JPS6372838A - Initial period operating method for melting in electroslag refining - Google Patents

Abstract

PURPOSE:To prevent the generation of flashes and molten metal leakage in an initial period of melting and to improve the quality in the bottom of an ingot in an electroslag refining process by packing a yarn-shaped noncombustible material between a crucible and crucible closing body. CONSTITUTION:A high-quality ingot is formed by immersing a consumable electrode into molten slag, melting the consumable electrode by the Joule heat generated in the molten slag when the electrode is energized, removing impurities by the slag refining effect during the fall of electrolytically molten drops in the molten slag and laminating and solidifying the molten drops successively in the water-cooled copper crucible 1. The yarn- or cord-shaped noncombustible material (asbestos yarn) 3 is held packed between the stationary crucible 1 and a stool 2 which is the crucible closing body. A starting block 4 and an igniting agent 5 are installed on the stool 2. The generation of flashes and molten metal leakage between the crucible 1 and the closing body 2 in the initial period of melting is thereby prevented and the penetration of the noncombustible material 3 to the bottom of the ingot after the refining is obviated. The quality at the bottom of the ingot is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a melting initial operation method used in an electroslag remelting method that can obtain high quality ingots.

(Conventional technology) Conventionally, vacuum induction melting (
VIM) method, vacuum arc remelting (VAR) method, electroslag remelting (ESR) method, plasma arc melting (PAM) method.

PIM, PAR, PPC) method, electron beam melting (E B
There are various methods such as R) method, each of which has its own characteristics.

Among these, electroslag remelting (ESR)
This method involves melting a consumable electrode using the Joule heat of a molten slag in the atmosphere or under an inert gas, and laminating and solidifying the droplets that have fallen through the molten slag in a water-cooled copper crucible.

The ESR furnaces used to carry out this ESR method can be roughly divided into ∎ fixed crucible method, ∎ ingot drawing method, ∎ moving crucible method, and ∎ multi-electrode method, which can be selected and adopted as appropriate. Ru.

In such an ESR method, a consumable electrode is immersed in molten slag and energized, the J1 electrode is melted by the Joule heat generated in the molten slag, and the droplets of the consumable electrode fall through the molten slag. When doing this, impurities are removed by the refining action of the slag, and the slag is successively cast into a water-cooled steel crucible and solidified in layers to become a high-quality ingot.

At the start of operation using this ESR method, for example, in the case of the crucible fixed method, as shown in FIG.
A starting block 23 is placed on top of the crucible 22, a young explosive 24 is placed on the starting block 231, and granular magnesia (MgO) 25 is packed between the stool 21 and the crucible 22. This was done to prevent leakage between the crucible 22 and the stool 21 during the initial stage of melting.

In addition, even in the case of the ingot drawing method, granular magnesia is packed between the crucible and the dummy bar that closes the crucible, so that no dripping or leakage occurs between the crucible and the dummy bar during the initial stage of melting. That's what I was doing.

(Problems to be Solved by the Invention) However, when magnesia is packed between the crucible and a crucible closing body such as a stool or a dummy bar in the early stage of melting, as in the conventional case, as shown in FIG. As shown, the magnesia 25 is trapped in the bottom of the ingot 26 after melting, and when the ingot 26 is subsequently forged and agglomerated, the magnesia 25 may get inside, reducing the quality of the ingot. The problem was that it could happen.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems, and is capable of preventing hot water from leaking between the crucible and the crucible closing body at the initial stage of melting. The object of the present invention is to provide an initial operation method for electroslag remelting that can improve the quality of the bottom of the ingot after electroslag remelting.

[Structure of the Invention] (Means for Solving the Problems) The initial melting operation method in electroslag remelting according to the present invention melts the consumable electrode by the Joule heat of the molten slag, and melts the droplets that have fallen in the molten slag. When electroslag remelting is carried out to solidify the electroslag in a crucible, a filamentous or string-like noncombustible material is packed between the crucible and a crucible closing body such as a stool or a dummy bar.

The electroslag remelting method to which the present invention is applied can be applied to any method such as a fixed crucible method, an ingot drawing method, or a moving crucible method, and the type of molten slag is not particularly limited.
, Al2O2, etc. are used. Binary or ternary systems are used.

In the present invention, when remelting a consumable electrode by the electroslag remelting method, a thread-like or string-like noncombustible material is packed between the crucible and a crucible closing body such as a stool or a dummy bar in the initial stage of melting.

In this case, as the thread-like or string-like noncombustible material, asbestos yarn, ceramic fiber, carbon fiber, etc. are used, and m-fibers bundled into a string shape are used as appropriate.

In this way, by filling the thread-like or string-like non-combustible material between the crucible and the crucible closing body such as a stool or dummy bar, it is possible to prevent dripping or leakage between the crucible and the crucible closing body at the early stage of melting. This can be prevented, and the quality of the ingot bottom can be made good without the noncombustible material getting caught in the bottom of the ingot after remelting.

(Example 1) FIG. 1 is a diagram showing an example of the present invention, in which a fixed crucible 1 is used for electroslag remelting.
Asbestos yarn 3, which is a string-like noncombustible material, is stuffed between the crucible and the stool 2, which is a crucible closing body. Then, using the starting block 4 placed on the stool 2 and the ignition agent (self-soluble flux) 5 placed on the starting block 4, ignition is performed in the same manner as in the conventional method.

According to this embodiment, in electroslag remelting using a fixed crucible method, it is possible to prevent dripping or leakage between the crucible 1 and the stool 2 at the initial stage of melting, and the bottom of the ingot/toe can be prevented. We were able to improve the quality of the product.

(Example 2) FIG. 2 is a diagram showing another example of the present invention, in which a fixed or movable crucible 11 and a dummy bar 12 as a crucible closing body are used to perform electroslag remelting. In between, asbestos yarn 1, which is a string-like noncombustible material,
3 is packed. In this case, the L of the dummy bar 12
A concave noncombustible material receiving portion 12a is formed at the end peripheral portion, and the asbestos yarn 13 is stuffed into this noncombustible material receiving portion 12a. Then, using the starting block 14 placed on the dummy bar 12 and the ignition agent (self-soluble flux) 15 placed on the starting block 14, ignition is performed in the same manner as in the conventional method.

In this embodiment, when performing electroslag remelting using the crucible moving method or the ingot drawing method, it is possible to prevent leakage of hot water between the crucible 11 and the dummy bar 12 at the initial stage of melting. , it was possible to improve the quality of the ingot bottom.

[Effects of the Invention] As explained above, according to the present invention, electroslag remelting is performed in which the consumable electrode is melted by the Joule heat of the molten slag, and the droplets that have fallen in the molten slag are layered and solidified in a crucible. When carrying out this process, thread-like or string-like non-combustible material was packed between the crucible and the crucible closing body such as a stool or dummy bar, so that there was no possibility of leakage between the crucible and the crucible closing body at the early stage of melting. It is possible to prevent this from occurring, and it is possible to improve the quality of the bottom of the ingot, which is a very excellent effect.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional explanatory diagram of a pot and a stool showing one embodiment of the present invention, Fig. 2 is a cross-sectional explanatory diagram of a pot and a dummy bar showing another embodiment of the present invention, and Fig. 3 is a vase showing a conventional example. and FIG. 4 is a cross-sectional explanatory view of an ingot according to a conventional example. 1... Crucible, 2... Stool (crucible blocker), 3... Asbestos yarn (string-like or string-like noncombustible material), 11... Crucible, 12... Dummy bar (crucible blocker), 12a...
Noncombustible material receiving part, 13... Asbestos yarn (string-like or string-like noncombustible material). Figure 1 Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) When carrying out electroslag remelting, in which the consumable electrode is melted by the Joule heat of the molten slag, and the droplets that have fallen in the molten slag are layered and solidified in a crucible,
A melting initial operation method in electroslag remelting, characterized in that a thread-like or string-like noncombustible material is packed between the crucible and a crucible closing body such as a stool or a dummy bar. (2) The initial melting operation method for electroslag remelting according to claim (1), wherein the noncombustible material is string-like asbestos yarn.