US3519781A - Electroslag remelting and welding processes - Google Patents

Electroslag remelting and welding processes Download PDF

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Publication number
US3519781A
US3519781A US738477A US3519781DA US3519781A US 3519781 A US3519781 A US 3519781A US 738477 A US738477 A US 738477A US 3519781D A US3519781D A US 3519781DA US 3519781 A US3519781 A US 3519781A
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United States
Prior art keywords
slag
metal
springs
electrode
electroslag remelting
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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.)
Expired - Lifetime
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US738477A
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English (en)
Inventor
Frank E G Ravault
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Foseco International Ltd
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Foseco International Ltd
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Filing date
Publication date
Priority claimed from GB09968/66A external-priority patent/GB1181663A/en
Application filed by Foseco International Ltd filed Critical Foseco International Ltd
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Publication of US3519781A publication Critical patent/US3519781A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K25/00—Slag welding, i.e. using a heated layer or mass of powder, slag, or the like in contact with the material to be joined
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/34—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material comprising compounds which yield metals when heated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/16—Remelting metals
    • C22B9/18—Electroslag remelting

Definitions

  • a starter tablet for use in the electroslag remelting and welding processes which is a block of a composition which comprises ingredients which react together exothermically when fired to yield a slag suitable for use in the said electroslag processes, wherein the block has within it, and projecting from it on opposite faces, metal springs which serve, inter alia, to improve electrical contact.
  • This invention relates to improvements in electroslag remelting and welding processes. It is of particular value in the electroslag remelting process and will be described with particular reference to that use. However it may also be applied to the closely similar electroslag welding process as herein later described.
  • the electroslag remelting process is a process for refining metals, particularly steel.
  • the metal to be refined is used as an electrode
  • the electrode is immersed at its end in a bath of molten refining slag contained in a water-cooled mould, and electrical current is caused to pass through the system.
  • the mould usually consists of a hollow steel cylinder with a copper baseplate, and two components being separated by an insulating refractory gasket (eg. asbestos).
  • the molten metal falls through the molten slag layer in the form of droplets and thereby undergoes a cleansing action which reduces inter alia the sulphur and inclusion contents of the metal.
  • the refined metal collects in the water cooled mould and is progressively solidified with a superior crystalline micro-structure to produce an ingot which possesses improved mechanical properties and is eminently suitable for subsequent rolling, drawing, forging and other working.
  • the slag used for the purpose may be of any composition which is suitable for the refining effect required, the principal restricting factor being that it must be electrically conductive to the correct degree so that its resistance to the electric current is responsible for producing the required heat.
  • the composition of the slags has been based upon fluorspar, fluorspar/alumina, fluorspar/lime, fluorspar/magnesia, fluorspar/lime/alumina or uorspar/magnesia/ alumina systems with, possibly, minor additions of other substances intended to effect specific alloying or refining modifications of the metal.
  • a thin layer of the slag remains between the metal and the mould wall, conferring a very smooth surface to the ingot produced.
  • the electroslag remelting process may be compared with the consumable arc or vacuum arc steelmaking method. It does, however, offer considerable advantages over the latter process, both economically by requiring lower capital and running costs and technically in that the ingots produced have superior surface quality, a lower sulphur content, a more uniform and ner grained structure and much improved hot-working ductility.
  • Powdered slag is then poured into the space between electrode and mould wall, the electric power is switched on to trigger the reaction between the aluminum/magnesium and the nitrate and/or iron oxide.
  • the exothermic reaction assists in melting a small quantity of the slag which then becomes conductive and the remainder is gradually melted.
  • this method needs a high starting current (much higher than the current for normal running of the process) and the electrical system has to be constructed in a way that it will withstand current surges without being damaged. As only a small quantity of slag is initially melted, it cannot rapidly attain the required running temperature whilst unmelted powder material continues to chill the slag pool.
  • the slag is rather viscous and can contain lumps of unmelted material which are likely to become entrapped in any molten metal which is produced. In fact, it is quite usual to crop and discard the bottom 5% of the ingot produced because of its poor quality and high slag inclusion content.
  • the position of the electrode in the slag is usually automatically controlled so that it produces the required current density, i.e. when the resistance of the system changes the extent to which the electrode is irnmelsed in the slag is automatically varied to compensate, so that a steady current density is maintained.
  • the electrode tends to move up and down in rapid oscillation in an attempt to stabilise the current density. This may result in the electrode touching the mould bottom and becoming welded thereto.
  • the powdered slag remains suspended above the liquid level and bridges across the annulus between electrode and mould wall.
  • the exothermic cornposition On initiating the electroslag remelting or welding process by passing the electric current the exothermic cornposition is fired, generating the required molten slag. Additional slag-forming ingredients can then be added as required and will in turn melt to establish and maintain the required body of molten slag.
  • the firing of the ingredients may be effected by the provision of wires extending through the composition which protrude therefrom and make Contact with the electrode and the base of the mould. When the current is initially switched on, these wires act as a resistance heating element.
  • application No. 634,737 described starter tablets for use in the foregoing process which comprise a block of a composition -which comprises ingredients which react exothermically when fired, characterized in that the said ingredients burn to yield a slag suitable for use in the electroslag remelting process, and the block has within it, and projecting from it on opposite faces, metal wires or rods.
  • These wires or rods may be in the form of a comb or mesh within the body of the composition.
  • starter tablets for use in the electroslag remelting or welding process which are blocks of a composition which comprises ingredients which react exothermically when fired to yield a slag suitable for use in the electroslag remelting process wherein the block has within it, and projecting from it on opposite faces, coil type, .metal springs.
  • the springs are generally separate from one another, but may be electrically connected together.
  • the coil type metal spring may be of spiral, helical or leaf type. Coiled type springs are preferred for reasons hereinafter explained.
  • the projecting ends of the springs enable good electrical contact to be made between the electrode and mould base through the springs since they take up any irregularities in either mould base or electrode and ensure good electrical contact.
  • This electrical contact may be further enhanced by flattening the ends of the springs, and/or welding a metal plate thereupon.
  • the metal from which the springs, and plates if fitted, are made is selected having regard to the metal of the electrode.
  • steel springs are used, but when refining nickel alloys, springs made of e.g. Nimonic alloys may be employed.
  • an additional advantage of using coiled springs is that of the greater amount of wire in the body of the composition, and thereby a greater and more even generation of heat within the block during starting.
  • the springs when uncompressed will protrude 12 to 18 mm. from the face of the block.
  • the method of this invention may be adapted also to the electroslag welding process, e.g. as used for the welding of steel.
  • the weld metal is used as the electrode and instead of providing a mould as in the electroslag remelting process it is arranged that a cavity is formed between two opposite water-cooled shoes and two interspaced opposite metal elements which are to be welded together. The same technique of providing the molten metal from the electrode is used.
  • FIG. 1 shows a starter block according to the present invention
  • FIG. 2 shows part of an alternative form of starter block according to the present invention.
  • the starter block 1 has embedded within it a number of spiral springs 2 the ends of which project from the face of the block.
  • each protruding spring end bears a metal plate 3.
  • each starter tablet contains several springs.
  • cylindrical blocks 15 cm. diameter and 7.5 cm. in thickness having 5 or 6 springs embedded therein with their ends protruding from the circular faces about 12.5 mm. have been found to be very satisfactory.
  • rectangular blocks of exothermic material cm. in length, 15 cm. in width, and 7.5 cm. in thickness, with 6 sets of springs (3 springs per set) embedded in the slab, have been used successfully for starting the electroslag refining process.
  • This shape starter slab is particularly useful when large rectangular ingots are produced by the electroslag process from a multiple assembly of single electrodes.
  • the present invention includes not only exothermic starter tablets as described above, but their use in electroslag remelting and welding processes.
  • a starter tablet for use in the electroslag remelting and welding processes employing an electrode, refining slag, a mold and electric current wherein said starting tablet is a block of a composition which comprises ingredients which react together exothermically when fired to yield a slag suitable for use in the said electroslag processes, wherein the block has within it, coil type metal springs lwhich project from opposite top and bottom surfaces of the tablet, adated to make contact with the electroslag electrode and the mold base.
  • a starter tablet which is a block of a composition which comprises ingredients which react together exothermically when fired to yield a slag suitable for use in the said electroslag processes, wherein the block'has within it coil type metal springs which project from opposite top and bottom surfaces of the tablet, adapted to make contact with the electroslag and the mold base.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US738477A 1966-05-05 1968-06-20 Electroslag remelting and welding processes Expired - Lifetime US3519781A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB09968/66A GB1181663A (en) 1966-05-05 1966-05-05 Production of Ingots by Electroslag Remelting Processes
GB29224/67A GB1209464A (en) 1966-05-05 1967-06-23 Electroslag remelting and welding processes

Publications (1)

Publication Number Publication Date
US3519781A true US3519781A (en) 1970-07-07

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US738477A Expired - Lifetime US3519781A (en) 1966-05-05 1968-06-20 Electroslag remelting and welding processes

Country Status (4)

Country Link
US (1) US3519781A (de)
FR (1) FR94688E (de)
GB (1) GB1209464A (de)
SE (1) SE356761B (de)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2260775A (en) * 1939-01-03 1941-10-28 Theodore N Fritzsch Electric welding
US3153719A (en) * 1961-08-04 1964-10-20 Kobe Steel Ltd Submerged welding and deposited metal
US3204082A (en) * 1963-07-29 1965-08-31 Inst Elektroswarki Patona Device for electric welding of vertical and inclined seams
US3211887A (en) * 1962-06-14 1965-10-12 Foster Wheeler Corp Welding shoe
US3293400A (en) * 1966-07-06 1966-12-20 Newport News S & D Co Submerged arc welding process
US3307014A (en) * 1964-09-14 1967-02-28 Fuji Iron And Steel Company Lt Arc welding process
US3337712A (en) * 1965-08-05 1967-08-22 British Oxygen Co Ltd Electric welding of upwardly extending seams

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2260775A (en) * 1939-01-03 1941-10-28 Theodore N Fritzsch Electric welding
US3153719A (en) * 1961-08-04 1964-10-20 Kobe Steel Ltd Submerged welding and deposited metal
US3211887A (en) * 1962-06-14 1965-10-12 Foster Wheeler Corp Welding shoe
US3204082A (en) * 1963-07-29 1965-08-31 Inst Elektroswarki Patona Device for electric welding of vertical and inclined seams
US3307014A (en) * 1964-09-14 1967-02-28 Fuji Iron And Steel Company Lt Arc welding process
US3337712A (en) * 1965-08-05 1967-08-22 British Oxygen Co Ltd Electric welding of upwardly extending seams
US3293400A (en) * 1966-07-06 1966-12-20 Newport News S & D Co Submerged arc welding process

Also Published As

Publication number Publication date
GB1209464A (en) 1970-10-21
SE356761B (de) 1973-06-04
FR94688E (fr) 1969-10-03

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