RU2233895C1 - Method of production of expendable electrodes - Google Patents

Abstract

FIELD: electrometallurgy; production of expendable electrodes.

SUBSTANCE: the invention is dealt with a method of production of expendable electrodes is pertinent to the field of electrometallurgy in particular to production of expendable electrodes for an electroslag remelting. The method provides for a filling up of the metallized pellets with a molten metal simultaneously fed to the ingot mould in the ratio of (2.7-3.3) : 1 with the pellets feeding rate of 3...5 kg\sec and molten metal of 1...2 kg\sec. The invention allows to produce an expendable electrode with a high chemical homogeneity and sufficient mechanical strength. As a result of an electroslag remelting of the expendable electrode, an ingot is produced, that has a dense defect-free structure with a sufficiently good surface and the lowest cost price.

EFFECT: the invention allows to produce an expendable electrode of high chemical homogeneity, sufficient mechanical strength, a dense defect-free structure, the lowest cost price.

3 dwg, 1 tbl, 1 ex

Description

The invention relates to the field of electrometallurgy, in particular to the production of consumable electrodes for electroslag remelting.

A known method for producing consumable electrodes, in which rods of size 5 × 5 × 25 cm are made with isostatic pressing of metallized pellets with an average diameter of 1.2 cm at a pressure of 559 MPa with additives and without additives of alloying additives. The consumable electrode consists of three butt welded rods with a mass of 3.2 kg each. Carbon-containing additives, such as silicon carbide, titanium carbide, or a mixture thereof, are introduced either directly into the composition of the remelted electrodes before pressing, or are given to the slag [1].

The disadvantage of this method is that there is an increased content of carbon and silicon in the ingot after remelting, an uneven distribution of carbon along the height of the ingot (its content in the lower part is much higher than in the upper), uneven compression ratio, which subsequently leads to insufficient mechanical strength, which makes it difficult to obtain consumable electrodes of large diameter.

A known method of producing consumable electrodes, including pressing the buried charge materials in batches into the matrix and at the same time, ligature additives in the amount of 30-70% are introduced into the first portion of the charge materials [2].

The disadvantage of this method is that there is an uneven distribution of the ligature additives along the height of the resulting consumable electrode, their content in the lower layer of the consumable electrode is higher than in the subsequent higher layers, during the pressing process, an unequal compression ratio is observed, as well as insufficient mechanical strength, which makes it difficult obtaining consumable electrodes of large diameter.

As a prototype, a method for producing consumable electrodes with filling solid charge waste, which is introduced in the amount of 5-55% of the electrode weight, with liquid metal overheated at a liquidus point of 40-200 ° C, is adopted. In this regard, metal charge waste, pre-sorted by size and chemical composition, is laid in the molds or in special forms and filled with liquid overheated melt of the same chemical (grade) composition. In this case, siphon casting or metal casting from above can be applied. Wastes (small-sized) are specified in the form during their filling with liquid metal or after filling. The amount (percentage) of solid waste in the total weight of the casting varies depending on the superheat temperature of the liquid metal [3].

The disadvantage of this method of producing consumable electrodes is that during the production process there may be a problem in the simultaneous selection of charge waste and liquid superheated melt of the same chemical (grade) composition, which leads to an increase in the cost of the resulting consumable electrode and the limited application of this method in real production conditions . In addition, it is necessary to use charge materials that meet the requirements of the chemical composition of the resulting metal for harmful impurities that are not removed during the ESR process. The preliminary task of charge waste in molds or in special forms, and then pouring it with liquid overheated melt can lead to an uneven distribution of charge waste along the height of the consumable electrode obtained, and subsequent adjustment by small-sized waste in the process of filling it with liquid metal or after filling greatly complicates the technological the process and leads to chemical heterogeneity in height of the resulting consumable electrode.

The objective of the invention is to obtain a consumable electrode with increased chemical uniformity in height, while maintaining high mechanical strength and at the same time reducing the cost of manufacturing a consumable electrode for electroslag remelting, while improving the quality of the finished ingot.

The problem is solved in that in the method for producing consumable electrodes, including pouring a solid metal component with liquid metal, according to the invention, metallized pellets are used as a solid metal component supplied to the mold simultaneously with liquid metal in the ratio (2.7-3.3): 1 , with a feed rate of metallized pellets 3 ... 5 kg / s and liquid metal 1 ... 2 kg / s.

The use of pellets as a solid metal component makes it possible to obtain a consumable electrode with enhanced chemical uniformity, which is achieved as a result of the fact that metallized pellets having a spherical shape and a constant particle size distribution thereby ensure their uniform distribution in the volume of the resulting consumable electrode, unlike metal charge waste and allow to obtain sufficient mechanical strength, as well as a low content of harmful impurities, not alyaemyh in ESR.

The simultaneous supply of metallized pellets and liquid metal makes it possible to control the feed rate of metallized pellets and liquid metal, as well as the uniform distribution of pellets in the volume of liquid metal.

The use of liquid metal as a liquid metal component allows you to obtain a given chemical composition of the resulting consumable electrode, and is also the main binder.

The method is illustrated by photographs No. 1-3, which shows a slice (middle part) of the resulting consumable electrode.

With the ratio of metallized pellets and liquid metal (2.7-3.3): 1 and a feed rate of 3 ... 5 kg / s, 1 ... 2 kg / s of metallized pellets and liquid metal, the resulting consumable electrode has a uniform distribution metallized pellets in the bulk of the molten metal (m _pellets / m _metal), while maintaining a high mechanical strength, and provides a result of the preparation electroslag remelting quality finished ingot with the lowest cost that fully satisfies the requirements stated above Tasks (see. FIG. 1).

With a ratio of metallized pellets and liquid metal <2.7: 1 and a feed rate of <3 kg / s, <1 kg / s metallized pellets and liquid metal, an uneven distribution of metallized pellets in the volume of liquid metal (m _pellets / m _metal ), respectively, is observed, which subsequently leads to the result of electroslag remelting of an ingot with chemical heterogeneity (see Fig. 2).

With a ratio of metallized pellets and liquid metal> 3.3: 1 and a feed rate> 5 kg / s,> 2 kg / s of metallized pellets and liquid metal, an uneven distribution of metallized pellets in the volume of liquid metal is observed (m _pellets / m _metal ), which subsequently leads to an ingot with chemical inhomogeneity as a result of electroslag remelting, as well as insufficient mechanical strength of the resulting consumable electrode, which complicates its further redistribution at the electroslag re-installation lava (see Fig. 3).

An example of a specific implementation of the method.

Industrial studies were carried out at OJSC “Zlatoust Metallurgical Plant” in ESPC No. 3.

Obtaining a consumable electrode includes the following technological operations: a molten metal smelted in an arc steel furnace is simultaneously fed into a mold having the form of a finished consumable electrode, and metallized pellets are fed through a screw mechanism. The following steel grades were used as a liquid metal for a bunch of metallized pellets: 07X17H6, EP56, 20X23H18, 40X13.

The resulting consumable electrodes were subjected to electroslag remelting at the A-550 installation in a mold with a diameter of 120 mm and a height of 500 mm under an ANF-6 flux in the amount of 2.5 kg for melting. In order to increase the fused part, invert heads were welded to the remelted consumable electrodes. The process was wired at a current of 2 kA, at a voltage of 55 V. The main melting period was held at a current of 2.5 kA and a voltage of 60 V. Shrinkage was not performed. The remelting process proceeded fairly steadily; slag foaming took place. Significant current surges were absent. Dust during the process was negligible. The results of the tests are presented in the table.

The study of the quality of the metal after electroslag remelting made it possible to ascertain the presence of a dense defect-free structure with a sufficiently good surface of the ingot, as well as the uniformity of the chemical composition over the height of the ingot in cases where the feed rate of metallized pellets and liquid metal was in the range of 3 ... 5 kg / s, 1 ... 2 kg / s, with the ratios of metallized pellets and liquid metal selected during the experiment (2.7-3.3): 1.

As a result of the proposed production method with a ratio of metallized pellets and liquid metal (2.7-3.3): 1 and a feed rate of 3 ... 5 kg / s, 1 ... 2 kg / s, respectively, the consumable electrode had the lowest cost compared to the prototype.

Industrial applicability

The proposed method can be used in a single and mass production, in the manufacture of consumable electrodes for electroslag remelting.

List of sources

1. Pat. USA class 75-10R, (C 22 V 4/00, V 22 D 27/02), No. 3997332.

2. Baranov V.A. Pat. 2083326, IPC6 B 22 F 3/02, publ. July 10, 1997. The patent holder is the Verkhnaya Salda Metallurgical Production Association.

3. Bakumenko S.P., Yakushev O.S., Shatov V.M. Auth. St. USSR, class B 22 d 7/00, C 21 s 5/56, No. 427778, stated 04/18/72, publ. 01/29/75.

Claims (1)

A method for producing consumable electrodes, including pouring a solid metal component with liquid metal, characterized in that metallized pellets are used as a solid metal component, supplied to the mold simultaneously with liquid metal in the ratio (2.7-3.3): 1 with a metallized feed rate pellets 3-5 kg / s and liquid metal 1-2 kg / s.

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