JPS61209746A - Method for cleaning up boundary of insert-cast clad steel - Google Patents

Abstract

PURPOSE:To clean up the boundary of cladding and to obtain an insert-cast clad steel by adding an adequate ratio of calcium fluoride to a molten base metal and oscillating a cladding metal in the stage of addition. CONSTITUTION:Ca-F2 is added to the base metal 1 via a conduit for adding Ca-F2 at 50-500gr per ton of the base metal to prevent the sticking of scum 7 to the surface of the cladding metal 2 and to clean the cladding boundary in a casting stage. The effect of cleaning up the cladding boundary is further improved if the molten metal is cast while the cladding metal 2 is oscillated by an oscillating means 9 in addition to the CaF2 addition. A method of a voice coil type for converting an electric signal to a mechanical signal or the like is used as the means for oscillating the cladding metal and the oscillation is most adequately applied to the metal at 0.01-5kHz frequency is 1-100mu amplitude. The clad steel having the clean boundary is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a method for producing cast clad clad steel, which is particularly important for improving the quality of clad steel by adding CaF* during casting. The present invention relates to a method for cleaning the cladding interface.

Conventional technology cast-in clad steel is mainly applied to the combination of wear-resistant steel and mild steel, mild steel and tempered high-strength steel, and even stainless steel and mild steel, and is widely used.

To manufacture such cast-in clad steel, a composite material is suspended and fixed in a mold, and molten metal, which is the base material, is poured around the composite material to obtain a composite steel ingot. During blooming and rolling, the scum that inevitably occurs on the surface of the molten metal gets between the laminate and the base metal, and
Oxidized scale is generated on the surface of the laminate due to the radiant heat of the molten metal, and both of these are factors that cause poor adhesion between the laminate and the base material in the processes after blooming. Therefore, conventionally, at the time of casting, an antioxidant was applied to the surface of the composite material to protect the surface from the radiant heat of the molten metal and to repel scum. As the antioxidant, organic substances containing carbon and hydrogen as main components, easily vaporized metals such as zinc, calcium, and magnesium, ammonium fluoroborate (NH4BF4), and other thermally decomposable fluorides are usually used.

Problems to be Solved by the Invention However, simply applying an antioxidant to the surface of the laminated material does not necessarily maintain good cleanliness at the rad interface. In other words, simply applying the antioxidant as described above cannot completely prevent the scum generated on the surface of the molten metal during casting from adhering to the surface of the laminate.
A portion of the material adheres to the surface of the cladding material and remains as an inclusion at the clubbed interface, which may not satisfy the shear strength required for clad steel or may cause pinhole defects.

Means for Solving the Problems The present invention improves the above-mentioned conventional drawbacks and provides a method for cleaning the crab interface, which is an essential factor in producing clad steel with highly reliable quality. When manufacturing composite steel ingots by the casting method, which involves applying an antioxidant to the surface of the composite material, the CaF
This is a method for cleaning the interface of cast clad clad steel, the gist of which is casting while adding a molten metal.

The present invention will be explained in more detail below.

FIG. 1 is a diagram schematically showing the casting method according to the present invention. In the figure, the molten metal (6) is poured into the mold (1) through the injection hole (4) provided in the base board (2) by under pouring. The antioxidant (3) applied to the surface of the laminating material ■ is
When it comes into contact with the molten metal (6), it immediately generates gas and acts to repel the scum (2), but some of the scum (6) may adhere to the surface of the laminate (6).

In the present invention, in this casting process, by adding CaF* through the caFm addition conduit (8),
This method prevents scum from adhering to the surface of the cladding material (2) and cleans the cladding interface. The CaFmm addition is optimally 50 to 500 gr per ton of base metal molten metal.

Furthermore, in addition to the addition of caFm, the effect of cleaning the cladding interface is even more remarkable when the composite material (1) is cast while being subjected to vibrations via the vibration imparting means (2). Here, as means for imparting vibration, a method of converting a voice coil type electric signal into a mechanical signal, a method of converting a box coil type electric signal into a mechanical signal, etc. are used. The vibration applied to the laminate (2) is optimally set to a frequency α of 01 to 5 kHz and an amplitude of 1 to 100 μ.

The effect of caFm is not affected by the type of antioxidant applied to the surface of the laminate, and can be applied to any of the conventional antioxidants.

Made for The above principle of operation is estimated as follows.

In FIG. 1, the molten metal (6) is poured into the mold (1) through the injection hole (4) provided in the base plate (2) by under pouring. Scum ■ is formed on the surface of the injected molten metal (6), but the surface of the laminate (2) immediately generates air and gas when it comes into contact with the molten metal (6).
Since the container is coated with an antioxidant (3) that has the function of repelling the adhesion of scum ω to the laminate material (2) by generating gas, the scum ω cannot adhere to the surface of the laminate material (2). However, application of the antioxidant (3) alone cannot completely prevent the adhesion of scum ■ and keep the crab interface clean; once attached, the scum ■ remains as an inclusion on the cladding interface, resulting in poor product quality. have a negative impact.

According to the present invention, Ca F
By adding *, the melting point of scum ■ is lowered,
Since the flotation and separation properties can be improved, it is possible to create a state in which the scum ■ tends to adhere to the laminate material (2) (and even if it adheres, it is easy to float and separate.) Vibration to the laminate material ■ The application of the scum provides a continuous impact and promotes the floating separation of the scum.

Example Hereinafter, the present invention will be explained in more detail using examples.

Example 1 A large number of materials and thicknesses shown in Table 1 were prepared,
After removing the oxide film on one side of each, NH, BF,
An antioxidant prepared by dissolving powder in an organic solvent was applied using a spray gun. Then, as shown in Figure 1,
Casting the laminating material ■ coated with antioxidant (3)! (1) while adding caFm in various amounts,
Cast WS with a C content of 0.01% or less by under-pouring,
A composite steel ingot was obtained.

The casting conditions at this time, the total thickness of the steel ingot, and the amount of antioxidant applied are also shown in the same table.

The steel ingot obtained as described above was bloomed at a reduction ratio of aO, then hot rolled to a product thickness of 20 fins, and then 10 pieces were A micro specimen was taken and the cleanliness of the cladding interface was investigated using an optical microscope.

The results are expressed as the cladding interface cleanliness index of the product and are shown in Table 3. Here, the cleanliness index refers to the inclusion rate calculated using the following formula, which is divided into five levels within the range shown in Table 2, each with a cleanliness index of 1°1a45.

However, Ili indicates the length of each inclusion found in the clad steel at an arbitrary cut surface, and L indicates the entire length of the clad interface inspected at that time.

From the results of Table 1, Table 2, Table 3, Table 3, Examples Mal to l1bIO of the present invention
It can be seen that the cladding interface cleanliness index in the inverted specimens 11 to 14 was significantly improved, and that the optimum amount of caFm added is 50 to 500 gr per ton of molten metal, and that no effect is observed outside this range. .

1 Example 2 Table 4 was prepared using the same method as Example 1, but Z a
F * Addition amount is 350 gr per ton of molten metal, 1
The following is the result of investigating the cleanliness index of the crab interface by applying vibration to the barbed material under various conditions using a vibration applying means (9) that converts a box coil type electrical signal into a mechanical signal. In addition to CaFt ffi addition, S cladding interface cleanliness index in inverted 1 to tk3 of the present invention in which 1 motion was added is CaF! Addition only] was found to be even more effective than Comparative Example Na4 [Effects of the Invention As stated above, adding CaF at the time of casting when producing cast clad clad steel is effective at reducing the cladding interface. It is extremely effective for cleaning cladding steel, and as a result, clad steel of excellent quality can be obtained.

Furthermore, when adding CaFmm, it is more effective if vibration is applied to the laminated material.

[Brief explanation of drawings]

FIG. 1 is a schematic explanation of the casting method according to the present invention. 1... Mold 2... Laminating material 3.
...Antioxidant 4...Injection hole 5...
... Base plate 6 ... Molten metal 7 ...
Scum 8...CaFt addition conduit 9...
...Vibration imparting means Applicant: Sumitomo Metal Industries, Ltd. Figure 1

Claims (2)

[Claims] (1) When manufacturing composite steel ingots by the casting method, which involves applying an antioxidant to the surface of the laminated material, 50 to 50% of calcium fluoride (CaF_2) is added per ton of molten base material.
A method for cleaning the interface of cast clad steel, characterized by casting while adding 0gr. (2) Frequency 0.01~5KHz, amplitude 1~1 on the laminated material
A method for cleaning the interface of cast clad clad steel according to claim 1, wherein vibration of 00μ is applied.