Classifications

• • 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
  • C22C9/02—Alloys based on copper with tin as the next major constituent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
  • B21D22/02—Stamping using rigid devices or tools
  • B21D22/022—Stamping using rigid devices or tools by heating the blank or stamping associated with heat treatment
• • 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
  • C22F1/08—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 present invention relates to a copper alloy, its use and a method for producing molded parts, and the molded parts produced therefrom.
• Water is a valuable raw material and indispensable for everyday use. For this reason, the drinking water must be of a microbiological nature when it is removed from the supply system in such a way that subsequent enjoyment does not lead to human illness. In order to achieve this, high demands are placed on materials that come into direct contact with the drinking water. Copper is the most precious commodity and is considered an indispensable material in industry and technology for water-bearing systems. Because copper has bacteriostatic properties and also offers excellent corrosion resistance. Copper also shows positive properties in terms of shape. This makes it easy to cast copper alloys, and its high strength and toughness make the material particularly valued for plastomechanical shaping.
• Gunmetal is one of the copper casting alloys and is characterized by the combination of good castability with optimal machinability and high strength. Due to the good corrosion resistance, gunmetal is particularly suitable for water-bearing systems such as fittings and sanitary engineering. Common gunmetal alloys contain tin to increase strength and corrosion resistance. Zinc is added as an inexpensive substitute for copper. In order to be able to economically process the gunmetal products produced, the heavy metal lead is added, which acts as a chip breaker in the alloy and enables machining on CNC machines and conventional automatic lathes.
• the ideal gunmetal would be free of lead and other questionable substances, with the same or better economic efficiency in production and without affecting the corrosion resistance, the high mechanical strength and the good processability.
• the EP 2290114 A1 describes a lead-free gunmetal alloy with 4 to 6% by weight of tin, 4 to 6% by weight of zinc and less than 0.25% by weight of lead.
• This alloy can be used to produce lead-free components using a casting process. The subsequent mechanical processing to create the functional surfaces of these components remains unconsidered. Without lead, the specified composition shows a homogeneous ⁇ -MK structure, which tends to form long chippings and cannot be machined economically. The required casting process also requires a higher amount of material to produce the molded part than alternative forming processes.
• the US 2012/0082588 A1 , the EP 2 241 643 A1 , the EP 3 225 707 A1 and the US 9,181,606 B2 disclose copper alloys.
• the describes a forming process of a lead-free gunmetal alloy EP 2 872 660 B1 A process is described for preconditioning a gunmetal alloy with 2 to 8% by weight of tin, 2.5 to 13% by weight of zinc and less than 0.25% by weight of lead, which is suitable for hot pressing and at the end of the hot pressing process has a homogeneous structure.
• Hot forming enables the economical production of molded parts with little material. Although the process sequence up to the shaping of the blank is explained, the subsequent machining process necessary to work out the functional surfaces of the components is also not taken into account here.
• the chemical composition and the subsequent hot forming result in a homogeneous microstructure and here too, due to the lack of a chip breaker, long chip formation is to be expected during machining, which makes economical machining of the components difficult.
• the EP 1 801 250 A1 describes low migration components made of a copper alloy that has a relatively high proportion of Si, in addition to smaller but significant proportions of Mn, Al and Zr. Similar copper alloys are also in the WO 2007/068470 disclosed.
• a copper alloy which comprises as few components as possible is lead-free or essentially lead-free and, moreover, can dispense with expensive metal components and / or metal components which are difficult to mix.
• the present invention makes it possible to produce molded parts with high mechanical strengths, with high dimensional stability and with high corrosion resistance from a gunmetal alloy, which has a chip breaker in the structure, by means of hot forming with a low use of material, which subsequently also is economical after the hot pressing process Machining can be subjected.
• the hot-formable gunmetal alloy of the present invention requires no elements such as Al, Si, Pb, Sb, Te, Se, C and Bi to form a chipbreaker in the structure and is therefore highly reusable.
• the present invention therefore provides a copper alloy which, in particular for the production of molded parts from at least one hot-forming process with subsequent machining, has the following composition in% by weight: Sn: 2 to 6% Zn: 0 to 5% S: 0.05 to 0.6% Pb: less than 0.25% Ni: less than 0.6% sb: less than 0.2%, optionally further containing phosphorus up to a maximum of 0.06% by weight, B up to a maximum of 0.003% by weight, Zr up to a maximum of 0.03% by weight and inevitable impurities, the total of the impurities preferably being 0.25% by weight does not exceed, and the rest is Cu.
• the alloy according to the invention in particular contains no elements from the group Al, Si, Sb, Te, Se, C and Bi and, in preferred embodiments, likewise no Pb.
• the copper content in the alloy is preferably 88% by weight or more, more preferably 90% by weight or more.
• the known disadvantages from the prior art can be overcome with the copper alloys disclosed here.
• semi-finished products / intermediate products made from the copper alloy can be subjected to hot forming very well.
• the alloy according to the invention enables the production of molded parts (which may then be further processed, for example by machining), which are still have excellent mechanical properties and show no reduction in corrosion resistance.
• the molded parts obtained in this way can also be processed in an economical manner, since in particular the undesired long chip formation is avoided. It can thus be seen that, despite the processes taking place during hot forming in the structural structure of the alloy, there are still chip-breaking components, although the alloy according to the invention dispenses with typical chip-breaking components such as Pb or Si.
• the present invention provides a copper alloy that has an excellent balance of desired properties. Shaped parts can thus be produced from this alloy, in particular by hot forming, possibly combined with further processing steps as described here, without compromising the further, desired properties of the copper alloy and its suitability for use in hot forming.
• the alloy according to the invention can therefore advantageously be used for the production of molded parts, these production methods comprising hot forming, possibly combined with further processing methods, for example subsequent machining.
• the individual alloy components each alone, but also in their interaction, enable good and reproducible control of the alloy properties.
• Tin acts as a solid solution in the alloy and thus increases the tensile strength, yield strength and hardness, but reduces the elongation at break. Tin also increases corrosion resistance, with corrosion resistance increasing as the tin content increases.
• tin in the structure caused strong segregations, which lead to the formation of zone crystals during solidification.
• copper crystals with less tin are separated out and the residual melt is enriched with a tin content which is above the average content of the alloy.
• Sulfur is almost insoluble in solid copper and the original properties of the material, such as corrosion resistance, are not affected by the addition of sulfur. Due to the insolubility in solid copper, sulfur leads to a constitutional behavior that influences the solidification process of copper-tin alloy in a similar way to lead. Unlike lead, sulfur does not exist in the structure at the end of solidification, but in the form of an intermetallic metal-sulfur compound that is evenly distributed in the structure. It could be seen that this phase is incoherent and brittle in the structure and thus creates a chip-breaking mechanism.
• the properties of the sulfides influence the mechanical, plastic behavior of the gunmetal material.
• the influence is determined via the proportions of the sulfide phases in the material. From a sulfur content of more than 0.6% by weight, the stress-transferring ⁇ -Cu matrix is so badly affected by the sulfides that a hot pressing process is very difficult.
• the sulfur content of 0.05% by weight to 0.6% by weight, particularly preferably 0.1% by weight to 0.45% by weight ensures that sufficient sulfide inclusions are present in the structure to make a chip-breaking one Generate mechanism and ensure a hot forming process.
• Zinc is added to the alloy as an economical substitute for copper. It was recognized that there is a close relationship between the zinc content and the sulfur content via the point in time and the type of distribution of the sulfide formation. The higher the zinc content, the sooner the sulfide inclusions form in the structure during casting solidification. If the zinc content is above 5% by weight, the sulfide formation is shifted to temperatures in the range of the solidification temperature of the gunmetal alloy. In this temperature range, there are still high molten parts in the cast structure, which are connected to one another in places.
• the sulfides Due to the high zinc content, the sulfides form early. These sulfides are inhomogeneous and concentrated in places in the structure and thus complicate the hot pressing process by locally weakening the ⁇ -MK matrix. If the zinc content is low, the formation is shifted to lower temperatures and the sulfides are present in former melt areas separately and homogeneously distributed.
• the zinc content of 0 to 5% by weight, particularly preferably 0 to 3% by weight of zinc, ensures that sulfide formation at higher temperatures is avoided.
• the copper alloy according to the invention due to the specific composition, is particularly suitable for use in a production process for molded parts, this process comprising at least one hot forming. Due to the special composition of the alloy, further processing steps can also be carried out without problems after hot forming, for example subsequent machining.
• Hot forming according to the invention can be a hot pressing process, for example. According to the invention, however, other hot forging operations are also possible which are known to the person skilled in the art. Before hot forming, for example a hot pressing process, the blank is heated to 600 ° C to 950 ° C. From 600 ° C the yield strength is sufficiently deep to plastically deform the red bronze material using a hot forming process. According to the invention, hot forming can be carried out at any suitable temperature in the above-mentioned temperature window, for example at 700 to 900 ° C. The respective temperature is selected by the person skilled in the art depending on the type of molded part, the desired speed of the forming, etc.
• the ⁇ -MK matrix is then dynamically recrystallized, which eliminates the zone mixed crystal with different tin concentrations that previously existed in the as-cast state and ensures a homogeneous concentration over the cross-section and thus constant mechanical characteristics and corrosion properties.
• the sulfides are redistributed and brittle in the structure at room temperature, with which they act as chip breakers. It was found that even with thermoformed molded parts with low sulfur contents from 0.05% by weight, the tool slips back during mechanical processing due to the frictional relationships between the chip and the tool that change over time. These changes in friction are due to the inhomogeneous structure that follows the hot pressing process consists of a copper-containing ⁇ -MK matrix with sulfides embedded in it. Due to the slip sliding, shear bands are created in the chip, which lead to lamellar chips and shear chips and break in the further course of the machining process when removed via a chip breaker in the tool. This prevents long chips and enables economical machining.
• the mean grain size in the cast state should not be more than 2 mm.
• the person skilled in the art is familiar with the measures required to ensure such an average grain size.
• Grain refinement is possible, for example, through the use of chemical additives such as zirconium and boron up to a content of 0.005 to 0.03% by weight or other alternative methods for grain refinement such as electromagnetic stirring, ultrasound excitation, vibration, gas injection or by means of strong supercooling Melt during casting.
• the copper alloy described above is particularly suitable for use in the production of molded parts, the production comprising at least one hot forging. It is also possible to use it for the production of molded parts, in which further processing steps take place after the at least one hot forming, for example a subsequent machining operation.
• the corresponding manufacturing process is particularly suitable for the production of components, for example media, e.g. Gas or water-carrying lines and components to be connected, such as fittings, etc.
• molded parts are components of house installation pipe systems, including pipes, fittings, end caps and connecting pieces. The basic process steps for the production of such molded parts are known to the person skilled in the art and are therefore not described in detail here.
• a molded part for the drinking water installation was produced from a lead-free gunmetal in the grain-refined state by means of hot forming with subsequent machining. It was shown that chip breakers were present in the structure of the alloy after the hot pressing process, so that economical, fully automated mechanical processing was possible.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Forging (AREA)
• Domestic Plumbing Installations (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

Applications Claiming Priority (1)

Publications (3)

Family

ID=66826940

Family Applications (1)

Country Status (8)

Cited By (3)

Citations (8)

Family Cites Families (4)

• 2018
  • 2018-06-12 DE DE102018004702.5A patent/DE102018004702A1/de not_active Withdrawn
• 2019
  • 2019-06-07 CA CA3045574A patent/CA3045574C/fr active Active
  • 2019-06-10 JP JP2019108120A patent/JP2020012193A/ja active Pending
  • 2019-06-10 US US16/436,634 patent/US20190376162A1/en not_active Abandoned
  • 2019-06-12 DK DK19179717.4T patent/DK3581667T3/da active
  • 2019-06-12 EP EP19179717.4A patent/EP3581667B1/fr active Active
  • 2019-06-12 PL PL19179717.4T patent/PL3581667T3/pl unknown
  • 2019-06-12 CN CN201910505480.XA patent/CN110592422A/zh active Pending
• 2021
  • 2021-10-21 JP JP2021172295A patent/JP2022025096A/ja active Pending
• 2024
  • 2024-10-04 JP JP2024174877A patent/JP2025013821A/ja active Pending
  • 2024-10-21 US US18/922,088 patent/US20250283197A1/en active Pending

Patent Citations (8)

Also Published As

Similar Documents

Legal Events