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 the use of cored wires with a filling in the form of passivated, reactive metals.
• 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.
• published patent application DE 39 08 815 A1 describes a process for passivating pyrophoric metals, in particular magnesium, with 0.5 to 5% by weight of an s-triazine and / or guanidine derivative as a passivating agent, based on the weight of the metal , described.
• 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 alloying 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.
• the present invention was based on the object of using a cored wire with a content enable pyrophoric metal for the treatment of molten metals in an economical manner. Further objects of the invention are evident from the description below.
• a finely divided pyrophoric metal such as magnesium is used, which has been coated with a passivating agent based on organic nitrogen compounds, preferably organic NCN compounds from the series of s-triazines and / or guanidine derivatives.
• a passivating agent based on organic nitrogen compounds, preferably organic NCN compounds from the series of s-triazines and / or guanidine derivatives.
• Preference is given to passivating the pyrophoric metal in particular magnesium, melamine or melamine cyanurate, guanyl urea or guanyl urea phosphate.
• 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, and 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. Such adhesion promoters 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.
• additional components in the form of alloys, metals or other agents can be added to the passivated pyrophoric metal.
• additional components are, for example, one or more alloys from the series calcium silicon, ferrosilicon, rare earth metals-containing ferrosilicon, magnesium and / or calcium-containing ferrosilicon, ferromanganese, the metals copper, manganese and tin.
• Calcium carbide, carbon and silicon dioxide can optionally also be added to the passivated pyrophoric metal as further components.
• the proportions of the additional filler components in a mixture with the passivated pyrophoric metal can be up to 90% by weight.
• 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, optionally with a content of 0.3 to 1.3% by weight of rare earth metals.
• a wire fill 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 that alloys the treated metal at the same time 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 in accordance with 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-off conditions and the good reproducibility of the reactive component, there is a significant quality improvement in the treated metal melts. For example, in the manufacture 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 magnesium pretreated in this way is packed in a cored wire with the following key figures: Wire diameter 9 mm Wire weight 178 g / m Filling weight 65 g / m Fill factor 36.5%
• a base iron of the following analysis was melted in the induction crucible furnace: 3.75 wt% carbon 2.40% by weight silicon 0.18% by weight of manganese 0.014 wt% phosphorus 0.008% by weight sulfur The iron was treated by winding 18 m of the wire to obtain the results shown in Table 1.
• Magnesium powder (99.8% Mg) was passivated as described in Example 1. 40 parts by weight of the passivated magnesium were then mixed with 51 parts by weight of ferrosilicon (75% Si) with a particle size of 0.2 to 0.7 mm and 9 parts by weight with rare earth metal-containing ferrosilicon (FeSiSE 36) with a particle size of 0 , 01 to 1 mm mixed and packed in a cored wire, which has the following characteristics: Wire diameter 9 mm Wire weight 206 g / m Filling weight 94 g / m Fill factor 46% Magnesium content 36 g / m Silicon content 30 g / m SE content 3 g / m
• the precipitated graphite showed a portion of> 90% in spherical form in a cast Y2 sample (25 mm).
• the number of Spärolites of 250 balls / mm2 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)

Cited By (1)

Families Citing this family (12)

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/fr 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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