RU2313590C1 - Consumable electrode producing method - Google Patents

Abstract

FIELD: electrometallurgy, possibly melting ingots of highly active metals and alloys including ingots of titanium and its alloys.

SUBSTANCE: method comprises steps of pouring solid metallic component with liquid metal; using as solid metallic component waste lumps and briquettes of cuttings and charge; producing liquid metal for pouring by melting with use of electric arc electrode welded to electrode holder; forming briquettes with length mainly equal to length of electrode and placing them along wall of crystallizer in parallel relative to its axis.

EFFECT: possibility for producing electrode of desired mechanical strength by consolidation of waste lumps and briquettes and producing ingots by single refining of predetermined chemical content along the whole length of ingot, improved explosion safety of melting process, lowered cost price of product.

1 tbl, 2 dwg

Description

The invention relates to the field of electrometallurgy and can be used for smelting ingots of highly reactive metals and alloys, including ingots of titanium and its alloys.

Known consumable electrode for smelting ingots from titanium and its alloys, containing mutually interconnected pressing portion parts of bulk and loose components from titanium sponges, ligatures and return waste. To improve the adhesion of the individual batch parts of the electrode to one another, their end surfaces are made with alternating radial sectors of protrusions and depressions, as well as with central spherical protrusions and depressions (Dobatkin V.I., Anoshkin N.F. et al. Titanium alloy ingots. - M .: Metallurgy, 1966, p. 48).

The disadvantage of this electrode is the low mechanical strength due to poor adhesion between the low-plastic lumpy and bulk components of the charge. The consequence of this is the destruction of the electrode in a number of cases during transportation and melting in vacuum arc furnaces, defective ingots, emergency explosive situations when moving the arc to the crystallizer wall, the need to perform a large amount of welding work in an atmosphere protected from oxidation by hardening the electrodes by welding longitudinal strip plates to the surface of the weakened sections of the electrode.

The closest in technical essence to the present invention is a method for producing consumable electrodes, comprising pouring a solid metal component with liquid metal, while metallized pellets used in the mold simultaneously with the liquid metal in a certain ratio are used as a solid component. (RF patent No. 2233895, class C 22 B 9/18, publ. 10.08.2004. Bull. No. 22) - prototype.

The implementation of this method in relation to titanium alloys can only be carried out using a skull furnace to obtain a melt. However, the value of specific capital investments when using the skull method of melting is significantly larger than when using the vacuum arc melting of the consumable electrode in the mold.

In addition, when pouring melt into the waste loaded into the mold, there is no reliable welding between them and with the melt.

As a result, during subsequent remelting of the electrodes made in this way, pieces of the electrode may fall into the molten metal bath and form inclusions in the ingot.

The problem to which this invention is directed is to obtain a consumable electrode of the necessary mechanical strength due to the consolidation of lump waste and briquettes from shavings and primary charge, as well as to obtain an ingot after a single remelting of a given chemical composition along the entire length of the ingot, increasing the explosion safety of the melting process of the consumable electrode in a vacuum arc electric furnace and reducing the cost of production.

The technical result is achieved by forming a consumable electrode by melting by burning an electric arc that melts both the metal fixed on the electrode holder and lump waste and briquettes loaded into the mold.

The problem is solved in that in the method for producing a consumable electrode, including pouring a solid metal component with liquid metal, according to the invention, lump waste and briquettes from shavings and batch are used as solid metal component, loaded into the mold of a vacuum arc furnace in an amount not exceeding more than 2.5 times the mass of the electrode welded to the electrode holder, while the briquettes are made with a length predominantly equal to the length of the electrode obtained, and setting they are poured along the crystallizer wall parallel to its axis, and liquid metal for pouring is obtained by melting by an electric arc of an electrode welded to an electrode holder.

The method involves loading lumpy waste and briquettes from shavings and primary charge into the mold and consolidating them by vacuum arc melting into a consumable electrode for subsequent remelting into an ingot. The mechanical strength of the resulting consumable electrode is achieved by choosing the ratio of the masses of the molten electrode and the mixture loaded into the mold, the value of which should be 1: (0.5-2.5).

The chemical homogeneity of ingots made of consumable electrodes is achieved by the method of loading charge materials into the mold, providing the same content of the types of charge materials in each section of the volume of the internal space of the mold.

By increasing the amount of the solid component by more than 2.5 times the mass of the molten electrode, the required strength of the obtained electrode is not provided.

As a result of remelting the resulting consumable electrodes, titanium alloy ingots of a given chemical composition were made from a charge containing up to 92% of recycled waste.

The invention is illustrated by photographs, which depict: the consumable electrode obtained by the claimed method, the type of the bottom part (Fig. 1) and a single remelting ingot (Fig. 2) from electrodes obtained by the proposed method.

Example.

The proposed method was tested under industrial conditions in the smelting shop for the manufacture of a consumable electrode for smelting an ingot of a grade 5 titanium alloy. A consumable electrode with a diameter of 560 mm and a mass of 540 kg of grade 5 alloy formed by semi-automatic welding from lumpy waste was fixed on the electrode holder of a VD-650 vacuum arc furnace. grade 5 alloy.

Then, briquettes with a diameter of 220 mm from chips and primary charge in the amount of 2 pieces of 120 kg each, 800 mm long, with a density of γ = 3.9 g / cm ³ and lump waste of grade 5 alloy in the amount of 300 kg were loaded into a conical mold with a diameter of 670 mm and a diameter of 300 kg .

Further, a consumable electrode was formed by melting by burning an electric arc that melts both the electrode mounted on the electrode holder and the charge materials loaded into the mold.

As a result of vacuum arc remelting, a consumable electrode with a diameter of 660 mm, a mass of 1080 kg, a length of 790 mm, and a density of 4 g / cm ^{3 was} obtained. Obtained by the proposed method, 3 consumable electrodes were joined by oven welding into one electrode with a diameter of 660 mm, 2370 mm long, and a weight of 3240 kg, which was melted into an ingot in a DCS-5 vacuum arc furnace into a mold with a diameter of 770 mm.

The obtained ingot was investigated by chemical composition in the zones: up, middle, bottom. The results are presented in the table. The chemical composition met the requirements of ASTM B 348 for grade 5 alloy.

The difference in the content of alloying elements and impurities along the height of the ingot does not exceed 0.02%.

Table Sample O Al V Fe Mn Mo Ni Si Zr Sn Cu Cr FROM N N Top 0.174 6.14 4.09 0.17 0.005 0,027 0,025 0,028 0.02 0.008 0.008 0,032 0.019 0.009 <0.002 Mid 0.178 6.16 4.10 0.18 0.005 0,025 0,026 0,029 0.02 0.005 0.009 0,032 Bottom 0.176 6.14 4.08 0.18 0.004 0,026 0,023 0,027 0.02 0.006 0.008 0,030 0.019 0.009 <0.002

The proposed method for producing consumable electrodes in comparison with the known ones provides the necessary mechanical strength of the electrodes when more than 90% of recycled waste is involved in their composition, which can significantly reduce the cost of production. In addition, the sufficient strength of the obtained electrode provides reliable explosion safety of the subsequent process of smelting the ingot in a vacuum arc furnace.

Compared with the prototype, the proposed method for producing electrodes allows to reduce the specific capital costs per unit of manufactured products and improve the quality of the metal by eliminating inclusions in the ingots melted from these electrodes.

Claims (1)

A method for producing a consumable electrode, comprising pouring a solid metal component with liquid metal, characterized in that lump waste and briquettes from shavings and a charge are used as a solid metal component, and liquid metal for casting is obtained by melting an electrode with an electric arc welded to an electrode holder of a vacuum arc furnace, while the solid metal component is loaded into the mold of a vacuum arc electric furnace in an amount exceeding no more than 2.5 times the electrode is welded to the electrode holder, and the briquettes are made with a length predominantly equal to the length of the electrode obtained, and they are installed along the crystallizer wall parallel to its axis.

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