EP3967422A1 - Agitation et chauffage électromagnétiques d'un lingot - Google Patents

Agitation et chauffage électromagnétiques d'un lingot Download PDF

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Publication number
EP3967422A1
EP3967422A1 EP20195612.5A EP20195612A EP3967422A1 EP 3967422 A1 EP3967422 A1 EP 3967422A1 EP 20195612 A EP20195612 A EP 20195612A EP 3967422 A1 EP3967422 A1 EP 3967422A1
Authority
EP
European Patent Office
Prior art keywords
ingot
stirring
mould
casting
electromagnetic stirring
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.)
Withdrawn
Application number
EP20195612.5A
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German (de)
English (en)
Inventor
Martin SEDÉN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Schweiz AG
Original Assignee
ABB Schweiz AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by ABB Schweiz AG filed Critical ABB Schweiz AG
Priority to EP20195612.5A priority Critical patent/EP3967422A1/fr
Publication of EP3967422A1 publication Critical patent/EP3967422A1/fr
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D7/00—Casting ingots, e.g. from ferrous metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/02—Use of electric or magnetic effects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/15—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting by using vacuum

Definitions

  • the present disclosure relates to electromagnetic stirring and heating of a steel ingot for ingot casting.
  • Steel ingot casting is an old and widely spread technique to manufacture steel where ingot moulds are filled with molten steel, followed by a solidification process of several hours depending on ingot size.
  • several ingot moulds are generally filled simultaneously by the up-hill teeming technique giving a low and controlled rising speed of the steel in the mould.
  • the steel solidifies starting from the side walls and the base of the mould.
  • the solidification front then moves inwards towards the centre of the ingot.
  • the resulting temperature gradients in the ingot initiate free convection which is the weak driving force of the flow in the liquid steel.
  • the strongest flow speed appears along the mush-liquid interface where melt locally flows downwards with typical speeds of a few centimetres per second. Closer to the centre of the ingot, the flow recirculates upward again.
  • electromagnetic stirrers to several other steel industry processes has been developed, such as e.g. continuous casting which is an efficient casting method for high productivity.
  • continuous casting For some special high-end steel grades however, the slower ingot casting method yields a superior quality of the final product.
  • the application of controlled strong stirring in the ingot casting process has the potential of taking the manufacturing of clean steel to a higher level by increasing the quality of the end product by means of increasing molten steel flow speeds to 0.5 m/s. So far, electromagnetic stirring for ingot casters is a relatively unexplored field.
  • PTC Pullasma Treatment Casting
  • PTC imposes an electric field over the height of the ingot by applying a rotating DC electrode above the ingot and another electrode at the base of the mould.
  • a plasma arc strikes the top surface of the ingot in a rotating manner, feeding a varying current density to the steel in the mould.
  • the varying current density induces a varying magnetic flux density, and together, the current and the magnetic field create a time varying stirring force on the ingot.
  • the applied stirring is claimed to increase yield by about 10% for high grade steel ingots.
  • Electromagnetic stirring of ingots provides melt flow speeds at least ten times higher than those of free convection.
  • An electromagnetic stirrer can easily adapt its strength, thus controlling the different stages of solidification where different amounts of convection may be needed.
  • electromagnetic stirring is a contactless technology with minimum maintenance.
  • the electromagnetic fields can penetrate mould, covers and mould powder and apply stirring without risking oxidation of the top surface of the ingot steel such as with the plasma arc technology.
  • PTC needs to replace electrodes frequently, but there is no wear on the electromagnetic stirrer which has a very long lifetime.
  • One objective of the present invention is to improve top ingot porosity deficiencies for electromagnetic casting of ingots.
  • a method for electromagnetic stirring and heating for ingot casting is performed during casting of an ingot in an ingot mould.
  • the method comprises electromagnetic stirring of the ingot.
  • the electromagnetic stirring is configured to macroscopic stir the ingot with a varying frequency in the range 0-10 Hz.
  • the method further comprises electromagnetic heating of the ingot.
  • the electromagnetic heating is configured to superimpose a varying frequency in the range 20-200 Hz, on top of the electromagnetic stirring varying frequency, to induce heat at a top of the ingot.
  • a same coil hardware may be used for inducing both the electromagnetic stirring as well as the electromagnetic heating.
  • the electromagnetic stirring may be configured to produce a horizontal, linear, straight stirring with a vertically circulating flow pattern of the ingot.
  • the electromagnetic stirring maybe configured to produce a circulating horizontal stirring at the top of the ingot.
  • the method may be performed during vacuum casting of the ingot.
  • an ingot casting device for ingot casting.
  • the ingot casting device comprises a mould for casting of an ingot.
  • the electromagnetic stirring and heating device is arranged at a top of the mould.
  • the electromagnetic stirring and heating device is configured to macroscopic stir the ingot with a varying frequency in the range 0-10 Hz, and to heat at a top of the ingot with a superimposed varying frequency in the range 20-200 Hz, on top of the electromagnetic stirring varying frequency.
  • the electromagnetic stirring and heating device may be configured to produce a horizontal, linear, straight stirring with a vertically circulating flow pattern of the ingot.
  • the electromagnetic stirring and heating device may alternatively be configured to produce a circulating horizontal stirring at the top of the ingot.
  • an ingot casting device for ingot casting.
  • the device comprises a mould for casting of an ingot and an electromagnetic stirring and heating device arranged at a top of the mould.
  • the electromagnetic stirring and heating device is configured to macroscopic stir the ingot with a varying frequency in the range 0-10 Hz, and to heat at a top of the ingot with a superimposed varying frequency in the range 20-200 Hz, on top of the electromagnetic stirring varying frequency.
  • the mould may be arranged in a vacuum chamber.
  • the electromagnetic stirring and heating device may be configured to produce a horizontal, linear, straight stirring with a vertically circulating flow pattern of the ingot.
  • the electromagnetic stirring and heating device may be configured to produce a circulating horizontal stirring at the top of the ingot.
  • electromagnetic stirring as presented herein offers the following features compared to non-vacuum casting:
  • the ingot casting device is configured to superimpose varying frequencies to accommodate strong macroscopic stirring with a low frequency in the range 0-10 Hz together with a high frequency component in the range 20-200 Hz to induce heat at the top of the ingot to compensate for the heat loss without mould powder at the top of the melt.
  • the macroscopic stirring achieved with the low frequency range 0-10 Hz provides a strong stirring in the whole volume of the ingot.
  • the top of the ingot is the riser head of the ingot.
  • the quality and yield of the cast products can be increased significantly thus increasing productivity and efficiency.
  • the ingot casting device comprises a mould for casting the ingot and an electromagnetic stirring and heating device (EMS) 6.
  • the mould comprises a head mould 2 and a bottom mould 1 separated by insulation 3.
  • the insulation 3 is further arranged on the inside of the head mould 2, in order to reduce thermal loss into the atmosphere and the stirrer.
  • the insulation 3 between the head mould 2 and the bottom mould 1 is used to support the insulation arranged on the inside of the head mould 2.
  • the insulation 3 between the head mould 2 and the bottom mould 1 further reduces heat loss.
  • the head mould 2 is configured to support the riser head of the ingot during casting.
  • the ingot casting device also comprises a vacuum chamber 4, in which the mould 1-3 is arranged.
  • the ingot casting device further comprises the EMS 6 arranged on top of the vacuum chamber 4.
  • the EMS 6 is configured to induce a horizontal, linear fluid flow at the top of the ingot.
  • the induced flow is illustrated with an arrow.
  • the induced horizontal, linear fluid flow is further configured to induce a circular fluid flow down into the bottom mould 1.
  • the EMS 6 is further configured to induce heat in the top of the ingot, illustrated with undulating waves.
  • the EMS 6 is configured to macroscopic stir the ingot with a varying frequency in the range 0-10 Hz, and to heat at a top of the ingot with a superimposed varying frequency in the range 20-200 Hz, on top of the electromagnetic stirring varying frequency.
  • the ingot casting device is configured to cast a steel ingot in the mould 1-3 without use of mould powder at the top of the melt.
  • the diameter of the top of the ingot can be about 0.5 m or larger, and the wall thickness of the mould can be about 0.3 m.
  • the ingot casting device comprises a mould for casting the ingot and an EMS 6.
  • the mould comprises a head mould 2 and a bottom mould 1 separated by insulation 3.
  • the insulation 3 is further arranged on the inside of the head mould 2 and on top of the ingot.
  • the head mould 2 is configured to support the riser head of the ingot during casting.
  • the ingot casting device also comprises the EMS 6 arranged at the top of the ingot.
  • the EMS 6 is arranged around the head mould 2.
  • the EMS 6 is configured to induce a circular, horizontal fluid flow of the ingot at the top of the ingot.
  • the induced flow is illustrated with arrows in Fig. 2b .
  • the induced circular, horizontal fluid flow is further configured to induce a dual circular fluid flow down into the bottom mould 1, illustrated with arrows in Fig. 2a .
  • the EMS 6 is further configured to induce heat in the top of the ingot, although not as important with the use of mould powder 5 arranged on top of the ingot.
  • the EMS 6 is configured to macroscopic stir the ingot with a varying frequency in the range 0-10 Hz, and to heat at a top of the ingot with a superimposed varying frequency in the range 20-200 Hz, on top of the electromagnetic stirring varying frequency.
  • the ingot casting device may be configured to cast a steel ingot in the mould 1-3 with or without use of mould powder 5 at the top of the melt.
  • the ingot casting device comprises a mould for casting the ingot and an EMS 6.
  • the mould comprises a head mould 2 and a bottom mould 1 separated by insulation 3.
  • the insulation 3 is further arranged on the inside of the head mould 2.
  • the insulation 3 between the head mould 2 and the bottom mould 1 is used to support the insulation arranged on the inside of the head mould 2.
  • the insulation 3 between the head mould 2 and the bottom mould 1 further reduces heat loss.
  • the head mould 2 is configured to support the riser head of the ingot during casting.
  • the ingot casting device also comprises a vacuum chamber 4, in which the mould 1-3 is arranged.
  • the ingot casting device further comprises the EMS 6 arranged on top of the vacuum chamber 4.
  • the EMS 6 is configured to induce a horizontal, linear fluid flow at the top of the ingot.
  • the induced flow is illustrated with an arrow.
  • the induced horizontal, linear fluid flow is further configured to induce a circular fluid flow down into the bottom mould 1.
  • the EMS 6 is further configured to induce heat in the top of the ingot, illustrated with undulating waves.
  • the EMS 6 is configured to macroscopic stir the ingot with a varying frequency in the range 0-10 Hz, and to heat at a top of the ingot with a superimposed varying frequency in the range 20-200 Hz, on top of the electromagnetic stirring varying frequency.
  • the ingot casting device is configured to cast a steel ingot in the mould 1-3 without use of mould powder at the top of the melt.
  • the ingot casting device comprises a mould for casting the ingot and an EMS 6.
  • the mould comprises a head mould 2 and a bottom mould 1 separated by insulation 3.
  • the insulation 3 is further arranged on the inside of the head mould 2 and above the ingot.
  • the head mould 2 is configured to support the riser head of the ingot during casting.
  • the ingot casting device further comprises the EMS 6 arranged on top of the top part of the insulation 3.
  • the EMS 6 is configured to induce a horizontal, linear fluid flow at the top of the ingot.
  • the induced flow is illustrated with an arrow.
  • the induced horizontal, linear fluid flow is further configured to induce a circular fluid flow down into the bottom mould 1.
  • the EMS 6 is further configured to induce heat in the top of the ingot, illustrated with undulating waves.
  • the EMS 6 is configured to macroscopic stir the ingot with a varying frequency in the range 0-10 Hz, and to heat at a top of the ingot with a superimposed varying frequency in the range 20-200 Hz, on top of the electromagnetic stirring varying frequency.
  • the ingot casting device may be configured to cast a steel ingot in the mould 1-3 with or without use of mould powder 5 at the top of the melt.
  • the ingot casting device comprises a mould 1-3 for casting of an ingot.
  • the EMS 6 is arranged at a top of the mould.
  • the electromagnetic stirring and heating device is configured to macroscopic stir the ingot with a varying frequency in the range 0-10 Hz, and to heat at a top of the ingot with a superimposed varying frequency in the range 20-200 Hz, on top of the electromagnetic stirring varying frequency.
  • the EMS 6 may be configured to produce a horizontal, linear, straight stirring with a vertically circulating flow pattern of the ingot.
  • the EMS 6 may alternatively be configured to produce a circulating horizontal stirring at the top of the ingot.
  • Electromagnetic stirring in the presented embodiments is based on the common principle of a multiphase AC current being fed to an electromagnetic stirrer of the EMS 6 which generates a travelling magnetic field in the ingot.
  • the direction of this travelling magnetic flux density wave is for the linear fluid flow along the circumference of the ingot.
  • For the circular fluid flow the direction of the travelling magnetic flux density wave is along the stirrer length at the top of the ingot.
  • These harmonic magnetic field waves induce eddy currents in an electrically conducting ingot, combining with the magnetic field to produce a force distribution in the ingot.
  • the main force direction is aligned with the travelling magnetic wave, thus creating a stirring flow in the molten metal.
  • Electromagnetic heating providing local heat at the top of the ingot, is created using the same coil hardware as for stirring, but with a higher frequency range.
  • î stir is the current amplitude for the stirring component
  • ⁇ stir is the angular frequency for the stirring component
  • ⁇ k,stir is the phase displacement for phase k of the stirring component
  • î heat is the current amplitude for the heating component
  • ⁇ heat is the angular frequency for the heating component
  • ⁇ k,heat is the phase displacement for phase k of the heating component.
  • ⁇ k,stir is important for travelling wave stirring.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
EP20195612.5A 2020-09-10 2020-09-10 Agitation et chauffage électromagnétiques d'un lingot Withdrawn EP3967422A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP20195612.5A EP3967422A1 (fr) 2020-09-10 2020-09-10 Agitation et chauffage électromagnétiques d'un lingot

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Application Number Priority Date Filing Date Title
EP20195612.5A EP3967422A1 (fr) 2020-09-10 2020-09-10 Agitation et chauffage électromagnétiques d'un lingot

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EP3967422A1 true EP3967422A1 (fr) 2022-03-16

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EP20195612.5A Withdrawn EP3967422A1 (fr) 2020-09-10 2020-09-10 Agitation et chauffage électromagnétiques d'un lingot

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4470448A (en) * 1980-06-05 1984-09-11 Ti (Group Services) Limited Electromagnetic stirring
US20080164004A1 (en) * 2007-01-08 2008-07-10 Anastasia Kolesnichenko Method and system of electromagnetic stirring for continuous casting of medium and high carbon steels
US20150028724A1 (en) * 2012-03-13 2015-01-29 Etrema Products, Inc. Single crystalline microstructures and methods and devices related thereto
US20190366425A1 (en) * 2015-12-15 2019-12-05 Grandfield Technology Pty Ltd Ingot Casting

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4470448A (en) * 1980-06-05 1984-09-11 Ti (Group Services) Limited Electromagnetic stirring
US20080164004A1 (en) * 2007-01-08 2008-07-10 Anastasia Kolesnichenko Method and system of electromagnetic stirring for continuous casting of medium and high carbon steels
US20150028724A1 (en) * 2012-03-13 2015-01-29 Etrema Products, Inc. Single crystalline microstructures and methods and devices related thereto
US20190366425A1 (en) * 2015-12-15 2019-12-05 Grandfield Technology Pty Ltd Ingot Casting

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