KR101010906B1 - Copper/zinc/silicon alloy, use and production thereof - Google Patents

Abstract

A Cu-Zn-Si alloy includes, in % by weight, 70 to 80% of copper, 1 to 5% of silicon, to 0.5% of boron, up to 0.2% of phosphorus and/or up to 0.2% of arsenic, a remainder of zinc, plus inevitable impurities. Products using the alloy and processes for producing the alloy are also provided. The alloy is distinguished by an improved resistance to oxidation and by uniform mechanical properties.

Description

Copper / Zinc / Silicone Alloys, Manufacturing Method and Uses thereof {COPPER / ZINC / SILICON ALLOY, USE AND PRODUCTION THEREOF}

The present invention relates to a copper-zinc-silicon alloy, to a method and to the use of this type of copper-zinc-silicon alloy.

The primary requirement for copper-zinc-silicon alloys is that they must be resistant to dezincification and be machinable. Until now, the good machinability of the brass alloy of this form has been realized by adding lead, as described, for example, in Patent Document EP 1 045 041 A1. Recently, however, lead-free brass alloys with good machinability have been developed, as described in patent documents EP 1 038 981 A1 and DE 103 08 778 B3. Both lead-free and lead-containing copper-zinc-silicon alloys tend to be oxidized at temperatures between 300 ° C. and 800 ° C. to form scale layers. Since this scale layer is only loosely bonded to the metal, it can be easily released from the metal and thus dispersed through the production equipment, which can lead to a destructive pollution effect. Production equipment is expensive to clean and raises manufacturing costs. Another disadvantage of the known Cu-Zn-Si alloys is that the materials do not have homogeneity and therefore the mechanical properties of the materials change for long workpieces.

In view of this fact, the present invention aims to provide a copper-zinc-silicon alloy which not only improves in terms of homogeneity but also has a low tendency to form scales, and an object of the present invention is to provide a use method and a manufacturing method of this type of brass alloy. It is done.

The first object of the invention relates to an alloy, in accordance with the invention, 70 to 80% copper, 1 to 5% silicon, 0.0001 to 0.5% boron, 0 to 0.2% phosphorus and / or Arsenic, a copper-zinc-silicon alloy comprising the remaining amount of zinc and unavoidable impurities.

The content of copper is 70-80%, since the copper content is less than 70% or more than 80% has an adverse effect on the machinability of the alloy. The same applies when the silicon concentration is out of the range of 1 to 5% described above. The concentration of boron in the alloy is 0.0001 to 0.5%. Surprisingly, it has been found that addition of boron within the above concentration ranges reduces scale formation, while significantly improving the binding of the remaining scale to the material. It is also surprising that the addition of boron improves the homogeneity of the microstructure and, as a result, prevents fluctuations in mechanical properties. Phosphorus and arsenic may each be present in the alloy at a concentration of up to 0.2% and may be substituted for one another. Phosphorus and arsenic have a beneficial effect on the formation and corrosion of early cast microstructures, further improving the melt flowability and reducing the susceptibility to stress corrosion cracking. The remaining main component of the alloy is zinc.

In addition to the advantages listed above, which avoid the easy separation of the scale layer which increases the production cost, improve the mechanical properties and further provide good machinability and formability with high resistance to corrosion, dezinc and stress corrosion Resistance to cracking is also particularly prominent in the present invention. Dezinc tests conducted according to ISO 6509 resulted in a dezinc depth of only 26 μm or less.

A second object of the present invention for the use of this type of copper-zinc-silicon alloy is to provide electrical engineering parts, sanitary container parts, containers for the transport or storage of liquids or gases, torsionally loaded parts, recyclables. It is achieved by the use of parts, drop-forged parts, semifinished products, strips, sheets, profile sections, plates and the like, or as a refined, rolled or cast alloy.

Cu-Zn-Si alloys are intended for contacts, pins, or fastening members in electrical engineering, for example as stationary or fixed contacts that include clamping and plug connections or plug-in contacts. Used.

The alloy has high corrosion resistance to liquid and gaseous media. In addition, the alloys are very resistant to dezincification and stress corrosion cracking. The alloy is thus suitable for vessels for transporting or storing liquids or gases, in particular for vessels used in refrigerators, or for valves in pipes, water extensions, valve extensions, pipe connectors and sanitary vessels.

Low corrosion rates also ensure that the properties of metal leaching, i.e., loss of alloying components through the action of a liquid or gaseous medium, are inherently low. In this regard, the materials are suitable for applications requiring low pollutant emissions for environmental protection. Thus, the alloy according to the invention can be used in the field of recyclable components.

The lack of susceptibility to stress corrosion cracking means that, for technical reasons, the alloy is recommended for use in threaded or clamped connections where high elastic energy is stored. Thus, the alloy is particularly suitable for all parts subjected to tensile and / or torsional loads, inter alia nuts and bolts. After cold forming, the material has a high value for proof stress. Thus, a higher tightening torque can be realized in the screw connection which must not be deformed flexibly. The yield strength ratio of Cu-Zn-Si alloys is lower than that of free-machining brass. Screw connections that are tightened only once and thus intentionally expanded during the process can have particularly high holding forces.

A possible use of the Cu-Zn-Si alloy is for the starting material in the form of a tube as well as in the form of a strip. The alloys are also well suited for strips, sheets and plates which can be milled or punched, in particular for thermal, decorative engraving or leadframe applications.

A third object associated with the production of this type of copper-zinc-silicon alloy is the continuous casting and hot rolling treatment in a conventional manner at 600-760 ° C. followed by deformation, in particular cold rolling, preferably further annealing. And by carrying out the modifying step.

The above objects associated with the production of copper-zinc-silicon alloys of this type are also achieved by continuous casting and extrusion treatment in a conventional manner at temperatures of 760 ° C. or lower, preferably 650-680 ° C., followed by cooling in the atmosphere.

In an advantageous refinement of the copper-zinc-silicon alloy, the alloy comprises 75-77% copper, 2.8-4% silicon, 0.001-0.1% boron, 0.03-0.1% phosphorus and / or arsenic, And zinc and unavoidable impurities as the remaining elements.

In another preferred embodiment, the copper-zinc-silicon alloy comprises 0.01-2.5% lead, 0.01-2% tin, 0.01-0.3% iron, 0.01-0.3% cobalt, 0.01-0.3% by weight At least one element selected from the group consisting of nickel and 0.01-0.3% manganese. The addition of lead has a positive effect on machinability.

In this case, the alloy is 0.01% to 0.1% lead, 0.01% to 0.2% tin, 0.01% to 0.1% iron, 0.01% to 0.1% cobalt, 0.01% to 0.1% nickel and 0.01% to 0.1% by weight. It is advantageous to include at least one element selected from the group consisting of manganese.

In a preferred refining, the Cu-Zn-Si alloy further comprises up to 0.5% silver, up to 0.5% aluminum, up to 0.5% magnesium, up to 0.5% antimony, up to 0.5% titanium and 0.5 by weight From less than% zirconium, preferably 0.01 to 0.1% silver, 0.01 to 0.1% aluminum, 0.01 to 0.1% magnesium, 0.01 to 0.1% antimony, 0.01 to 0.1% titanium and 0.01 to 0.1% zirconium Contains one or more elements selected.

In another preferred embodiment, the Cu—Zn—Si alloy further comprises 0.3% or less cadmium, 0.3% or less chromium, 0.3% or less selenium, 0.3% or less tellurium, 0.3% or less bismuth, Preferably at least one element selected from 0.01-0.3% cadmium, 0.01-0.3% chromium, 0.01-0.3% selenium, 0.01-0.3% tellurium and 0.01-0.3% bismuth.

Embodiments of the present invention will be described in more detail with reference to the accompanying drawings and the following description.

1 shows the formation of a scale layer after annealing at 600 ° C. for 2 hours for a CuZn21Si3P alloy, (a) an alloy without boron, (b) an alloy containing 0.0004% boron, ( c) is an alloy containing 0.009% boron.

Figure 2 shows the formation of a cast microstructure of CuZn21Si3P alloy, where (a) is an alloy without boron, (b) is an alloy containing 0.0004% boron, and (c) contains 0.009% boron It is an alloy.

The CuZn21Si3P alloy based on the embodiment of the present invention varies in the concentration of components as follows: 75.8 to 76.1% of copper, 3.2 to 3.4% of silicon, 0.07 to 0.1% of phosphorus, zinc and unavoidable impurities as the remaining amount. In the example of the alloy, the content of boron differs from 0%, 0.004% and 0.009%. The alloy is produced by continuous casting followed by quenching after extrusion at a temperature of 760 ° C, preferably 650-680 ° C.

All of these alloys have good resistance to dezinc. Dezinc test results according to ISO 6509 showed that the zinc depth was only less than 26 μm.

When the CuZn21Si3P alloy is exposed to a temperature of 300-800 ° C., such as, for example, during a high temperature operation, scales are formed which can easily peel off and contaminate the production equipment. Extensive scale formation on the surface of the boron-free CuZn21Si3P alloy is illustrated in Figure 1 (a). In FIG. 1A, the surface of the specimen is markedly gray. This gray color represents the scale formation surface of CuZn21Si3P alloy. Only a few bright spots are irregularly distributed on the surface of the alloy. In contrast, in Fig. 1 (b), the CuZn21Si3P alloy having a boron content of 0.0004% has a much higher number of bright spots on the surface than the boron free alloy. These bright spots represent bright metal regions of the alloy. These bright metal regions, ie regions without scale at all, are evenly distributed over the surface of the alloy. The proportion of the surface on which the scale is formed is significantly reduced, and the remaining scale is more firmly bonded to the metal than in the case of fluorine-free alloys. Figure 1 (c) shows a CuZn21Si3P alloy containing 0.009% boron. This figure shows an increase in the number of bright metallic surfaces, or white spots. In some areas there is a relatively large continuous area of bright metal material, the figure also shows a very regular distribution on the surface of the alloy. The proportion of the surface on which the scale is formed is further reduced, and the remaining scale is firmly bonded to the metal. Thus, it has been clarified that a low boron concentration of 0.0001 to 0.5% limits the formation of the scale on the CuZn21Si3P alloy while at the same time significantly increasing the binding of the scale to the metal, thereby avoiding unnecessary contamination of the production equipment.

Similar results were found for Cu-Zn-Si-P alloys with different lead contents, for example 0.01%, 0.05%, 0.1% or 2.5%.

Boron not only reduces the susceptibility to scale formation of Cu—Zn—Si alloys, but also has a positive effect on the mechanical properties, since boron makes the microstructure of the alloy more homogeneous. This change to the microstructure of the alloy is illustrated in FIG. 2 as a function of boron concentration. The boron-added CuZn21Si3P alloy has a rough and heterogeneous microstructure (Figure 2 (a)), while the CuZn21Si3P alloy containing 0.0004% boron is already much more homogeneous, with a very uniform grain size. It has a fine structure. Further increasing the boron content to 0.009% yields a more uniform CuZn21Si3P alloy with greater homogeneity, where the grains of the microstructure are no longer visible to the naked eye (FIG. 2 (c)).

In addition to optical changes to the microstructure, the addition of boron also has a beneficial effect on the mechanical properties. This is particularly evident for rods extruded from Cu-Zn-Si alloys. To determine the mechanical properties, samples were taken at the start and end of the rods. The tensile strength of the rod made of CuZn21Si3P alloy without boron shows a difference of more than 60 N / mm 2 at the starting point of the rod compared to the completion point of the rod. In contrast, the corresponding alloys with a boron content of 0.0004% have a difference in tensile strength of less than 40 N / mm 2 between the starting and finishing points of the rods. When 0.009% of boron is added to the CuZn21Si3P alloy, the difference in tensile strength between the starting point and the finishing point is less than 5 N / mm 2.

Thus, the material as a whole has the same mechanical properties. Therefore, uniform strength is obtained throughout the extrusion length. This is due to the grain-refining action by boron.

The table below shows the relationship between the boron content of the Cu—Zn—Si alloy and the increase in homogeneity of the alloy microstructure or the decrease in strength difference in the extruded workpiece.

alloy
location
The tensile strength
Unit: N / ㎡ CuZn21Si3P
Extrusion starting point
Extrusion completion point 514
578 Containing 0.0004% of boron
CuZn21Si3P Extrusion starting point
Extrusion completion point 507
545 Containing 0.009% of boron
CuZn21Si3P Extrusion starting point
Extrusion completion point 508
512

Claims (13)

On a weight percent basis, containing 70-80% copper, 1-5% silicon, 0.0001-0.5% boron and residual zinc, With or without 0.2% phosphorus, arsenic or mixtures thereof, Cu-Zn-Si alloys containing unavoidable impurities. The method of claim 1, Cu-Zn-Si alloy, comprising 75 to 77% copper, 2.8 to 4% silicon, 0.001 to 0.1% boron, and 0.03 to 0.1% phosphorus and / or arsenic on a weight percent basis . The method of claim 1, Group consisting of 0.01-2.5% lead, 0.01-2% tin, 0.01-0.3% iron, 0.01-0.3% cobalt, 0.01-0.3% nickel, and 0.01-0.3% manganese, by weight percent Cu-Zn-Si alloy, characterized in that it further comprises one or more elements selected from. The method of claim 3, On a weight percent basis from the group consisting of 0.01-0.1% lead, 0.01-0.2% tin, 0.01-0.1% iron, 0.01-0.1% cobalt, 0.01-0.1% nickel and 0.01-0.1% manganese Cu-Zn-Si alloy, further comprising at least one element selected. The method of claim 1, At least one element selected from the group consisting of up to 0.5% silver, up to 0.5% aluminum, up to 0.5% magnesium, up to 0.5% antimony, up to 0.5% titanium, and up to 0.5% zirconium Cu-Zn-Si alloy characterized in that it further comprises. The method of claim 1, On a weight percent basis from the group consisting of 0.01 to 0.1% silver, 0.01 to 0.1% aluminum, 0.01 to 0.1% magnesium, 0.01 to 0.1% antimony, 0.01 to 0.1% titanium and 0.01 to 0.1% zirconium Cu-Zn-Si alloy, characterized in that it further comprises at least one element selected. The method of claim 1, Further comprising at least one element selected from the group consisting of up to 0.3% cadmium, up to 0.3% chromium, up to 0.3% selenium, up to 0.3% tellurium, and up to 0.3% bismuth Cu-Zn-Si alloy characterized by the above. The method of claim 1, On a weight percent basis, at least one element selected from the group consisting of 0.01-0.3% cadmium, 0.01-0.3% chromium, 0.01-0.3% selenium, 0.01-0.3% tellurium, and 0.01-0.3% bismuth Cu-Zn-Si alloy, characterized in that it further comprises. Electrical engineering parts, sanitary container parts, containers for the transport or storage of liquids or gases, torsionally loaded parts, recyclable parts, drop-forged parts, semi-finished products, strips, sheets, profile sections The Cu-Zn-Si alloy according to any one of claims 1 to 8, which is used as a plate or a refined, rolled or cast alloy. As a manufacturing method of the Cu-Zn-Si alloy in any one of Claims 1-8, A continuous casting and hot rolling treatment in a conventional manner at 600 to 760 캜, followed by a deformation treatment. As a manufacturing method of the Cu-Zn-Si alloy in any one of Claims 1-8, Continuous casting and hot rolling treatment in a conventional manner at 600-760 ° C. followed by cold rolling and further annealing and deformation steps. As a manufacturing method of the Cu-Zn-Si alloy in any one of Claims 1-8, A continuous casting and extrusion treatment in a conventional manner at a temperature of 760 ° C. or lower, followed by cooling in air. As a manufacturing method of the Cu-Zn-Si alloy in any one of Claims 1-8, A continuous casting and extrusion treatment in a conventional manner at a temperature of 650 to 680 ° C., followed by cooling in air.

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