JP3286469B2 - Cast iron processing agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast iron treating agent required for the production of cast iron, and more particularly to a cast iron treating agent effective for a graphite spheroidizing treatment and a graphite vermiculizing treatment required for the production of cast iron. It is about.

[0002]

2. Description of the Related Art Graphite spheroidization will be described as a typical example of using a cast iron treating agent. Spheroidal graphite cast iron has been used for about half a century since its development, but its use has been expanded year by year to become the mainstream of castings. What is going on. Spheroidal graphite cast iron is superior in material strength to gray cast iron, so that castings can be reduced in weight, dimensional accuracy, casting yield and machinability are superior to cast steel, and casting costs are inexpensive. Therefore, the fields of gray cast iron and cast steel have been replaced by spheroidal graphite cast iron. A magnesium alloy is generally used for the graphite spheroidizing treatment, and magnesium has been used in combination with about 15 or more metals. At present, a ferrosilicon-magnesium alloy containing calcium and a rare earth element is mainly used.

[0003] Since the boiling point of magnesium is about 1370K and the temperature of the molten iron to be treated is about 1770K,
At the moment when the magnesium comes into contact with the molten iron, it evaporates, and its vapor pressure reaches about 12 atm, showing an explosive reaction.

[0004] Since magnesium has a very low solubility in molten iron, it is necessary to make the contact time with molten iron as long as possible.

[0005] Therefore, in the conventional ferrosilicon magnesium spheroidizing agent, the content of magnesium is reduced to about 10% or less (usually 4 to 5%) and the contact time with molten iron is reduced in order to alleviate the radical reaction. Means have been taken to increase the length and place a spheroidizing agent at the lowest part of the molten iron and cover it with a cover material to prevent floating.

[0006] As a typical method of treating a spheroidizing agent which has been conventionally used, there is the following method. (A) Laying and pouring method: A spheroidizing agent is placed in a pocket at the bottom of a ladle for receiving molten iron, and the molten iron is injected after punching the spheroidizing agent and coating it with steel scrap or ferrosilicon. This method is currently most frequently employed because of its simplicity. (B) Tundish method: Molten iron is poured with the lid on top of the ladle of the pouring method. (C) Pressure addition method: A high-purity magnesium spheroidizing agent is pressed into molten iron with a high-pressure cylinder or reacted in a high-pressure vessel. (D) Converter method: The ladle on which the spheroidizing agent is set is inverted and reacted. (E) In-mold method: a spheroidizing agent is reacted with molten iron in a mold.

However, in the most common pouring method, remarkable white smoke is generated at the time of treatment, and the yield of magnesium of the treated metal is as low as 50 to 60%. This is because the ferrosilicon magnesium alloy has a density of about 4.3 g / cm ^3.
This is because the spheroidizing agent floats up early because it is considerably smaller than about 7.2 g / cm ³ of molten iron.

[0008] Therefore, before the vaporized magnesium is absorbed by the molten iron, it reacts with oxygen in the air to form magnesium oxide, generating white smoke and reducing the amount of magnesium captured in the molten iron.

As a method for producing a spheroidizing agent which does not float by the pouring method, a mixture of magnesium powder, carbonyl nickel powder, iron powder, and copper powder was used in Japanese Patent Publication No. 45-337 (International Nickel Limited, USA). A method of compressing and sintering to form briquettes having a porosity of 20 to 50% and a surface area / volume of greater than 8 is described in JP-B-56-5436 (Foseco International Nickel Limited, UK). There has been proposed a method of compressing iron granules into briquettes having a density exceeding 4.3. At present, however, cover materials (punched steel plate scraps, ferrosilicon, etc.) are added to ferrosilicon and magnesium spheroidizing agents. It is forced to process.

[0010] Further, the temperature of the pocket portion of the ladle tends to decrease and metal tends to adhere to the pocket portion, so that the pocket portion must be repaired frequently.

The methods (b), (c) and (d) require special equipment, and the method (e) lowers the casting yield and increases the cost.

Further, since the conventional ferrosilicon magnesium spheroidizing agent contains about 45% of silicon,
When the amount of the spheroidizing agent is increased or decreased, the component adjustment of the product becomes complicated, or when the ferrosilicon / magnesium spheroidizing agent is left in the air for a long period of time, the surface of the spheroidizing agent is oxidized and the performance is reduced.

Although the problems of the prior art have been described above by taking graphite spheroidizing as an example, these problems are common to other processes using a cast iron treating agent.

[0014] An object of the present invention is to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide a cast iron treating agent which can obtain a high quality product with a small amount of use, and is excellent in workability and economic efficiency.

[0015]

The features of the cast iron treating agent according to the present invention include a granular or bulky additive necessary for a graphite spheroidizing treatment or a graphite vermiculizing treatment of cast iron, and a coating agent for coating the additive. A coating material of a solid metal mainly composed of iron or nickel is provided, and a solid metal plate is used as the coating material to bring the apparent density of the entire treatment agent as close as possible to the density of the molten metal. In other words, a vent portion consisting of a hole or a gap is provided.

The apparent density of the cast iron is 4.5 to 4.5.
Desirably, it is 7.6 g / cm ³ .

[0017] The cast iron treating agent of the present invention is obtained by coating the additive necessary for the graphite spheroidizing treatment or the graphite vermiculizing treatment of cast iron with a predetermined solid metal, that is, a continuous metal represented by a plate to form small pieces. It has features. Its shape is spherical,
The shape is not particularly limited, such as a cylindrical shape, a disk shape, and a box shape. Its size is usually 0.1～100Cm ³ mm, preferably 1 to 30
cm ³ . The thickness of the metal plate is usually 0.5 to 10 m
m, preferably about 1 to 5 mm.

FIGS. 1 and 2 show an example of the shape. FIG. 1 shows a metal pipe such as a steel pipe filled with an additive and both ends are sealed by pressing or the like. FIG. 2 shows a metal pipe such as a steel plate which is processed and formed. As described above, the covering material is composed of an integral metal, a metal tube, or a metal plate, and has an additive therein by appropriate means such as grinding, pressing (forging), welding, bonding with an adhesive, a stopper, and discharge bonding. Formed into the body. It is also possible to take measures such as grinding a metal lump and cutting it out and sealing it with a cover material. in addition,
The additive may include Mg.

As described above, the solid metal plate constituting the coating material of the cast iron treating agent of the present invention is usually provided with small vent holes.
This vent hole allows the inside to be vented and the pressure inside the treatment agent to be relaxed during casting. In the case of, for example, forging, it is not necessary to provide a separate vent because the gap between the joining surfaces serves as a vent.

Since the cast iron treating agent of the present invention is used for the graphite spheroidizing treatment or the graphite vermicular treatment as described above, these treatments will be described individually.

First, the graphite spheroidizing process will be described.
By using the treating agent of the present invention in the typical pouring method, the floating of the treating agent during the treatment can be substantially prevented and the generation of white smoke during the treatment can be prevented. Products can be obtained. In addition, the ladle pocket and cover material are not required, thus improving workability.

A typical example of the metal plate for coating the cast iron treating agent used here is a steel plate. For example, JIS G34
61. A steel pipe having an outer diameter of 16 to 32 mm and a wall thickness of 1 to 5 mm is filled with magnesium and a rare earth element, and is formed into a shape shown in FIG. 1 by pressing, or is formed into a shape shown in FIG. It is formed into the shape shown.

Due to the properties of the material, steel is easily deformed when heated, while magnesium, which is an additive component to be coated, melts at 923K. Utilizing these characteristics, the deformability of a steel pipe that heats a steel material to about 770 to 970K is 3 at normal temperature.
It is more than doubled and shows the feature that it can be molded freely with very weak force with magnesium built in. On the other hand, even at room temperature, a steel pipe or a steel sheet can be cold forged and the additive can be automatically sealed therein.

Depending on the application, a nickel alloy other than steel can be used as the coating metal material.

The cast iron treating agent for spheroidization produced as described above was treated with 200 kg and 500 kg by the method shown in FIG.
The results of confirming the presence or absence of floating of the cast iron treating agent and the thermal behavior, magnesium yield, metal structure and mechanical properties of the product by pouring molten iron into the ladle bottom are summarized below.

(A) A thermocouple was installed in a 200 kg cast iron treating agent, and the thermal behavior of the cast iron treating agent from the surface to the inside was measured. As shown in FIG. After being filled, the cast iron treating agent was sequentially dissolved from the surface layer without floating, and it was confirmed that the spheroidizing agent and the inoculant were sequentially diffused into the molten iron. In addition, since a large amount of molten metal and a large amount of molten metal exist at the top at the start of diffusion, it has been proved that the conditions for the cast iron treating agent are more easily absorbed into the molten iron.

(B) The density of the cast iron treating agent is 4.5 to 7.6.
At g / cm ³ , particularly good results were obtained in preventing floating. The most stable density for preventing levitation was 6.2 g / cm ³ or more. Another reason for promoting the prevention of floating is that the melting temperature of the coating metal steel sheet is about 1700K, which is lower than the injection temperature of molten iron of about 1770K, and the temperature of melting the surface of the coating metal steel sheet and lowering the heat of fusion. As a result, the cast iron treating agents are strongly fused together in a semi-molten state (FIG. 4).

(C) 20.7k on the bottom of a 500kg ladle
g (magnesium content: 1.21%, ferrosilicon content for inoculation: 4.7%, density: 7.0 g / cm ³ ), a spheroidizing cast iron treating agent was installed, and 500 kg of molten iron at 1,770 K was placed thereon. Injected. At the time of injection, there is no floating of treatment agent,
Immediately after the end of the injection, bubbling and convection of the molten metal occurred and about
Continued for 8 seconds. The reaction was mild with little generation of white smoke.

(D) The magnesium yield of the spheroidal graphite cast iron produced using the above-mentioned cast iron treating agent was about 80%, and the addition amount could be reduced by about 40% compared with 54% of the conventional method. The metal structure and the number of graphite particles are about 2 times smaller than the conventional method.
The mechanical properties showed good results.

(E) The cast iron treating agent of the present invention can be formed into an arbitrary shape and size with respect to the amount of molten iron to be processed, and the molded body is covered with a strong steel plate, so that it is easy to handle.

(F) The cast iron treating agent of the present invention can be manufactured at a lower cost than a ferrosilicon treating agent.

From the above results, the treatment agent for cast iron using the coating material containing iron as a main component is vermicular graphite cast iron (CV
It can also be applied to additives of cast iron).

If a coating material containing nickel as a main component is used instead of iron, it can be applied as a cast iron treating agent for alloy cast iron having a high nickel content (such as niresist cast iron).

[0035] These characteristics show that the cast iron treating agent of the present invention is uniformly diffused into the molten metal by bubbling and convection of the molten metal without floating during the processing, and thus works efficiently for the purpose. by.

Next, vermicular graphite cast iron (CV cast iron)
The treatment agent will be described. The vermiculite graphite cast iron has a worm-like graphite shape, and shows an intermediate form between gray cast iron and spheroidal graphite cast iron. Not only is it not inferior in strength to spheroidal graphite cast iron, but also because of its good castability, it is evaluated as a material with industrially balanced generality, and its use in automotive parts and ingot cases is expanding. .

Vermicular graphite cast iron is a new material, and its production methods include (a) adjusting the amount of magnesium added, (b) adding spheroidization inhibiting element (mainly titanium) and magnesium in combination, and (c) calcium Alternatively, a method of adding selenium has been conventionally employed.

However, since vermicular graphite cast iron is a new material and requires a caterpillar-like unstable metal structure, in (a), additives must be controlled in a very narrow range, and process control is required. While difficult, (b), (c)
In this case, the amount of the additive can be increased to facilitate the management, but there is a problem that the quality of the additive is easily affected by the amount of the additive.

Magnesium was coated on a steel sheet in the same manner as described above to prepare the cast iron treating agent of the present invention (magnesium content: 1.21%), and 2.2% was added to the molten iron by a pouring method. On the other hand, as a conventional method, 1% of a commercially available additive for vermicular graphite cast iron (magnesium content: 5%) and 3% of a cover material were added, and the metal structure and mechanical properties of the product were evaluated. . Therefore, it can be said that the cast iron treating agent of the present invention can be applied to vermicular graphite cast iron with the same effect as that of spheroidal graphite cast iron.

Next, the inoculation cast iron treating agent will be described. Inoculation is carried out by adding 0.2 to 0.3% of granular additives to the molten cast iron to promote the graphitization of the cast iron. This is performed to improve the shape and the number of graphite particles, improve the material, and improve the mechanical properties.

Since the inoculant loses its efficacy in a short time after the inoculation, in order to use the inoculant efficiently, it is important that the inoculant is uniformly dispersed in the molten metal and inoculated at a time as close to casting as possible. It is. For that purpose, conventionally (a) a ladle inoculation method in which an inoculant is set at the bottom of a ladle when pouring into a ladle or added along a ladle flow, and And the in-mold method of setting an inoculant in a mold, and the like.

However, in the ladle inoculation method of (a), since the inoculant is not uniformly dispersed sufficiently, the amount of addition is large and fading is likely to occur. In the method of (b), a certain amount of inoculant is added. In addition, the method (c) has a problem that the product yield is low.

A commercially available ferrosilicon, calcium and carbon based inoculant was coated with a steel plate, and used as a cast iron treatment agent for inoculation having the shape shown in FIG. 1 and set on the bottom of the ladle. An equivalent inoculation effect was obtained at 0.15% against 0.3% of the method. This is considered to be because the convection of the molten metal by bubbling was maintained for about 30 seconds, and the inoculant was sufficiently diffused.

Although the cast iron treating agent of the present invention has a simple structure and is easy to produce, it exhibits a remarkably excellent effect. However, the basic idea of the present invention is to coat the additive with a solid metal plate to treat the agent. The object of the present invention is to make the density of the cast iron as close as possible to the density of the molten metal, prevent the floating of the cast iron treating agent by the fusing effect of the coating materials, dissolve the additive sequentially from the surface layer, and diffuse the additive uniformly by the convection of the molten metal. The optimum density varies depending on the processing purpose, but in the present invention, the thickness, size,
It can be adjusted to the optimum density depending on the shape and the like. As an overall density range, the apparent density of the treating agent alone is 4.5 to 7.6.
It can be adjusted appropriately in the range of g / cm ³ .

In order to make the density of the treating agent close to the density of the molten metal, it is preferable to narrow down the additives only to the elements necessary for each treatment as much as possible, such as ferrosilicon having a low density (density of about 5 g / cm ³ ). It is preferable to prevent entry of impurities.

Further, since the treating agent of the present invention has a solid metal plate coating material, it has the effect of maintaining the preservability of the additive and preventing breakage at the time of transportation, and also regulates the internal pressure by opening small holes. There is also an advantage that processing such as is easy.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 JIS G 3461, outer diameter 15.9 mm, wall thickness 2.
Using a 9 mm commercially available steel pipe, a cast iron treating agent having the shape shown in FIG. 1 was manufactured, and the floating behavior of the cast iron treating agent and the thermal behavior during the treatment were measured. In FIG. 1, 1 indicates a 2.9 mm steel sheet, 2 indicates an additive, and 3 indicates a small hole for decompression. After pressing the steel pipe flat so that the inner gap is 3 mm, one side is closed by pressing, and the inside of the pipe contains granular magnesium (Mg).
And an additive of ferrosilicon for inoculation (hereinafter referred to as FeSi) were filled and sealed to obtain a spheroidizing cast iron treating agent. Single weight and volume of the cast iron treatment agent, in respectively 30g and 4.3 cm ^3, an apparent density was 7.04 g / cm ^3. As a method for producing a cast iron treating agent utilizing the hot property of a metal, a coating material is heated to about 1000 K and granular Mg and Fe are contained therein.
When Si was filled, molding was easy and the apparent density of the cast iron treating agent also increased. This is because the strength of the coating material when heated is greatly reduced and the elongation is greatly increased.
This is because Mg permeated into the gaps between the granular FeSi due to melting with K.

8.3 kg of this cast iron treating agent was set in a 200 kg ladle as shown in FIG. 3, a 1773 K molten metal was poured, and the floating of the cast iron treating agent and the thermal behavior during the treatment were measured. A, b, and c shown in FIG. 4 indicate the positions of the thermocouples, and indicate the internal thermal behavior at a distance of 10 mm, 30 mm, and 60 mm from the molten metal contact surface, respectively. In FIG. 4, 9 indicates a 200 kg hot water and 10 indicates a cast iron treating agent.

From the start of the molten metal to the end of the molten metal 20 seconds later,
There was no floating of the cast iron treating agent, and thereafter, convection of the molten metal as shown in FIG. 3 continued for about 25 seconds. The reaction was mild and the amount of white smoke was very small, and a situation was observed in which the additive was uniformly diffused.

On the basis of the above results, the density of the cast iron treating agent was changed, and the floating of the cast iron treating agent, convection time of the molten metal, environment, Mg
The yield and metallographic structure were investigated. Table 1 shows the results of processing 500 kg of molten metal. When the cast iron treating agent of the present invention was used, the Si of the original hot water was 0.3% higher than the conventional method. This is because the amount of Si in the cast iron treating agent of the present invention is very small.

[0064]

[Table 1]

As a result, when the cast iron treating agent of the present invention was used, if the density became 5.6 or more, there was no surfacing, the reaction was mild, the amount of white smoke was small, and the Mg yield was as high as about 80%. Since the diffusion in the molten metal becomes uniform, the number of spheroidal graphite particles was about twice or more as compared with the conventional method.

Example 2 A density of 7.0 g / c manufactured by the method described in Example 1.
As shown in FIG. 3, m ³ , Mg content 1.21%, Fe-Si content for inoculation 4.7%
g Set in a ladle and poured 1773K molten metal. In the conventional method, a commercially available ferrosilicon magnesium (hereinafter, Fe-Si-Mg) sphering agent having a Mg content of 5% is used.
500 kg of 6 kg and 1.5 kg of Fe-Si based inoculants
It was set in a ladle, covered with a cover material of about 24 kg, and poured. In the cast iron treating agent of the present invention,
Was 0.28% higher than the conventional method. This is because the amount of Si contained in the cast iron treating agent of the present invention is extremely small. Table 2 shows the chemical components of Motoyu.

[0067]

[Table 2]

At the time of pouring, there was no floating of the cast iron treating agent, the reaction was mild, and the convection of the molten metal continued for 58 seconds. Table 3 shows the chemical components of the treated product, and FIGS. 5 and 6 show the microstructures when the conventional method and the cast iron treating agent of the present invention were used, respectively. The Mg yield in the present invention is as high as about 80%, the mechanical properties are good,
As for the microscopic structure, the number of graphite particles also showed a dense structure of twice or more.

[0069]

[Table 3]

From the above results, the use of the cast iron treating agent for spheroidizing graphite of the present invention can greatly reduce the amount of additives used and improve the working environment. Further, since the cast iron treating agent for inoculating graphite of the present invention is uniformly diffused in the hot water, the graphite is refined and the number of grains is greatly increased, so that a change in the metal structure due to the product thickness (chilling, Fading)
Is avoided and the mechanical properties are improved.

Example 3 JIS G 3461, outer diameter 15.9 mm, wall thickness 2.
Using a 9 mm commercially available steel pipe, a cast iron treating agent having the shape shown in FIG. 1 was produced in the same manner as in Example 1, and used as a vermicular spheroidal graphite cast iron treating agent, to produce vermicular spheroidal graphite cast iron (hereinafter CV graphite cast iron). . Conventional methods include commercially available sphering agents for CV (Fe-Si, Ca, Mg, Ti
In the present invention, 2 kg and 6 kg of the cover material are combined with the above cast iron treating agent (Mg content: 1.3%, density: 7.1 g /
(cm ³ ) 4.0 kg was placed and added to 200 kg of molten metal by a pouring method to perform a molten metal treatment. In the present invention, the content of Si in the hot water was set to be 0.25% higher than that of the conventional method.
Table 4 shows the results.

[0072]

[Table 4]

By applying the cast iron treating agent of the present invention, the floating of the treating agent and the diffusion of the molten metal were sufficiently performed. As a result, the chemical components and the mechanical properties were equivalent to those of the conventional method, and the yield of Mg was about In the case of an unstable material such as CV graphite cast iron, a stable metal structure and mechanical properties could be obtained even at a low addition. FIG. 7 shows the structure of CV spheroidal graphite cast iron using the Y block test piece manufactured in this example.

Example 4 Using commercially available Fe-Si-based, Ca-Si-based, and Si-C-based inoculants, each having the density shown in FIG.
Processed to 0, 6.6, and 6.4 g / cm ³ to make a cast iron treatment for inoculation, set in a ladle and 500 kg
Was injected at 1773K. Table 5 shows the composition of the cast iron treating agent for inoculation and the amount added to the 500 kg of molten metal.

[0075]

[Table 5]

In this case, since the Ca-Si-based and Si-C-based inoculants have a lower density than the Fe-Si-based inoculants, it is necessary to increase the proportion of the coating material. However, in the chill test showing the inoculation effect, when the cast iron treating agent of the present invention was applied, the chill depth equivalent to that of the conventional method could be obtained with the inoculation amount of about 60% of that of the conventional method. . This is nothing but the result that the inoculant gradually dissolves in the molten metal and is diffused uniformly by the convection of the molten metal, so that a small amount of persistent inoculation is performed.

Example 5 Using a stainless steel tube of JIS G 3463, Mg and FeSi for inoculation, the additive was coated with a stainless steel plate by the method shown in Example 1, and processed into the shape shown in FIG. This treatment agent uses stainless steel as a coating material instead of iron for the spheroidizing treatment of Ni-resist spheroidal graphite cast iron with high nickel (hereinafter Ni). Since the density of Ni is high, a higher density treatment agent is possible. Becomes Table 6 shows the composition of the treating agent used here. The density of this treatment agent is 7.4 g
/ Cm ³ and a unit weight of 29.5 g (Mg content 1.15)
%) Of this cast iron treating agent was added to 50 kg of hot water and reacted at 1773K. The prevention of floating and the stirring of the molten metal were maintained, and the reaction was mild. Table 7 shows the chemical components and mechanical properties of the product.

[0082]

[Table 6]

[0083]

[Table 7]

As a result of setting Ni% of the original hot water to be lower by 0.5% in advance, as shown in Table 7, appropriate chemical components and mechanical strength were obtained, and the metal of niresist spheroidal graphite cast iron as shown in FIG. 8 was obtained. The tissue was obtained.

[0096]

As described above, the cast iron treating agent of the present invention has the following characteristics. (1) The density of the granular or massive cast iron treating agent of the present invention is
It can be very close to the density of the molten metal to be treated, and can reliably prevent the cast iron treating agent from floating during the treatment. (2) The cast iron treating agent of the present invention reduces the temperature of the surroundings due to the solid metal plate covering at the time of the treatment, lowering the surrounding temperature, and the covering metal plates fuse together to help prevent floating. Even if the density is low, it is difficult to float. (3) Since the cast iron treating agent of the present invention dissolves sequentially from the surface layer after treatment and causes convection of the molten metal, the inoculation time of the additive is long,
Diffusion becomes uniform. Therefore, the product has a very fine metal structure, and the material properties are improved. (4) Since the necessary minimum amount of additives can be contained in the cast iron treating agent of the present invention, impurities are reduced and defects such as inclusions are reduced. (5) The cast iron treating agent of the present invention can be applied to spheroidization of graphite and vermicularization of graphite. (6) Since the cast iron treating agent of the present invention covers and protects the additive with a strong metal plate, damage during transport and oxidation of the additive,
Preservability against moisture absorption and the like can be maintained. (7) By using the cast iron treating agent of the present invention, white smoke,
The work environment of dust and the like can be improved, and the cleaning management of the ladle becomes easy. (8) Since the cast iron treating agent of the present invention can be easily produced, the production cost is low.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of the shape of a cast iron treating agent formed by press cutting using a metal tube.

FIG. 2 is a schematic view showing an example of the shape of a cast iron treating agent formed by pressing and welding using a flat metal plate.

FIG. 3 is a schematic view of a ladle for pouring;

FIG. 4 is a graph showing the thermal behavior during the treatment of the cast iron treating agent.

FIG. 5 is a micrograph (100 magnification) showing the structure of a spheroidal graphite cast iron according to a conventional method.

FIG. 6 is a micrograph (magnification: 100) showing the structure of spheroidal graphite cast iron with the cast iron treating agent of the present invention.

FIG. 7 is a micrograph (100 magnification) showing the structure of vermicular graphite cast iron.

FIG. 8 is a micrograph (100 magnification) showing the structure of niresist spheroidal graphite cast iron.

[Explanation of symbols]

1 Coated metal plate, 2 Additive, 3 Small hole, 4 Welding site, 5 Ladle, 6 Cast iron treating agent, 7 Motoyu,
8 Convection of molten metal, 9 yuan hot water, 10 Cast iron treating agent

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C21C 1/10 C21C 7/04 C22B 9/10 C22C 1/02

Claims (4)

(57) [Claims] 1. A granular or massive additive required for a graphite spheroidizing treatment or a graphite vermicular treatment of a cast iron, and a solid metal coating material containing iron or nickel as a main component for coating the additive. A cast iron treating agent in which the coating material is made of a solid metal plate to make the apparent density of the entire treating agent as close as possible to the density of the molten metal, and the coating material layer is provided with a vent portion consisting of small holes or gaps. . 2. The cast iron treating agent according to claim 1, which has an apparent density of 4.5 to 7.6 g / cm ³ . 3. The coating material is composed of an integral metal, a metal tube or a metal plate, and is formed by grinding, forging, welding, an adhesive, a fastener, or discharge bonding into an enclosure having an additive therein. Item 3. The cast iron treating agent according to Item 1 or 2. 4. The method according to claim 1, wherein said additive comprises Mg.
The cast iron treating agent according to any one of claims 1 to 3.