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
  • C22C9/06—Alloys based on copper with nickel or cobalt as the next major constituent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
  • B22D11/059—Mould materials or platings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/12—Accessories for subsequent treating or working cast stock in situ
• • 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
  • C22C9/01—Alloys based on copper with aluminium as the next major constituent

Definitions

• the invention relates to the use of a hardenable copper alloy as a material with selectively adjustable electrical conductivity for the production of casting molds, in particular continuous casting molds, in which molten metal is stirred by the action of electromagnetic forces.
• the liquid metal melt is brought transversely to the strand withdrawal direction during the casting in the stirring device under the action of an electrical rotating field and is set in a circular motion by the resulting induction currents, which is essentially concentric to the longitudinal axis of the strand.
• the result is a homogeneous cast structure that meets particularly high quality requirements.
• stirring devices are usually arranged below the mold so that the remaining molten metal in the partially solidified strand can be stirred just below the mold.
• the mold materials used in the continuous casting of steel generally have high thermal conductivity at the same time as high mechanical strength to ensure optimum heat dissipation and cooling performance.
• the associated high maximum casting speed increases the economic efficiency of continuous steel casting.
• the high electrical conductivity of the proven mold materials such as copper-chromium-zirconium alloys, with greater than 85% IACS proves to be disadvantageous.
• the high electrical conductivity leads to an undesirably high shielding effect of the mold material in relation to the magnetic field generated for stirring. This weakening of the magnetic field results in a lower depth effect of the stirring effect.
• the stirring effect can be increased by increasing the current intensity, the technical effort required for this increases disproportionately. Overall, therefore, an optimal stirring effect cannot be achieved with mold materials having a high thermal conductivity.
• Mold materials with lower thermal conductivity are already known. However, these have extremely high strengths, so that they are preferably used at higher temperatures. In addition, the processing of these mold materials is relatively complex due to the extremely high strength. Another disadvantage is that the elongation at break at temperatures above 350 ° C is too low.
• the known mold materials with lower thermal conductivity are therefore not an economical alternative to the highly conductive mold materials, such as copper-chrome-zirconium alloys, for use in casting plants with electromagnetic stirring devices.
• the object of the present invention is therefore to provide a hardenable copper material, in particular for use in casting plants with an electromagnetic stirring device, which produces low field damping and which also has favorable strength and elongation at break properties.
• the solution to this problem consists in the use of a hardenable copper alloy of 0.1 to 2.0% nickel, 0.3 to 1.3% chromium, 0.1 to 0.5% zirconium, up to 0.2% of at least one Elements from the group comprising phosphorus, lithium, calcium, magnesium, silicon and boron, the rest copper including impurities as a material with selectively adjustable electrical conductivity for the production of casting molds, in particular continuous casting molds, in which molten metal is stirred by the action of electromagnetic forces.
• the alloy to be used according to the invention preferably contains 0.4 to 1.6% nickel, 0.6 to 0.8% chromium, 0.15 to 0.25% zirconium, at least one element from the group 0.005 to 0.02% boron , 0.005 to 0.05% magnesium and 0.005 to 0.03% phosphorus, balance copper including unavoidable impurities.
• the boron additive can be added to the melt, for example as calcium boride.
• the copper alloy according to the invention is distinguished by a particularly advantageous combination of mechanical and physical properties. With an electrical conductivity below 80% IACS, this copper alloy also fulfills the essential requirement for low field damping of a mold wall made from this alloy.
• a low titanium content forms intermetallic compounds with the components nickel and iron in the alloy, which increase strength.
• composition of nine example alloys is given in Table 1 in% by weight.
• X denotes the total content of the individual elements boron, magnesium and / or phosphorus, which are added up to a total of 0.05% as deoxidizing agents. Higher levels can also be used to increase the strength of the alloy.
• Copper alloys with different nickel contents of 0.2 to 2%, about 0.7% chromium, 0.16 to 0.2% zirconium, up to 0.02% boron, magnesium and / or phosphorus, the rest of copper including manufacturing-related impurities were initially melted, cast into rolled ingots and then hot rolled at 950 ° C in several passes with a total degree of forming of 65%. After at least 1 hour solution annealing at 1 030 ° C and a subsequent quenching in water, the rolled plates were at at least 4 hours 475 ° C hardened. After final machining, the mold plates each had the property values summarized in Table 2, depending on the nickel content (0.2 to 2% nickel).
• the first-mentioned property value is assigned to the copper alloy with 0.2% nickel content to be used according to the invention.
• the alloys to be used according to the invention have an electrical conductivity which can be set by choosing the nickel concentration within the range of about 35 to 80% IACS, the mechanical properties remaining largely unchanged. With increasing nickel content up to 2.0%, the yield strength and the tensile strength of the material change only slightly in the entire concentration range in the hardened state higher parameters. A small increase also applies to the heat resistance, e.g. B. at 350 ° C. In contrast, the elongation at break is largely independent of the nickel content, which at a temperature of 350 ° C is reduced only to 10% elongation for an alloy with 2.0% nickel.
• the resistance of the alloy to be used according to the invention was tested both at room temperature and at a temperature of up to 350 ° C. - corresponding to a cyclical temperature load in the casting operation.
• the fatigue crack formation resulted in a large degree of independence from the nickel content, so that the known favorable behavior of the copper-chromium-zirconium alloys previously used in the casting operation is also given with regard to the long service life.
• the increasing hardness with increasing nickel content provides an additional improvement in properties, which also results in a more favorable tribological behavior of the mold material.
• alloy to be used according to the invention is not only limited to the plate mold described in the exemplary embodiments.
• Corresponding advantages also arise with other molds with which metallic mold strands can be produced in a semi-continuous or fully continuous manner, for example tubular molds, block molds, casting wheels, casting rolls and casting roll shells.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Continuous Casting (AREA)
• Adornments (AREA)
• Conductive Materials (AREA)
• Dental Preparations (AREA)
• Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Macromonomer-Based Addition Polymer (AREA)
• Laminated Bodies (AREA)
• Colloid Chemistry (AREA)

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Publications (2)

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Citations (6)

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• 1994
  • 1994-08-06 DE DE4427939A patent/DE4427939A1/de not_active Withdrawn
• 1995
  • 1995-06-29 AT AT95110134T patent/ATE186076T1/de active
  • 1995-06-29 ES ES95110134T patent/ES2139780T3/es not_active Expired - Lifetime
  • 1995-06-29 DE DE59507131T patent/DE59507131D1/de not_active Expired - Lifetime
  • 1995-06-29 EP EP95110134A patent/EP0702094B1/fr not_active Expired - Lifetime
  • 1995-07-05 KR KR1019950019576A patent/KR100374051B1/ko not_active Expired - Lifetime
  • 1995-07-24 RU RU95113726/02A patent/RU2160648C2/ru active
  • 1995-07-25 ZA ZA956181A patent/ZA956181B/xx unknown
  • 1995-07-31 PL PL95309841A patent/PL177973B1/pl unknown
  • 1995-08-03 CN CN95108676A patent/CN1058532C/zh not_active Expired - Lifetime
  • 1995-08-04 FI FI953730A patent/FI112669B/fi not_active IP Right Cessation
  • 1995-08-04 JP JP7200045A patent/JPH08104928A/ja active Pending
• 1997
  • 1997-07-28 US US08/901,820 patent/US6565681B1/en not_active Expired - Lifetime

Patent Citations (6)

Non-Patent Citations (4)

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