JPS5946700B2 - Manufacturing method of clad steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing clad steel using a continuous casting machine.

Conventional methods for manufacturing clad steel include hot pressing of dissimilar steel sheets, explosion bonding, and manufacturing methods using steel ingots, as well as methods for manufacturing alloy steel sheets using a continuous casting machine and adding separately manufactured alloy steel sheet coils to the slab immediately after leaving the water-cooled mold. A method of crimping it onto a surface has been developed.

Although some of these methods have already been put into operation, they are often inferior in terms of mass productivity and workability.

Manufacturing clad steel using a continuous casting machine is superior in terms of mass production and workability.

However, conventionally, in order to enrich the alloy layer on the surface layer of the slab,
Because this method involves introducing alloy wire, hoops, coils, etc. into a continuous casting mold as a solid, the added alloy does not spread uniformly, resulting in the formation of a non-uniform alloy layer structure on the surface layer of the slab.

This invention proposes a manufacturing method that enables mass production of clad steel by enriching the required alloy layer in the surface layer of a slab with good mass productivity and workability using a continuous casting machine.

That is, in the continuous casting method, this invention uses a partition wall that is partially immersed below the surface of the molten steel in the continuous casting mold.
Part of the molten steel surface between the inner wall of the mold is isolated, the isolated molten steel surface is sealed with an inert gas, and a certain amount of molten alloy is supplied to the isolated molten steel surface by an electromagnetic pump to add the alloy to the molten steel. This is a method for manufacturing clad steel characterized by forming an alloy layer on the surface layer of the slab.

Embodiments according to the present invention will be described below with reference to the drawings.

In a normal continuous casting method, molten steel 4 is injected into a continuous casting mold 1 from a tundish 2 through an immersion nozzle 3, as shown in FIG.

A partition wall 6 made of refractory material is provided near the inner wall of the mold 1, and a part of the partition wall 6 is immersed below the surface of the molten steel.

The alloy 8 to which Ni, Cr, etc. are added is prepared in advance in the melting furnace 7.
The liquid is dissolved in the water and then supplied in a fixed amount by the electromagnetic pump 9.

Between the partition wall 6 and the inner wall of the mold 1, the melted alloy 8 is added to the molten steel 4 together with an inert gas such as Ar gas from the inert gas pipe 12 to facilitate diffusion while preventing oxidation.

When the molten alloy 8 is added, it forms a solute retention area of the alloy below the surface of the molten steel 4. This part cools and solidifies while descending in the mold 1 together with the molten steel 4, and the alloy is deposited on the surface layer of the slab. form a layer.

In order to increase the thickness of the alloy layer formed on the surface layer of the slab, it is necessary to increase the amount of this alloy retention area.

A part of the alloy in the retention area is diffused by the movement of the molten steel by the immersion nozzle 3, but the amount in the retention area can be changed by changing the shape or size of the partition wall 6, the immersion depth, etc., or by increasing the amount of alloy added. It can be adjusted by

Further details will be given with specific examples.

In the mold 1 used in the normal continuous casting method, the immersion nozzle 3 has an inverted Y shape and its opening angle is 20 mm, as shown in Figure 1.
0, and the partition wall 6 is made of fireproof clothing and is 300 mm from the inner wall of the mold 1.
A portion of 80 mm is immersed at the mTIL position.

Ni melted in the melting furnace 7 is sent to the runner 10 by the electromagnetic pump 9, and the amount is 0.36 to 0.72 kg/m, so it is determined as a fixed amount.

On the other hand, the mold size for molten steel is 2501 m thick and 180 m wide.
The casting speed was 0.45 m/-, the steel type was AH1304C, and the powder was GP109AG.

The enrichment state of Ni in the surface layer of the clad steel according to the present invention obtained under the above conditions was investigated.

Drill sampling was performed at point A on the short side of the slab near the Ni addition point and point B on the long side of the slab.
The content was investigated.

The results are shown in Figure 2. According to this, below the slab surface layer 6
mm, it was possible to obtain a fairly uniform enrichment of Ni and form an alloy layer on the intended surface layer of the slab.

Note that the presence of powder has no effect on alloy addition.

Various types of melting furnaces such as electric melting furnaces can be used as the melting furnace, and a method in which the runner is an inclined trough without using an electromagnetic pump can also be used.

The method according to the invention can also be used in the steel ingot method as well.

As described above, the present invention enables mass production of clad steel by forming an alloy layer on the surface layer on the long side of the slab, and also forms an alloy layer with good weldability on the surface layer on the short side of the slab. This has the effect of making it possible to

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example according to the present invention, and FIG. 2 is a chart showing the state of Ni enrichment in the surface layer of the clad steel obtained according to the present invention. In the figure, 1... Mold, 2... Tundish, 3... Immersion nozzle, 4... Molten steel, 5... Solidified layer, 6... Bulkhead, 7...
...melting furnace, 8...alloy, 9...
Electromagnetic pump, 10... runner, 11...
induction coil.

Claims (1)

[Claims] 1. In the continuous casting method, the molten steel surface is partially isolated from the inner wall of the mold by a partition wall that is partially immersed below the molten steel surface in the continuous casting mold, and the isolated molten steel surface is shielded with an inert gas, 1. A method for producing clad steel, which comprises supplying a certain amount of molten alloy to the surface of the isolated molten steel using an electromagnetic pump, adding the alloy to the molten steel, and forming an alloy layer on the surface of the slab.