Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon

Definitions

• the invention relates to a brass alloy for use in the manufacture of semi-finished products intended for machining, the brass alloy consisting essentially of copper and zinc and having at least one additional alloying component.
• Corresponding brass alloys are often produced as semi-finished products in strip or wire form and subsequently processed into finished products. The further processing takes place frequently by application of cutting operations.
• lead When machining brass, it has proven advantageous in the past to add lead to the alloy in an amount of up to four percent by weight.
• the lead has a positive effect as a chip breaker, extends the tool life and reduces the tensile forces. Important material parameters such as strength and corrosion resistance are not adversely affected by an addition of lead.
• the object of the present invention is therefore to define a lead-free brass alloy of the aforementioned type, which achieves good machinability, adequate mechanical properties and the lowest possible wear on the cutting tools used.
• the aim of this invention is also to minimize the proportion of ecologically harmful alloying elements.
• This invention is further based on the object to achieve specific properties by the targeted combination of non-polluting alloying elements and on the manufacturing process.
• the idea is based on the inventions essential to the invention in order to achieve the desired material properties: a) The microstructure is influenced by changing the copper / zinc ratio such that an alpha / beta crystal mixture is present in which the proportion of beta phase is about 30 to 70%. Since the beta phase shows a brittle behavior under normal decomposition conditions, its increased proportion leads to a more favorable machining behavior. b) Further alloying elements serve to stabilize the alpha and the beta phase, in particular during the production process of the semifinished product. c) In addition, the chipping behavior and the mechanical properties are positively influenced by the targeted addition of further precipitates of forming elements. On the one hand excretions favor a short breaking chip.
• a fourth advantage can be achieved by influencing the arrangement or orientation of the two phases alpha and beta and / or the precipitates, so as to adjust the processing properties in a targeted manner (eg by a combination of forming or heat treatment).
• a content of lead is at most 0.1 weight percent, that the proportion of zinc 40.5 to 46 weight percent and the proportion of copper is at most 59 weight percent and that the alloy Mixed crystal with proportions of both an alpha-structure and a beta-structure, wherein the weight fraction of beta-structure is at least 30% and at most 70% and that the proportion of each additional alloying component at most 1.0 percent by weight and the sum of the shares of all additional Alloy components is at least 0.5 percent by weight.
• certain properties of the alloy are particularly desired depending on the application. For this purpose, it is envisaged to add each of the mentioned alloying elements in a higher concentration in each case, without thereby increasing the total amount of alloying elements (except copper and zinc).
• the precipitations contained in the microstructure which are also found in the soft alpha microstructure, support the chipping behavior positively.
• the alpha microstructure of the mixed crystal forms a cubic face-centered spatial structure.
• the beta-mixed crystal forms a cubic body-centered structure.
• the proportion of the beta structure is at least 50%. This is particularly supported by the fact that a zinc content of about 42 percent by weight is present.
• the elements iron and nickel have a regulative influence on the grain growth of the alpha and beta phase, with nickel additionally promoting the stabilization of the alpha structure. Too high levels lead to embrittlement of the alloy.
• the elements tin, silicon, manganese and iron stabilize and increase the proportion of the beta phase.
• phosphorus may be provided.
• a maximum proportion of phosphorus in the range of 0.1% by weight is intended.
• the content of copper is 54 to 59.0% by weight.
• the proportion of zinc is 40 to 46 weight percent.
• a first additional alloying component is defined by the proportion of iron being from 0.1 to 0.5 percent by weight. Iron is used to control the grain size of the alpha and beta phases. Contents less than 0.1% do not have a sufficient effect. Shares greater than 0.5% would lead to very large iron precipitates, which have a negative effect on the mechanical properties of the alloy.
• the proportion of iron is 0, 2 to 0, 3 weight percent.
• a second additional alloying component is defined by the proportion of nickel being from 0.1 to 0.5 percent by weight. Nickel stabilizes the alpha phase.
• the proportion of nickel is 0.2 to 0.3 weight percent.
• a third additional alloying component is defined by the proportion of silicon being 0.01 to 0.20 percent by weight. Silicon stabilizes the beta phase and together with other elements forms fine precipitates, which have a positive effect on the cutting behavior and are responsible for grain refining.
• the proportion of silicon is 0.03-0.08% by weight.
• a fourth additional alloying component is defined by the proportion of manganese being 0.01 to 0.20 percent by weight. Manganese stabilizes the beta phase and together with other elements forms fine precipitates, which have a positive effect on the cutting behavior and are responsible for grain refining.
• the proportion of manganese is 0.03 to 0.08 weight percent.
• a fifth additional alloying component is defined by the proportion of tin being from 0.1 to 0.5 percent by weight.
• the proportion of tin is from 0.2 to 0.3 percent by weight.
• Phosphor leads to an improved corrosion resistance of the alloy, in particular P also counteracts a delicacy.
• a preferred embodiment of the alloy preferably has the following percentages by weight with respect to its composition. Copper in the range of 54% to 59.5%, 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% and tin in the range of 0.1% to 0.5% and lead with a maximum of 0.1%.
• the lead content of the alloy is, also due to the use of scrap in the production of such alloys, max. 0.1%.
• the proportions of copper and / or zinc are optionally reduced.
• the proportion of copper is 57.0% to 57.5%, the proportion of zinc 41.9 to 42.5, the proportion of nickel 0.2% to 0.3%, the proportion of iron 0.2% to 0.3%, the proportion of silicon 0.03% to 0.08%, the proportion of manganese 0.03% to 0.08% and the proportion of tin 0.2% to 0.3 % and lead content less than 0.1%.
• the sum of the weight proportions of all other possible components is not more than 0.2%.
• compositions it is basically possible to add only some of the listed elements to the alloy. According to a very particularly preferred embodiment, however, it is envisaged to add all the above-listed elements with a weight proportion within the respectively defined intervals in combination with one another to the alloy.
• the lead content is in an interval of 0.01% to 0.1%. Due to the relationship between the alpha mixed crystal and the beta-mixed crystal according to the invention, the desired material properties can be achieved even with reduced lead contents.
• the alpha-mixed crystal leads to a relatively good deformability of the alloy and gives this tough properties.
• the Mixed crystal is relatively poorly deformable and brittle. These properties are desirable for good sparability.
• the relationship of the alpha and beta fractions according to the invention thus gives the alloy sufficient toughness to aid ductility and brittleness to aid machinability.
• a preferred production process can be carried out such that first an extrusion in a temperature range of 600 to 750 0 C is performed. This produces a microstructure which has a proportion of the beta mixed crystal of about 50 percent by weight.
• an intermediate annealing In this case, an intermediate annealing at a temperature of about 500 to 600 ° C. is carried out after a first forming step. The intermediate annealing leads to a recrystallization and thus to a Kornneu Struktur. As a result, a fine-grained microstructure is supported.
• the brass alloy of copper and zinc with a lead content of 0.01 to 0.1 percent and with at least one further alloying component.
• This further alloying component influences the microstructure of the mixed crystal in order to achieve the respective desired material properties depending on the application.
• This embodiment leads to a particularly high proportion of beta-mixed crystals between 55 and 70% beta-portion, which causes a particularly short-breaking chip.
• Another preferred embodiment is provided in terms of weight percent by the following alloy.
• the brass alloy according to the invention serves to produce so-called semi-finished products which are subjected to at least one further processing step.
• the semi-finished products are typically produced by a casting process. Typical embodiments of such semi-finished products are wires, profiles and / or rods.
• the further processing step comprises at least one machining operation.
• the further processing step may comprise a combination of shaping and machining.
• the shaping can be carried out both at room temperature and at an elevated temperature. At elevated temperatures, a half-warm temperature of up to about 450 ° Celsius and a hot-work temperature be distinguished in a range of 600 ° Celsius to 850 ° Celsius.

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• 2009
  • 2009-08-18 DE DE102009038657A patent/DE102009038657A1/de not_active Withdrawn
• 2010
  • 2010-08-17 PL PL10768172T patent/PL2467507T3/pl unknown
  • 2010-08-17 DE DE112010003316T patent/DE112010003316A5/de active Pending
  • 2010-08-17 HU HUE10768172A patent/HUE043477T2/hu unknown
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  • 2010-08-17 US US13/391,195 patent/US20120207642A1/en not_active Abandoned
  • 2010-08-17 EP EP10768172.8A patent/EP2467507B1/de active Active
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