,879 and 4,612,167 disclose titanium-containing copper-based alloys. Said patent 4,601,879 discloses copper-based alloys containing 0.25-3.0% nickel, 0.25-3.0% tin and 0.12-1.5% titanium. Exemplary alloys have a conductivity of 48.5-51.4% IACS and a yield strength of 568.8-579.2 MPa (82.5-84 ksi).

Said patent 4,612,167 discloses copper alloys containing 0.8-4.0% nickel and 0.2-4.0% titanium. An exemplary alloy has a conductivity of 51% IACS and a yield strength of 663.3-679.2 MPa (96.2 ksi-98.5 ksi).

Copper-nickel-titanium alloys commercialized by AMAX Copper, Inc. (Greenwich, CT) have nominal compositions of Cu-2%Ni-1%Ti and Cu-5%Ni-2.5%Ti. Among the reported Cu-2%Ni-1%Ti alloy properties, the yield strength is 441.3-551.6MPa (64-80ksi), the ultimate tensile strength is 503.3-655.0MPa (73-95ksi), and the elongation is 9%. Conductivity is 50-60% IACS. Among the reported Cu-5%Ni-2.5%Ti alloy properties, the yield strength is 620.6-689.5MPa (90-100ksi), the ultimate tensile strength is 744.7MPa (108ksi) UTS, the elongation is 10%, and the conductivity is 40-53% IACS.

Many current and future applications require a conductivity of at least 50% IACS and a yield strength of at least 724 MPa (105 ksi) for the copper alloy. There remains a need for copper-titanium alloys capable of achieving the required electrical conductivity and strength, and methods of making said alloys.

Summary of the invention

In the present invention, there is provided an age-hardenable copper-based alloy and a method of processing said alloy into a commercial product useful for any application requiring high strength and relatively high electrical conductivity, typical forms of which include strip, Sheet, wire, foil, tube, powder or casting. When processed according to the method of the present invention, the alloy achieves a yield strength of at least 724 MPa (105 ksi) and a conductivity of 50% IACS, making the alloy particularly suitable for use in circuit connectors and interconnects.

The basic composition of the alloy is (by weight) 0.35-5% titanium, 0.001-10% X, wherein X is selected from Ni, Fe, Sn, P, Al, Zn, Si, Pb, Be, Mn , Mg, Bi, S, Te, Se, Ag, As, Sb, Zr, B, Cr and Co and their combinations, and the rest are copper and unavoidable impurities. The alloy has a conductivity of at least 50% IACS and a yield strength of at least 105 ksi.

In a preferred aspect of the invention, the basic composition of the alloy is 0.35-2.5% titanium, 0.5-5.0% nickel, 0.5-0.8% iron, cobalt and mixtures thereof, 0.01-1.0% magnesium, up to 1% Cr, Zr, Ag and their combination, the rest is copper and unavoidable impurities.

In the absence of beryllium, these alloys avoid the possible health hazards associated with current beryllium-copper alloys, while providing a similar combination of strength and electrical conductivity.

Brief description of several drawings

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart illustrating a first method of processing the copper alloy of the present invention.

Figure 2 is a flow chart illustrating a second method of processing the copper alloy of the present invention.

Figure 3 is a flow chart illustrating a third method of processing the copper alloy of the present invention.

Detailed description of the invention

Copper alloys with good formability and resistance to stress relaxation with a combination of strength and electrical conductivity are required for many current carrying applications. Two exemplary uses are under the hood automotive use and multimedia use (eg computer, DVD player, CD reader, etc.).

For automotive applications, copper alloys are required to have good formability, electrical conductivity of at least 50% IACS and resistance to stress relaxation up to 200°C. For multimedia interconnection applications, copper alloys are required to have a yield strength of more than 724MPa (105ksi), electrical conductivity higher than 50% IACS, and mechanical stability at room temperature and operating temperatures slightly higher than room temperature, characterized by about Excellent resistance to stress relaxation at 100°C.

When processed by the method of the present invention, the alloy composition surprisingly provides the optimum combination of properties required for automotive and multimedia applications, as well as other electrical and electronic applications. The alloy is capable of simultaneously providing high strength and high electrical conductivity, and simultaneously providing high electrical conductivity and extremely high strength.

The alloy composition of the present invention contains Cu-Ti-X, wherein X is selected from Ni, Fe, Sn, P, Al, Zn, Si, Pb, Bi, S, Te, Se, Be, Mn, Mg, Ag, As, Sb, Zr, B, Cr and Co and combinations thereof. The titanium content is 0.35-5%, and the total amount of element "X" is 0.001-10%.

When X is selected from Ni, Fe, Co, Mg, Cr, Zr, Ag and their mixtures, the strength and conductivity are the highest.

Oxygen, sulfur and carbon may be present in the alloys of the present invention at levels typical of electrolytic (cathode) copper or remelted copper or copper alloy scrap. Typically, each of said elements is present in an amount of about 2-50 ppm, preferably each is present in an amount below 20 ppm.

Other additive elements that affect the properties of the alloy may also be included. Such additive elements include elements that improve the free machinability of the alloy, such as bismuth, lead, tellurium, sulfur and selenium. When added to improve free machinability, the additive may be present in an amount up to 2%. Preferably the total amount of free machinability additives is about 0.8% to 1.5%.

Copper alloys, especially in copper alloys made from recycled or scrap copper, can typically present total impurity levels of up to about 1%. As a non-exhaustive list, such impurities include magnesium, aluminum, silver, silicon, cadmium, bismuth, manganese, cobalt, germanium, arsenic, gold, platinum, palladium, hafnium, zirconium, indium, antimony, chromium, vanadium, and beryllium . Each impurity should be present in an amount below 0.35%, preferably below 0.1%.

It should be recognized that some of the aforementioned impurities, or other elements, may be present to the benefit of the copper alloys of the present invention when they are present at levels overlapping those specified above. For example, strength or punchability can be improved. The present invention is intended to include these low levels of additives.

In a more preferred embodiment of the invention, the titanium content is 0.35-2.5%, and, in a most preferred embodiment, the titanium content is 0.8-1.4%.

When titanium exists in the copper alloy matrix in a solid solution form, the electrical conductivity is severely reduced. "X" should preferably be effective to cause titanium to precipitate out of solid solution during aging annealing. Suitable "X" elements for promoting the precipitation include Ni, Fe, Sn, P, Al, Si, S, Mg, Cr, Co and combinations of these elements.

A preferred additional element is nickel. The combination of Ni and Ti produces CuNiTi as a precipitate, and the presence of Fe and Ti produces _Fe2Ti as a precipitate.

Another preferred additional element is magnesium. The addition of Mg increases the stress relaxation resistance and softening resistance of the final size and state product. Mg can also provide resistance to softening during the aging annealing heat treatment in the process.

When present in low amounts, the addition of the elements Cr, Zr and/or Ag can increase strength without unduly reducing conductivity.

A preferred alloy of the present invention having improved yield strength, electrical conductivity, stress relaxation resistance and moderate (modest) bendability combination essentially consists of about 0.5-5.0% nickel, about 0.35-2.5% titanium, about 0.5- 0.8% iron or cobalt, about 0.01-1.0% magnesium, optionally up to about 1.0% one or more selected from Sn, P, Al, Zn, Si, Pb, Bi, S, Te, Se, Be, Mn, Mg, Ag, As, Sb, Zr, B, Cr and their mixtures, and the remainder being copper and impurities. Preferably, the optional elements include up to about 1% of one or more elements selected from Cr, Zr and Ag.

A more preferred range of the alloy is: about 0.8-1.7% nickel, about 0.8-1.4% titanium, about 0.90-1.10% iron or cobalt, about 0.10-0.40% magnesium, up to about 1.0% of one or more selected from Elements based on Cr, Zr, Ag or Sn and their mixtures, the rest are copper and impurities.

In a first embodiment of the invention, the alloy composition and processing provide a yield strength of at least about 793 MPa (115 ksi), and preferably at least about 827 MPa (120 ksi). For this embodiment, the conductivity is up to about 40% IACS. In a second embodiment of the present invention, the composition and processing provide a yield strength greater than about 724 MPa (105 ksi), and preferably up to at least about 793 MPa (115 ksi). In this second embodiment, the conductivity of the alloy is preferably about 45-55% IACS. In a third embodiment, the composition and processing provide a yield strength of about 552-690 MPa (80-100 ksi) and a conductivity of about 55-65% IACS.

Figure 1 shows a process according to a first embodiment of the present invention in the form of a flow chart. The alloys of the present invention were melted and cast by conventional methods10. 12 The as-cast alloy was hot rolled at about 750-1000°C. After grinding to remove oxides, the alloy is cold rolled 14 with a reduction in cross-sectional area ("area reduction") perpendicular to the rolling direction of about 50-99%. The alloy may then be solution treated 16 at a solution annealing temperature of about 850-1000°C for a period from about 10 seconds to about 1 hour, followed by quenching 18 or rapid cooling to ambient temperature to obtain an average grain size of about 5 Equiaxed crystals of -20 μm. Thereafter, the alloy may be subjected to a first cold rolling 20 with an areal reduction of up to about 80%, preferably about 30-80%. After the first cold rolling 20, the first annealing 22 is performed, the annealing temperature is about 400-650°C, preferably about 450-600°C, and the time is from about 1 minute to 10 hours, preferably about 1-8 hours. The alloy is then cold rolled a second time 24 to finished dimensions at an area reduction ratio of about 10-50%. After the second cold rolling, a second annealing 26 may be performed at a temperature of about 150-600°C, preferably about 200-500°C, for about 15 seconds to about 10 hours.

Alternatively, according to another embodiment of the invention, no in-process solution heat treatment is employed during the machining of the alloy to its final dimensions. That is: the alloy can be machined to final dimensions by using a cycle of lower temperature annealing treatment(s) with intervening cold working. This alternative method is especially useful for making more conductive products.

Figure 2 shows another alternative process of the present invention in flow chart form. The alloys of the present invention were melted and cast by conventional methods10. 12 The as-cast alloy is hot rolled at about 750-1000°C, and subsequently quenched or rapidly cooled. After grinding to remove oxides, the hot rolled alloy is cold rolled 14 with an areal reduction of about 50-99%. The alloy may then be subjected to a first annealing treatment 28 at an annealing temperature of about 400-650° C. for a time of from about 15 seconds to about 10 hours. The cold rolling and first annealing steps may optionally be repeated if desired. Subsequently, the alloy is subjected to cold rolling 30 with an area reduction ratio of about 40-80%, after which a second annealing 32 is performed at a temperature of about 400-650°C, preferably about 450-600°C, for a time of about 1 -10 hours. The alloy is then cold rolled 34 to finished dimensions at an area reduction ratio of about 10-50%. Optionally, thereafter, a third anneal 26 may be performed at about 150-600°C, preferably at about 200-500°C, for a period of from about 15 seconds to about 10 hours.

A second alternative preferred embodiment of the process of the present invention uses an alloy having a composition in the preferred range. This process enables the production of alloys of the invention with nominal properties of about 758 MPa (110 ksi) YS (yield strength) and about 50% IACS conductivity. Referring to Figure 3, the alloy is melted and cast 10 using conventional methods. 12 The as-cast alloy was hot rolled at about 750-1000°C. After grinding to remove oxides, the hot rolled alloy is cold rolled 14 at an area reduction ratio of about 50-99%. The alloy is then solution treated 16 at about 950-1000° C. for from about 15 seconds to about 1 hour. Next, the alloy is cold-rolled 20 at an area reduction ratio of about 40-60%, and then annealed for the first time 28 at an annealing temperature of about 400-650°C, preferably about 450-600°C, for about 1-10 hours, preferably about 1-3 hours. After the first anneal 28, cold rolling 30 is performed with an area reduction ratio of about 40-60%. The alloy is then subjected to a second anneal 32 at a lower temperature than the first anneal 28 . The second anneal is performed at about 375-550°C for about 1-3 hours. The twice-annealed alloy is then cold rolled 34 to finished size at an area reduction ratio of at least about 30%, wherein the alloy may be subjected to a third Second annealing 26, time about 1-3 hours.

The alloys of the invention and the process of the invention will be better understood with reference to the following examples.

Example

In the examples following certain process descriptions, properties and units are in abbreviated form. For example, "= inches, WQ=water quenched, slash marks /=continuous (for), SA=solution annealed, CR=cold rolled or cold rolled, YS=yield strength, TS=tensile strength, EL=elongation Ratio, %IACS=conductivity, MBR/t=ratio of minimum bending radius to strip thickness, SR=stress relaxation resistance, Gs=grain size, μm=micron, beg.=start, recr.=recrystallization, n.c.r. = not fully recrystallized, sec. or s = seconds, hrs. or h = hours, MS/m = million Siemens/meter, ksi = thousand pounds per square inch.

Example 1

Using the method shown in Figure 1, a series of 4.5 kg (10 lb) laboratory ingots having the analytical composition shown in Table 1 were melted in quartz crucibles and cast in steel molds using the Durville casting method. After pouring, the ingot size was 10.16cmx10.16cmx4.45cm (4″X4″X1.75″). After holding at 950°C for 3 hours, the ingot was hot rolled to 2.8cm (1.1″ ), reheated at 950°C for 10 minutes, and further hot-rolled to 1.27cm (0.50″) in 3 passes, after which water quenching was carried out. The obtained hot-rolled sheet was homogenized by holding at 1000°C for 2 hours After chemical treatment, water quenching is carried out. After dressing and grinding to remove the oxide layer, the alloy is cold rolled to 1.27mm (0.050"). The alloys were then solution treated at 1000°C for 20–60 seconds, with the exception of alloy J 346, which was solution treated at 950°C for 60 seconds. After solutionizing and quenching, the alloy was cold rolled down 50% to 0.64mm (0.025″) and aged annealed at 550°C for 3 hours. Then, the alloy was cold rolled down 50% to 0.32mm (0.0125″ ) size, and stress annealing at 275°C for 2 hours. Table 2 presents the performance measurements.

The data in Table 2 shows that a high yield strength of 621-765 MPa (90-111 ksi) and a conductivity of 38.2-63.8% IACS were obtained. Cu-Ni-Ti-Fe alloys J345 and J346 achieved stress relaxation resistance close to the expected value of 95% after 1000 hours at 105°C. Cu-Ni-Ti-Mg alloy J354 reached the expected value.

Example 2

According to the process shown in FIG. 2, the alloys in Table 1 were processed like Example 1 until undergoing homogenization heat treatment after obtaining the hot-rolled sheet size. In this example, the alloy was machined to finished dimensions without in-process solution heat treatment. After dressing and grinding to remove the oxide layer, the alloy was cold rolled to 2.54mm (0.100″), and the first aging anneal was performed at 550°C for 3 hours. Then, the alloy was cold rolled by 70% to 0.76 mm (0.030"), and a second aging anneal was performed at 525°C for 3 hours. The alloy was then cold rolled down by 50% to a dimension of 0.38mm (0.015") and stress-relieved annealed at 275°C for 2 hours. Properties were measured under these conditions and the results are shown in Table 3.

Consistent with the data in Table 2, the alloy of this example has both a high yield strength of 676-738 MPa (98-107 ksi) and a higher electrical conductivity of 49.9-69.7% IACS. When Fe or Mg is added to the Cu-Ni-Ti base alloy, the stress relaxation resistance increases. Comparing alloy J354 and alloy J351, it can be seen from the data in Table 3 that when Mg is added to Cu-Ni-Ti alloy, the highest stress relaxation resistance can be obtained.

Example 3

A series of 4.5 kg (10 lb) laboratory ingots having the analytical composition shown in Table 4 were melted in quartz crucibles and cast in steel molds using the Durville pouring method according to the process shown in Figure 1 . After pouring, the ingot size was 10.16cmx10.16cmx4.45cm (4″X4″X1.75″). After holding at 950°C for 3 hours, the ingot was hot rolled to 2.8cm (1.1″ ) thick, reheated at 950°C for 10 minutes, and further hot rolled to a thickness of 1.27cm (0.50″) in 3 passes, after which water quenching was carried out. After dressing and grinding to remove the oxide layer, the alloy was cold Rolled to 1.27mm (0.050″).

Then, alloys other than J477 were solution treated at 1000° C. for 25 seconds, and then water quenched to obtain a controllably fine recrystallized grain size with a diameter of about 12-24 μm. The treatment process of alloy J477 is: solution heat treatment at 950 ° C for 25 seconds + WQ to obtain a grain size of 9 μm.

All alloys were cold rolled down 50% to 0.64mm (0.025") thick and age annealed at 550°C for a time effective to maximize electrical conductivity without excessive softening of the matrix. At 550°C The holding time is shown in Table 5. Then, the alloy was cold-rolled and reduced by 50% to a size of 0.32mm (0.0125″), and stress-relieved annealed at 275°C for 2 hours, and the properties were measured under this condition. The results are as follows Table 5 shows.

The data in Table 5 show that although the base alloy J477 can provide a good combination of properties of 634 MPa (92 ksi) YS and 58.1% IACS conductivity, the addition of Fe can increase the strength of the base alloy to 690 MPa (100 ksi) (J483 vs J477 ), with only a slight decrease in conductivity. Moreover, by comparing alloys J491 and J481, it is shown that the addition of Mg can improve the stress relaxation resistance at 105°C when the contents of Ni, Ti and Fe are kept constant. The advantage of Mg can also be seen by comparing the properties of alloy J491 (Table 5) with alloys J345 and J346 in Table 2.

Example 4

The alloys in Table 4 were machined to finished dimensions according to the process shown in Figure 2, but without in-process solution heat treatment. After trimming and grinding to remove the oxide layer, the hot-rolled alloy is cold-rolled to 0.050 ", and the first aging annealing is carried out. The temperature and time of annealing are shown in Table 6, which can effectively make the electrical conductivity max. The alloy was then cold rolled down 50% to a 0.025" size and subjected to a second aging anneal at temperatures and times selected as shown in Table 6 so as not to cause excessive The softened case maximizes conductivity. Table 6 shows the specific age annealing process used for each alloy. Then, the alloy was cold-rolled and reduced by 50% to 0.0125″ size, and stress-relieved annealed at 275°C for 2 hours, the properties were measured under this condition, and the results are shown in Table 7. Using this process, adding Fe and Mg The alloy offers lower but still good strength and higher electrical conductivity as well as good resistance to stress relaxation.

Example 5

Using the method shown in Figure 3, a series of 4.5 kg (10 lb) laboratory ingots having the analytical composition shown in Table 8 were melted in quartz crucibles and cast in steel molds using the Durville casting method. After pouring, the ingot size was 10.16cmx10.16cmx4.45cm (4″X4″X1.75″). After holding at 950°C for 3 hours, the ingot was hot rolled to 2.8cm (1.1″ ) thick, reheated at 950°C for 10 minutes, and further hot rolled to a size of 1.27cm (0.50″) in 3 passes, after which water quenching was carried out. After dressing and grinding to remove the oxide layer, the alloy was cold Rolled to a thickness of 2.54mm (0.100"), and solution heat treated in a furnace at 950°C for 40 seconds, and then water quenched to obtain a controllable and fine recrystallized grain size of 8-12μm. Afterwards, the alloy was cold rolled down by 50% to a dimension of 1.27mm (0.050″) and aged annealed at 565°C for 3 hours in order to maximize electrical conductivity without excessive softening of the matrix. The alloy was then cold rolled The rolling reduction is 50% to 0.64mm (0.025") size, and the second aging annealing is carried out at 410°C for 2 hours, and the cold rolling is carried out to 0.25mm (0.010"). Subsequently, 2 stress relief annealing at 250°C Hours. Performance was measured under this condition and the results are shown in Table 9.

Comparing the reference alloy J694 with the zirconium-containing alloy J698, it is confirmed that a small amount of zirconium can increase the yield strength without affecting the electrical conductivity. Comparing alloy J694 with silver-containing alloy J699, it is confirmed that a small amount of silver can improve both yield strength and electrical conductivity. Comparing alloy J694 with chromium-containing alloy J700, it was confirmed that small amounts of chromium can slightly increase the yield strength with a slight decrease in electrical conductivity.

Example 6

Using the method shown in Figure 3, a series of 4.5 kg (10 lb) laboratory ingots having the analytical composition shown in Table 10 were melted in quartz crucibles and cast in steel molds using the Durville casting method. After pouring, the ingot size was 10.16cmx10.16cmx4.45cm (4″X4″X1.75″). After holding at 950°C for 3 hours, the ingot was hot rolled to 2.8cm (1.1″ ) thick, reheated at 950°C for 10 minutes, and further hot rolled to a size of 1.27cm (0.50″) in 3 passes, after which water quenching was carried out. After dressing and grinding to remove the oxide layer, the alloy was cold Rolled to 2.54mm (0.100"), and solution heat treated in a furnace at 1000°C for 25-35 seconds, and then water quenched to obtain a controllable fine recrystallized grain size of 6-12μm. Afterwards, the alloy is cold rolled down by 50% to a size of 1.27mm (0.050″), and aged annealed at 550-600°C for 3-4 hours. Then, the alloy is cold rolled down by 50% to 0.64mm (0.025″) ) size, and age annealed again at 410-425°C for 2 hours, followed by cold rolling to 0.25mm (0.010"), and stress relief annealed at 250-275°C for 2 hours.

Table 11 shows the performance at finished dimensions, showing that the addition of Mg (J604 vs. J603) and/or Zr addition (J644 vs. J603) results in a better combination of yield strength and conductivity.

The addition of Cr alone is less effective if no Mg is added (compare the lower intensity of J646 (column D) in Table 11 with the higher intensity of J700 in Table 9). Also shown in the following Mg content range by table 11, how the addition of Mg improves yield strength (and tensile strength), wherein when Mg addition is respectively 0,0.16,0.25, when 0.31wt%, its yield strength (and Tensile strength) are 703 (758), 710 (772), 745 (772), 745 (800), 758 (814) MPa [102 (110), 103 (112), 108 (116), 110 (118 ) ksi], while the conductivity remains almost constant at about 48% IACS.

Example 7

This example illustrates how composition and processing affect yield strength and conductivity. An ingot with a size of 10.16cmx10.16cmx4.45cm (4″x4″x 1.75″) was processed as follows to obtain alloys J694 and J709 with the compositions shown in Table 12: holding at 950°C for 3 hours, hot rolling to 1.27cm (0.50"), followed by water quenching. After trimming and grinding to remove scale, the alloy was cold rolled to 2.54mm (0.10") and solution heat treated at 1000°C for 35 seconds before water quenching. The alloy was then cold rolled to 1.27 mm (0.050"), solution treated at 950°C for 35 seconds and water quenched. Further processing is shown in Table 13 and properties are given in Table 14.

Table 12

Alloy Composition J694 Cu-1.78Ni-1.34Ti-0.98Fe-0.24Mg

Alloy Composition J709 Cu-0.93Ni-0.90Ti-1.05Fe-0.24Mg

Table 13

craft Process steps from 1.27mm (0.05 inches) onwards J1 Annealing at 565°C for 3 hours + cold rolling to 0.64mm (0.025 inches) + annealing at 410°C for 2 hours + cold rolling to 0.38mm (0.015 inches) + annealing at 250°C for 2 hours J2 Annealing at 565°C for 3 hours + cold rolling to 0.025 inches + annealing at 410°C for 2 hours + cold rolling to 0.008 inches + annealing at 250°C for 2 hours

Table 14

The foregoing has presented one or more embodiments of the invention. However, it should be understood that various changes may be made without departing from the spirit and scope of the invention. Accordingly, other implementations are within the scope of the following claims.

Claims (15)

1. copper base alloy, it basic composition is, by weight: 0.35-5% titanium, 0.001-10% are selected from Ni, Fe, Co, Mg, Cr, Zr, the rest is copper and unavoidable impurities at one or more elements of Ag and their combination, the electroconductibility of described alloy is 50%IACS at least, and yield strength is 724MPa at least.

2. according to the copper base alloy of claim 1, it contains and is selected from one or more following elements: maximum 5.0% Ni, maximum 1.10% Fe, Co or their mixture, maximum 1.0% Mg, maximum 1% one or more be selected from the element of Cr, Zr and Ag.

3. according to the copper base alloy of claim 2, also contain in its essentially consist: 0.35-2.5% titanium, 0.5-5.0% nickel; 0.5-0.8% iron, cobalt or their mixture; 0.01-1.0% magnesium; Maximum 1% Cr, Zr, Ag or its combination; The rest is copper and unavoidable impurities.

4. according to the copper base alloy of claim 2, its essentially consist also contains: the 0.8-1.4% titanium; 0.8-1.7% nickel; 0.9-1.1% iron, cobalt or their mixture; 0.1-0.4% magnesium; Maximum 1% Cr, Zr, Ag or its combination; The rest is copper and unavoidable impurities.

5. the copper base alloy of the yield strength with improvement, electroconductibility and the combination of stress relaxation drag, it basic composition is, by weight: the 0.35-2.5% titanium; 0.5-5.0% nickel; 0.5-1.5% iron, cobalt or their mixture; 0.01-1.0% magnesium; Maximum 1% Sn, Cr, Zr, Ag, Sn, P, Al, Si, Pb, Bi, S, Te, Se, Be, Mn, As, Sb, B or their mixture; The rest is copper and unavoidable impurities.

6. according to the copper base alloy of claim 5, it contains maximum 1% Cr, Zr, Ag or their mixture.

7. according to the copper base alloy of claim 6, it basic composition is: the 0.8-1.4% titanium; 0.8-1.7% nickel; 0.90-1.10% iron, cobalt or their mixture; 0.10-0.40% magnesium; The Cr of 0.01-1.0%, Zr, Ag or their mixture; The rest is copper and unavoidable impurities.

8. the preparation method of the copper base alloy of the yield strength with improvement, electroconductibility and the combination of stress relaxation drag, it is characterized in that: casting (10) copper base alloy, described alloy basic composition is, by weight: 0.35-10% titanium, 0.001-6% are selected from Ni, Fe, Co, Mg, Cr, the rest is copper and unavoidable impurities at one or more elements among Zr and the Ag; At the described alloy of 750-1000 ℃ of following hot rolling (12); Depress the described alloy of comparison with the area of 50-97% and carry out the first time cold rolling (14); Under 850-1000 ℃ described alloy is carried out the annealing first time (16), the time, afterwards, cooling (18) was to room temperature fast from 10 seconds to 1 hour; Depress the described alloy of comparison and carry out the second time cold rolling (20) to be up to 80% area; Under 400-650 ℃ described alloy is carried out the annealing second time (22), the time was from 1 minute to 10 hours; With the area of 10-50% depress than with described alloy cold rolling for the third time (24) to final dimension, the time of wherein said each annealing steps and temperature effectively make the described alloy of final dimension have the yield strength of 724MPa at least and the electroconductibility of 50%IACS at least.

9. method according to Claim 8, it is characterized in that: at described cold rolling step for the third time (24) afterwards, under 150-600 ℃ described alloy is annealed (26), the time was from 15 seconds to 10 hours.

10. yield strength, electroconductibility and combination of stress relaxation drag with improvement, has simultaneously the preparation method of the copper base alloy of suitable bendability again, it is characterized in that: casting (10) copper base alloy, basic composition is of described alloy, by weight: 0.35-10% titanium, 0.001-6% are selected from Ni, Fe, Co, Mg, Cr, the rest is copper and unavoidable impurities at one or more elements among Zr and the Ag; (12) described alloy under 750-1000 ℃ of following hot pressing; Implement one or more circulations, described circulation comprises with the area of 50-99% depresses than colding pressing following (14) described alloy and carry out aging anneal (28) from 15 seconds to 10 hours afterwards under 400-650 ℃ annealing temperature; Depress than (30) the described alloy down of colding pressing with the area of 40-80%; By annealing 1-10 hour down, described alloy is carried out age hardening handle (32) at 400-650 ℃; With the area of 10-50% depress than with described alloy finally cold rolling (34) to final dimension, the time of wherein said annealing steps and temperature effectively make the described alloy of final dimension have the yield strength of 724MPa at least and the electroconductibility of 50%IACS at least.

11. the method according to claim 10 is characterized in that: at described final cold rolling step (34) afterwards, under 150-600 ℃ described alloy is annealed (26), the time was from 15 seconds to 10 hours.

12. preparation method with copper base alloy of high-yield strength and suitable intensity, electroconductibility, it is characterized in that: casting (10) copper base alloy, described alloy basic composition is, by weight: 0.35-10% titanium, 0.001-6% are selected from Ni, Fe, Co, Mg, Cr, the rest is copper and unavoidable impurities at one or more elements among Zr and the Ag; (12) described alloy under 750-1000 ℃ of following hot pressing; Depress than (14) the described alloy down of colding pressing with the area of 50-99%; Under 950-1000 ℃ described alloy is carried out solution annealing (16), the time afterwards, was quickly cooled to envrionment temperature from 15 seconds to 1 hour; Depress than (20) the described alloy down of colding pressing with the area of 40-60%; Under 400-650 ℃ described alloy is carried out aging anneal (28), the time is 1-10 hour; Depress than (30) the described alloy down of colding pressing with the area of 40-60%; Under 375-550 ℃ the ratio temperature that aging anneal is low for the first time, alloy is carried out the aging anneal second time (32), time 1-3 hour; And, to depress than cold rolling (34) to final dimension with at least 30% area, the time of wherein said annealing steps and temperature effectively make the described alloy of final dimension have the yield strength of 724MPa at least and the electroconductibility of 50%IACS at least.

13. the method according to claim 12 is characterized in that: at described final cold rolling step (34) afterwards, under 150-600 ℃ described alloy is annealed (26), the time was from 15 seconds to 10 hours.

14. preparation method with copper base alloy of high-yield strength and suitable intensity, electroconductibility, it is characterized in that: casting (10) copper base alloy, basic composition is of described alloy, by weight: 0.35-10% titanium, 0.001-6% are selected from Ni, Fe, Co, Mg, Cr, the rest is copper and unavoidable impurities at one or more elements of Zr and Ag and their combination; At the described alloy of 750-1000 ℃ of following hot rolling (12); Depress than cold rolling (14) described alloy with the area of 50-99%; Under 950-1000 ℃ described alloy is carried out solution annealing (16), the time, afterwards, cooling (18) was to envrionment temperature fast from 10 seconds to 1 hour; Depress than cold rolling (20) described alloy with the area of 40-60%; Described alloy is carried out aging anneal (28), and annealing temperature is 500-575 ℃, and the time, perhaps, annealing temperature was 425-475 ℃, time 2.5-3.5 hour from 15 seconds to 10 hours; Depress than cold rolling (30) described alloy with the area of 40-60%; Under 500-550 ℃ temperature, alloy is carried out the aging anneal second time (32), time 1-4 hour; And, to depress than finally cold rolling (34) to final dimension with at least 30% area, the time of wherein said annealing steps and temperature effectively make the described alloy of final dimension have the yield strength of 724MPa at least and the electroconductibility of 50%IACS at least.

15. the method according to claim 14 is characterized in that: at described final cold rolling step (34) afterwards, under 150-600 ℃ described alloy is annealed (26), the time was from 15 seconds to 10 hours.

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