JPH0521989B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a metal material mainly composed of Fe, which has high strength and high wear resistance, and a method for producing the same. [Conventional technology] Conventionally, materials containing Fe as the main component have been widely used as wear-resistant metal materials, and in particular, materials with carbide formed in the Fe matrix to improve its hardness have been mainly used. There is. In such materials, the size of the carbide and the amount of its dispersion are very important, and in order to obtain good wear resistance, it is desirable that the carbide be finely dispersed and its amount of dispersion be large.
However, although conventional commercially available tool steels have a metal structure in which fine carbides are precipitated, there is a limit to the amount of their distribution. That is, in order to increase the amount of carbide distribution, it is necessary to increase the C content, but in that case, the carbides become huge. From this point of view, attempts have been made to obtain high C-containing metal materials by rapidly cooling and solidifying them from a molten state. Like high C
- Wear-resistant materials or sliding members made of plasma-sprayed high Cr cast iron powder have become known. However, in all of these cases, although carbides are finely precipitated in the cross-sectional composition of the thermally sprayed coating, the coating contains defects such as pores, and there are oxides intervening in the coating. things exist. This structure is due to plasma spraying in the atmosphere in the known method. That is, during thermal spraying, the surfaces of powder particles heated and melted in a plasma jet are oxidized, and in a coating containing such an oxide film, defects such as holes are likely to occur between the laminated thermal spray particles. Although a film having such a structure has locally finely precipitated carbides, it is not necessarily homogeneous and is not preferable in terms of obtaining good wear resistance. In order to improve these problems, the above-mentioned publication also proposes a method of thermal spraying a material made by mixing high C-high Cr cast iron powder with self-fusing alloy or Cu alloy powder. However, the structure cannot be a structure in which carbides are homogeneously dispersed, but rather a structure in which two phases coexist, which is not fully satisfactory in terms of obtaining good wear resistance. In this way, high C-
In high Cr cast iron materials, the presence of internal defects such as the dispersion state of carbides, oxide films, and pores pose problems in obtaining good wear resistance. Furthermore, as shown in Japanese Patent Application Laid-open No. 59-47346 and Japanese Patent Application Laid-Open No. 59-47347, there are known examples regarding high alloy powders, methods for producing sintered alloys thereof, and sintered alloys. This is a method to obtain good wear-resistant parts.
- A homogeneous sintered alloy is obtained by using high Cr cast iron powder as a raw material powder and heating and sintering this powder at a temperature at which equilibrium carbides precipitate. In this case, a wear-resistant member having a structure in which fine carbides of 1 μm or less are finely dispersed can be obtained, but since it is a sintered material, there are restrictions on its shape and size. Furthermore, when using the wear-resistant sintered alloy as a coating layer on the surface of a member, there are technical problems such as bonding. In addition, in methods such as casting and forging, high C-high Cr
It is extremely difficult to finely and homogeneously disperse carbides in cast iron materials. [Problems to be solved by the invention] As mentioned above, the conventional high C
High Cr cast iron materials contain defects such as oxide films and pores, and have problems as wear-resistant materials.
On the other hand, in the case of sintered materials, there are problems such as restrictions on the shape of the product. In view of these points, the object of the present invention is to provide plasma spraying resistant material in which carbides are finely and homogeneously dispersed, and whose internal structure is free from defects such as oxides and pores and has good abrasion resistance. The purpose of the present invention is to provide a wearable iron-based material and a manufacturing method thereof. [Means for solving the problem] The plasma sprayed wear-resistant iron-based material of the present invention is made of Fe.
A material containing C and Cr as the main component, in which precipitated carbides with a size of 0.1 to 5 μm are homogeneously dispersed, the oxygen content is less than about 3000 ppm, and the density is 97% of the theoretical degree. It is characterized by the above. This wear-resistant ferrous material is a base material (e.g. mild steel)
The wear-resistant ferrous material may be formed as a coating that is plasma sprayed in a vacuum atmosphere onto a substrate, or by plasma spraying in a vacuum atmosphere onto a substrate and then removing the substrate. It may be formed as a member consisting of. [Operation] The wear-resistant iron-based material of the present invention sufficiently satisfies the various properties required of a wear-resistant material, such as fine and homogeneous dispersion of carbides, prevention of carbide shedding, and toughness. [Example] The present inventors focused on the relationship between the size of carbides and their distribution state in a high-C, high-Cr cast iron material and wear resistance. Generally, in order to obtain good wear resistance, a structure in which a large amount of fine carbides are uniformly distributed is desirable. For this purpose, it is desirable to have a large C content, but on the other hand, as the C content increases, the size of carbide precipitates increases. Therefore, high C cast iron is produced by rapidly cooling and solidifying the molten metal.
It is possible to obtain high C cast iron in which C is supersaturated as a solid solution. From this point of view, the present inventors considered that the plasma spraying method is suitable. Furthermore, in high C cast iron formed by plasma spraying, the size and distribution of carbides are important, and in order to obtain a material with good wear resistance, the oxygen content in the material,
Density is important. The Fe-C-Cr system is effective in forming fine carbides in materials formed by plasma spraying.
This is because Cr carbide can be precipitated as a carbide in addition to Fe carbide. In order to effectively precipitate such carbides, the amount of C must be 1wt%.
The above is necessary. On the other hand, the content of Cr is
5wt% or more is required to form Cr carbide. By the way, plasma spraying has a rapid solidification effect, but there is a limit to the cooling rate even in plasma spraying, and if the C content is too high, the precipitated carbides will become large. Therefore, the present inventors investigated Fe-C-Cr-based materials with various components formed by plasma spraying, using parameters such as the size of carbides, oxygen content in the material, and density of the material. The relationship between wear resistance and wear resistance was investigated. As an abrasion resistance test, a sliding abrasion test using a roll was conducted. The sliding material was a roll material with a hardness of 840Hv, and the test was conducted under conditions of lubrication with turbine oil. The roll material used in the test had a composition of wt%
It is a quenched and tempered bearing steel material of 0.9C, 0.5Si, 0.5Mn, 3.0Cr, 0.5Mo, the balance being iron. Load is 100
Kg/cm ³ and the number of repetitions was 10,000. JIS tool steel SKD-1 was used as a comparison material. The following is a first example of the method for manufacturing a wear-resistant iron-based material according to the present invention.
This will be explained with reference to FIGS. 3 to 3. Figure 1 shows the results when the size of the carbide was varied. From the figure, it can be seen that when the size of carbide is 5 μm or more, the wear resistance decreases. on the other hand,
When the carbide is 0.1 μm or less, the wear resistance tends to decrease slightly. Thus, in order to obtain good wear resistance, it is desirable that the size of the carbide is 5 μm or less. The samples and manufacturing process conditions shown in FIG. 1 are as shown in the following table.

[Table] As a post-treatment, quenching in oil was performed after heating at 950°C for 30 minutes in an Ar atmosphere. Next, we examined the oxygen content in the material.
Figure 2 shows the results. In this case, the size of the carbide is approximately 1 μm. From the figure, it can be seen that the oxygen content in the material is a very important factor, and when it is more than 3000 ppm, the wear resistance is poor and decreases. The samples and manufacturing process conditions shown in FIG. 2 are as shown in the following table.

【table】

[Table] As a post-treatment, quenching in oil was performed after heating at 920°C for 30 minutes in an Ar atmosphere. Next, Figure 3 shows the results of studying the density of the material. In this case, the size of the carbide is about 1 μm. The figure shows that when the density of the material is less than 97% of the theoretical density, its wear resistance decreases significantly. The samples and manufacturing process conditions shown in FIG. 3 are as shown in the following table.

〔Effect of the invention〕

According to the present invention, unlike conventional high-C wear-resistant materials, the size of carbides in high-C materials can be reduced by 0.1.
We made the material as fine as ~5μm and made the distribution state homogeneous, and the oxygen content in the material was 3000ppm or less.
By setting the density to 97% or more of the theoretical density, high C-high Cr cast iron can fully satisfy the various properties required for wear-resistant materials, such as fine and homogeneous dispersion of carbides, prevention of carbide etc. from falling off, and toughening. Wear materials can be provided. Moreover, by adopting the plasma spraying method in a reduced pressure atmosphere for its manufacturing method,
By coating the material of the present invention only in parts where wear resistance is required, the toughness, strength,
It is possible to take advantage of the characteristics of the material constituting the base material of the component in terms of cost and the like. Alternatively, it can be formed as a component made only of the wear-resistant iron-based material of the present invention, and in this case, it becomes possible to manufacture thin-walled, complex-shaped components that are difficult to produce using sintering methods or the like.

[Brief explanation of drawings]

1, 2, and 3 are experimental results showing the relationship between carbide size, oxygen content, density, and wear amount, respectively. It is a micrograph showing the metal structure of a thermal sprayed wear-resistant iron-based material.

Claims (1)

[Claims] 1 Contains 1 to 6 wt% of C and 5 to 45 wt% of Cr,
The remainder is Fe, and precipitated carbides with a particle size of 0.1 to 5 μm in diameter are homogeneously dispersed, and the oxygen content is low.
A wear-resistant iron-based material characterized by having a thermally sprayed layer with a density of 3000 ppm or less and a density of 97% or more of the theoretical density. 2 Contains 1 to 6 wt% of C and 5 to 45 wt% of Cr,
The balance is Fe, and alloy powder with a particle size of 1 to 100 μm is used.
1 to 6 wt of C is applied to the surface of the base material by plasma spraying in a reduced pressure non-oxidizing atmosphere of 15 to 100 Torr.
%, contains 5 to 45 wt% Cr, and the balance is Fe,
A wear-resistant iron characterized by the fact that precipitated carbides with a particle size of 0.1 to 5 μm in diameter are homogeneously dispersed, forming a sprayed layer with an oxygen content of 3000 ppm or less and a density of 97% or more of the theoretical density. Manufacturing method of system materials. 3. The method for producing a wear-resistant iron-based material according to claim 2, wherein the base material is removed after the thermal spray layer is formed.