Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/0006—Adding metallic additives
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/04—Removing impurities by adding a treating agent
  • C21C7/06—Deoxidising, e.g. killing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/04—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbonitrides
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium

Definitions

• the present invention relates generally to adding alloys to molten metal and steel in particular. More particularly, this invention relates to adding alloys and deoxidants to molten steel in order to increase recovery in the metal.
• Recovery is a measure of the amount of alloys and additives contained in the molten steel after injection. Recovery is expressed as the percent of alloy or additive injected in the steel that is contained in the steel after injection. The greater the percentage contained in the steel after injection, the greater the recovery will be. Greater recoveries mean lower cost to the steel maker because less cored wire is injected. Also, greater recovery usually means the final steel chemistry will be more predictable and repeatable. [0006] It has been well known that additive alloys (typically ground to powders under one millimeter in diameter) encased in a steel jacketed cored wire that is injected deep into molten baths results in a significant improvement in recovery.
• the oxide layer 19 becomes a barrier to the molten additive alloy core 16.
• 70% FeTi has a melting temperature of 1085 C
• TiO 2 has a melting temperature of 1850 C
• the molten steel 10 temperature is usually about 1600 C. This problem is illustrated in Fig. 3. These mechanisms have the affect of not allowing the additive alloy particle 16 to be fully dissolved in the metal molten 10 before the particle 16 rises to the slag surface where it is absorbed.
• the purpose of the additive alloy 16 being injected into the molten bath 10 is to form nitrides and/or carbides beneficial to the final product.
• CaCN 2 Calcium Cyanamid
• the recovery of nitrogen is found to be greatly improved when the CaCN 2 is added to the molten bath 10 using cored wire injection as described in U.S. Patent No. 4,897,114.
• the present invention may be embodied as an alloy delivery device.
• the delivery device may include a blended substance having at least one additive alloy and at least one deoxidizing agent.
• the blended substance may be covered by an elongated sheath.
• the sheath may be a substantially hollow wire in which the blended substance resides.
• the at least one additive alloy may be FeNb, FeV, or FeTi.
• the at least one deoxidizing agent may be Ca, CaSi, Si, Al, or CaCN 2 .
• the deoxidizing agent may be a powder typically comprised of particles having a diameter of less than one millimeter.
• the additive alloy may be ground powder particles typically having a diameter of less than one millimeter.
• the deoxidizing agent may be present in an amount of typically 5% to 50% of the mixture by weight or volume.
• the present invention may be embodied as a method for providing an additive alloy to molten metal, wherein at least one deoxidizing agent is blended with at least one additive alloy to provide a blended substance.
• the blended substance may be encased in a metal sheath to provide an alloy delivery device.
• Molten metal may be produced and the alloy delivery device may be provided into the molten metal.
• the delivery device may be fed into the molten metal and the sheath may be allowed to melt in the molten metal. Once melted, the blended substance is allowed to mix with the molten metal and thereby results in dispersing the blended substance into the molten metal.
• the recovery of the alloying additive in the molten steel is enhanced by blending deoxidizing powders with the additive alloys, such as, but not limited to, Ca, CaSi, Si, Al, CaCN 2 , etc., in varying amounts (typically, but not limited to, 5% to 50% of the mixture by weight or volume).
• the additive alloys such as, but not limited to, Ca, CaSi, Si, Al, CaCN 2 , etc.
• the deoxiding powders are released in close proximity to the additive alloy powders.
• the deoxiding powders react with the dissolved oxygen content of the molten metal creating an oxygen depleted zone in the same area as the additive alloy particles.
• the zone where the powders are released in the molten bath is both depleted in oxygen and enriched with carbon and nitrogen.
• the present invention provides an additive- enhanced or alloy-enhanced molten steel with improved recovery.
• Fig. 1 depicts a prior art method, wherein an oxygen enriched molten bath reacts with an additive alloy, thereby forming an oxide layer over an additive alloy core.
• Fig. 2 demonstrates that, in the prior art methods an oxide layer will reduce the density, thus increasing the buoyancy of the additive alloy in the molten steel bath.
• Fig. 3 depicts a high melting temperature oxide layer that acts as a barrier to dissolution of the low melting temperature additive alloy core.
• Fig. 4 depicts an embodiment of the present invention, wherein CaCN 2 particles reacting with oxygen in the bath cause an oxygen-depleted zone. At the same time carbon and nitrogen are released into the molten bath, causing enrichment in the oxygen-depleted zone.
• Fig. 5 depicts an embodiment of the present invention in which the deoxidizing agent does not release carbon or nitrogen into the molten bath.
• Fig. 6 is a flow chart of a method according to the invention.
• the present invention may be used to provide increased recovery in additive- enhanced or alloy-enhanced molten steel.
• deoxidizing powders 31 to additive alloy powders 28 in cored wires for the injection into molten baths causes a chemical reaction between the deoxiding powder 31 and the oxygen atoms contained in the molten bath 10. This reaction reduces the oxygen content in the localized zone 34 in which the additive alloy powders 28 are released. This can be seen in Fig. 4 and Fig. 5.
• the amount by which these additive alloy powders 28 are oxidized is greatly reduced, thereby increasing the recovery of the additive alloy 28.
• the amount required to be injected into the molten metal 10 is reduced, thus saving time and money for the metal producer. Further, by increasing the recovery, the final chemistry of the molten steel becomes more predictable and repeatable - both being desired process traits.
• an alloy delivery device may include a blend of an additive alloy such as FeNb, FeV, or FeTi, and a deoxidizing agent of Ca, CaSi, Si, Al, or CaCN 2 .
• This blend may be housed in an elongated metal sheath.
• the present invention has recognized the deoxidizing and/or the carborizing and nitriding potential if CaCN 2 is combined with certain oxidizable nitride and/or carbide formers (e.g., FeNb, FeV, FeTi) and is then introduced into the molten bath by cored wire injection.
• Fig. 4 illustrates that when CaCN 2 particles 31 are blended with nitride and/or carbide forming additive alloys 28 in cored wires, the CaCN 2 particles 31 established a zone 34 around the additive alloy particle 28, wherein the oxygen content is reduced and the carbon and nitrogen contents are enriched.
• the deoxidizing agent is in the form of a powder with particles that typically have a diameter of less than one millimeter, while the additive alloy is in the form of a ground powder with particles that typically have a diameter of less than one millimeter.
• the deoxidizing agent is present in an amount typically of 5% to 50% of the mixture by weight or volume.
• Fig. 6 depicts a method according to the invention.
• a deoxidizing agent of Ca, CaSi, Si, Al, or CaCN 2 is blended 100 with an additive alloy, which may be FeNb, FeV, or FeTi.
• the blended material may be encased 103 in a metal sheath in order to provide an alloy delivery device.
• the alloy delivery device is provided 109 into the molten metal.
• the sheath is allowed 112 to melt, and the blended substance is disbursed into the molten metal.
• Fig. 6 depicts such a method.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Continuous Casting (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 2008
  • 2008-05-19 CN CN200880023283A patent/CN101688260A/zh active Pending
  • 2008-05-19 SK SK50057-2009A patent/SK500572009A3/sk unknown
  • 2008-05-19 US US12/122,889 patent/US20080314199A1/en not_active Abandoned
  • 2008-05-19 WO PCT/US2008/064062 patent/WO2008144617A1/en not_active Ceased
  • 2008-05-19 FI FI20096347A patent/FI20096347A7/fi not_active Application Discontinuation
  • 2008-05-19 EP EP08769509A patent/EP2158337A4/de not_active Withdrawn
  • 2008-05-19 JP JP2010508627A patent/JP2010527410A/ja active Pending
  • 2008-05-19 AT AT0916108A patent/AT507365A2/de not_active Application Discontinuation
  • 2008-05-19 ES ES200950056A patent/ES2343302B1/es not_active Withdrawn - After Issue
  • 2008-05-19 CA CA002686285A patent/CA2686285A1/en not_active Abandoned
  • 2008-05-19 SE SE0901523A patent/SE0901523L/sv not_active Application Discontinuation
  • 2008-05-19 TR TR2009/08693T patent/TR200908693T1/xx unknown
  • 2008-05-19 BR BRPI0811753-5A2A patent/BRPI0811753A2/pt not_active Application Discontinuation
  • 2008-05-19 PL PL390678A patent/PL390678A1/pl not_active Application Discontinuation
  • 2008-05-19 RU RU2009146821/02A patent/RU2529132C2/ru active
  • 2008-05-19 DE DE112008001288T patent/DE112008001288T5/de not_active Withdrawn
  • 2008-05-19 MX MX2009012438A patent/MX2009012438A/es unknown
  • 2008-05-19 KR KR1020097024596A patent/KR20100029078A/ko not_active Withdrawn
  • 2008-05-19 CZ CZ20090857A patent/CZ2009857A3/cs unknown
• 2009
  • 2009-11-16 GB GBGB0919971.2A patent/GB0919971D0/en not_active Withdrawn
  • 2009-12-01 ZA ZA200908515A patent/ZA200908515B/xx unknown

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