GB1594457A

GB1594457A - Manufacture of wire by the projection of a stream of liquid metal alloy

Info

Publication number: GB1594457A
Application number: GB4315177A
Authority: GB
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 1976-10-15
Filing date: 1977-10-17
Publication date: 1981-07-30
Also published as: DE2746364B2; CA1096204A; AU2978477A; DE2746364A1; BE859796A; LU78329A1; JPS5847936B2; JPS5353524A; FR2367564B1; ATA741077A; ES463225A1; DE2746364C3; IT1090895B; SE425950B; AU512576B2; AT357713B; FR2367564A1; SE7711665L

Description

(54) THE MANUFACTURE OF WIRE BY THE PROJECTION OF A STREAM OF LIQUID METAL ALLOY (71) We, MICHELIN & CIE (COMPAGNIE GENERALE DES ETABLISSEMENTS MICHELIN), a French body corporate, of4 Rue du Terrail, Clermont-Ferrand, Puy-de-Dome, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to the manufacture of wire by the projection of a stream of liquid metal or metal alloy into a cooling medium and to steels for use in this manufacture.

Plant for making wire by this method essentially comprise a crucible containing liquid steel provided with at least one die through which a molten stream of the steel is forced by means of pressure exerted on 'the liquid metal. The stream of steel passes into a cooling medium contained within a cooling enclosure in which the molten stream solidifies to a solid wire.

In such plants, any interference with the geometry of the orifice in the die may bring about an alteration in the geometrical and mechanical properties of the wire, possibly accompanied by an abnormal frequency of wire breakages. In particular, the orifice in the die may become obstructed by crystalline matter. Analysis of this matter reveals that it is composed of oxides or combinations of refractory oxides having a higher melting point than that, approximately 1,500"C, of currently used steels. The most frequently encountered oxides are alumina, lime and titanium oxide.

It is an object of the present invention to retard if not to eliminate obstruction of the orifice in the dies by these oxides or combinations of refractory oxides.

Therefore according to the invention in one aspect there is provided a method of manufacturing wires by projecting a stream of silicon steel through a die into a cooling medium, the steel used containing one or more elements of which the free enthalpy for oxide formation has a greater absolute value than the free enthalpy for formation of silicon oxide at the temperature at which the steel is projected through the die, the content of the or each of those elements in the steel being less than 150 ppm.

According to another aspect of the invention there is provided silicon steel when used in the manufacture of wires by the projection of a stream of liquid steel through a die into a cooling medium, the steel containing one or more elements of which the free enthalpy for oxide formation has a greater absolute value than the free enthalpy for formation of silicon oxide at the temperature of projection through the die, the content of the or each of those elements being less than 150 ppm.

Other suitable steels are silicon steels and manganese steels such as described in British Patent No. 1 396 406.

The Applicants' studies and research have in fact led to the discovery of refractory oxides and/or combinations of oxides deposited in the orifice of the die when there are present in the steels, elements, and more particularly the metal elements of those oxides and/or combinations of oxides. Furthermore, it has been discovered that those strongly deoxidising or strongly reducing elements of which the absolute value of free oxideforming enthalpy is greater in absolute terms than the free silicon oxide forming enthalpy at the temperature at which the silicon steel projected through the die, i.e. at temperatures about the melting point, usually around 1150"C, and up to those used in practice, are the elements whose content in the steel must be limited if deposits in the die orifice are to be reduced.

The free enthalpy or Gibbs' Free energy is defined according to Wisniewski S., Staniszewski B., and Szymanik R. in "Thermodynamics of Non equilibrium Processes" -D. Reidel Publishing Company.

By way of example, it will now be described with reference to the drawings how an oxide can be formed when aluminium is present in the steel, aluminium being a deoxidising agent which is frequently used in steel working.

Figure 1 of the drawings is a diagram of chemical equilibrium of simultaneous oxidation of silicon and aluminium in liquid steel at 1,1500C (according to K.

Schwerdtfeger and H. Schrewe, Electric Furnace Proceedings, 1970, page 96) while Figure 2 shows a short length of steel wire obtained by the method of and with the steel according to the invention.

Referring to Figure 1 the abscissa represents the percentage aluminium content in the steel while the ordinate represents the percentage silicon content.

The plane bounded by these two axes is divided into three zones I, II, III. Zone J comprised between the ordinate and the curve 10 is the zone of silica (SiO2) formation. Zone II comprised between the curve 10 and the curve 20 is the zone for formation of mullite, an alumina silicate (3A12O3.2SiO2). Finally zone III between the curve 20 and the abscissa is the zone for formation of alumina (A12O3).

For a steel having a content of 3.5% silicon and 0.015% (150 ppm) aluminium (i.e. point A), the first refractory oxide formed will be alumina, the point A being situated in the zone III. For steel containing smaller aluminium contents, the point A will be moved progressively in the direction of the point B situated on the curve 20. The result would be that in order to avoid formation of mullite and/or alumina, the aluminium content of the steel in question would have to be at least less than that corresponding to point B for constant percentage of silicon.

However, it has been discovered according to the invention that in contrast with what was expected, it is sufficient in practice, in order to obtain long die life, to limit the aluminium content to 150 ppm and preferably to 100 ppm.

These limit contents are likewise suitable with regard to the other elements such as calcium, titanium, zirconium, yttrium and cerium, of which the free enthalpy for oxide formation is in absolute terms greater than the free enthalpy for silicon oxide formation at the temperature of silicon steel projected through the die (M. Olette and M. F.

Ancey-Moret, Revue de Metallurgie, June 1963, pages 569 to 581).

For example, when a steel of the composition: Si3.5%, Mn--1.20/,, C0.7%, Al-200 ppm, is projected through a die at 1,500"C, the stream is irregular at first, diminishes in diameter and is then interrupted after 15 minutes operation of the die. However when the aluminium content is reduced to 90 ppm, there is no disturbance of the stream even after two hours of operation of the die, which corresponds to a production of several tens of kilometres of wire.

The same long die life has been noted with steels having the following compositions: Si3.5% Cr0.8% Mn-0.1 C0.4% and 80 ppm of calcium or 90 ppm cerium or 80 ppm titanium.

In order to avoid undesirable high contents of these elements in the steel used according to the invention, any convenient means may be used. Thus, it is possible, for example, to select the raw materials used in the formation of the steel so that the content of these elements is limited. It is also possible partially to oxidise the liquid steel and then to decant undesirable inclusions formed by the precipitation of oxides of these elements. It is further possible in the case of aluminium to use the reaction of magnesia with the liquid steel. Thus the magnesium formed is volatilised while the insoluble alumina may be decanted off to leave a steel low in aluminium content.

WHAT WE CLAIM IS: 1. A method of manufacturing wires by projecting a stream of silicon steel through a die into a cooling medium, the steel used containing one or more elements of which the free enthalpy for oxide formation has a greater absolute value than the free enthalpy for formation of silicon oxide at a temperature at which the steel is projected through the die, the content of the or each of those elements in the steel being less than 150 ppm.

2. A method as claimed in Claim 1 in which the content of the or each of those elements in the steel is less than 100 ppm.

3. A method as claimed in Claim 1 or Claim 2 in which the silicon steel has an aluminium, calcium, cerium or titanium content of less than 150 ppm.

4. A method of manufacturing wires by projecting a stream of silicon steel into a cooling medium substantially as herein described.

5. Silicon steel when used in a method of manufacturing wires by projecting a stream of liquid steel through a die into a cooling medium as claimed in any one of claims 1 to 4 the steel containing one or more elements of which the free enthalpy for oxide formation has a greater absolute value than the free enthalpy for formation of silicon oxide at the temperature of projection through the die, the content of the or each of those elements being less than 150 ppm.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. described with reference to the drawings how an oxide can be formed when aluminium is present in the steel, aluminium being a deoxidising agent which is frequently used in steel working. Figure 1 of the drawings is a diagram of chemical equilibrium of simultaneous oxidation of silicon and aluminium in liquid steel at 1,1500C (according to K. Schwerdtfeger and H. Schrewe, Electric Furnace Proceedings, 1970, page 96) while Figure 2 shows a short length of steel wire obtained by the method of and with the steel according to the invention. Referring to Figure 1 the abscissa represents the percentage aluminium content in the steel while the ordinate represents the percentage silicon content. The plane bounded by these two axes is divided into three zones I, II, III. Zone J comprised between the ordinate and the curve 10 is the zone of silica (SiO2) formation. Zone II comprised between the curve 10 and the curve 20 is the zone for formation of mullite, an alumina silicate (3A12O3.2SiO2). Finally zone III between the curve 20 and the abscissa is the zone for formation of alumina (A12O3). For a steel having a content of 3.5% silicon and 0.015% (150 ppm) aluminium (i.e. point A), the first refractory oxide formed will be alumina, the point A being situated in the zone III. For steel containing smaller aluminium contents, the point A will be moved progressively in the direction of the point B situated on the curve 20. The result would be that in order to avoid formation of mullite and/or alumina, the aluminium content of the steel in question would have to be at least less than that corresponding to point B for constant percentage of silicon. However, it has been discovered according to the invention that in contrast with what was expected, it is sufficient in practice, in order to obtain long die life, to limit the aluminium content to 150 ppm and preferably to 100 ppm. These limit contents are likewise suitable with regard to the other elements such as calcium, titanium, zirconium, yttrium and cerium, of which the free enthalpy for oxide formation is in absolute terms greater than the free enthalpy for silicon oxide formation at the temperature of silicon steel projected through the die (M. Olette and M. F. Ancey-Moret, Revue de Metallurgie, June 1963, pages 569 to 581). For example, when a steel of the composition: Si3.5%, Mn--1.20/,, C0.7%, Al-200 ppm, is projected through a die at 1,500"C, the stream is irregular at first, diminishes in diameter and is then interrupted after 15 minutes operation of the die. However when the aluminium content is reduced to 90 ppm, there is no disturbance of the stream even after two hours of operation of the die, which corresponds to a production of several tens of kilometres of wire. The same long die life has been noted with steels having the following compositions: Si3.5% Cr0.8% Mn-0.1 C0.4% and 80 ppm of calcium or 90 ppm cerium or 80 ppm titanium. In order to avoid undesirable high contents of these elements in the steel used according to the invention, any convenient means may be used. Thus, it is possible, for example, to select the raw materials used in the formation of the steel so that the content of these elements is limited. It is also possible partially to oxidise the liquid steel and then to decant undesirable inclusions formed by the precipitation of oxides of these elements. It is further possible in the case of aluminium to use the reaction of magnesia with the liquid steel. Thus the magnesium formed is volatilised while the insoluble alumina may be decanted off to leave a steel low in aluminium content. WHAT WE CLAIM IS:

1. A method of manufacturing wires by projecting a stream of silicon steel through a die into a cooling medium, the steel used containing one or more elements of which the free enthalpy for oxide formation has a greater absolute value than the free enthalpy for formation of silicon oxide at a temperature at which the steel is projected through the die, the content of the or each of those elements in the steel being less than 150 ppm.

6. Silicon steel as claimed in Claim 5

which has a content of aluminium, calcium, cerium or titanium of less than 150 ppm.

7. Silicon steel as claimed in Claim 5 or Claim 6 in which the content of the or each of those elements in the steel is less than 100 ppm.

8. Silicon steel as claimed in Claim 5 substantiallv as herein described.

9. Silicon steel wire when made by a method as claimed in any of claims 1 to 4.

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