JP2000328199A - Wear resistant material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material exhibiting excellent wear resistance even in a high temp. corrosive environment by incorporating cast iron with respectively specified amounts of C, Si, Mn, Cr and Co or Ni and moreover adding it with Al, V, Nb, Ta, Mo, Ti or the like. SOLUTION: The compsn. of a cast iron material is composed of, by weight, 0.8 to 4.0% C, <=2.0% Si, <=2.0% Mn, 10 to 30% Cr and 15 to 50% Co or Ni, and the balance Fe with inevitable impurities. If required, at least one or more kinds among Al, V, Nb, Ta, Mo and Ti are moreover incorporated therein. In this material, for improving its wear resistance, hard crystallized carbides are utilized. The carbides take the form of M7C3, M23C6 type carbides similar to that of a high Cr cast iron material. In the base structure, for improving its heat resistance and corrosion resistance, Fe is substituted for Co or Ni, and moreover, fine carbicies are dispersedly crystallized out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear-resistant material used in equipment such as iron making, construction, and crushed stone, and in particular, for a mechanical part which is subject to wear damage in a high-temperature and corrosive environment.

[0002]

2. Description of the Related Art Conventionally, as wear-resistant materials of this type, C: 1.0 to 6.0% and Cr: 10.0 to 30.
High chromium cast iron materials containing 0% and optionally adding Ni, Mo, V and the like have been widely used. For example, Japanese Unexamined Patent Publication No. Hei 5-253665 discloses a part subjected to sediment wear in construction machines or a wear-resistant part in a cement factory or a steel mill.
Tokiko Sho 50 as a work roll for rolling in steel equipment
The material disclosed in JP-A-37019 is used. These materials have exhibited extremely hard chromium carbides, i.e. M ₇ C ₃ and M ₂₃ C ₆ -type carbide and martensite or bainite, or excellent abrasion resistance have these tempering base tissue.

[0003]

However, the high chromium cast iron material disclosed in the above patent gazette, which is widely used as an abrasion-resistant material, has excellent performance at room temperature or in a low-temperature environment of less than about 500 ° C. as described above. Although exhibiting abrasion resistance, under a high temperature environment, particularly, the base structure was softened or corroded, and sufficient abrasion resistance could not be exhibited. Accordingly, an object of the present invention is to exhibit excellent wear properties even in a high-temperature corrosive environment, which has been a problem of the conventional high-chromium cast iron materials and wear-resistant materials in a high-temperature corrosive environment.

[0004]

SUMMARY OF THE INVENTION The gist of the present invention is to maintain the excellent wear resistance of a high chromium cast iron material in a high-temperature environment, so that C: 1.0 to 4.0 by weight%.
%, Cr: 10 to 30%, Co or Ni at 15 to 50%, and A together with Ni.
A wear-resistant material characterized in that at least one of l, V, Nb, Ta, Mo, and Ti is added in an amount of 1% or more and 10% or less, with the balance being Fe and unavoidable elements.

[0005] First, on the metallographic structure and chemical components of the present invention.
The features are outlined. The present invention improves the abrasion resistance.
Therefore, one of the biggest features is to use hard crystallized carbide.
The form of the carbide is the same as high chromium cast iron material
M₇C_Three, M_{twenty three} C₆Type carbide. On the other hand, base organizations
Co or Ni to improve thermal and corrosion resistance
Replace Fe and disperse and crystallize fine carbides
You. Furthermore, in the material of the present invention to which Ni is added, wear resistance is improved.
Al, V, which combine with Ni and precipitate to improve
Hard and fine precipitation by adding Nb, Ta, Mo and Ti
Compound, for example, Ni _ThreeAl, Ni_ThreeNb is distributed in the base organization
It is to be clothed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the components of the outer layer are described below. C is an element indispensable for obtaining the most important hardness for securing the wear resistance. If the amount of C is less than 0.5%, hard carbides are less crystallized, and the amount of C dissolved in the matrix becomes insufficient, so that sufficient base hardness cannot be obtained even by quenching. On the other hand, if the content exceeds 4.0%, coarse carbides are crystallized, the amount thereof is also excessive, and the material becomes brittle as a structural material. During use, the coarse carbides are peeled off, and damages such as breakage occur. This was set as the upper limit in order to lower the performance.

[0007] Cr combines with C to crystallize and form chromium-based hard M ₇ C ₃ and M ₂₃ C ₆ type carbides as described above, and to improve wear resistance. It is an important element to be added. However, if the addition amount is small, the effect cannot be sufficiently exhibited, while if too large, the carbide becomes coarse and the amount becomes too large similarly to C, resulting in brittleness and the object of the present invention cannot be achieved. Therefore, the optimum range is set to 10% or more and 30% or less.

[0008] Co and Ni are one of the most important elements in the present invention. Although both elements are used in heat-resistant or corrosion-resistant alloys having completely different uses from the present invention, in this case, materials containing extremely small amounts of C as compared with the material of the present invention, that is, those having no wear resistance are limited. Was. For example, in JP-A-8-20848, C: 0.1%
Hereinafter, in JP-A-7-62478, C:
A material of 0.02% or more and 0.15% or less is disclosed. In the material of the present invention containing a large amount of C, any of the elements forms a solid solution with Fe to form a base structure. F
e significantly reduces the material strength at a high temperature and easily oxidizes, so that the performance as a material, that is, the abrasion resistance is significantly reduced.

On the other hand, Co and Ni have a small decrease in strength even at high temperatures and are hardly oxidized, so that high wear resistance can be maintained at high temperatures under a corrosive environment. However, if the addition amount is less than 15%, a large amount of F is present.
e acts preferentially, and the effect of its addition does not appear significantly. On the other hand, if it exceeds 50%, the hardness of the material, especially the base structure itself, is reduced, so that the intended sufficient wear resistance cannot be secured.

FIG. 1 shows the Vickers hardness of the eutectic structure at room temperature after casting in the material of the present invention of 2.0% C-15% Cr in relation to the addition amounts of Co and Ni. As described above, the hardness increases due to the addition of Co and Ni, and the hardness of the eutectic portion increases remarkably in the range of the addition amount of 15% or more and 50% or less, thereby exhibiting sufficient wear resistance. Therefore, the optimum range is set to 15% or more and 50% or less.

[0011] In the high chromium cast iron material, the base structure after casting is generally soft austenite,
When Co is added, a part of the base structure is transformed into hard martensite or bainite, and the hardness is further increased. In the material of the present invention, Co or Ni in this range is used.
A eutectic reaction occurs at a low C content due to the addition of, resulting in the formation of a eutectic structure in which fine carbides are dispersed and crystallized,
Toughness is added in addition to wear resistance. Further, even in the hypereutectic material in the high C region, crystallization of soft graphite is suppressed,
It became possible to form a structure in which fine carbides were dispersed.

FIG. 2 shows a typical metal structure of the present invention as C:
FIG. 2 is a diagram showing a micrograph of a material having a chemical composition of 2.0% -Cr15% -Ni: 45% at a magnification of 200 times;
The black part is carbide. As described above, it can be seen that the eutectic structure increases and fine carbides are dispersed, and the effect is remarkable. Next, it becomes difficult to form a hard martensitic structure due to the decrease in Fe element in the matrix as Ni increases. Therefore, when Al, Nb, Ti, and Ta, which combine with Ni to form a hard compound, are added, hard and fine precipitates are generated in the matrix structure, which is effective for improving wear resistance. 1% or more 1% or more 10
% Is desirable.

[0013] Mo is an element capable of obtaining a hard carbide like Cr, and contributing to the secondary hardening when tempering at a high temperature. Therefore, when it is added in the range of 3% or less as in the case of the conventional high chromium cast iron, there is an effect of improving its wear resistance. Since W produces hard carbides like Mo, it is effective to substitute W with these elements in the range of 3% or less. V is an element useful for improving abrasion resistance because it preferentially forms extremely hard granular MC-based carbides. However, when the content increases, one of the features of the present invention is that of chromium-based M ₇ C ₃ ,
Since the crystallization of M ₂₃ C ₆ type carbide is suppressed, it is desirable to keep the content to 1% or less.

In the present invention, both Si and Mn have a deoxidizing effect, and at the same time, from the viewpoint of improving the fluidity of the molten metal, the content of each of 2% or less contained in general white cast iron may be contained. desirable. In the present invention, the production was performed by casting, but the metal composition is composed of a carbide and a base structure, and since these are also produced in a rapidly solidified powder, they can be produced by a powder metallurgy method. It is easily presumed that the effect of the present invention can be achieved.

[0015]

EXAMPLE As an example of the present invention, a liner for inserting a raw material such as iron ore and coke in a blast furnace of an iron making facility was manufactured using the chemical components shown in Table 1 and used. The dimensions and shape of the product are 900 mm wide, 500 mm long and 40 thick
mm. Conventionally, a high chromium cast iron material was used, and a conventional example is shown in the table. This liner is installed in the upper part of the blast furnace and is subject to collision and sliding wear by hard raw materials. Usually, it is used in an atmosphere of about 200 ° C., but if the operation of the blast furnace is unstable, it is often 60
Exposure to high temperatures above 0 ° C. Therefore, high wear resistance is desired while enduring high temperature atmosphere. The materials in the table were each melted in a high frequency induction furnace and cast on a 12 mm thick ordinary steel plate. After that, the quenching is 900 as the hardening heat treatment.
C., cooled by a blast, and tempered at 500.degree.

Table 1 also shows the results of the use evaluation in addition to the material properties such as the chemical components, crystallized carbides and hardness of each material.
Here, the hardness is represented by Shore hardness as a total hardness of the eutectic and primary crystal structures. The abrasion resistance was represented by the ratio of elapsed time per unit wear of the liner surface. Although some of the materials of the present invention are lower in hardness at room temperature than the conventional materials compared to the conventional high chromium cast iron materials, it is clear that the wear resistance of all of the materials of the present invention is remarkably improved.

[0017]

[Table 1]

[0018]

As described above, according to the present invention, an extremely high-performance wear-resistant material can be obtained in a high-temperature and corrosive environment. As a result, the replacement cycle of the members is greatly extended, complicated replacement work is reduced, and operability is improved. Therefore, the present invention is extremely effective industrially.

[Brief description of the drawings]

FIG. 1 shows C in a 2.0% C-15% Cr material of the present invention.
The figure showing the relationship between the amount of o and Ni added and the hardness of the eutectic structure after casting,

FIG. 2 shows C: 2.0%-as a typical metal structure of the present invention.
Cr: 5% -Ni: 45%
It is a figure shown by 00 time.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yasuhiro Matsubara 1232 Komorino-cho, Kurume-shi, Fukuoka In-house Kurume National College of Technology (72) Inventor Shinya Sasaguri 1232, Komorino-cho, Kurume-shi, Fukuoka In-house of Kurume National College of Technology

Claims (3)

[Claims] C .: 0.8 to 4.0%, Si: 2.0% or less, Mn: 2.0% or less, Cr: 10 to 30%, Co: 15 to 50% by weight%. A wear-resistant material characterized in that the balance is Fe and unavoidable elements. 2. In% by weight, C: 0.8 to 4.0%, Si: 2.0% or less, Mn: 2.0% or less, Cr: 10 to 30%, Ni: 15 to 50% A wear-resistant material characterized in that the balance is Fe and unavoidable elements. 3. The wear-resistant material according to claim 2, wherein at least one of Al, V, Nb, Ta, Mo, and Ti is contained in an amount of 1% by weight or more and 10% by weight or less.