ES2828578T3 - Brass alloy - Google Patents

Abstract

The brass alloy made from 54 to 64% by weight of Cu and from 36 to 46% by weight of Zn, wherein the alloy has an indium content of 0.005 to 1.0% by weight, has the addition of at least one of the Fe, Sn, Ni or Mn components in a total of 0.01 to 3.0% by weight but without the addition of Bi, - optionally has a Si proportion of 0.01 to 0.2% by weight , - optionally has a Sb content of up to 0.5% by weight, - optionally has a cadmium content of up to 0.5% by weight, - optionally has a Ca content of up to 1.0% by weight, - optionally has a Mg content of up to 1.0% by weight, - optionally has a Se content of up to 0.5% by weight, - optionally has a phosphorus content of at most 0.1% by weight, and - optionally it has a Cr proportion of 0.01 to 0.2% by weight, together with impurities.

Description

DESCRIPTION

Brass alloy

[0001] The invention relates to a brass alloy with the characteristics of the preamble of claim 1.

[0002] Corresponding brass alloys are often produced as semi-finished products in strips, in the form of wire, rods, sheets or plates and then processed into final products. Additional processing is often carried out by machining processes.

[0003] In machining brass it has proven advantageous to add lead to the alloy in an amount of up to four percent by weight. Lead has a positive effect as a chip breaker, prolongs tool life and reduces cutting forces. Important material parameters such as strength and corrosion resistance are not adversely affected by the addition of lead.

[0004] Despite the positive properties of lead, efforts are being made, among others, supported by the EU Directive 2011/65 / EU (RoHS II) and its precursors 2002/95 / EC (RoHS I), the Extreme Directive 2000/53 / CE and Directive 2002/96 / CE on waste electrical and electronic equipment to replace lead as a cutting element in brass.

[0005] Studies previously carried out with alternative alloy variants, however, have not led to materials that meet the necessary requirements. These are significantly more expensive than lead-containing brass alloys, cause excessive tool wear, or also contain alloying elements that are harmful to the environment. In WO2011 / 020468, for example, a brass alloy with good machinability is described.

[0006] In the production of brass alloys, both good machinability and good formability are sought. A simultaneous optimal fulfillment of both requirements is difficult, since, as a general rule, all measures that positively support a desired property lead to a deterioration of the second property. Typically, a compromise is chosen in such a way that a high level of strength with sufficient deformability is provided at the same time.

[0007] The object of the present invention is therefore to create an alternative brass alloy that has good machinability, adequate mechanical properties and causes the least possible wear on the cutting tools used.

[0008] According to the invention, a brass alloy with the characteristics of claim 1 is proposed to achieve the objective. Other preferred embodiments of the invention can be found in the dependent claims, the figures and the associated description.

[0009] According to the basic idea of the invention it is proposed that the brass alloy has an indium content of 0.005 to 1.0 percent by weight and an addition of at least one of the components Fe, Sn, Ni or Mn of 0.01 together of 3.0 weight percent and without the addition of bismuth.

[0010] It has been found that the chip breaker properties of the brass alloy can be positively influenced by the addition of indium, whereby the workability of the brass alloy can be improved. Indium practically replaces previously used lead and achieves the same advantages, so that the lead content in the brass alloy can be reduced to zero in extreme cases and the brass alloy can still be machined very well.

[0011] The properties achievable by the addition of indium are in particular:

- good machinability,

- high strength but still with good ductility,

- a very good hot and cold formability sufficient

- sufficient corrosion resistance.

In this case, the indium content is preferably 0.005 to 1.0 percent by weight, whereby the obtainable advantages can be achieved. In particular, the indium content may be less than 0.25 percent by weight, so that favorable structural properties can already be achieved. In general, the content of indium should be chosen to be quite less, since indium is a comparatively expensive element. In this way, the indium content should be selected as low as possible and yet favorable structural properties should be achieved, for which an indium content of at least 0.05 and a maximum of 0.25 percent has been shown to be useful in weigh.

[0013] In addition, the brass alloy contains a proportion of zinc from 36.0 to 46 weight percent and the proportion of copper is 54-64 weight percent.

[0014] Furthermore, preferably, the alloy has a solid solution in units of an alpha structure or alpha / beta structure. In extreme cases, a brass alloy with an alpha structure of 100% is also conceivable if the zinc content is close to or equal to 36 percent by weight. However, a mixed structure of alpha and beta structures is preferred, as a result of which, in particular, good machinability can be achieved. In particular, the copper content may preferably be at most 60 weight percent and the zinc content may preferably be between 36 and 40 weight percent, as a result of which a structure that is particularly favorable in terms can be achieved. machinability.

[0015] In this case, a mixed structure can be realized with particularly good properties, wherein the weight percentage of the beta structure is 20 to 80 weight percent, preferably 50 percent by weight.

[0016] In addition, it can provide the least one additional alloying component with a proportion of at most 3.0 weight percent, the sum of the proportions of all components additional alloy preferably less 0.2 percent in weigh.

[0017] The proportion of copper is preferably 54 to 64.0 percent by weight, and the proportion of zinc is preferably about 42 percent by weight.

[0018] The inventive idea mentioned below seeks to achieve the desired properties of the material: a) By adding indium to positively influence the breaking properties of the chip. b) The structure is influenced by the proposed copper / zinc ratio in such a way that a mixture of alpha / beta crystals is present where the beta phase proportion is around 20 to 80%. Since the beta phase shows a brittle behavior under normal machining conditions, its higher proportion leads to a more favorable machining behavior. C) Other alloying elements serve to stabilize the alpha and beta phase, especially during the manufacturing process of the semi-finished product. d) Furthermore, the machining behavior and mechanical properties are positively influenced by the selective addition of other elements that form precipitates. On the one hand, rainfall favors chip breakage and, on the other, grain refinement is achieved, which translates into better ductility and high strengths. e) A fourth advantage can be achieved by influencing the arrangement or orientation of the two alpha and beta phases and / or the precipitates in order to adjust the processing properties in a specific way (for example, by a combination of formation and treatment thermal). The chip breaking properties are deliberately achieved by the additives in the alloy and, in particular, through the indium, so that an addition of bismuth is not deliberately provided. However, it cannot be ruled out that small amounts of bismuth enter the alloy due to contaminated scrap, but this should not be understood as a deliberate addition of bismuth. However, the solution according to the invention offers the advantage that the chip breaking properties are now achieved with alloying additives instead of the lead and bismuth components to be avoided, which are much less harmful with regard to possible damage to health.

[0019] The precipitates contained in the structure positively support machinability.

[0020] The alpha structure of the mixed crystal forms form an off-center cubic structure. The mixed beta crystal structure, however, forms a body-centered cubic structure. It is particularly advantageous if the proportion of beta structure is at least 50%. This is particularly supported by the fact that there is a zinc content of around 42 percent by weight.

[0021] The elements of iron and nickel have a regulatory influence on grain growth of the alpha phase and beta, wherein the nickel also promotes stabilization alpha structure. Excessively high proportions make the alloy brittle.

[0022] The elements tin, silicon, manganese and iron stabilize and increase the proportion of beta phase.

[0023] To improve the corrosion resistance, the addition of phosphorus can be envisaged. In particular, a maximum proportion of phosphorus in the range of 0.1 weight percent is intended. Based on a typical alloy composition, the proportion of copper is expected to be 54 to 64.0 percent by weight.

[0024] A first additional alloying component is defined where the proportion of iron 0.05 bis 0.5 percent by weight, preferably 0.2 to 0.3 percent by weight. Iron is used to control the grain size of the alpha and beta phases. Contents less than 0.01% do not have a sufficient effect. Proportions greater than 0.5% would lead to very large iron precipitates, which have a negative effect on the mechanical properties of the alloy.

[0025] A second additional alloy component is defined where the nickel content is 0.05 bis 0.5 weight percent, preferably 0.2 to 0.3 weight percent, which advantageously stabilizes the alpha phase. .

[0026] A third additional alloying component is defined where the proportion of silicon is 0.01 to 0.20 weight percent, preferably 0.03 to 0.08 weight percent. Silicon stabilizes the beta phase and, together with other elements, forms fine precipitates, which have a positive effect on machining behavior and are responsible for grain refinement.

[0027] A fourth additional alloy component is defined where the manganese proportion is 0.01 to 0.20 weight percent, preferably 0.03 to 0.08 weight percent. Manganese stabilizes the beta phase and, together with other elements, forms fine precipitates, which have a positive effect on machining behavior and are responsible for grain refinement, similar to the proposed additional alloying component of silicon.

[0028] A fifth additional alloy component is defined wherein the tin content is 0.05 to 0.5 weight percent, preferably 0.2 to 0.3 weight percent.

[0029] A sixth additional alloy component is defined where the Cr proportion is 0.01 to 0.2 weight percent.

Furthermore, the addition of calcium and / or magnesium can in each case provide a proportion of 0.05 to 1.0 percent by weight. Phosphorus leads to better corrosion resistance of the alloy, in particular P also counteracts dezinification.

[0031] It contributes to an optimal composition of the alloy that the proportion of elements other than copper, zinc, indium, iron, nickel, silicon, manganese, antimony, calcium, cadmium, selenium, magnesium, lead or tin, is less than 0.2 percent by weight.

[0032] A preferred embodiment of the alloy in the composition preferably has the following weight percentages. Copper in the range of 54% to 64%, Zinc in the range of 36% to 40.5%, Iron in the range of 0.1% to 0.5%, Nickel in the range of 0.1% to 0 , 5%, silicon in the range of 0.01% to 0.2%, manganese in the range of 0.01% to 0.2%, antimony, calcium, cadmium, magnesium and selenium in the range of up to 0, 1% and tin in the range of 0.1% to 0.5% and lead in a proportion of 0.1% or less. The proportion of indium is preferably 0.005 to 0.5%. The lead content of the alloy, also due to the use of scrap in the production of such alloys, is max. 0.1%.

Consequently, the proportion of the above additives are optionally reduced levels of copper and / or zinc.

According to a particularly preferred embodiment, the proportion of copper is from 57.0% to 57.5%, the proportion of zinc is from 41.9% to 42.5%, the proportion of nickel is 0 , 2% to 0.3%, the proportion of iron is 0.2% to 0.3%, the proportion of silicon is 0.03% to 0.08%, the proportion of manganese is 0.03 % to 0.08%, antimony, calcium, cadmium, magnesium and selenium is in the range of up to 0.1% and the proportion of tin is 0.2% to 0.3% and the proportion of lead and indium less than 0.1%. In addition, it is particularly preferable that the sum of the proportions by weight of all possible additional components is at most 0.2%.

According to a further preferred embodiment, the proportion of copper is from 54 to 58%, zinc from 41 to 45%, nickel from 0.2 to 0.3%, iron from 0.2 to 0.3% , silicon 0.03 to 0.06%, manganese 0.03 to 0.08%, calcium 0.3 to 0.5%, magnesium 0.6 to 0.9%, antimony <0.1%, cadmium <0.1%, selenium <0.1%, the sum of lead and indium <0.1%, other components <0.2%.

With respect to the above composition, it is basically possible to add only some of the listed elements to the alloy. According to a particularly preferred embodiment, however, it is contemplated to add all the elements listed above to the alloy in a proportion by weight within the respective defined ranges in combination with each other.

[0037] According to a typical embodiment, provided that the lead content in a range is 0.005% to 0.1%. The indium content should also be 0.005% to 0.5%. Due to the relationship according to the invention between mixed alpha crystal and mixed beta crystal, the desired properties of the material can be achieved even with low contents of lead or indium. The mixed alpha crystal leads to relatively good deformability of the alloy and gives it tough properties. Mixed beta crystal, on the other hand, is relatively difficult to deform and is brittle. These properties are desirable for good machinability. The ratio according to the invention of the alpha and beta components gives the alloy sufficient toughness to support deformability and sufficient brittleness to support machinability.

[0038] In addition to the pure relationship between alpha and beta components, influencing the grain size of solid solutions has also proven useful. It has been shown to be positive in supporting comparatively small and uniform grain sizes. When iron and silicon are added, iron silicides are formed, which hinder the growth of grains and therefore have a positive effect on the structure. The addition of tin and / or iron promotes the formation of mixed beta crystals.

[0039] It is also shown that the addition of manganese in combination with oxygen or phosphorous favors the precipitation of oxides or phosphides, and thus a finer grain structure is achieved as a result. This in turn promotes good machinability. In small amounts, the proportions of phosphorus are also positive with respect to the training of the microstructure.

With regard to the manufacture of the alloy, a preferred production process can be carried out in such a way that the hot forming (eg hot rolling or extrusion) is carried out in a temperature range of 600 to 750 ° C. This creates a structure that has a beta mixed crystal content of about 50 percent by weight. To support both good machinability and good deformability, intermediate annealing is possible. In this case, after a first shaping step, an intermediate anneal is carried out at a temperature of about 400 to 600 ° C. Intermediate annealing leads to recrystallization and thus the formation of new grains. This supports a fine-grained microstructure.

By properly performing intermediate annealing, it is possible to achieve a beta mixed crystal weight ratio of 30 to 60%. This increases the formability of the semi-finished product.

[0042] According to the invention, it is in particular intended to form the brass alloy from copper and zinc, with a lead content of 0.005 to 0.1%, an indium content of 0.005 to 0.5% and with at least other alloy component. This additional alloying component influences the mixed crystal microstructure to achieve the required material properties for the application.

According to a further preferred embodiment, it is envisaged to make the following alloy in terms of percentages by weight.

[0044] Cu 55 to 56%, Fe 0.2 to 0.3%, Ni 0.1 to 0.2%, Si 0.01 to 0.03%, Mn 0.1 to 0.2%, Sn 0.3 to 0.5%, In 0.05 to 0.2%, Sb <0.1%, Ca <0.1%, Cd <0.1%, Se <0.1%, Pb <0 , 1%, Zn remainder. This embodiment leads to a particularly high proportion of mixed beta crystals with a beta proportion between 55 and 70%, which produces a particularly short refractive index.

[0045] A further preferred embodiment is provided in terms of the weight percent represented by the following alloy.

[0046] Cu 57 to 57.5%, Fe 0.2 to 0.3%, Ni 0.2 to 0.3%, Si 0%, 0% Mn, Sn 0.2 to 0.3%, In 0.05 to 0.2%, Sb <0.1%, Ca <0.1%, Cd <0.1%, Se <0.1%, Pb <0.1%, Zn remainder. The aim of the composition proposed here is to achieve slightly higher alpha content and less harsh excretions.

Furthermore, the making of the following alloy in terms of weight percentages is also contemplated in terms of preferred embodiments.

[0048] Cu 56 to 56.5%, Fe 0.4 to 0.5%, Ni 0.2 to 0.3%, Si 0%, Mn 0.1 to 0.2%, Sn 0.35 to 0.5%, In 0.05 to 0.2%, Sb <0.1%, Ca <0.1%, Cd <0.1%, Se <0.1%, Pb <0.1%, Zn remainder. As a result, less hard precipitates are formed and the formation of mainly precipitated iron precipitates is promoted. The higher addition of manganese and tin results in a higher beta component compared to the previous embodiment.

[0049] The brass alloy according to the invention serves for the production of so-called semi-finished products, which undergo at least one additional processing step. Semi-finished products are typically produced by a casting process. Typical embodiments of such semi-finished products are strips, wires, profiles and / or rods. The further processing step comprises at least one machining process. The further processing step can also comprise a combination of shaping and machining. Shaping can be carried out both at room temperature and at elevated temperature. At elevated temperatures, a warm temperature of up to 450 ° C and a hot forming temperature in a range of 600 ° C to 850 ° C can be distinguished.

[0050] By adding the alloying elements iron, nickel, magnesium, calcium or chromium, precipitates can be produced in the mixed crystals, which in turn favors chip breakage with subsequent mechanical processing, so that these Alloy components have a favorable effect similar to those used up to now and lead that is avoided when possible. Chip breakage can be favorably influenced by a specific ratio of the iron and tin alloy components to each other, since the ratio of these two alloy components particularly favors the formation of precipitates. Such a favorable iron to tin ratio would be 1.0 to 1.2, for example.

[0051] Next, the formation of precipitates or refinement of the grain, and therefore the chip breakage is positively influenced if the brass alloy adds chromium in an amount of 0.01 to 0.2 percent by weight and / or calcium and / or magnesium in an amount of in each case from 0.05 to 1.0 percent by weight.

[0052] Ideally, the amount of bismuth is equal to 0.0 percent, that is, the brass alloy is bismuth-free. The properties that promote chip breaking are achieved only through the content of indium and other components of the alloy such as iron, tin, nickel, manganese, magnesium, calcium or chromium. It is also worth the effort to achieve this because bismuth should also be avoided if possible, or at least used only in the smallest amount possible, due to properties that are harmful to health. For this reason, the proportion of bismuth in the brass alloy according to the invention is already limited to a maximum value of 0.1 percent by weight, therefore it is desirable to keep the proportion of bismuth as low as possible. For example, it is possible for a small amount of bismuth to enter the brass alloy through the use of contaminated scrap. This proportion of really unwanted bismuth is used by the solution according to the invention to form the precipitates and to refine the grain and thus positively influence the machining behavior, and at least the lead, which is also harmful to health, can be dispensed with in the alloy. . If the proportion of bismuth cannot be completely reduced to 0.0, for example due to impurities in the added scrap, the proportion should not exceed a maximum value of <0.003 percent by weight, if possible. Alternatively, in this case also a lead content of a maximum of 0.1 weight percent can be provided to adjust the desired chip breakage. In any case, bismuth is not actively added to the brass alloy according to the invention, but is only accepted if it cannot be avoided for technical reasons. However, since it can have positive effects on the material properties of the brass alloy despite its deleterious properties, very small amounts can also be accepted.

[0053] It is also possible that the structural properties, in particular the formation of the beta phase as needles, are produced by pressing or extraction, or at least that the formation of the beta phase is improved, or carried out in the direction desired. Alternatively, the development of a more globular morphology of the beta phase in the mixed crystal can be supported by a combination of the pressing, annealing and extraction processing steps in this order or pressing, extraction, annealing, extraction, whereby the Grain size and structural components of the beta phase are determined by extraction. The process temperature can be adjusted during annealing, pressing or extraction. Here, the higher the process temperature, the larger the grains and the thicker the structure.

Claims (14)

1. The brass alloy made from 54 to 64% by weight of Cu and 36 to 46% by weight of Zn, wherein the alloy has an indium content of 0.005 to 1.0% by weight, has the addition of at least one of the Fe, Sn, Ni or Mn components in a total of 0.01 to 3.0% by weight but without the addition of Bi, - optionally it has a Si proportion of 0.01 to 0.2% by weight, - optionally has a Sb content of up to 0.5% by weight, - optionally has a cadmium content of up to 0.5% by weight, - optionally has a Ca content of up to 1.0% by weight, - optionally has a Mg content of up to 1.0% by weight, - optionally has a Se content of up to 0.5% by weight, - optionally has a phosphorous content of at most 0.1% by weight, and - optionally has a Cr content of 0.01 to 0.2% by weight, together with impurities 2. brass alloy according to claim 1, characterized in that - the alloy has a solid solution that has proportions of alpha structure or alpha / beta structure with precipitates. 3. brass alloy according to claim 2, characterized in that - the proportion by weight of the beta structure is from 20 to 80% by weight. 4. Brass alloy according to any of the preceding claims, characterized in that - the total of the proportions of all the components of the alloy provided in addition to Cu and Zn is at least 0.2% by weight. 5. Brass alloy according to any of the preceding claims, characterized in that the proportion of Zn is 42% by weight. 6. Brass alloy according to any of the preceding claims, characterized in that the proportion of Fe is from 0.05 to 0.5% by weight. 7. Brass alloy according to any of the preceding claims, characterized in that the Ni proportion is 0.05 to 0.5% by weight. 8. Brass alloy according to any of the preceding claims, characterized in that the Mn content is 0.01 to 0.20% by weight. 9. Brass alloy according to any of the preceding claims, characterized in that the proportion of Sn is from 0.05 to 0.5% by weight. 10. Brass alloy according to any of the preceding claims, characterized in that the proportion of substances that are not Cu, Zn, Fe, In, Ni, Si, Mn, Sb, Ca, Cd, Se, Pb or Sn is less than 0 , 2% by weight. 11. brass alloy according to any of the preceding claims, characterized in that the brass alloy has the following percentages by weight: Cu 55 to 56%; Fe 0.2 to 0.3%; In 0.005 to 0.5%; Ni 0.1 to 0.2%; Yes 0.01 to 0.03%; Mn 0.1 to 0.2%; Sn 0.3 to 0.5%; Sb <0.1%; Ca <0.1%; Cd <0.1%; Se <0.1%; Pb <0.1%; Zn remainder. 12. Brass alloy according to any of claims 1 to 10, characterized in that the brass alloy has the following percentages by weight: Cu 57 to 57.5%; Fe 0.2 to 0.3%; In 0.005 to 0.5%; Ni 0.2 to 0.3%; Sn 0.2 to 0.3%; Sb <0.1%; Ca <0.1%; Cd <0.1%; Se <0.1%; Pb <0.1%; Zn remainder. 13. brass alloy according to any of claims 1 to 10, characterized in that the following percentages by weight are implemented: Cu 56 to 56.5%; Fe 0.4 to 0.5%; In 0.005 to 0.5%; Ni 0.2 to 0.3%; Yes 0%; Mn 0.1 to 0.2%; Sn 0.35 to 0.5%; Sb <0.1%; Ca <0.1%; Cd <0.1%; Se <0.1%; Pb <0.1%; Zn remainder. 14. Brass alloy according to any of claims 1 to 10, characterized in that the following weight percentages are implemented: Cu 54 to 58%; 45% Zn 41; Ni 0.2 to 0.3%; Fe 0.2 to 0.3%; Yes 0.03 to 0.06%; Mn 0.03 at 0.08%; Ca 0.3 to 0.5%; Mg 0.6 to 0.9%; Sb <0.1%; Cd <0.1%; Se <0.1%; the total of Pb and In <0.1%; and other components <0.2%.