EP4039838A1 - Alliage de laiton et procédé de fabrication d'un demi-produit à partir d'un tel alliage de laiton - Google Patents

Alliage de laiton et procédé de fabrication d'un demi-produit à partir d'un tel alliage de laiton Download PDF

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Publication number
EP4039838A1
EP4039838A1 EP22154005.7A EP22154005A EP4039838A1 EP 4039838 A1 EP4039838 A1 EP 4039838A1 EP 22154005 A EP22154005 A EP 22154005A EP 4039838 A1 EP4039838 A1 EP 4039838A1
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EP
European Patent Office
Prior art keywords
brass alloy
weight
proportion
alloy according
brass
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22154005.7A
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German (de)
English (en)
Inventor
Andrea Torresi
Dirk Rode
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Hme Brass Germany GmbH
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Hme Brass Germany GmbH
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Publication date
Application filed by Hme Brass Germany GmbH filed Critical Hme Brass Germany GmbH
Publication of EP4039838A1 publication Critical patent/EP4039838A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • C22C9/04—Alloys based on copper with zinc as the next major constituent
    • 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
    • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
    • 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 producing semi-finished products for machining and a method for producing a semi-finished product intended for machining.
  • Brass is an alloy of copper with zinc. Zinc contents of 5 - 45% by weight are common.
  • the alloy can contain lead and other alloying elements such as aluminum, iron, manganese, nickel, silicon or tin, which primarily serve to increase strength and improve sliding properties and corrosion resistance.
  • the added alloying elements determine the processing options and manufacturing processes, with production as a wrought alloy being the most important form in practice. The usual processing follows by archetypes in continuous or discontinuous casting plants and forming with extrusion or rolling and drawing, as well as subsequent thermal treatment. In this way, semi-finished products are produced in the form of rods, hollow rods or strips, which are further processed into different geometries, such as wires. With the specifically set material properties, products are made from it, eg for sanitary areas, electrical applications and in mechanical engineering and vehicle construction. Copper-zinc cast alloys are produced as sand, permanent mold, centrifugal, continuous and pressure casting.
  • brass alloys with less than 37% zinc show a homogeneous alpha structure with a cubic face-centered lattice.
  • the beta structure also occurs as a second phase.
  • the atoms of the crystal lattice are arranged body-centered cubic.
  • Body-centered cubic space lattices have fewer slip planes, so that this component of the structure has less plasticity.
  • the brass material contains both alpha and beta phases.
  • the proportion of the beta phase in the overall structure increases with the zinc content.
  • the material properties of the brass alloy are significantly changed by the beta structure.
  • the gamma phase can occur, the brittleness of which must be taken into account with larger proportions in the structure.
  • the aforementioned classification of the microstructure also results from the addition of approx. 1.5 - 3.5% by weight of lead to the alloy.
  • Lead in these amounts is insoluble in a copper-zinc alloy.
  • Lead inclusions form, which act as chip breakers, improving machinability.
  • Brasses with a higher zinc content are influenced in terms of material properties, in particular by the content of other alloying elements, such as the addition of aluminium, tin, nickel, iron, silicon and manganese.
  • the additives mentioned shift the phase boundaries of the copper-zinc system with their alpha and beta components. They influence the composition and properties of the structure.
  • the alloying elements generally serve to improve the strength, as well as the sliding and wear properties as well as the corrosion resistance.
  • the material CuZn21Si3 dispenses with e.g. B. the addition of lead. Instead, silicon and the silicides formed from it are used as chip breakers. It is a special brass with a low Zn content and a relatively high Si content. This creates a separate material class with a mandatory separate material cycle. The processing of these materials requires a modified manufacturing process and shows better machinability in further processing, but only with significant process adjustments.
  • the machinability of brass materials can be increased by adding bismuth (Bi).
  • bismuth bismuth
  • the addition of bismuth is viewed critically in processing. Bismuth can lead to very strong embrittlement effects. Even trace impurities in other wrought copper-zinc materials can lead to catastrophic failures. The addition of bismuth is therefore not accepted in Europe, so that hardly any materials containing Bi are used.
  • tellurium acts as a chip breaker through the formation of high-melting tellurides in copper-zinc alloys and thus provides better machining properties.
  • tellurium is also a material that is in great demand in other technological areas, so that tellurium cannot be used economically to improve the machinability of brass materials.
  • the DE 10 2009 038 657 A discloses a brass alloy that is essentially lead free but includes a mandatory combination of iron, nickel and tin.
  • the obligatory nickel content can lead to the most common form of contact allergy, the so-called nickel allergy, when it comes into contact with the skin.
  • the nickel allergy causes a rash, so alloys made from these materials cannot be used for applications where skin contact cannot be excluded.
  • the invention has for its object to show a brass alloy for the production of semi-finished products for machining that has a sufficient Possesses machinability and therefore has sufficient strength, sufficient ductility and sufficient electrical conductivity.
  • the brass alloy in question should be able to be produced economically and, despite being sufficiently machinable, should avoid high silicon contents and be as bismuth-free as possible so that the alloy does not lead to trace impurities in other copper-zinc wrought materials Substantially lead-free (Pb ⁇ 0.1% by weight).
  • a method for producing a semi-finished product intended for machining is the subject of patent claim 13.
  • a brass alloy for the production of semi-finished products for machining, the brass alloy consisting of the following alloying elements in % by weight: Cu 54.0 - 59.0 Zn 40.5 - 46.0 pb 0.02 - 0.10 feet 0.10 - 0.50 Mn 0.10 - 0.50 sn 0.10 - 0.60 P ⁇ 0.20 optional S 0.010 - 0.030 si 0.020 - 0.20 co 0.10 - 0.30 Te ⁇ 0.50 and smelting-related impurities below 0.20, the proportion of Ni in the smelting-related impurities being less than 0.080.
  • the material is essentially lead-free, as the lead content is limited to a maximum of 0.10% by weight. The minimum proportion is 0.02% by weight.
  • a further characteristic of the brass alloy according to the invention is the combination with small proportions of other alloying elements which serve to simultaneously or optionally stabilize the beta microstructure with the aim of promoting machinability.
  • the beta microstructure is decisive for the strength and machinability of the material, due to its body-centered cubic crystal structure, which has a chip-breaking effect and is therefore beneficial with regard to machinability.
  • alloying elements uses both solid solution strengthening and precipitation hardening as strengthening mechanisms. Machinability is significantly improved compared to lead-free brass alloys without the addition of these alloying elements.
  • the beta phase is stabilized by reducing the alpha-stabilizing nickel content.
  • Nickel is avoided as far as possible and should not exceed a maximum content of 0.08% by weight within the scope of the unavoidable impurities caused by the melting process and is not specifically alloyed.
  • the stabilization of the beta phase can also take place via targeted temperature control during the first hot forming process step.
  • the lowering of the nickel content also has the effect that the alloy according to the invention cannot trigger a nickel allergy. This increases the handling and also the application-related benefits of the brass alloy.
  • the alloying elements iron and manganese are added in a targeted manner in order to increase the basic strength values of yield point and tensile strength of the brass alloy according to the invention; furthermore, the material properties are determined by subsequent cold forming and heat treatment.
  • Iron is used as an element that refines the structure, which initially has a positive effect on a homogeneous, less coarse-grained structure. Furthermore, iron shows a favorable influence the machinability, especially in combination with other effects.
  • the minimum proportion of 0.10% by weight should not be undercut in order to achieve a significant influence on the stability of the structure when combined with other alloying elements. Depending on the selection of the thermal processing parameters in particular, too high a proportion of iron greater than 0.5% by weight could lead to larger precipitations, especially in combination with manganese.
  • the brass alloy according to the invention optionally contains silicon, but in very limited proportions. Compared to the known brass alloys with a high silicon content of 2-3% by weight, the Si content should be limited to 0.020-0.20% by weight. This very small addition of silicon leads to the formation of a few silicides, particularly in the form of iron silicides. Iron silicides have a positive effect on machinability. However, it has surprisingly been shown that the combination with the other measures mentioned leads to relatively good machinability, even if the silicon content is limited to values below 0.20. Due to its close similarity, the alloying element manganese is completely soluble in copper and contributes to increasing the strength of the brass alloy through the effect of mixed crystal formation. In the absence of silicon, this is surprising insofar as only very few manganese silicides can be formed in view of the non-existent or very low silicon proportions of max. 0.20%.
  • a small proportion of cobalt is optionally alloyed in, but this is limited to a maximum of 0.30% by weight and preferably does not exceed 0.1% by weight in order not to have too strong an interaction with manganese to cause recrystallization inhibition.
  • the brass alloy according to the invention contains tin. Tin has good solubility with copper and zinc. Although tin is usually alloyed in as an element that has a favorable influence on the corrosion behavior, this only plays a subordinate role in the brass alloy according to the invention. Rather, the alloying of tin ensures that tin is included in the mixed crystal, since fewer copper atoms are replaced directly in the lattice of the crystals due to the omission of nickel. The tin content is therefore relatively high at up to 0.6% by weight.
  • the proportion of lead is based on a maximum upper limit of 0.10% by weight.
  • Lead has a relatively positive influence on machinability even with a smaller content, whereby the influence decreases as the lead content decreases.
  • the alloy according to the invention contains phosphorus up to a maximum of 0.20% by weight.
  • Phosphorus has a beneficial effect on the molten liquid during the casting process and, in the absence of nickel and silicon, surprisingly plays a positive role through the formation of extremely fine phosphides, which, in addition to the other alloying element effects, also have a positive effect on the machining behavior assessed to evaluate the alloy.
  • Arsenic is not used for environmental reasons.
  • the brass alloy according to the invention contains smelting-related impurities or production-related admixtures with a total content of less than 0.20% by weight, the proportion of Ni due to the special alloy composition being attributable to the smelting-related impurities and being less than 0.080% by weight.
  • the impurities caused by the melting process or admixtures caused by the manufacturing process are only present in such small proportions that they avoid undesirable side effects.
  • All element concentrations of the brass alloy according to the invention are designed in such a way that they can be classified as particularly environmentally friendly and user-friendly.
  • the compositions are roughly based on the values specified in the DIN EN 12164 - 12168 series of standards, but the ranges of element combinations mentioned can also be outside the framework defined there.
  • the content of Zn is preferably in a range of 41.50 - 42.50% by weight.
  • the proportion of Fe is preferably in a range from 0.20 to 0.40% by weight.
  • the content of Sn is preferably in a range of 0.20 - 0.40% by weight.
  • the content of Mn is preferably in a range of 0.10 - 0.30% by weight.
  • the proportion of Si is preferably in a range of 0.080 - 0.150% by weight.
  • the maximum Co content is 0.1% by weight.
  • the brass alloy according to the invention has a beta solid solution content of more than 71% and less than 78%. It is preferably around 75%; with beta mixed crystal proportions of up to 70%, the machining-promoting effect of this microstructure proportion is not used clearly enough with the relatively higher alpha microstructure proportion.
  • a preferred brass alloy with the aforementioned properties has the following composition (all data are in percent by weight): Cu 57.60 - 58.00 Zn 41.50 - 42.50 pb 0.02 - 0.10 feet 0.20 - 0.40 Mn 0.10 - 0.30 sn 0.20 - 0.40 P ⁇ 0.20 optional S 0.010 - 0.030 si 0.080 - 0.150 co 0.10 - 0.30 Te ⁇ 0.50 and melting-related impurities below 0.20, the proportion of Ni in the impurities resulting from the smelting being less than 0.080.
  • the brass alloy according to the invention has the following composition (all data in percent by weight): Cu 57.60 - 58.00 Zn 41.50 - 42.50 pb 0.02 - 0.10 feet 0.26 - 0.34 Mn 0.10 - 0.15 sn 0.26 - 0.34 P ⁇ 0.20 si 0.030 - 0.060 optional S 0.010 - 0.030 co 0.10 - 0.30 Te ⁇ 0.50 and melting-related impurities below 0.20, the proportion of Ni in the impurities resulting from the smelting being less than 0.080.
  • All of the above brass alloys are binary alloys containing copper and zinc.
  • the alloys do not contain any other specifically alloyed elements.
  • the alloying elements mentioned add up to 100% by weight.
  • the brass alloy therefore consists of the alloying elements mentioned meaning of a concluding list.
  • the proportions of copper and zinc are selected within the specified limits in such a way that a total of 100% by weight is achieved with the other mandatory and optional alloying elements, including the impurities of less than 0.2% by weight caused by the smelting. If the copper content is set to a low level of, for example, 54% by weight, the proportion by weight of zinc closes the gap of up to 100% by weight. The same applies to a higher proportion of copper.
  • the proportion of zinc is selected to be correspondingly lower, so that the gap is closed at 100% by weight.
  • the respective residual proportions of copper and zinc are within the weight percentage ranges specified in the respective patent claims or in the respective exemplary embodiments.
  • the alloy is completely quantitatively and qualitatively recorded by the rest, such as Zn. The sum of all specified parts by weight is always 100% by weight.
  • the invention also relates to a method for producing a semi-finished product intended for machining using a brass alloy according to the above features, the brass alloy being extruded at a temperature between 550° C. and 750° C.
  • extrusion should not be followed by a longer holding time with standing heat or insufficient cooling, but should be cooled intensively within a few minutes.
  • accelerated cooling to a temperature below 450 °C within 3 seconds can take place, e.g. B can be realized with an air/water mixture.
  • the additional cooling results in a structure that is easier to process, depending on the requirements in the subsequent machining process. Due to the relatively high quenching rate based on the extrusion temperature, a microstructure with a high beta microstructure content of approx. 75% is set. The quenching speed brings about both precipitation and solid solution strengthening, which leads to the desired material that is sufficiently easy to machine.
  • the material according to the invention is for the first time environmentally friendly and user-friendly due to the targeted simultaneous freedom from lead (Pb ⁇ 0.1% by weight) and freedom from nickel (Ni ⁇ 0.080% by weight) with relatively good machinability material created.
  • Pb ⁇ 0.1% by weight the targeted simultaneous freedom from lead
  • Ni ⁇ 0.080% by weight the targeted simultaneous freedom from nickel
  • With the method according to the invention using the brass alloy according to the invention, geometries in particular in the form of bars, hollow bars and profiles can be produced.
  • the figure 1 shows an image of tangled chips of a binary brass alloy CW510L or CuZn42. They represent the starting point of the brass alloy according to the invention and demonstrate unfavorable chip formation, which leads to problems in the removal of the chips and thus causes susceptibility to failure during machining if higher demands are placed on the cutting performance.
  • the material according to the invention was evaluated using the usual machining parameters.
  • the machining with external turning of round bars as part of a routine production takes place in the example of the Figures 1 and 2 on the same machines, under the same conditions, without specific adaptation of the machining parameters such as tool material, geometries and machining parameters such as cutting infeed, speed and cooling/lubricant strategy.
  • the comparison is only intended to enable a relative evaluation of the materials in the individual case shown, without making an absolute statement on machinability.
  • the material according to the invention lead-free and thus more environmentally friendly and also improved in handling due to the absence of nickel, is significantly more suitable for machining than the comparison material.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Conductive Materials (AREA)
EP22154005.7A 2021-01-29 2022-01-28 Alliage de laiton et procédé de fabrication d'un demi-produit à partir d'un tel alliage de laiton Pending EP4039838A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102021102120.0A DE102021102120A1 (de) 2021-01-29 2021-01-29 Messinglegierung und Verfahren zum Herstellen eines Halbzeugs aus dieser Messinglegierung

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EP4039838A1 true EP4039838A1 (fr) 2022-08-10

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EP22154005.7A Pending EP4039838A1 (fr) 2021-01-29 2022-01-28 Alliage de laiton et procédé de fabrication d'un demi-produit à partir d'un tel alliage de laiton

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009038657A1 (de) 2009-08-18 2011-02-24 Aurubis Stolberg Gmbh & Co. Kg Messinglegierung
DE102015212937A1 (de) * 2015-07-10 2017-01-12 Aurubis Stolberg Gmbh & Co. Kg Messinglegierung
EP3529389B1 (fr) * 2018-01-09 2020-03-04 Otto Fuchs - Kommanditgesellschaft - Alliage cuivre-zinc

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004244672A (ja) 2003-02-13 2004-09-02 Dowa Mining Co Ltd 耐脱亜鉛性に優れた銅基合金

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009038657A1 (de) 2009-08-18 2011-02-24 Aurubis Stolberg Gmbh & Co. Kg Messinglegierung
DE102015212937A1 (de) * 2015-07-10 2017-01-12 Aurubis Stolberg Gmbh & Co. Kg Messinglegierung
EP3529389B1 (fr) * 2018-01-09 2020-03-04 Otto Fuchs - Kommanditgesellschaft - Alliage cuivre-zinc

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