Classifications

• • 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
  • C21C1/00—Refining of pig-iron; Cast iron
  • C21C1/02—Dephosphorising or desulfurising
  • C21C1/025—Agents used for dephosphorising or desulfurising
• • 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
  • C21C7/04—Removing impurities by adding a treating agent
  • C21C7/06—Deoxidising, e.g. killing

Definitions

• the present invention relates to a cored wire for the treatment of molten metals and the use thereof.
• Pyrophoric metals such as magnesium, calcium, aluminum and corresponding alloys thereof, in particular in finely divided form, pose particular problems in their handling and use.
• the metals are used in the finely divided form for treatment, such as for the deoxidation of iron and steel melts, for the desulphurization of pig iron melts, for the production of certain alloys and others.
• DE 39 08 815 A1 and the corresponding EP-A-0 388 816 describe a process for passivating pyrophoric metals, in particular magnesium, with 0.5 to 5% by weight of an s-triazine and / or guanidine Derivatives described as passivating agents, based on the weight of the metal.
• Such passivated fine-particle metals are characterized by their favorable burning behavior and are therefore particularly suitable as treatment agents for metallurgical melts, e.g. in the desulfurization of pig iron.
• DE 39 08 815 is hereby incorporated by reference into the present disclosure.
• patent specification DE 39 24 558 C1 describes an agent in the form of a cored wire and a method for its production, the use of which consists in treating cast iron melts with a magnesium-containing silicon alloy.
• the advantage of the flux cored wire described can be seen in the shifting of the excretion form of the cast iron carbon in the direction of spheroidal graphite by adding 5-30% by weight of pure magnesium and 0.1-5% by weight of rare earth metals, as well as in the reduction of the process steps desulfurization, magnesium treatment and Inoculating cast iron melts on a single treatment measure to be carried out simultaneously.
• EP-A-0 066 305 describes the use of passivated magnesium or calcium as a wire filling.
• the passivation of these metals is achieved with a surface coating that consists essentially of Aluminum oxide, magnesium oxide, finely divided silica, graphite or coke powder.
• the premature reaction of the reactive agent is suppressed only during the treatment process, e.g. the premature melting and evaporation of the magnesium core is to be overcome.
• the process has serious disadvantages, such as afterglow or afterburning of the wire, and the release of harmful metal oxides during and after the treatment.
• the present invention was based on the object of providing a cored wire with improved internal forces for the treatment of molten metals.
• a finely divided pyrophoric metal namely magnesium
• a passivating agent based on organic nitrogen compounds, preferably organic NCN compounds from the series of the s-triazines and / or guanidine derivatives.
• organic nitrogen compounds preferably organic NCN compounds from the series of the s-triazines and / or guanidine derivatives.
• a passivating agent based on organic nitrogen compounds, preferably organic NCN compounds from the series of the s-triazines and / or guanidine derivatives.
• melamine or melamine cyanurate guanylurea or guanylurea phosphate is preferably used.
• Cyanoguanidine (dicyandiamide) is particularly preferably used as a passivating agent.
• the passivating agent is used in an amount of 0.5 to 5% by weight, preferably 3% by weight, based on the weight of the pyrophoric metal, namely magnesium, and is applied to the metal with the aid of an adhesion promoter. Viscous mineral oils, vegetable oils or preferably silicone oils are used as adhesion promoters. Adhesion promoters of this type are generally used in an amount of 0.1 to 0.5% by weight, based on the metal to be coated (see published patent application DE 39 08 815 A1).
• the particle size of the passivating agent is 5 to 60 ⁇ m, preferably less than 10 ⁇ m.
• wires filled with the passivated metal particles described above has the advantage over the wires filled with non-passivated pyrophoric metals that the yield of reactive component is higher and incorrect treatment and rejects are excluded.
• cored wires also contribute to operational and occupational safety and environmental protection, since after the winding process has ended they neither glow nor burn and do not release any, possibly harmful, metal oxides into the environment.
• the cored wire according to the invention also contains 60 to 40% by weight of ferrosilicon.
• additional components in the form of ferrosilicon containing rare earth metals can be added to the passivated pyrophoric metal, namely magnesium.
• a preferred wire filling, which in addition to passivated magnesium contains further treatment agents for the purpose of desulfurization and inoculation, is, for example, a mixture of 40 to 60% by weight of passivated magnesium with 60 to 40% by weight of ferrosilicon, with a content of 0.3 to 1.3% by weight of rare earth metals.
• such a wire filling consists of 49% by weight of magnesium and 51% by weight of ferrosilicon, optionally with a content of 0.5 to 1% by weight, preferably 0.9%. %, Rare earth metal.
• a cored wire which also alloys the treated metal, contains, in addition to the desulfurizing and inoculating components, alloying elements such as copper, manganese or tin in appropriate proportions.
• the wire filling can also contain non-metallic components, e.g. Calcium carbide, carbon or silicon dioxide. These components are used for desulfurization, carburization or as a filler to dampen the reaction. Their amount generally depends on the sulfur content of the base iron, the amount of carbon required or the intended degree of reaction damping.
• non-metallic components e.g. Calcium carbide, carbon or silicon dioxide.
• the particle size of the passivated pyrophoric metal is preferably between 0.1 to 2 mm and is particularly preferably 0.2 to about 0.7 mm.
• the additional components are in a particle size of preferably 0.05 to 2.0 mm, particularly preferably 0.1 to 1.6 mm.
• a typical cored wire sheathing consists of folded steel, rare copper tape, the wall of which is a thickness of 0.25 or 0.4 mm; Such cored wires with a total diameter of 5.9 and 13 mm are used.
• the cored wire used according to the invention is characterized by a safe application, a high yield of the reactive component and by being environmentally friendly. Due to the constant burn-up conditions and the good reproducibility of the reactive component, there is a significant quality improvement in the treated metal melts. For example, in the production of spheroidal graphite cast iron using a cored wire filled with passivated magnesium particles, this has less oxidized magnesium on the bath surface after the treatment has ended. As a result, the reject rate caused by surface defects (Dross) is significantly reduced.
• Magnesium powder (99.8% Mg) with a particle size of 0.2 to 0.7 mm was mixed with 0.3% by weight of silicone oil and passivated with 3% by weight of dicyandiamide with a particle size of 98% ⁇ 10 ⁇ m by coating.
• the precipitated graphite showed a proportion of> 90% in spherical form in a cast Y2 sample (25 mm).
• the number of Spärolites of 250 balls / mm 2 corresponded to the inoculation power of this type of wire.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Metal Extraction Processes (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Wire Bonding (AREA)
• Conductive Materials (AREA)
• Luminescent Compositions (AREA)
• Resistance Heating (AREA)
• Ropes Or Cables (AREA)
• Polishing Bodies And Polishing Tools (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=6445240

Family Applications (1)

Country Status (6)

Families Citing this family (13)

Family Cites Families (10)

• 1991
  • 1991-11-21 DE DE4138231A patent/DE4138231C1/de not_active Expired - Lifetime
• 1992
  • 1992-11-16 AT AT92119560T patent/ATE146822T1/de not_active IP Right Cessation
  • 1992-11-16 EP EP92119560A patent/EP0546351B1/de not_active Expired - Lifetime
  • 1992-11-16 DE DE59207767T patent/DE59207767D1/de not_active Expired - Fee Related
  • 1992-11-20 US US07/979,218 patent/US5264023A/en not_active Expired - Fee Related
  • 1992-11-20 JP JP4311855A patent/JPH05222427A/ja active Pending
  • 1992-11-20 TR TR92/1130A patent/TR26635A/xx unknown

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