JPH01228653A - Method for pouring molten metal into mold in continuous casting and submerged nozzle for pouring molten metal - Google Patents

Abstract

PURPOSE:To extend the service life of a nozzle and to improve the quality of a cast slab by forming outer circumferential layer of peripheral wall near powder line part of the submerged nozzle with permeable porous refractory and executing molten metal supplying while blowing inert gas from the outer circumferential surface. CONSTITUTION:On the outer circumferential surface near the powder line of the submerged nozzle 3 arranged at lower part of a tundish 1, the permeable porous refractory layer 3B is formed and at the back face thereof, distributing groove 3C is set. The porous refractory layer 3B is formed, by which the refractory granule is made to about 10-30% porosity. Successively, at the time of supplying the molten metal, the inert gas of Ar gas, etc., is supplied from gas supplying pipe 3E to blow the inert gas from the outer circumferential surface of the nozzle 3. The inert gas prevents oxidation of the metal and also erosive action by the powder layer 5 to the outer circumferential surface of the nozzle 3 is restrained. By this method, the service life of the nozzle 3 is extended and the quality of the cast slab is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for pouring molten metal into a mold in M continuous casting and a 9ffl nozzle for pouring molten metal.

Conventional technology The injection of molten metal into the mold in continuous casting was
Using the immersion nozzle disclosed in Publication No. 2-4353, etc., the molten metal from the tundish is injected into the mold, powder is added to the surface of the molten metal, and the state of immersion is maintained up to the powder line to prevent oxidation of the molten metal. In addition, the powder line part is equipped with a large powder attack-resistant material that prevents erosion caused by powder and floating non-metallic inclusions (collectively referred to as slag) on the surface of the mold, thereby extending its life. I came here with the aim of

Problems to be Solved by the Invention However, in the conventional molten metal injection method and molten metal injection immersion nozzle described above, the slab layer on the surface of the molten metal in the mold adheres to the powder line of the immersion nozzle or moves up and down due to fluctuations in the molten metal level. The powder line portion of the submerged nozzle is washed away by the powder layer, and the powder line portion of the submerged nozzle is subject to significant erosion and erosion, and an expensive powder erosion-resistant refractory must be applied to the powder line portion.

Also, even if such measures are applied, only a few charges (300
When aiming for high productivity and stable quality by continuously casting (usually called continuous casting) molten metal of 1000 ton/ch) without interruption, the bottleneck is the erosion of the molten metal in the powder line area with a charge of about 1000 yen. Therefore, casting had to be stopped one after another.

Means for Solving the Problems (1) The present invention solves the above-mentioned problems, and its characteristic means is continuous casting.

When injecting molten metal into the mold through the immersion nozzle for injecting molten metal from the tundish into the mold, the molten metal is injected while gushing out inert gas from the outer circumferential surface of the powder line part of the immersion nozzle, which corresponds to the powder layer on the surface of the molten metal in the mold. A method for injecting molten metal into a mold in continuous casting, characterized by injecting the molten metal into a mold.

(2) In a submerged nozzle that injects molten metal into a mold from a tundish in continuous casting equipment, the outer peripheral layer of the nozzle peripheral wall, which corresponds to the powder line part that comes into contact with the powder layer on the surface of the molten metal in the mold, is made of an air-permeable porous refractory. This is a submerged nozzle for injecting molten metal into a mold in continuous casting, which is connected to a supply pipe from the outside and has a flow path for supplying inert gas to the porous large material.

In the present invention, the inert gas is appropriately selected from A gas, He gas, etc., which does not have an adverse effect on the oxidation prevention of the molten metal to be continuously cast.

In addition, the breathable porous refractory material that gushes out the inert gas is, for example, a breathable porous refractory material with a porosity of about 10 to 30%, which is formed mainly of refractory particles such as spherical or polygonal particles as aggregate. One composition using a block or cylindrical product etc. is not limited to powder erosion resistant refractories such as Zr02-C, but any material with excellent spalling resistance is sufficient; for example, AQ203 -C series etc. are listed.

In addition, one or more inert gas supply channels to the permeable porous refractory in the outer peripheral layer of the nozzle corresponding to the powder line portion of the immersion nozzle are connected to an external supply pipe and are formed in the nozzle body. The discharge opening may be connected directly to a distribution hole formed in the porous refractory, or to the back surface, upper surface, or lower surface of the breathable porous refractory, or to a distribution groove formed therein.

Me, in addition to positioning the outer circumferential surface of the 'A11 air porous refractory at least in the powder layer of the surface of the molten metal in the mold,
The powder layer may be located on either side of the powder layer or below the powder layer.

Furthermore, the inert gas gushing out from the outer peripheral surface of the breathable porous refractory is 30.005 to 0.051.
/ cm2, and expel it outward from the outer peripheral surface of the powder layer to prevent contact with it, as well as to prevent lip ring and scattering of the powder layer, and cover the exposed molten metal surface with an inert gas to prevent its oxidation. It is something to do.

Function The present invention supplies inert gas to the breathable porous refractory disposed in the powder line portion of the immersion nozzle, and injects the molten metal into the mold while causing the inert gas to gush out from the entire outer surface of the porous refractory. By this, the powder layer floating on the surface of the molten metal in the mold is pushed outward from the outer surface of the air-permeable porous refractory to prevent contact therewith,
As a result, the exposed molten metal surface is covered with an inert gas curtain to reliably prevent oxidation.

This reliably prevents erosion of the immersion nozzle by the powder layer, significantly extending its life, and increasing the number of charges in the continuous casting several times.

This advantageously ensures high productivity and stable quality.

Embodiment FIGS. 1 and 2 show an embodiment of a submerged nozzle according to the present invention.

3 and 4 show other embodiments, and FIGS. 5 and 6 show still other embodiments.

In Figures 1 and 2, 1 is a tandish, 2 is a mold (casting cross section, width: 1900s++s, length = 28
0mm, height: 800m), 3 is immersion nozzle, 4
5 is the molten steel in the mold, and 5 is the powder layer on the surface of the molten steel -L.

The immersion nozzle 3 is a nozzle body 3A (outer diameter 1 [18 mm diameter, material: M), which has a molten steel pouring channel 3a (80 mm layer φ) and a discharge port 3b (vertical near 0, horizontal = 80). O3-C system) and the breathable porous fireproof layer 3B arranged in the powder line part
(Inner diameter 140I, outer diameter 185+u+, height 200mm-
1 material: Zr02-C system), an inert gas distribution groove 3C formed in an annular shape at the center of the back surface of the outer peripheral layer 3B, and a nozzle body 3.
It is composed of a flow path 30 installed inside A for supplying inert gas to the distribution groove 3C, and an inert gas supply pipe 3E connected to an external supply source in the flow path 3D.

In FIGS. 3 and 4, the immersion nozzle 3 has an air permeable porous refractory layer 3B made of Zr02-C, and an inert gas distribution groove 3C formed in an annular shape over the entire back surface of the core layer 3B. In this example, the others are approximately concave as shown in FIGS. 1 and 2.

In FIGS. 5 and 6, the immersion nozzle 3 has an air-permeable porous refractory layer placed over the inner and outer circumferential surfaces of the nozzle, the material of which is Zr02-C, and the inert gas distribution holes 3F are formed in the layer 3.
This is an example in which the inert gas is formed in a ring shape inside the core layer 3B to expose the inert gas from the inner and outer circumferential surfaces of the core layer 3B.
It is the property of In this example, the purpose of gushing out the inert gas into the nozzle is to form a gas curtain on the inner wall surface of the nozzle to prevent the adhesion of oxidation products, etc. in the molten metal.

In FIGS. 7 and 8, the material of the permeable porous refractory outer peripheral layer 3B of the immersion nozzle 3 is Zr02-C.

A plurality of vertical inert gas distribution holes 3G are installed in the core layer 3B at equal intervals, and the lower end of the supply path 3D+ is formed by forming an annular groove on the nozzle body 3^ side with an opening at each end. One part of the upper end of the annular groove supply path 3D+ is formed in the nozzle body 3A and is connected to the supply path 302, and the other parts are substantially concave with each other.

Although not shown in these embodiments, the outer peripheral surface of the permeable porous refractory layer 3B, except for the outer peripheral surface, distribution grooves, and distribution holes, may be coated with a non-porous refractory material or directly attached to the nozzle body 3A. This seals the inert gas and prevents hot water from pouring in, ensuring uniform gushing of the inert gas from the outer peripheral surface, and preventing it from peeling off from the nozzle body 3A.

Next, Table 3 shows examples of unexploded [Jl] which were actually continuously cast using these immersion nozzles.

However, in all six cases, the components of the injected molten steel are shown in Table 1, and the powder components are shown in Table 2.

Also, the amount of molten steel poured out from the nozzle is * 8.5 tons/i
n.

Casting speed 1. Axis/win.

(Hereinafter, blank space) As described above, according to the immersion nozzle and injection method of the present invention,
The nozzle life was approximately twice as long as that of the conventional method, and Pj slab-quality steel with very few inclusions was obtained with good productivity.

Effects of the InventionAs is clear from the explanation in Section I-, the conventional continuous casting charge had a maximum lO charge, but in the embodiment shown in FIGS. I was able to mint as many as 5 charges.

Regarding the quality of the slab, the amount of oxidized inclusions per 1410 kg was reduced to 2501 g and 170 layer g compared to the conventional method, and further reduced to 100 mg in the examples shown in Figures 7 and 8, demonstrating the effectiveness of the prediction tool. .

In the conventional molten metal injection method and the immersion nozzle for molten metal injection, the erosion of the powder line portion was severe, and the level of the molten metal had to be changed in stages to alleviate the erosion.

The immersion nozzle for injecting molten metal of the present invention can prevent contact with powder and nonmetallic inclusions (generally referred to as slag) on the molten metal surface, thereby making it possible to maintain a constant molten metal level. As a result, there was less slag entrainment, which reduces fluctuations in the hot water level, and quality was improved.

[Brief explanation of the drawing]

1 to 8 show four embodiments of the immersion nozzle according to the present invention, FIG. 1, FIG. 3, FIG. 5, and FIG. 7 are longitudinal sectional views, and FIG. 1-I cross-sectional view in the figure, Figure 4 is a ■-■ cross-sectional view in Figure 3, Figure 6 is a m-[I cross-sectional view in Figure 5, and Figure 8 is a TV-IV cross-sectional view in Figure 7. It is. 1... Tanditshu, 20 fists, mold, 311.
11 Immersion nozzle, 3A--Nozzle body, 3B... Breathable porous refractory, 3G... Distribution groove, 3D, Fist,
Waste flow path, 3E...gas supply pipe, 3F...1 distribution hole,
4・-φ molten steel, 5・φ・powder layer. Representative Patent Attorney I:, Masao Figure 1 3C Figure 7 Figure 7

Claims (2)

[Claims] (1) In continuous casting, when injecting molten metal into the mold from the tundish through the immersion nozzle for injecting molten metal into the mold, inert A method for injecting molten metal into a mold in continuous casting, characterized by injecting molten metal into a mold while gushing out gas. (2) In a submerged nozzle that injects molten metal into a mold from a tundish of continuous casting equipment, the outer peripheral layer of the nozzle peripheral wall corresponding to the powder line part that comes into contact with the powder layer on the surface of the molten metal in the mold is made of an air-permeable porous refractory. An immersed nozzle for injecting molten metal into a mold in continuous casting, which is formed of a molten metal and has a flow path connected to an external supply pipe to supply an inert gas to the porous refractory.