DE2948636A1 - WIRE-SHAPED AGENT FOR TREATING METAL MELT - Google Patents

Description

METALLGESELLSCHAFT Frankfurt / M., November 15, 1979

Aktiengesellschaft DrMl / HGa

Reuterweg 14

6000 Frankfurt / M. ·

Prov. No. 8450 II

Wire-shaped means for treating molten metal

It is known to supply the treatment agent in wire form to molten metal, wherein z. B. a coat! wire out Ferrous metal the actual present in the core of the wire z. B. encloses powdered treatment metal. A treatment wire known from DE-OS 27 38 379 consists, for example, of a powdery! Core material from magnesium alloys, such as Mg-Si-Mn or Mg-Fe-Si alloys, or calcium alloys, such as Ca-Si-Mn or Co-Si-Fe alloys. These alloys can also contain rare earth metals. The powdery core material is usually compacted. Furthermore, from DE-OS 25 31 573 a wire-shaped means for treating molten metal known, in which between the outer jacket made of ferrous metal and core material made of relatively volatile metal, e.g. B. Magnesium, an insulating material z. B. iron powder is arranged. With the previously known treatment agent, the addition of the core material is intended occur simultaneously with the melting of the jacket material and an early melting and evaporation of the magnesium core can be prevented.

The previously known wires do not meet the requirements of metallurgical practice in all cases. Provided Manganese or iron alloyed magnesium silicon alloys are used, is the reactivity of the magnesium

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greatly reduced in such alloys and a larger one Amount of alloy with often undesirable alloying elements required. As far as treatment wires with coated magnesium wire are used, it turns out the rigidity of the wire is often seen as a hindrance. An uneven course of the reaction can also be caused by training Do not avoid vapor bubbles of different sizes in the metal that has evaporated in the melt, such as magnesium.

The invention is based on the object of addressing the disadvantages indicated when treating metal melts with wire-shaped Avoid additives. The melt should be offered in such a structure that that the active substances unfolded in the finest form and absorbed by the melt without significant losses will.

To solve this problem it is proposed according to the invention, a wire-shaped means for treating To form molten metal from reactive metal powder coated with ferrous metal in such a way that the powdery mixture of at least one of the metals (A) magnesium, calcium and rare earths as well consists of at least one of the metals (B) iron, nickel and manganese.

The composition of the wire-shaped and silicon-free Treatment agent can be varied within wide limits, so that it can be used for both deoxidation and desulfurization can be used by molten metal, as well as for alloying a molten metal, or around a To bring about microstructure refinement of any kind in the melt. The wire-shaped treatment agent is particularly suitable for the treatment of cast iron melts for the production of spheroidal graphite iron.

The components of the metal powder mixture are in

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generally in a certain relationship to each other. Thus, the metal component A, v / ie calcium, magnesium or rare earth metal, belongs to the meball component'c · B, such as iron, nickel or manganese in a mixing ratio of 40 "to 60 parts by weight. 60 to 40 parts by weight. In many cases it has it has proven advantageous to maintain a ratio of 50 to 50 parts by weight.

For the effectiveness of the treatment miibol it is de of further importance that the components of the metal powder mixture are present in the same grain size. Here it has been found to be advantageous to have a grain size the metal powder from 0.02 to 1.0 mm. A preferred range is a grain size of 0.05 to 0.25 mm, in which range particularly favorable results with particle sizes of the metal powder from 0.07 to 0.16 mm can be achieved.

The jacket made of ferrous metal enclosing the metal powder mixture generally has a wall thickness of 0.2 to 0.5 mm, v / whether a wall thickness of 0.3 mm is preferred.

The method of operation of the wire-shaped treatment agent according to the invention is with continuous immersion into the molten metal about v / as follows. When using a mixture of powder of metals With different melting points in particular, it is to be expected that the powder of the metal component with the higher melting or boiling point as the nucleus for the formation of gas bubbles in the powder component with the lower one Boiling point acts. With a powder mixture of z. B. Magnesium and iron increase accordingly when immersed in a molten metal of z. B. above 1200 ° C comparatively many small Mg vapor bubbles in the melt

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and largely dissolve on their way to the metal surface. In this way an optimal Mg output is achieved. For example, with an iron-metal-coated treatment agent made of magnesia powder and iron powder, a magnesium output of over 60 % is achieved in the treatment of a cast iron melt, and the graphite of the cast iron melt is completely spherical. If, on the other hand, the treatment is carried out with the same wire filled with powder made of pure magnesium metal, the Mg yield is about 2 %.

With the treatment agent according to the invention, any formation of smoke or eruptions is surprisingly avoided, so that almost 100 % of the z. B. added magnesium can be effectively implemented with the iron or steel melt. With the treatment agent according to the invention, it is possible in a safe and reproducible manner to advantageously deoxidize, desulfurize, modify graphite forms, such as compacted or spheroidal graphite, or to inoculate the iron or steel melt.

The invention is illustrated by the following examples explained in more detail and by way of example.

example

A sheathed body with an outer diameter of 3.2 mm was made from a shell made of mild steel strip (wall thickness of the iron jacket 0.3 mm) and a core made of a mixture of 50 % metallic magnesium powder and 50% iron powder, both with a grain size of 0.07 up to 0.16 mm, using a wire-making machine. represents. The product is mechanically compressed and deformed and a body is produced in the form of a wire.

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The magnesium content, based on the running meter of wire, was 1.9 g. 12 kg of this wire (= 610 g of magnesium) were fed into 4000 kg of a cast iron melt of the composition ^{at a temperature of 1420 to 1450 ° C. by means of an automatic feed device}

3.70 % carbon, 2.40 % silicon
0.67 % manganese

0.032 % magnesium

Remainder iron

introduced. The feed rate was about 100 m / min.

After the end of the experiment, the treated iron melt had a magnesium content of 0.042 %, v / as corresponds to a magnesium output of 65.6%. The treatment proceeded completely calmly and without smoke development and without eruptions or without the ejection of melt fractions.

The graphite in the casting was 100 % spherical.

In a comparative experiment, the same wire was used, but only with a filling of pure magnesium metal powder manufactured. The magnesium content was

2.2 g per meter of wire. 1.18 kg of magnesium from a melt of the composition (4000 kg) 3.70 % carbon 2.40 % silicon
0.67 % manganese

0.042 % magnesium

Remainder iron

at 1420 to 1450 ⁰ C with a feed rate of 100 m / min. The treatment proceeded with strong smoke development and pulsating melt.

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- / - ? 29A8636

After the end of the test, the melt had a magnesium content of 0.047%, which corresponds to a magnesium output of about 1.7 % .

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ORIGINAL INSPECTED

Claims (3)

Claims 1. Wire-shaped means for treating metal melt from reactive metal powder coated with ferrous metal, characterized by a powdery mixture of at least one of the metals (A) Magnesium, calcium and rare earths as well as at least one of the metals (B) iron, Nickel and manganese. 2. Agent according to claim 1, characterized by a mixing ratio of A: B from 40 to 60 to 60 to 40 parts by weight 3. Agent according to claims 1 to 2, characterized by a grain size of the metal powder of 0.02 to 1.0 mm, preferably 0.05 to 0.25 mm. 1 30024/0181 ORlGiNJAL INSPECTED