RU1836464C - Method of manufacture of ingots and castings by electroslag remelting - Google Patents

Abstract

Usage: obtaining ingots or castings by electroslag remelting. SUMMARY OF THE INVENTION: In a stationary mold, a stationary consumable electrode is remelted, in which an axial hole is made and a tubular melting element is installed in it. Through the axial hole in the electrode during the remelting process, filler material is supplied in the form of a wire or liquid metal in an amount of not more than 0.7 6pl „where Gnn. - smelting capacity, t / h. An electric current can be supplied to the wires with the magnitude necessary to heat them to a temperature that provides fusion with liquid metal. Through the axial cavity of the electrode, wire coolers are introduced in an amount of not more than 0.4 CPl. with a feed rate of not more than 0.2 h + 0.07 D / d, where d is the diameter of the refrigerator, cm, D is the diameter of the ingot, cm:. h is the depth of the slag bath, see. The tubular element or its inner surface is made of non-conductive floating material, for example, slz-forming material. 3 s.p. f-ly, 2 ill.

Description

The invention relates to electrometallurgy and can be used in the preparation of ingots and castings of unlimited sizes by electroslag remelting.

The purpose of the invention is to improve the quality of the metal.

Figure 1 is a flow diagram of a method; figure 2 is a section aa in figure 1.

In the mold 1, the inner part of which is made in the shape and size of the required ingots or castings, the electrode 2 is fixedly mounted, also having the form of an ingot or casting, but with dimensions that provide the necessary clearance between the surface of the electrode 2 and the mold 1.

An opening 3 is provided in the electrode 2 along the vertical axis, in which a melting tubular element 4 is installed, which is electrically isolated from the electrode 2. After filling the slag into the crystallizer 1 through the slag channel 5 and starting to melt the electrode 2 through the tubular element 4, filler material is fed into the slag bath , for example, in the form of steel wires 6 or liquid metal. A current is supplied to steel wires 6 through current-carrying mouthpieces 7 to ensure that they are heated both in the gap between the mouthpiece and the bath and in the slag bath to the required temperature, for example, to the solidus temperature of the wire material. The wire feed rate or liquid metal outflow is set depending on the desired smelting capacity. Improving the quality of ingots or

00

s

Os Јv

about

B

castings having large cross-sections are achieved by supplying cold wires through the tube 8 to the central part of the liquid metal bath. The heat removal from the central part of the liquid bath by cold wires reduces the depth of the metal bath and improves the metal crystallization process.

The heat balance of the smelting can be changed by dosing the electric power supplied to the stylish wires entering through the tubular element 3, as well as due to the feed rate of the wire-coolers, their diameter and quantity. In this case, depending on the requirements, it is possible to carry out heat extraction from the central part of the bottom with the complete melting of the filler material or partial melting in a liquid metal bath

unmelted wires.

As the distance between the current supply of the mouthpiece 7 and the slag bath decreases during the remelting process, the electric resistance decreases and, accordingly, the current increases,

In order to maintain a constant electrical power, it is necessary to reduce the voltage accordingly as the current increases.

The amount of filler material in the form of wires or liquid metal supplied through the central hole of the guide channel should be no more than 0.7 Gn /, where bpl is the total productivity of electroslag melting, t / h,

The condition under which the amount of material to be reduced is greater than 0.7 of the total smelting capacity corresponds to increased gaps between the electrode and the mold or a relatively larger diameter of the axial hole in the electrode. In the first case, prerequisites arise for the formation of surface defects in the ingot or otliak.

In both cases, the economic expediency of melting in this way is reduced.

The heat power released in the wire supplied to the molten bath under voltage is mainly generated in the region between the current-carrying mouthpiece and the slag bath, thereby providing minimal heat / yielding to the metal bath. Therefore, in order to prevent the passage of current through the tubular element when the wires under voltage come into contact with it, the element itself or its inner surface must be non-conductive, for example, coated with a slag-forming coating,

In this case, the guide channel should not impair the properties of the slag bath and the metal during its melting.

The amount of metal refrigerators introduced into the liquid bath should be no more than 0.4 SPL, where: bpl - total melting capacity t / h.

If the number of refrigerators is more than 0.4 of the smelting capacity, there will be a danger of slagging of the metal bath and non-fusion of the refrigerators with liquid metal. In order to prevent non-melting of metal-bath refrigerators, the wire feed speed of refrigerators

should be no more

0.2 b + 0.07 D

d

cm / s

where d is the diameter of wire refrigerators, cm; D - diameter s / gig in cm; h is the depth of the slag bath, see,

This method makes it possible to produce any size high-quality ingots and castings, in particular, to re-melt the spent rolls of the rolling mills to obtain cast roll blanks with minimal allowances.

The method has high environmental purity, due to the possibility of complete isolation of the melting space from the air.

The method is implemented as follows. .

The electrode, in this case, an exhaust roll of 3 m long, barrel diameter 920 mm and necks 460 mm, having 80 mm diameter holes along the central axis, with a pre-welded extension cord 9, is fixedly mounted and fixed in the current-carrying parts 10 of the electroslag remelting unit. A tubular element is isolated from the electrode in the hole of the electrode - roll and is also fixedly fixed in the clamps 11 of the installation. Four steel wires with a diameter of b mm are threaded into the central hole of the guide channel 3 through the current lead A1 of the mouthpiece 7: Eleven steel wires - refrigerators with a diameter of 6 mm are inserted into the tubular channels 8, more isolated than the electrode 6 and the tubular element 4, lir ;;

Crystallizer elements are installed, consisting of two halves with a connector along the vertical axis, having a diameter of internal surfaces; barrels - 1080 mm, necks - 580 mm. You can use one-piece cylindrical elements of the mold. 8, in this case, elements 12, 13, 14, 15 first become in sequence. Elements 16 and 17 are inserted

on the electrode 2 and is installed with it.

The remelting speed is assumed to be 0.6 m / h. The melting process is started by pouring slag through the hole 5 in the mold and applying voltage to the electrode 2. After lowering the current from the starting values to the level of normal melting, the electrode is fed into the wire through the tubular element 4. The wire feed speed during melting of the roll neck is -550 m / h, voltage 85 V. This provides the heat balance necessary for the self-melting of wires.

After stabilization of the electrical parameters of the remelting process, the supply of 2-wire refrigerators with a diameter of 6 mm and a speed of 270 m / h is turned on.

Claims (4)

1. A method of half-bar ingots or castings by electroslag remelting, including remelting of a stationary expendable electrode in a stationary a mold, the configuration of which corresponds to the configuration of the electrode, characterized in that. which, in order to improve the quality of the metal, the consumable electrode is remelted with an axial cavity in which a melting tubular element is placed, through which filler material in the form of wires or liquid metal is fed into the slag bath in an amount of not more than 0.7 Split. where Spl - productivity of smelting, t / h. 2. The method according to claim 1, with respect to the fact that an electric current is supplied to the wires supplied through the tubular element in the electrode for heating mx to a temperature ensuring their fusion with the molten metal of the ingot. 3. The method according to claim 1, characterized in that through the axial cavity of the electrode wire refrigerators are introduced in an amount of not more than 0.4 Cfl with a feed rate of 0.2 h 4- 0.070 no more cm / s, where d is the diameter of the refrigerator, cm; D is the diameter of the ingot, cm; h is the depth of the slag bath, see 4. The method according to claim 1, characterized in that in the case of energized wires, the tubular element or its inner surface is made of non-conductive floating material. vwwv n fptfoj g