EP3198048A1

EP3198048A1 - Electrical connection element

Info

Publication number: EP3198048A1
Application number: EP15756842.9A
Authority: EP
Inventors: Timo ALLMENDINGER; Kai Weber
Original assignee: Wieland Werke AG
Current assignee: Wieland Werke AG
Priority date: 2014-09-25
Filing date: 2015-08-29
Publication date: 2017-08-02
Anticipated expiration: 2035-08-29
Also published as: WO2016045770A1; TW201617460A; CN106715731A; DE102014014239B4; PL3198048T3; TWI651422B; KR20170059436A; US20170204501A1; EP3198048B1; JP6514318B2; DE102014014239A1; JP2017532436A

Abstract

Electrical connection element containing a copper-zinc alloy. The copper-zinc alloy comprises (in percent by weight): 28.0 to 36.0 % Zn, 0.5 to 1.5 % Si, 1.5 to 2.5 % Mn, 0.2 to 1.0 % Ni, 0.5 to 1.5 % Al, 0.1 to 1.0 % Fe, optionally also up to a maximum of 0.1 % Pb, optionally also up to a maximum of 0.1 % P, optionally up to a maximum of 0.08 % S, the remainder being Cu and inevitable impurities. According to the invention, mixed silicides containing iron, nickel and manganese are incorporated in the matrix. The structure comprises an α-matrix, which contains inclusions of ß-phase from 5 up to 45 percent by volume and of mixed silicides containing iron, nickel and manganese up to 20 percent by volume. The structure further comprises mixed silicides containing iron, nickel and manganese having a stemmed shape and iron and nickel enriched mixed silicides having a globular shape.

Description

Description Electrical connection element

The invention relates to an electrical connection element containing a copper-zinc alloy according to the preamble of claim 1.

Numerous new automotive applications for safety, comfort and performance can only be realized through the targeted use of electronic functions and components. Due to the increasing demands on the connectors and thus on the materials used, a trend towards copper high-performance alloys has been evident in recent years. These precipitation-hardening copper materials are characterized by high

mechanical strength, high conductivity and good ductility.

Based on the first generation of Cu-HP alloys, for example CuNi3SiMg with an electrical conductivity of slightly more than 20 MS / m, the combination of properties of high strength and high conductivity had to be further optimized.

A first step in this direction was the development of precipitation-hardening copper alloys, for example based on the system

CuCrAgFeTiSi with 46 MS / m and strengths up to 610 MPa. Another important advantage of this alloy is the very good relaxation resistance of the material when used at elevated temperatures up to 200 ° C. This type of alloy can cover applications in the automotive, industrial electronics and telecommunications sectors. In addition, bronze materials are used, which are characterized by a fine

Structure with a grain size of a maximum of 3 μητι distinguished. As a result, already substantially high mechanical strengths are achieved at the same time greatly improved forming properties. As a result of the significantly improved formability, processors can realize correspondingly narrow bending radii. Likewise, the improved bendability causes the roughness in the

Forming zones is much lower than when using standard bronzes. Thus, subsequent coatings can be carried out with a smaller layer thickness, which can achieve considerable cost savings in further processing. The electrical conductivity is identical to that of standard bronzes and is around 7.5 to 12 MS / m.

Another precipitation-hardening CuNM CoSi alloy with Ni-Co mixed silicides is also very well suited for an economical

Miniaturization of connectors. The material is high strength, has with

29 MS / m a comparatively good electrical and thermal conductivity and can be processed well.

The materials described are particularly suitable for processing on punching / bending machines and can be machined only with great effort.

Other copper materials in the form of rods and wires that are

These are also well-suited for the machining of bushings and pins for connectors. They are also known in the material portfolio of cost-effective brass materials with the CuZn37PbO, 5, CuZn35Pb1, CuZn35Pb2, CuZn37Pb2, CuZn36Pb3 and CuZn39Pb3 alloys, which are used for demanding applications in the production of turned connectors. Depending on the technical requirements come in these cases

Materials with high electrical conductivity, high mechanical strength and both of these properties are used in combination. CuPbl P, for example, is another easily machinable material that also has a high electrical conductivity of around 50 MS / m. It is particularly suitable for connectors and other electronic applications.

In addition to the solid-solution-hardening alloys, the alloy spectrum is rounded off by further precipitation-hardening materials. These include, for example, CuNi1 Pb1 P and CuNiPbO, 5P as low-alloy copper material with high strength, good conductivity of at least 32 MS / m and good machinability. Due to the Pb content, the material is particularly suitable for machining machined plug-in contacts in electrical engineering and electronics.

Even with the multi-component tin bronze CuSn4Zn4Pb4P, each with a 4% tin, zinc and lead content, high strengths can be set with corresponding spring properties. This tin bronze is good cold formable and can be excellently machined. Special applications are springy electronic contacts.

In the meantime, the various environmental directives and substance restrictions must always be taken into account when developing alloys. There are further development potentials for alternative or supplementary alloys which characterize combinations of suitable combinations of connectors. In addition to the physical properties above all a good one plays

Machinability a crucial role.

The invention has the object of developing an electrical connection element made of a lead-free or lead-free copper alloy.

The invention is represented by the features of claim 1. The other dependent claims give advantageous embodiments and further developments of the invention. The invention includes the technical teaching for the construction of an electrical connection element containing a copper-zinc alloy. The copper-zinc alloy consists of (in% by weight):

28.0 to 36.0% Zn,

0.5 to 1.5% Si,

1, 5 to 2.5% Mn,

0.2 to 1, 0% Ni,

0.5 to 1.5% AI,

0, 1 to 1, 0% Fe,

optionally up to a maximum of 0, 1% Pb,

optionally up to a maximum of 0, 1% P,

optionally up to 0.08% S,

Balance Cu and unavoidable impurities.

According to the invention, iron-nickel-manganese-containing mixed silicides are incorporated in the matrix. The microstructure consists of an α-matrix, in the inclusions of ß-phase from 5 to 45 vol .-% and iron-nickel-manganese-containing

Mixed silicides are contained up to 20 vol .-%. Furthermore, the structure contains the iron-nickel-manganese-containing mixed silicides with a stalk-like shape and iron-nickel-enriched mixed silicides with a globular shape.

Surprisingly, it has been found that the alloy composition according to the invention is suitable for electrical connection elements. So far, an application of such alloys according to the German patent application DE 10 2007 029 991 A1 of the Applicant was only for a use for

Sliding elements in internal combustion engines, transmissions or hydraulic

Aggregates provided. The content of this publication is fully incorporated into the present description. Such deviant

Applications have a different purpose for a property combination optimized for specific purposes. A combination of properties consisting of an increase in the strength, the temperature resistance of the microstructure and the complex wear resistance with sufficient at the same time Toughness properties with regard to. on motor applications.

In contrast, the invention is based on the idea to provide an electrical connection element with a copper-zinc alloy with embedded iron-nickel-manganese-containing mixed silicides, which can be prepared in particular by means of the continuous or semi-continuous continuous casting process. Due to the mixed silicide formation and structure formation, the copper-zinc alloy has a very high electrical conductivity for this material group.

Also, the alloy has high hardness and strength values, yet a necessary degree of ductility, expressed by the elongation at break value in a tensile test, is ensured. With this combination of features, the subject invention proves to be particularly suitable for electrical

Connecting elements, such as turned connectors,

Plug-in devices, electrical terminals, optionally with screw connections.

In the preliminary manufacturing step of casting the alloy, an early precipitation of iron- and nickel-rich mixed silicides takes place first. These precipitates, on further growth, can grow into large-sized mixed-silicide iron-nickel-manganese, often of stalked form. Furthermore, a considerable proportion remains rather small with a globular shape, which is finely distributed in the matrix. The finely divided silicides are considered to cause stabilization of the β-phase

takes place. In particular, the alloy has a high during cold forming

Ductility on. In electrical fasteners, this is when crimping, which is usually the material of a strong plastic deformation

is exposed, especially important. So a beading, crushing or folding of the material under almost any degree of deformation is possible without causing cracking in the material. The material is also particularly suitable for machining electrical connecting elements. The good machinability is already achieved by a ß-phase of 5 vol .-%. At higher levels, up to 45% by volume of β-phase also improves chip formation during the cutting process, in that desirably short chips are formed. With a content of β-phase below 5% by volume, the machinability in the use as automatic material for high metal removal rates is no longer satisfactory. With a β-phase content of more than 45% by volume, it can be seen that the toughness of the material and the temperature resistance of the microstructure deteriorate. The final state of the alloy from the respective manufacturing process leads to a β-phase, which is embedded like an island in a microstructure of an α-matrix. Such ß-phase islands are particularly favorable for the machinability and the

Corrosion resistance of the alloy. A particularly high surface quality of the machined surfaces is achieved with a β-phase content, however, in particular from 10 to 25% by volume. In the specified volume interval of 5 to 45 vol .-% of ß-phase also a comparatively low tool wear, so that the

Tools have correspondingly long service life and thus the

Tool costs are reduced. Shares of iron-nickel-manganese-containing mixed silicides above 20 vol .-% would require such a large increase in hardness that the material suffers in its balance in the combination of favorable properties. Particularly noteworthy is the relaxation resistance of the material, whereby the spring force of an electrical connection element is maintained.

Thus, the particular advantage of the alloy according to the invention is based on an optimized combination of properties for the purposes in the form of a

Increasing the strength, the temperature resistance of the structure and the electrical conductivity with sufficient toughness properties. In addition, the claimed material solution takes into account the substituted due to conventional alloys lead content the

Need for an environmentally friendly lead-free alloy alternative.

In addition, this material is predestined for special applications where a high degree of plasticizability is required despite the high hardness and strength requirements.

In an advantageous embodiment of the invention, the copper-zinc alloy

30.0 to 36.0% Zn,

0.6 to 1, 1% Si,

1, 5 to 2.2% Mn,

0.2 to 0.7% Ni,

0.5 to 1, 0% AI,

0.3 to 0.5% Fe.

Due to the narrower limits is a particularly advantageous

Alloy composition selected. This will be the

Toughness properties and electrical conductivity, optionally further improved with a final stress relief annealing. Preferably, the final flash annealing is carried out at 300 ° C to 400 ° C for 3 to 4 hours.

In a further advantageous embodiment of the invention, the copper-zinc alloy may contain 33.5 to 36.0% Zn. At these higher levels of zinc, it is still possible to use those required for electrical fasteners

Toughness properties and good electrical conductivity realize. By the highest possible zinc content of the proportion of other elements, in particular the copper content is reduced accordingly. As a result, the alloy has a correspondingly lower metal price due to a higher proportion of cheaper zinc.

Advantageously, the electrical conductivity of the alloy may be at least 5.8 MS / m. Particularly preferred conductivities are at least 10 MS / m to over 13 MS / m. These values are comparable

Materials, such as the lead-containing brasses, not achieved. Even values above 13 MS / m can be adjusted by suitable further processing steps.

Advantageously, the structure consisting of an α-matrix, in which inclusions of β-phase of from 5 to 45% by volume and of iron-nickel-manganese-containing mixed silicides of up to 20% by volume are contained after further processing, the at least one hot forming and / or cold forming and optionally further annealing steps may be formed. With the β-deposits and hard phases of different size distribution in an α-matrix, this alloy ensures an advantageous temperature resistance of the microstructure with sufficient toughness properties for the production of the connecting elements.

For further processing, the alloy may be advantageous in its

Further processing has gone through the following steps:

- extrusion or hot rolling in a temperature range of 600 to 800 ° C,

- At least one cold forming, preferably by drawing or cold rolling.

Also, in a preferred embodiment of the invention, the alloy may have undergone the following steps in its further processing:

- Extrusion or hot rolling in a temperature range of 600 to 800

° C

- A combination of at least one cold working, preferably by drawing or cold rolling and at least one annealing in a temperature range of 250 to 700 ° C, preferably with an annealing time of 20 minutes to 5 hours. By means of a combination of cold forming by drawing and one or more annealing of the starting materials in the form of round wires, Profile wires, round bars, profile bars, hollow bars and tubes in the

Temperature range of 250 to 700 ° C, it is possible to set a fine distribution of heterogeneous structure. In this way, the demand for the improvement of the electrical conductivity is met.

Of particular interest is also the relationship between the height and distribution of the proportion of ß-phase and the temperature resistance of the

Structure. Since, however, this cubic-body-centered crystal assumes an indispensable strength-increasing function in the copper-zinc alloys, the minimization of the β content should not be exclusively in the foreground. By means of the production sequence of extruding or hot rolling / drawing or cold rolling / intermediate annealing, the microstructure of the copper-zinc alloy can be modified in its phase distribution such that, in addition to high strength, it also has sufficient temperature resistance, ductility and good electrical conductivity.

In a preferred embodiment, in the further processing after forming at least one flash annealing in a temperature range of 250 to 450 ° C and preferably an annealing time of 2 to 5 hours followed.

During production, there is a need to reduce the level of residual stresses by means of one or more flash anneals. The lowering of residual stresses is also important for ensuring a sufficient temperature resistance of the structure and for the

Ensuring a sufficient straightness of the round wires, profile wires, round bars, profiled bars, hollow bars and tubes as precursors of the electrical connection elements. Further embodiments of the invention will be explained in more detail with reference to tables. This is according to the investigations to an am best viewed embodiment. Other deviating embodiments are, however, within the scope of the invention

equally to achieve the inventive advantages. Cast bolts of the copper-zinc alloy according to the invention were produced by continuous casting or chill casting. The chemical composition of the continuous casting of the alloy 1 and the chill casting of the alloys 2 and 3 is shown in Table 1. Table 1: Chemical composition of the cast bolts or ingots (in

% By weight) without indication of possible impurities

Production sequence 1:

• Extruding the cast bolts from Leg. to tubes at the temperature of 670-770 ° C

• combination of cold forming / intermediate annealing (630-700 ° C /

50min-3h) / straightening / relaxation annealing (300-400 ° C / 3h)

After continuous production, the structural parameters, the electrical conductivity and the mechanical properties of the tubes with dimensions (30.1x24.7) mm are at the level shown in numerical values in Tab. Table 2: Structural parameters, electrical conductivity and mechanical properties at two positions of the tubes in the final state (Leg. 1)

Production sequence 2:

· Extrusion of cast bolts from Leg. 1 to round bars at the

Temperature of 650-750 ° C

• combination of cold forming / annealing (630-720 ° C / 50min-4h) /

Straightening / Relaxation Annealing (300-450 ° C / 2-4h) After continuous production, the structural characteristics, the electrical conductivity and the mechanical properties of the 13.40 mm, 16.35 mm and 45.50 mm diameter round bars are displayed the level shown in numerical values in Tab. 3. Table 3: Structural parameters, electrical conductivity and mechanical properties

Properties of Round Rods in Final Condition (Leg. 1)

Rounded Grain Electric Rm Rp0.2 Breaking Hardness bar Grade Size Conductivity [MPa] [MPa] Elongation HB

0 [mm] [%] [pm] [MS / m] A5 [%]

13,40 5 20-25 11, 4 607 512 12.4 191

16.35 15-20 25 10.9 638 549 12.0 199

45.50 10-15 25 10.7 570 420 20.1 172 Production sequence 3:

• Hot rolling of cast blocks from Leg. 2 and 3 to slabs in the

Temperature of 650-730 ° C

Cold rolling of the plates with a conversion of 15 to 25%

if necessary with relaxation annealing (300-450 ° C / 2-4h)

In addition, between the individual process steps, if necessary milling the surfaces.

Table 4: Structural parameters, electrical conductivity and mechanical

Properties of the slabs in the final state (slab thickness 3 mm, with and without flash annealing ESG as last process step)

Alloy beta grain electr. Rp0.2 fracture hardness

Content size Conductive [MPa] [MPa] Elongation HB

[%] [Mm] A5 [%]

[MS / m]

Leg. 2

14 15-20 8.9 608 540 7.8 188 (without ESG)

Leg. 2

13 15-20 10.5 646 543 15.6 192 (ESG 340 ° C / 3h)

Leg. 2

13 15-20 10.7 615 483 19.0 184 (ESG 400 ° C / 3h)

Leg. 3

20 20-25 1 1, 0 596 516 1 1, 3 178 (without ESG)

Leg. 3

18 20-25 12.7 593 464 18.6 176 (ESG 340 ° C / 3h)

Leg. 3

18 20-25 12.7 580 428 21, 6 170 (ESG 400 ° C / 3h) Production sequence 4:

• Hot rolling of cast blocks from Leg. 2 and 3 to slabs in the

Temperature of 650-730 ° C

• Combination of annealing (650 ° C / 3h) and cold rolling of the plates with

a transformation of 15 to 25% optionally with

Relaxation annealing (300-450 ° C / 2-4h)

In addition, between the individual process steps, if necessary milling the surfaces. Table 5: Structural parameters, electrical conductivity and mechanical

Alloy beta grain electr. Rp0.2 fracture hardness

Content size Conductive [MPa] [MPa] Elongation HB

[%] [pm] speed A5 [%]

[MS / m]

Leg. 2

10 10-15 9.3 573 510 1 1, 8 180 (without ESG)

Leg. 2

10 10-15 10.6 587 470 19.4 176 (ESG 340 ° C / 3h)

Leg. 2

10 10-15 10.6 583 452 20.0 174 (ESG 400 ° C / 3h)

Leg. 3

15 20-25 10,5 555 482 13,5 172 (without ESG)

Leg. 3

15 20-25 12.7 553 422 21, 0 166 (ESG 340 ° C / 3h)

Leg. 3

15 20-25 12.7 544 403 19.5 162 (ESG 400 ° C / 3h) Production sequence 5:

• Hot rolling of cast blocks from Leg. 2 and 3 to slabs in the

Temperature of 650-730 ° C

• Combination of cold rolling of the plates with a deformation of 15 to 65% / annealing (630-720 ° C / 50min-4h)

Table 6: Structural parameters, electrical conductivity and mechanical properties

Properties of the slabs in the final state (slab thickness 2.3 mm, without

Relaxation annealing ESG)

In particular, the characteristic value for the electrical conductivity can be further increased for the formats of the alloys 2 and 3 produced according to the production sequence 5 by an additionally performed flash annealing at a temperature of 250 to 450 ° C.

With regard to the exemplary embodiments, it should be emphasized that the β content is between 5 and 20% in all five production sequences. Further studies show that the β-contents are preferably between 5-30%. The island-like formation of the β-phase in the final state of fabrication, embedded in a microstructure of an α-matrix, can appear in a slightly different form. With increasingly lower contents of β-phase, islands which are more isolated from one another appear, which in the limiting case can form a kind of gusset filling in relation to the crystallites of the α-matrix.

Claims

claims

Electrical connection element containing a copper-zinc alloy consisting of (in% by weight):

28.0 to 36.0% Zn,

0.5 to 1.5% Si,

1, 5 to 2.5% Mn,

0.2 to 1, 0% Ni,

0.5 to 1.5% AI,

0.1 to 1.0% Fe,

optionally up to a maximum of 0.1% Pb,

optionally up to a maximum of 0.1% P,

optionally up to 0.08% S,

Balance Cu and unavoidable impurities,

characterized,

- That in the matrix iron-nickel-manganese-containing mixed silicides

are stored,

that the microstructure consists of an α-matrix in which inclusions of β-phase of from 5 to 45% by volume and of iron-nickel-manganese-containing mixed silicides of up to 20% by volume are contained,

- That in the microstructure, the iron-nickel-manganese-containing mixed silicides with stalk form as well as iron-nickel-enriched mixed silicides are present with globular shape.

2. Electrical connection element according to claim 1,

marked by:

30.0 to 36.0% Zn,

0.6 to 1, 1% Si,

1, 5 to 2.2% Mn,

0.2 to 0.7% Ni,

0.5 to 1, 0% AI,

0.3 to 0.5% Fe.

3. Electrical connection element according to claim 2,

marked by:

33.5 to 36.0% Zn,

4. Electrical connection element according to one of claims 1 to 3, characterized in that the electrical conductivity of the alloy is at least 5.8 MS / m.

5. Electrical connection element according to claim 4, characterized in that the electrical conductivity of the alloy is at least 10 MS / m.

6. Electrical connection element according to claim 5, characterized in that the electrical conductivity of the alloy is at least 13 MS / m.

7. Electrical connection element made of a copper-zinc alloy according to one of claims 1 to 6, characterized in that the consisting of an α-matrix microstructure, in the inclusions to ß-phase of 5 to 45 vol .-% and Iron-nickel-manganese-containing mixed silicides of up to 20% by volume are present after further processing, which includes at least one hot working and / or cold forming and optionally further

Including annealing steps is formed. Electrical connection element of a copper-zinc alloy according to claim 7, characterized in that the alloy has undergone the following steps in its further processing:

- extrusion or hot rolling in a temperature range of 600 to 800 ° C,

- At least one cold forming.

Electrical connection element of a copper-zinc alloy according to claim 7, characterized in that the alloy has undergone the following steps in its further processing:

- extrusion or hot rolling in a temperature range of 600 to 800 ° C,

- A combination of at least one cold forming and

at least one annealing in a temperature range of 250 to 700 ° C.

Electrical connection element of a copper-zinc alloy according to claim 8 or 9, characterized in that in the further processing after forming at least one flash annealing followed by a temperature range of 250 to 450 ° C.