DE3121089A1 - WIRE SHAPED AGENT FOR TREATING METAL MELT - Google Patents

Description

METALLGESELLSC'TAti'T "- * _: " · ΡΓε * αβ1 ^ ιτ £ "/ M. ,; 13.4.1981

Aktiengesellschaft - ^: · - - DitMLr / lIFA

Reuterweg 14
6000 Frankfurt / M.

Prov. No. 8697 M.

Wire-shaped means for treating molten metal

The invention relates to a wire-shaped treatment agent of molten metal.

As is known, molten metal is often given an aftertreatment with a metallic or non-metallic one Treatment agents. The treatment agent can also be supplied to the melt in a known manner in wire form. In such a wire-shaped means for treating Molten metal, reactive metal powder is coated with a ferrous metal.

The use of wire-shaped treatment agents results in practice in the cases of certain difficulties when an additive is introduced into the z. B. molten iron is easily volatile or vaporizable and may also be present in relatively large amounts on average. It exists thus the possibility that a component of the wire-shaped treatment agent, such as magnesium, at a temperature below the melting point of a z. B. molten cast iron evaporates before the cladding wire melted and of the melt is absorbed. It is therefore to overcome such difficulties from DE-OS 25 31 573 a wire-shaped Means for treating molten metal are known, in which between the outer jacket made of ferrous metal and the core material made of relatively volatile metal, e.g. B. magnesium, an insulating material made of z. B. iron powder or

Magnesium-containing coke is arranged. With the previously known treatment agent, the addition of the core material is intended take place simultaneously with the melting of the jacket material and an early melting and evaporation of the Magnesium core can be prevented.

In order to increase the reaction yield and to achieve a smooth, slowed reaction process according to an older proposal (patent application P 29 48 636) a powdery mixture of at least one of the metals (A) magnesium, calcium and rare earths as well at least one of the metals (B) iron, nickel and manganese is provided, which is coated with a shell made of ferrous metal is.

It has now been found that the treatment blue of Better control and vary metal melts within wide limits leaves, if the wire-shaped treating agent with certain, a premature reaction of the reactive agent inhibiting components is designed in certain "manner. Accordingly, a wirefree means for treating Molten metal, made from powdered powder coated with ferrous metal Mixture of at least one of the metals (A) magnesium, calcium and rare earths and at least one the Motalle (B) iron, nickel and manganese according to patent application P 29 48 638 according to the present invention in the manner designed in that the metal powder (A) has a reaction-retarding surface coating and the mixture has a contains reaction-inhibiting component (C) made of expandable silicates and / or a carbon carrier.

As both the layer thickness and particle size of the surface coating of the reactive metal (A) as well as the reaction-inhibiting component (C) varies greatly depending on the type and amount can be treated with molten metal

wire-shaped treatment agent according to the invention in can be varied within wide limits.

Oxidic substances can be used as a reaction-retarding or reaction-inhibiting coating for the reactive metal (A), which are useful in finely divided or fine-grained Form such as aluminum oxide, magnesium oxide, finely divided Silica. Furthermore, graphite or coke powder or clay-containing graphite masses are suitable for the coating.

The coating can be achieved in a simple manner by dry mixing the substances. However, it can also be expedient to provide a liquid, vaporizable medium in the mixing process, so that the coating is applied more firmly. The liquid medium can for example be water or an organic solvent. If necessary, a small addition of about up to 2 % of an organic or inorganic binder can also be expedient and bring about a firmly adhering, dense coating. The particle size of the coating material is generally between 0.02 and 1.0 µm, a particle size of 0.05 to 0.25 µm being advantageous.

For the effectiveness of the wire-shaped treatment agent It is also important that the metal components of the powder mixture are present in the same grain size. Here has it has been found to be advantageous to maintain a grain size of the metal powder of 0.02-2.0 mm. A preferred one The range is a grain size of 0.05 to 1.5 mm. Appropriately, the reactive and with the reaction delaying Metal component to be coated in the form of granules with a particle size of 0.8 to 1.2 mm, in particular in a grain size of 1 mm.

According to a further embodiment of the present invention the metal component (A) can also be in the form of an alloy

- η. . w -

powder, for example Mg / Fe / Si alloys or Ca / Si / Mg alloys, which may also contain rare earth metals. The magnesium content of the alloys is generally between 3 and 50 %,

The coated powder mixture of the treatment agent according to the invention also contains a metallurgically neutral, reaction-inhibiting component (C). In the context of the invention, metallurgically neutral means that the substance is not absorbed into the melt. Suitable substances for this component are expandable silicates or carbon carriers or mixtures of these components. As expandable silicates, for example, quartz porphyry glass, z. B. Perlite are used, which ^{expand when heated to temperatures above 1200 0} C due to the escape of the enclosed water to form rock foam. Expandable sheet silicates, such as vermiculite, are also suitable. While the expandable silicates, due to their low thermal conductivity, produce the strongest reaction-inhibiting effect, if desired, by using coke or graphite alone or in a mixture with the expandable silicates as component (C), a less strong reaction inhibition can be achieved and be adapted to the respective local conditions of the treatment process.

Even if the composition of the powder mixture of the invention Treatment wire can be varied in a wide range, so it has in general however, it has been found expedient to provide a composition in the following quantity ranges

30 to 80, preferably 50 to 70 wt -.% "A

ir 10 to 60, preferably 20 to 40% by weight of “B

I!

1 to 15, preferably 5 to 10% by weight of “C.

A composition corresponding to the powder mixture

60% by weight magnesium, 30 % by weight iron
10% by weight perlite

has proven to be particularly suitable for the treatment of cast iron melts for the production of spheroidal graphite iron.

The jacket made of ferrous metal enclosing the metal powder usually has a wall thickness of less than 1 mm and is preferably 0.15 to 0.5 mm. Of the Treatment wire itself usually has a diameter of 2-6 mm. In some cases of enamel treatments Treatment wires with a diameter of up to 20 mm can also be considerably thicker, albeit less flexible to be required. Wires with a diameter of 2 - 6 mm are used in a procedure with treating the pouring stream a molten metal used, while wires with a diameter greater than 6 mm and up to 20 mm, preferably up to 15 mm, can be used in the pan when treating molten metal such as cast iron.

The treatment wire according to the invention is flexible and can be conveyed with very simple wire feed devices if the diameter is not too great. It can then be used with success if a feed speed of the wire drive of z> 60 m / min is achieved. Preferably, however, speeds of 110 to about 200 m / min are used in order to ensure that the wire is immersed deeply into the melt so that optimum output is achieved. Depending on the amount of liquid metal to be treated, one or more wires can be wound into the melt at the same time. When using several wires

th result advantageously shorter treatment times and lower temperature losses.

If several wires are used at the same time, so these can either all be of the same quality or have different fillings, for example, can be used for molten metal treatment at the same time;

a) Two wires filled with Mg according to the present invention;

b) a wire as an alloy wire, also as a so-called "mono wire" can be represented, from elements or alloys of the elements Cu, Al, Ni, Cr, Mg, Ti, Ce, Bi, Te, Sb, Nb;

c) one or more wires with a filling of inoculant conventional type, such as ferrosilicon.

The treatment wire according to the invention is usually wound into the static melt in a ladle. It plays The shape of the pan does not play a crucial role in contrast to conventional Mg treatment methods that do not have wires use.

When using several treatment wires at the same time, it is advantageous not to place the wires in the same place to immerse in the melt. The usual dimension of the Tr., Isport pan appears for this method of Mg treatment suitable.

In addition to the introduction of the wire into the pan, according to the invention the treatment wire can also be wound directly into the pouring stream, pouring pool or into the casting mold, or into a separate treatment vessel or channel can be immersed between the furnace and the transport or pouring ladle.

If there is a greater variety of wires, they are preferably not used simultaneously, but in individual process steps.

th separately immersed in the melt of the treatment vessel. For example, treating a Cast iron melt for the production of spheroidal graphite cast iron can be carried out in the following way:

1st step: Desulfurization and deoxidization in one

Treatment wire according to the invention, containing a powder mixture of the composition e.g. 30 Ms 80 wt% Mg

10 to 60 wt .-% Fe 1 to 15 wt -.% Of graphite

2nd step: Modifying the graphite with eanem Be

action wire, as in step 1

3rd step: alloying with, for example, solid Cu wire for

Setting a desired matrix

4th step: Inoculation with a with, for example, pul-

deformed ferro-silicon filled wire as the final metallurgical treatment the shedding.

The advantages of such a multi-step procedure lie in the fact that, for example, the various process steps are carried out in quick succession at just one treatment station can be done. There is no need to transfer the melt to other vessels. This saves time and a high temperature loss is avoided. In addition, more precise and easier work is possible.

The invention is explained in more detail and by way of example using an exemplary embodiment.

Prov. No. 8697 M } /. : ; ^: --_. - ■ '. ";

Example:

A treatment body in the form of a wire was produced by means of a wire-making machine by deforming and compressing it. With an outer diameter of 5 mm of the wire, a sheath made of mild steel tape (jacket thickness 0.35 ms) enclosed a core made of a metal powder mixture. The powder mixture consisted of 69 % metallic magnesium powder, 26% iron powder, both with a particle size of 0.5 mm, and 5 % Graphite powder with a particle size - = 0.2 mm Before the production of the powder mixture, the magnesium metal powder was premixed with part of the graphite powder in order to ensure a reliable formation of the reaction-retarding coating on the magnesium surface.

The magnesium content, based on the running meter of wire, was 10 g.

\. The treatment wire was fed into cast iron melts by means of an automatic feed device. The cast - iron melt each were in an open, so

named slim pan (fit 1 to; ratio Height: diameter = 2: 1). It became a cast iron beast! The following composition was treated in experiments I and II:

3.80 % carbon 1.90 % silicon 0.29 % manganese - = 0.015 % sulfur, remainder iron

The other test conditions and the test results are listed in the following table:

Amount of treated cast iron senschineli.:e

Temperature before treatment: after treatment: feed rate: Treatment time: Amount of wire fed: Amount of Mg fed:

Sulfur content of the treated melt:

Magnesium content of the treated melt:

Mg output spherulite proportion

Test 'i 1,000 k [<1,465 ° C 1,405 ° C 110 m / min 108 see 9.5 kg 1.4 kg

0.005 % 0.059 %

42 %

= - 90 %

Ve 'such II 1. JOO kg

1.515 1.470 ⁰ C ⁰ C 110 m / min

75 see 8.0 kg 1.17 kg

0.008 %

0.044 %

37.6 %

The treatment of the cast iron lumps proceeded calmly and without the ejection of molten material. In the cast samples, more than 90 % of the graphite was formed in the ball.

The tests show that even with an increased magnesium content in the treatment wire, a smooth course of the treatment and a high output of magnesium of approx. AO % can be achieved.

When using e.g. perlite instead of graphite as a reaction-inhibiting Component of the earthing wire according to the design The treatment follow-up also proceeded without eruptions. In addition, the silicate component has the effect cleaning of the melt in the treatment wire by bonding of the reaction products or slag particles dispersed in the melt.

If copper or nickel in powder form is used instead of iron powder in the treatment wire according to the invention, the iron melt can be used be alloyed at the same time as the magnesium treatment, which leads to an increased percentage of pearlite in the basic structure.

Claims (6)

Prov. No. 8697 M '' ---: - "» · - '-'. · - P a t e η t a η s ρ r ü ch e 1. Wire-shaped means for treating molten metal, made from a powdered mixture coated with ferrous metal of at least one of the metals (A) magnesium, calcium and rare earths and at least one of the metals (B) Iron, nickel and manganese according to patent application P 29 48 636, characterized in that the metal powder (A) has a reaction-retarding surface coating and the mixture has a reaction-inhibiting component (C) composed of expandable silicates and / or a carbon carrier. 2. Wire-shaped means according to claim 1, characterized in that aluminum oxide, magnesium oxide, finely divided silica, graphite or coke powder is used as the coating. 3. Wire-shaped means according to claims 1 and 2, · characterized in that component (C) is perlite, vermiculite, coke, graphite or a mixture of these substances. 4. Wire-shaped means according to claims 1 to 3> characterized in that the grain size of the metal powder (A, B) and the component (C) is 0.02 to 2.0 mm. 5. Wire-shaped means according to claims 1 to 4, characterized by the composition of the powder mixture Il 30 to 80, preferably 50 to 70% by weight of “A 10 to 60, preferably 20 to 40% by weight of “B Il 1 to 15, preferably 5 to 10% by weight of “C 6. Wire-shaped means according to claims 1 to 5, characterized by the composition of the powder mixture 60 wt% magnesium
30% by weight 96 iron
10 wt .- # perlite