JP3456635B2 - Spherical carbide cast iron - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates to a spherical shape carbide cast iron, the purpose of corrosion resistance, abrasion resistance, all fully combines properties such toughness, chemical that is being high performance and high functionality with the development of industry industrial and machinery, ships, to provide a broadly applicable spherical shaped carbides cast iron is Ru can be in various industries such as petroleum.

[0002]

2. Description of the Related Art Conventionally, materials for equipment used in a high temperature environment such as various boiler facilities and chemical plant equipment have been required to have heat resistance and corrosion resistance. However, in recent years, along with the development of industrial technology, the improvement of high-temperature equipment and the high performance and high performance of various industries including the chemical industry have been remarkable, and the durability under more severe conditions has been required. For example, in the field of injection molding of engineering plastics, reinforcing materials such as FRP and various additives have been added to the resin in order to improve the strength, flame retardancy, abrasion resistance, etc. of the resin molded body. ing. As a result, the reinforcing material in the cylinder resin of the resin molded body is liable to be worn, and the strong corrosive gas generated from the additive is apt to be corroded. Further, the shapes of parts manufactured in various industries such as automobiles have become complicated, and wear of parts manufacturing apparatuses has become more remarkable than before.

In this way, with the advancement of the industry, the environment in which the equipment and the like used therein are used has become extremely severe, and in addition to its properties such as strength and heat resistance, its material is wear resistant. However, there is a demand for further improvement in corrosion resistance.

First, in order to obtain excellent wear resistance, use of white cast iron, which is hard cast iron, can be considered. However, this white cast iron has the drawback that it is very brittle because it has no graphite in its structure and is formed from pearlite and cementite. Therefore, it is difficult to obtain excellent wear resistance by using white cast iron. Therefore, it has been attempted to use toughness, spheroidal graphite cast iron that overcomes the drawbacks of white cast iron.

The above-mentioned spheroidal graphite cast iron has excellent toughness because the shape of flake graphite crystallized in its structure is spheroidized. This is because the shape of crystallized substances in the metallic material structure such as spheroidal graphite cast iron has a great influence on the toughness. That is, usually, the crystallized product has a strong non-metallic property and is covalently bonded or electrostatically bonded, that is, faced.
t), which is always plate-shaped, in which case the toughness is weak and, conversely, when the metallic property is strong, metallic bonding, that is, non-faced (non-faced)
facet) becomes a granular or spherical dendrite, and in this case the toughness is strong because the force is dispersed even when an impact is applied from the outside, and in the case of spheroidal graphite cast iron, magnesium (Mg) is added by 0.04% or more, Since the flake graphite crystallized in the cast iron structure has a spherical shape, it has excellent toughness. Moreover, this toughness is on the other side,
It is considered to be a factor that improves wear resistance, and the spheroidal graphite cast iron in which a part of covalent bonds is present has wear resistance comparable to white cast iron.

On the other hand, the present inventors have already filed Japanese Patent Application No. 9-30.
No. 7951, granular or spherical VC in cast iron structure
By crystallizing the system carbide and the Fe-Cr system carbide,
It has been found that an alloy cast iron having excellent wear resistance and impact resistance can be obtained.

[0007]

However, although the spheroidal graphite cast iron is excellent in wear resistance and toughness, it has a drawback that it is inferior in corrosion resistance, and the alloy cast iron described in Japanese Patent Application No. 9-307951 is also resistant to corrosion. It has excellent wear resistance and impact resistance, but has a drawback of slightly inferior corrosion resistance, and cast iron having both wear resistance, toughness and corrosion resistance has not yet been obtained. Therefore, spheroidal graphite cast iron and Japanese Patent Application No. 9-307951
In addition to the wear resistance and toughness of the alloy cast iron described in No.
It has been desired to create cast iron having excellent corrosion resistance.

By the way, as a steel material having excellent corrosion resistance, stainless cast steel is known, and specifically, in the JIS G5122 standard, a typical 18Cr-
8Ni SCS12, SCS13, SCS19, SC
S21 or 18Cr-11Ni-Mo SCS14, high Cr-Ni SCS11, 13Cr SCS1, S
There are stainless cast steels such as CS2 and high Cr type. All of these stainless cast steels contain Cr in an amount of 12% or more, and are passivated by the oxidation action of this Cr, and oxides such as FeO, Cr ₂ O ₃ and NiO are crystallized on the surface of the cast steel to rust the surface. It is configured to be protected from.

[0009] Therefore, the present inventors have made continued intensive study on the cast iron excellent corrosion resistance is imparted, by only the crystallized granular or spherical V- C carbides, imparting wear resistance and toughness In addition to the above, it was found that excellent corrosion resistance comparable to stainless cast steel can be imparted, and the present invention has been completed.

[0010]

That is, according to the invention of claim 1, C: 0.6 to 4.0% by weight, Cr: 13 to 30% by weight, Ni: 4 to 15% by weight, Si: 0. 2-4.5% by weight, Mn: 0.2-1.5% by weight, P: 0.01-0.
15% by weight, S: 0.01 to 0.05% by weight, V: 8 to
The present invention relates to spheroidal carbide cast iron comprising 15% by weight, the balance iron (Fe) and unavoidable impurities, and crystallizing covalently bonded granular or spherical V-C carbides in its structure. According to the invention of claim 2, in the alloy element,
(A) Mo: 0.05 to 15% by weight, (b) Ti: 0.
01-5 wt%, (c) B: 0.01-2 wt%,
(D) Cu, W, Zr , Co, Nb, Ta, at least two or more alloying elements of Y: 0.2 to 5 wt%, selected from among the (a) ~ (d) one about globular carbides cast iron according to claim 1, characterized by being blended with the above following. The above problems are solved by providing these inventions.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, described in detail engagement Ru spherical shape carbide cast iron in the present invention. Engaging Ru spherical shape carbide cast iron in the present invention,
C, V, Cr, Ni, S as essential components to iron (Fe)
i, Mn, P, and S are contained.

[0012] First, C and V are intended to improve wear resistance, are formulated granular or spherical V- C carbides in order to crystallize. The carbon (C) content is set to 0.6 to 4.0%. This is because if the content is less than 0.6%, the hardness and mechanical properties of the alloy cast iron hardly change, and if the content exceeds 0.6%, the hardness of the alloy cast iron increases and the mechanical properties also improve. When the amount is more than 4.0%, a part of C is thus degrading Fe-C r carbides <br/> (cementite), and corrosion resistance.

The vanadium (V) content is 8.0 to 1
It is set to 5%. This is because if the content is less than 8.0 %, high-hardness carbides are dispersed to form covalently bonded granular or spherical V.
- it can not be a C carbides crystallized, even though the amount is more than 15%, more than that of the effect can not be expected, it tends to cause segregation in the contrary, it is not preferable in both cases. Further, granular or spherical V- C carbides, the atomic ratio of V and C is about 1: 1 (weight ratio 4: 1) because it is, the content of V is approximately four times the content of C Is more preferable.

Chromium (Cr) and nickel (Ni) are added to improve corrosion resistance. Cr content is 13-30
%. This is because if the content is less than 13%, stable austenite (γ) cannot be crystallized, and the corrosion resistance to an oxidizing solution will be reduced.
This is because if it exceeds%, it causes segregation and deteriorates the strength, which is not preferable in any case. Ni
The content is set to 4.0 to 15%. This has a content of 4.
If it is less than 0%, the martensitic structure of the metal structure tends to occur, while if it exceeds 15%, segregation occurs and the matrix becomes softer, which is not preferable in any case. Further, by blending 4% or more, the corrosion resistance to a non-oxidizing solution is also improved.

Silicon (Si) is effective for deoxidizing, increasing hardness and improving castability, and when it is contained, its content is set to 0.2 to 4.5%. This is 0.2
If it is less than 4.5%, the effect due to the Si content cannot be exhibited, while if it exceeds 4.5%, the toughness decreases.
This is because neither case is preferable.

When manganese (Mn) is contained, its content is 0.2 to 1.5%. This is because if it exceeds 1.5%, segregation tends to occur, which is not preferable for VC alloy cast iron. Phosphorus (P) is effective in improving the castability by slightly increasing the hardness and improving the fluidity, and when it is contained, its content is 0.01-.
It is set to 0.15%. This is because if less than 0.01%, P
This is because the effect due to the compounding cannot be expected, and on the other hand, if it exceeds 0.15%, segregation or brittleness occurs, which is not preferable in any case.

When sulfur (S) is contained, the content is 0.01 to 0.05%. This is usually 0.05
%, Fe ₃ C (cementite) and MnS
This is because (manganese sulfide) is easily crystallized and the corrosion resistance is lowered, which is not preferable.

The above elements are essential components contained in iron (Fe). In the present invention, in addition to these essential components,
(A) Mo, (b) Ti, (c) B, (d) Cu, W,
Zr, Co, Nb, Ta, at least two or more alloying elements, of the (a) ~ one <br/> than above that is selected from a (d) may be suitably blended of Y.

Molybdenum (Mo) is effective for preventing the precipitation of quiche graphite and stabilizing the matrix. When Mo is contained, its content is 0.05 to 15%. This is less than 0.05%, not to obtain the effect by Mo formulation Conversely, if it exceeds 15%, the high hardness carbide is dispersed in the covalent granular or spherical V- C carbides crystallize This is not preferable in any case, since it causes instability and deteriorates corrosion resistance.

Titanium (Ti) is effective in denitrifying and refining the metal structure, and when contained, its content is 0.0
It is set to 1 to 5.0%. This is below 0.01%
This is because the effect of Ti blending cannot be obtained, and conversely, if it exceeds 5.0%, precipitation of Ti-based carbides becomes remarkable and the strength is deteriorated, which is not preferable in any case.

Boron (B) is effective in increasing the hardness by heat treatment, and when it is contained, the content is 0.01 to 2.0.
%. This is because if it is less than 0.01%, the effect due to the blending of B cannot be obtained, and conversely, if it exceeds 2.0%, it causes deterioration of the strength, which is not preferable in any case.

Copper (Cu), tungsten (W), zirconium (Zr), cobalt (Co), niobium (Nb),
Tantalum (Ta) and yttrium (Y) may be appropriately blended according to the purpose such as corrosion resistance, wear resistance, and heat resistance. These are effective even if blended alone, but more superior effects can be obtained by blending a plurality of them. Therefore, two or more elements are blended in combination. However, mischievous blending does not necessarily strengthen the covalent bond, so the total content of two or more elements is 0.2 to 5.0%.

In the present invention, the essential components C, V, C
In addition to r, Ni, Si, Mn, P and S, the above-described respective compounding components may be appropriately compounded and cast according to the purpose of use, and especially for stabilizing the hardness of high carbon content. Is a combination of Si, P, B, Zr, Cu, Nb, Ta and Y,
Cr, M for matrix stabilization and prevention of precipitation of quiche graphite
The compounding of o and W is effective for refining and degassing the metal structure during casting, and the compounding of Ti is effective for preventing the formation of martensite in the metal structure.

The spherical shaped carbide cast iron ing from the composition, in a usual manner, poured molten metal into the mold, it can be obtained by cast and then cooled. Since it is desirable to remove the casting stress generated during cooling, 973 to 1293
After holding at K for about 1 hour, normalizing and annealing may be performed.
If held after furnace cooling (annealing) or air treatment (normalizing) at 973～1173K, tissue austenite (gamma) + _{V P}
It becomes a _CQ complex. Further, when the furnace cooling (annealing) or air cooling (normalizing) after holding at 1173 to 1293K is performed, normalizing for improving strength and toughness, and casting stress removal for improving impact resistance are aimed at. Although a treatment such as annealing is required, the structure in this temperature range also becomes an austenite (γ) + V _P C _Q complex, and the above 973 to 1173
It is no different from alloy cast iron treated with K. When the normalizing treatment and the annealing treatment are performed as described above, there is no difference in the structure between the as-cast alloy cast iron and its structure.

[0025]

BRIEF DESCRIPTION more detail on the basis of the spherical shape carbide cast iron an embodiment of the present invention. However, the present invention is not limited to the following examples.

(Examples 1 to 5 and Comparative Examples 1 to 8) Melting conditions Pure iron (Fe), C: 0.05%, Si: 0.4%, M
n: 1.0%, P: 0.04%, S: 0.015%, N
i: 8.0% and Cr: 18.0% were blended, respectively, and carbon (C) was further blended in accordance with the blending shown in Table 1 to obtain casting raw materials of Blending Examples 1 to 8.

[Table 1]

Regarding each of the casting raw materials of the above-mentioned formulation examples 1 to 5, first, V was 8 , 10 or 15%, respectively.
3 kinds of the casting raw materials of Examples 1 to 5 shown in Table 2 were compounded, and then V was 0, 2.5, 4 , 6 or 16% respectively, and Comparative Example 1 shown in Table 2 was obtained. 5 to 5 casting materials
Got by type. Moreover, about each casting raw material of formulation examples 6-8, V was 0, 2.5, 4, 6, 8, 10, respectively.
Eight types of casting raw materials of Comparative Examples 6 to 8 shown in Table 2 were obtained by mixing 15 or 16%. 20K of these casting materials
g High-frequency induction furnace (ramming material MgO + Al ₂ O ₃ ) was used to perform melting and casting. The melted sample is JI
General rules for the production, testing and inspection of S G 307 cast steel products, 3.
2.1 Ciel type tensile test piece (JIS
Z 2201 metal material tensile 4 test piece), shell type impact test piece (JIS Z 2202 metal material impact 3 test piece notch), hardness test / microstructure observation test / wear test / corrosion resistance test piece 25 mm square × 50 mm After casting, a high-angled sample was held at 973 K for 1 hour and then air-cooled.

[Table 2]

[0028]

[Test Example] (Test Example 1) Observation of Microstructure The aforementioned Example 4 (4-8, 4-10) and Comparative Example 4 (4-
In order to observe the microstructure of the alloy cast iron obtained in Nos. 1, 4-2 and 4-16), micrographs (magnification: 400 and 1000) of the 973K heat-treated structure were taken. The results are shown in FIGS.

From the results shown in FIGS. 1 to 10 , it can be seen that in the cast iron alloy of Example 4 shown in FIGS . 1 to 4 , spheroidal carbide was crystallized. On the other hand, in the cast iron alloy of Comparative Example 4 shown in FIGS. 5 to 10 , it can be seen that no granular or spherical carbide is crystallized. That is, it can be said that the addition of V makes it possible to crystallize the spherical carbide, and that the crystallized amount of the spherical carbide increases as the added amount increases.

(Test Examples 2 and 3) Tensile Strength and Elongation The tensile strength and elongation of the alloy cast irons obtained in Examples 1 to 5 and Comparative Examples 1 to 8 were tested. The test piece is JIS
G 0307 According to JIS Z 2201 according to the shape and size (a) of the specimen under the general rules of manufacturing, testing and inspecting cast steel products.
A metal material tensile No. 4 test piece was collected. The test method uses this No. 4 test piece to measure both tensile strength and elongation according to JIS.
Z2241 It measured according to the standard of a metallic material tensile test method. The results of tensile strength are shown in Table 3 and the results of elongation are shown in Table 4.

[Table 3]

[Table 4]

From the results of Table 3, the tensile strength increases as the C content increases from 0.6% to 2.0%, but the C content becomes 3.0. It can be seen that the tensile strength decreases with an increase in the compounding amount of C when the content is increased to 10% or more. Regarding V, the blending amount is 0 to 6
%, The tensile strength increases as the blending amount increases, but when 8% or more is blended, the tensile strength decreases as the blending amount of V increases. Further, from the results in Table 4, it can be seen that the elongation takes a smaller value as the blending amount of C increases and also takes a larger value as the blending amount of V increases.

(Test Example 4) Impact Test The alloy cast irons obtained in Examples 1 to 5 and Comparative Examples 1 to 8 were subjected to an impact test. The test method is JIS Z 2242.
The Charpy impact test indicated in the metal material impact test method is used. Before the test, the oxide on the surface of the test piece is removed with a Belt abrasion grinder 10 × 10 × 55 mm.
The test piece of No. 3 processed into a JIS No. 3 test piece without a notch was tested. After the test, the fracture surface was observed, and those showing large defects were excluded. The results of the impact test are shown in Table 5.
Shown in.

[Table 5]

From the results shown in Table 5, the impact value reaches its maximum when the C content is 0.1%, but after it decreases once, it becomes a large value again when the C content is 0.6%. , Then it can be seen that it has decreased. Further, regarding the examples, it can be seen that the impact value increases as the blending amount of V increases.

(Test Example 5) Hardness Measurement The hardness of the alloy cast iron obtained in Examples 1 to 5 and Comparative Examples 1 to 8 was measured. Using "C scale" (H R _C) of "Rockwell hardness (H _R)" as an index of the hardness, using a "Rockwell hardness test method" (diamond indenter or ball indenter shown in Test Method JIS Z 2245 Then, a reference load was first applied, then a test load was applied, and when the test load was returned to the reference load again, the test was carried out according to (Definition formula based on the difference in the indenter penetration depth between the front and rear reference loads). . The results of hardness measurement are shown in Table 6.

[Table 6]

(Test Example 6) Abrasion test Using the abrasion tester shown in FIG. 11 , an abrasion test was conducted on the alloy cast irons obtained in Examples 1 to 5 and Comparative Examples 1 to 8 according to the following procedure. It was A 10 mm rod was cut out from a test material measuring 25 mm square and 50 mm high to form a test piece, which was attached with a screw holder (2) and cut into a length of 12 mm with a micro cutter. Further, for the grindstone to be brought into contact with the sample, a commercially available material Al ₂ O ₃ and a clay-based binder of about 3 are used.
A grindstone with a shaft (1) having a size of φ25 mm × 2 mm and # 80 abrasive grains (1) obtained by mixing 0% and shaping and sintering at about 1473K was used. Each surface of the sample was polished with a Belt polisher at # 80, paying particular attention so that the surface in contact with the grindstone was in a good flat state. After confirming that there were no deposits on the surface of the polished sample, its weight was measured with a precision balance and used as the weight before abrasion test. Next, the sample was attached to the holder part with the test surface facing downward, and the horizontal level adjusted to the same height as the grindstone was used to adjust the horizontality of the test surface to be horizontal, and the side surface was screwed. After adjusting the balance of the tester, place a 0.2 kg load weight (3) directly above the sample and attach a damping spring (5) to the side opposite to the sample via the balance (4). I stopped running free.
In this state, the abrasion tester was started at a rotation speed of 1700 rpm. The rotation time was 90 seconds, and after 30 and 60 seconds from the start, dressing was performed with a dressing grindstone to prevent clogging of the grindstone with a shaft. After the test was completed, the polishing powder adhering to the sample was thoroughly wiped off and removed, and again weighed with a precision balance, and the difference from the weight before the test was taken as the wear amount. The results of the abrasion test are shown in Table 7.

[Table 7]

From the results shown in Tables 6 and 7, the hardness decreases as the amount of V added increases, while the wear resistance shows
It can be seen that it increases as the amount of V added increases. That is,
Alloy cast iron showing the best wear resistance (Examples 4 and 4-10)
The hardness was not so high, and the result was contrary to the conventional idea that the hardness had to be increased in order to improve wear resistance. This is because the impact value of the alloy cast iron of the compound showing the highest wear resistance shows considerably large toughness, so that the excellent wear resistance is not only related to hardness, but also related to toughness, It is considered that excellent wear resistance can be obtained when these two properties are combined.

Test Example 7 Corrosion Resistance Test Example 4 (4-8, 4-10) and Comparative Example 4 (4-)
1 , 4-2 , 4-6 ) and H
A corrosion resistance test against ₂ SO ₄ (7N) and HCl (1N) was performed. As a test method, a sample 10 mm ³ was finished on the entire surface (Emery No. 320 finish), degreased and washed with an alcohol, and then the weight and surface area were measured and subjected to the test. Each test piece was separately put in a 500 cc container (beaker) of the same size, and 300 cc of H ₂ SO ₄ (7N),
HCl (1N) was poured respectively, H ₂ SO ₄ (7N) was boiled, HCl (1N) was soaked at room temperature for 140 hours, washed and dried, and then the weight and surface area of each sample were measured at room temperature for corrosion. Weight loss was measured in mg / cm ² . Incidentally, SUS304, which is said to have good corrosion resistance, was used as a comparative material and simultaneously measured. Table 8 shows the compounding ratio of SUS304.

[Table 8] The results of the corrosion resistance test are shown in Table 9.

[Table 9]

Based on the results shown in Table 9, the corrosion resistance of the alloy cast iron of the example, the alloy cast iron of the comparative example, and SUS304 are compared. First, comparing the corrosion resistance against boiling H ₂ SO ₄ (7N), the best corrosion resistance is shown at V6%, and the corrosion resistance decreases from V10%, but it shows that the corrosion resistance is several steps better than SUS304. . In this case, it is considered that the added amount of V does not affect the corrosion resistance so much, but if C, V, Cr, Ni, Si, Mn, P and S are added as essential components, the corrosion resistance is improved. It can be said that Next, comparing the corrosion resistance to HCl (1N) at room temperature, it is shown that the corrosion resistance decreases as the amount of V added increases, but the corrosion resistance is better than SUS304, and C, V, and Cr are also essential components. , Ni, Si,
It can be said that by adding Mn, P and S, the corrosion resistance can be improved. It should be noted that the alloy cast irons of Examples and Comparative Examples each contain 18% of Cr and 8% of Ni so as to correspond to stainless cast steel having excellent corrosion resistance. It is generally known that even if 18% Cr and 8% Ni are contained, the corrosion resistance is rapidly reduced when C is contained. However, the cast iron alloys in these test examples are all made of SUS304.
Shows better corrosion resistance than. It can be said that the alloy cast iron structure granular or spherical V- C carbides during that crystallizes, it is possible to maintain excellent corrosion resistance of stainless cast steel.

Summarizing the above results, the compounding amount of V is 4
When it is less than%, the hardness is high, but the wear resistance and corrosion resistance are poor. When it is blended in more than 15%, the wear resistance is excellent, but sufficient hardness cannot be obtained, and the content of C is 0.6
When it is less than%, the hardness and wear resistance are inferior, and when it is more than 4%, the tensile strength, elongation and impact value are inferior. Therefore, in order to improve the wear resistance and the corrosion resistance as well as having the mechanical strength to withstand the actual use, Fe
In addition, at least C, V, Cr, Ni, S as essential components
i, Mn, P, and S are required, and the C content is 0.
6 to 4.0%, and the compounding amount of V is 4.0 to 4.0.
It must be within the range of 15%. Further, it can be said that the wear resistance and the corrosion resistance can be improved as the blending amount of V is larger within this range, that is, as the crystallization amount of the granular or spherical V-C type carbide in the metal structure is larger. .

Test Example 8 Submersible Pump / Impeller Demonstration Test A submersible pump / impeller demonstration test was carried out as a wastewater treatment device for a sludge storage tank. The actual use of the sludge storage tank was pH 4 to 7 (designed pH 7 to 9), and sand was mixed as a foreign matter in the sludge.
The sludge concentration was around 3%. When this treatment equipment sludge storage tank water was analyzed by fluorescent X-ray analysis, the sludge concentration was 0.5.
_{%, FeSO 3: 18.0%,} SO 3: 6.1%, Al
₂ O ₃ : 4.2%, SiO ₂ : 8.8%, V ₂ O ₅ :
It was 2.9% and organic matter (C): 63.0%. P
The proven value of H was 5.0. An impeller having an outer diameter of φ230 was created using Example 4 (4-8) and conventional cast iron FC200 as materials, and was attached to a submersible pump for sludge treatment to perform a verification test. As a result, the impeller made using Example 4 (4-8) as a material was found to lose 0.30% after 1003 hours of operation. On the other hand, in the conventional cast iron impeller, the weight was reduced by 9.00% after 844 hours, and it was clearly superior to the one using the example material. From this, it can be said that the alloy cast irons of the examples are superior to the conventional cast irons in wear resistance and corrosion resistance.

[0041]

As described in detail above, according to the invention of claim 1, C: 0.6 to 4.0% by weight, Cr: 13 to 30% by weight, Ni: 4 to 15% by weight, Si: 0. 2 to 4.5% by weight, Mn: 0.2 to 1.5% by weight, P: 0.01 to 0.
15% by weight, S: 0.01 to 0.05% by weight, V: 8 to
A spheroidal carbide cast iron comprising 15% by weight, the balance iron (Fe) and unavoidable impurities, and crystallizing covalently-bonded granular or spheroidal VC carbides in its structure. In the invention described in 2, the alloy elements are
(A) Mo: 0.05 to 15% by weight, (b) Ti: 0.
01-5 wt%, (c) B: 0.01-2 wt%,
(D) Cu, W, Zr , Co, Nb, Ta, at least two or more alloying elements of Y: 0.2 to 5 wt%, selected from among the (a) ~ (d) one since spherical carbide cast iron according to claim 1, characterized by being blended on following excellent effects as follows.

That is, C, V, Cr, N as essential components
Since i, Si, Mn, P and S are mixed,
Carbides crystallized in the structure are spheroidized, and excellent wear resistance can be exhibited. Further, as described above, since the carbide is spheroidized, it can exhibit corrosion resistance comparable to that of stainless steel. In other words, engagement Ru spherical shape carbide cast iron in the present invention, toughness, strength, weldability, excellent in machinability, and excellent in corrosion resistance and wear resistance, yet a defect because the fluidity of the molten metal is good There are few castings. Therefore, with the development of industry, high functionality,
It has an excellent effect that it can be applied in a wide range in various industries such as chemical industry and industrial machinery, which are being improved in performance.

[Brief description of drawings]

FIG. 1 is a micrograph of a structure of an alloy cast iron having a V content of 8.0% obtained in Example 4 and magnified 400 times.

FIG. 2 is a micrograph of a structure of an alloy cast iron with a V content of 8.0% obtained in Example 4, taken 1000 times.

FIG. 3 is a micrograph of a structure of an alloy cast iron having a V content of 10.0% obtained in Example 4 magnified 400 times.

FIG. 4 is a 1000 × micrograph of the structure of an alloy cast iron having a V content of 10.0% obtained in Example 4.

FIG. 5 is a micrograph of a structure of an alloy cast iron having a V content of 0% obtained in Comparative Example 4 magnified 400 times.

FIG. 6 is a micrograph of a structure of an alloy cast iron having a V content of 0% obtained in Comparative Example 4 at a magnification of 1000 times.

FIG. 7 is a micrograph of a structure of a cast iron alloy having a V content of 2.5% obtained in Comparative Example 4 magnified 400 times.

FIG. 8 is a 1000 × micrograph of the structure of an alloy cast iron having a V content of 2.5% obtained in Comparative Example 4.

FIG. 9 is a micrograph of a structure of an alloy cast iron with a V content of 15.5% obtained in Comparative Example 4 magnified 400 times.

FIG. 10 is a micrograph of a structure of a cast iron alloy having a V content of 15.5% obtained in Comparative Example 4 at a magnification of 1000 times.

FIG. 11 is a side view of a testing machine used for a wear test of the spheroidal carbide cast iron of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (73) Patent holder 000140502 Okamoto Co., Ltd. 1-282 Miyake, Ginan-cho, Hashima-gun, Gifu Prefecture (72) Inventor Shigenori Nishiuchi 5-6-1005 Kusuhanaencho, Hirakata-shi, Osaka (72) Inventor Yutaka Kawano 20 at 47, Kobata Akatsuka, Uji City, Kyoto Prefecture 72 (72) Inventor Satoru Yamamoto 6 at 11 Ichijoji Hayama-cho, Sakyo-ku, Kyoto City Kyoto Prefecture (72) Inventor Kiyosuke Sugawara Misaki, Higashi-Osaka City, Osaka Prefecture Minami 2-chome 28-28 (56) Reference JP-A-6-240404 (JP, A) JP-A-62-47451 (JP, A) JP-A-57-2834 (JP, A) JP-A-62- 211319 (JP, A) JP-B-54-19371 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 37/08

Claims (2)

(57) [Claims] 1. C: 0.6 to 4.0% by weight, Cr: 13
-30 wt%, Ni: 4-15 wt%, Si: 0.2-
4.5% by weight, Mn: 0.2 to 1.5% by weight, P: 0.
01 to 0.15% by weight, S: 0.01 to 0.05% by weight, V: 8 to 15% by weight, balance iron (Fe) and unavoidable impurities, and covalently-bonded granular or spherical particles in its structure. A spheroidal carbide cast iron characterized by crystallizing VC carbide. 2. The alloy element comprises: (a) Mo: 0.05
˜15% by weight, (b) Ti: 0.01 to 5% by weight,
(C) B: 0.01 to 2% by weight, (d) Cu, W, Z
r, Co, Nb, Ta, at least two or more alloying elements of Y: 0.2 to 5 wt%, of the (a) ~ Ichi以above selected from <br/> among (d) The spheroidal carbide cast iron according to claim 1, wherein the spheroidal carbide cast iron is blended.