RU2426804C1 - Furnace for melting and refining of reaction metals and alloys - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: furnace consists of working chamber, of loading devices for charge, of independent sources of heating, of melting cold sole with cold lip and of crystalliser. The latter is made pass-through and transparent for electromagnetic field with frequency 0.1-5 MHz created with an inducer positioned on the crystalliser. The lip is additionally equipped with the inducer and is transparent for electro-magnetic field of 0.1-5 MHz frequency. ^ EFFECT: design of furnace optimally combining advantages of furnaces with cold sole and induction furnaces which facilitates production of ingots of high quality in one melt. ^ 2 cl, 1 dwg

Description

The present invention relates to the field of special electrometallurgy and can be used for smelting ingots of refractory and highly reactive metals and alloys, mainly titanium, used in aerospace engineering.

On an industrial scale, titanium alloys for aerospace engineering are produced by double vacuum arc remelting (VDF), triple VDF, or by electron beam melting (ELP) + VDF, plasma arc melting into a crystallizer (PDP) + VDP, skull-melting using skull-consumable method electrode (GRE) + VDP and induction melting (IP) is used to a limited extent in cold sectional crucibles.

A prerequisite in the production of these alloys is the absence of refractory inclusions formed from pieces of a mixture having a higher density and / or melting point than the base metal. These include gas-saturated (with a high content of nitrogen and oxygen) sponge inclusions and individual particles of ligatures and cutting tools enriched with refractory elements (tungsten, molybdenum, niobium) (as a rule, as part of the chip when it is involved in the technological process). Despite careful preparation and quality control of the charge materials, if the normal technological process is violated, such pieces may end up in the charge.

To date, the most widespread are VDP furnaces [1, p. 152]. The ingots smelted in these furnaces, especially by double or triple remelting methods, are characterized by high density and good surface quality.

The disadvantage of the furnace VDP is that in the mold combined zone of melting and solidification of the metal. With a relatively small depth of the melt bath, which moves in height during the melting process, the refractory particles contained, having a high density and melting point, do not have time to go into the liquid phase and freeze into the body of the ingot.

The category of VDP furnaces includes a skull furnace with a consumable electrode (GRE). The disadvantage of such a furnace is that in order to obtain the necessary density of the ingot and surface quality, additional melting of the obtained ingot by the VDP method in the mold is required.

Known induction vacuum furnace with a cold crucible containing an inductor made of sections of a cold crucible and a vacuum chamber, with a mechanism for drawing an ingot [2]. The furnace allows to obtain high-quality homogeneous alloys. The disadvantage of the furnace is the lack of the possibility of refining from inclusions of low and high density, restrictions on the diameter of the smelted ingots, associated with technical and economic indicators of the induction remelting process, for this reason the manufacture of large-sized ingots is unprofitable.

To exclude the ingress of solid inclusions in the melted alloys of reaction metals, for example, Ti and Zr, cold hearth furnaces and independent heat sources are widely used, in which the melting and crystallization zones are located separately. In this case, solid inclusions, due to their higher density, sink to the bottom of the molten bath and freeze into the skull. These include electron beam melting (ELL) and plasma arc remelting (RPS) [1, pp. 172-184].

Known cold hearth EBP furnaces for producing ingots of titanium alloys. The disadvantage is the selective evaporation of components having greater vapor pressure than that of the alloy base, so the range of alloys is very limited.

Known furnace PDE with a cold hearth, containing a housing with charge bins located in it, a mold with an ingot extraction mechanism. These furnaces, due to the limitation of the volume of the liquid bath, both on the hearth and in the mold, do not allow a sufficiently uniform ingot to be obtained for one remelting (additional remelting is required).

Known vacuum melting furnace with a cold hearth, including a loading device for loading the charge, a working chamber in which independent heat sources are installed [3] - prototype. The operation of such a furnace (plasmatrons are used as independent heating sources) shows that the unit allows to obtain ingots-billets intended for subsequent remelting without restriction by assortment, however, the obtained ingots are inferior in surface quality to ELL and induction furnace due to the peculiarity of heating the bath mirror in a mold and a drain toe by a plasma arc. Up to now, it has not been possible to develop a PDP technology that provides industrial ingots (700-850 mm) with a surface that is satisfactory for deformation.

The tasks to which this invention is directed are improving the quality of smelted highly reactive metals and alloys, reducing the cost of production, increasing the productivity of the furnace, increasing the stability of its operation.

The technical result of the invention is the creation of a furnace for remelting and refining highly reactive metals and alloys, which optimally combines the advantages of cold hearth furnaces and induction furnaces, which makes it possible to obtain ingots that satisfy the requirements of aerospace engineering for one remelting.

The specified technical result during the implementation of the invention is achieved by the fact that the furnace for melting and refining reaction metals and alloys contains a working chamber, charging devices for the charge, independent heat sources, a cold melter with a cold drain tip and a crystallizer, the mold is transparent and transparent to the electromagnetic field with a frequency of 0.1-5 MHz, created by an inductor located on the mold.

To eliminate the prerequisites for the freezing of the melt in the area of the drain sock, the drain sock is additionally equipped with an inductor and is transparent for the electromagnetic field with a frequency of 0.1-5 MHz.

The drawing shows a diagram of a furnace for melting and refining reaction metals and alloys.

The furnace includes a working chamber 1, a loading device 2, a cold melter under 3, with a cold drain toe 4 with an inductor (an inductor is not shown), independent heat sources 5 (in the example of a plasma torch), a sectional sectional mold 6, from the outer surface of which an inductor 7 is placed , the mold is equipped with an extraction mechanism 8.

The furnace operates as follows.

An inert gas atmosphere is created in the working chamber 1, by means of a charging device 2, a charge is supplied to the melting furnace 3, plasmatrons 5 are turned on, the furnace is brought to a stable thermal regime and melting is performed. In the process of melting on a cold hearth 3, a skull 9 is formed on which a melt bath 10 is formed, inclusions of a higher density compared to the melt are deposited on the bottom of the bath and freeze into the skull, low density - dissolve on the hearth, melt refined from solid particles through a drain sock 4 flows into the passage sectional crystallizer 6. The inductor 7 creates a magnetic field with a frequency of 0.1-5 MHz, this is the most economical mode for maintaining the melt in the liquid state and intensive mixing, which guarantees excellent averaging the chemical composition of the alloy. By means of the extraction mechanism 8, an ingot 11 with a high quality surface is formed. To prevent freezing of the melt, an inductor is installed in the area of the sock, creating a magnetic field with a frequency of 0.1-5 MHz, while the sock is made transparent to the electromagnetic field.

The advantages of the furnace for smelting and refining in comparison with the known furnaces are:

1. Compared with VDP furnaces, the manufacture of a pressed electrode for the first remelting is not required; metal contamination by solid inclusions is excluded.

2. Compared with IP furnaces, the power consumption is drastically reduced, as Induction heating is carried out only to maintain the required temperature of the melt in the crucible.

3. Ensuring the possibility of producing high-quality ingots of titanium alloys in one melting cycle.

Information sources

1. Melting and casting of titanium alloys. Ed. Alexandrova V.K. - M.: Metallurgy, 1994.

2. RF patent No. 2096713, IPC F27D 11/06, publ. 11/20/1997.

3. RF patent No. 2228962, IPC С22В 9/21, publ. 05/20/2004.

Claims (2)

1. Furnace for melting and refining of reaction metals and alloys, containing a working chamber, charging devices for a charge, independent heat sources, a cold melter with a cold drain toe and a mold, characterized in that the mold is transparent and transparent to an electromagnetic field with a frequency of 0 , 1-5 MHz generated by the inductor, which is located on the mold. 2. The furnace according to claim 1, characterized in that the drain sock is additionally equipped with an inductor and is transparent for an electromagnetic field with a frequency of 0.1-5 MHz.

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