JPH04128302A - Fe-base alloy powder and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] This invention provides an Fe-based alloy suitable for use as a raw material powder when producing a sintered body that requires wear resistance, particularly by powder metallurgy. This invention relates to powders and their manufacturing methods.

[Conventional technology]

Conventionally, as a method for producing a sintered body that requires wear resistance using a powder metallurgy method, for example, Fe is used as a raw material powder.
powder or Fe-based alloy powder, and Y.

Using one or more oxide hard powders of oxides such as A, Q, Zr, and Mg, these raw material powders are blended into a predetermined composition, and all under normal conditions.
A method for producing an Fe-based alloy sintered body in which fine oxide hard particles are uniformly distributed on a base of Fe or Fe-based alloy by mixing, press-forming into a green compact, and sintering the green compact. It has been known.

[Invention or problem to be solved]

However, in the conventional wear-resistant Fe-based alloy sintered body described above, the hard oxide particles tend to fall off during practical use because the adhesion of the hard oxide particles to the Fe or Fe-based alloy substrate is insufficient. As a result, there are problems in that the wear progresses quickly and the fallen oxide hard particles damage the mating material.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors focused on the raw material powder used for manufacturing the sintered body in order to develop a sintered body with excellent wear resistance, and as a result of their research, they found that oxidizing elements , that is, an element that forms a solid solution with Fe and has a greater affinity for oxygen than Fe, preferably AΩ, Si
, Ti, V, Cr, W, Be, Th.

1 to 3 of one or more of Y, and Zr
Contains 0% by weight, and further contains C as an alloy component as necessary.
When an Fe-based alloy powder material containing O and/or Ni is subjected to oxidation treatment under the conditions of holding at a temperature of 1000 to 1300°C for a predetermined time in an oxidizing atmosphere, preferably in a powder fluidized state, On a base material mainly composed of iron oxide, in every cross section passing through the center of the powder, between the center of the powder and the periphery of the powder, aggregates mainly composed of fine Fe and composite oxides of the above oxidizing elements are formed. An oxide powder containing an annular layer is formed, and this oxide powder is then subjected to a reduction treatment under the following conditions: maintained at a temperature of 200 to 500°C for a predetermined time in a reducing atmosphere. Then, the main iron oxide that made up the matrix in the oxide powder is reduced, and at the same time, the composite oxide of fine Fe and the oxidizing element that also made up the annular layer also becomes the oxide of the oxidizing element. As a result, fine particles are formed between the powder center and the powder periphery in every cross section passing through the powder center on the substrate made of Fe or Fe-based alloy. A Fe-based alloy powder is formed in which an annular layer composed of aggregates of hard oxide particles exists, but this Fe-based alloy powder is used as a raw material powder to produce a sintered body. In this case, the hard oxide particles in the sintered body are formed by the oxidation-reduction reaction of the oxidizing element contained as an alloy component as described above, so their adhesion to the substrate is extremely high and they do not fall off during practical use. The sintered body exhibits excellent abrasion resistance as the The research results showed that it is possible to manufacture sintered bodies with high strength because the sintered body is not damaged.

This invention was made based on the above research results. In addition, fine oxide hard particles, namely F
Fine oxide hard particles composed of an oxide of an oxidizing element that forms a solid solution with Fe and has a greater affinity with oxygen than Fe, preferably AΩ.

St, Ti, V, Cr, W, Be, T
Fe-based alloy powder in which an annular layer consisting of an aggregate of fine oxide hard particles composed of one or more of the oxides of ``h'', ``Y'', and ``Z'' exists.

(2) An oxidizing element, that is, an element that forms a solid solution with Fe and has a greater affinity for oxygen than Fe, preferably AN,
St, Ti, V, Cr, W, Be.

A Fe-based alloy powder material containing 1 to 30% by weight of an oxidizing element consisting of one or more of Th, Y, and Zr is maintained at a temperature of 1000 to 1300°C for a predetermined time in an oxidizing atmosphere. Under the following conditions, preferably in a powder fluidized state, oxidation treatment is applied to the substrate mainly consisting of iron oxide, so that fine particles are formed between the powder center and the powder periphery in every cross section passing through the powder center. Form an oxide powder in which an annular layer composed of aggregates of a composite oxide of Fe and the above oxidizing element exists, and then heat the oxide powder to a temperature of 200 to 500°C in a reducing atmosphere. Reduction treatment is carried out under the conditions of holding for a predetermined time to reduce the matrix mainly composed of iron oxide to Fe or Fe-based alloy, and at the same time converting the annular layer composed of aggregates of the above composite oxide to 1. A method for producing Fe-based alloy powder, which is transformed into an annular layer composed of fine oxide hard particles made of an oxide of a sexually active element.

It has the following characteristics.

Next, the reason why the manufacturing conditions are limited as described above in the method for manufacturing Fe-based alloy powder of the present invention will be explained.

(a) Content of oxidizing elements The oxidizing elements combine with oxygen to form hard oxide particles that are layered inside the powder and aggregated and distributed in a shell shape, without impairing the sinterability of the powder. , and has the effect of significantly improving the wear resistance of a sintered body manufactured using this as a raw material powder, but if its content is less than 1% by weight, the formation rate of oxide hard particles is insufficient and the desired On the other hand, if the content exceeds 30% by weight, the proportion of hard oxide particles formed becomes too large, and coarsening of these particles is unavoidable. Since a sintered body produced using this material becomes aggressive toward others, its content was determined to be 1 to 30% by weight.

(b) Oxidation treatment temperature If the temperature is less than 1000°C, the composite oxide of Fe and oxidizing elements will not form a ring-shaped agglomeration sufficiently, and if the temperature exceeds 1300°C, the powders will not commotion even if they are fluidized. The temperature is set at 1000 to 1
The temperature was set at 300°C.

(c) Reduction treatment temperature If the temperature is less than 200°C, it will take a long time to reduce the oxide powder, which is undesirable in actual operation;
If the temperature exceeds 0°C, the hard oxide particles undergo a reduction reaction and become unusable, so the temperature was set at 200 to 500°C.

〔Example〕

Next, the Fe-based alloy powder of the present invention and the method for producing the same will be specifically explained with reference to Examples.

Using atomized Fe-based alloy powder materials having the average particle diameter and composition shown in Table 1, these F
Methods 1 to IO of the present invention were carried out by subjecting the e-based alloy powder material to oxidation treatment and reduction treatment under the conditions shown in Table 1 to produce Fe-based alloy powders 1 to 1O of the present invention, respectively.

Next, the resulting Fe-based alloy powders 1 to 1 of the present invention
0, its cross-sectional structure was examined using a metallurgical microscope (magnification: 10
00 times), and measured the particle size on an arbitrary straight line passing through the center of the cross section of each of the 30 powders, as well as the outer diameter and inner diameter of the annular layer, calculated the average value of these, and It is shown in Table 2.

Furthermore, the resulting Fe-based alloy powders 1 to 1 of the present invention
0, average particle size: 5tm AI! 20 a powder, same 5
- MgO powder from the same 3rd warehouse and Y20s powder from the same 3rd warehouse were used as the raw material powder for forming the hard phase of the sintered body.
E powder was also used as a raw material powder, and these raw material powders were blended into the composition shown in Table 3, mixed 24 hours a day in a ball mill, dried, and then molded into a green compact at a pressure of 5 ton/cd. This green compact was sintered in a hydrogen atmosphere at a temperature of 1,350°C for 30 minutes, and Fe-based alloy sintered bodies (hereinafter referred to as sintered bodies of the present invention) each using Fe-based alloy powders 1 to 1O of the present invention were sintered in a hydrogen atmosphere. body) 1~1O and conventional sintered body 1~
3 were produced respectively.

Table 2 For the purpose of evaluating the strength of these various sintered bodies, tensile strength was measured and an abrasion test was conducted.

The wear test was carried out on a cast iron (FCI) with dimensions of outer diameter: 40 mm x inner diameter: 30 mm x width: 15 mm with the rotation axis horizontal.
2) A test piece cut out from the sintered body into a size of 8 mm x 8 m + * x 35 mm is brought into horizontal contact with the above heat-treated ring (hardness: HRC50), and in this state, a load of 5 kg is applied vertically to the test piece. The ring is 1.2
The test piece was rotated at a circumferential speed of m/sec, and the maximum wear depth of the test piece was measured after 10 minutes.

These results are shown in Table 3.

〔Effect of the invention〕

From the results shown in Tables 1 to 3, according to methods 1 to IO of the present invention, an annular layer composed of aggregates of fine oxide hard particles formed by an oxidation-reduction reaction is formed inside the powder. The existing Fe-based alloy powder can be manufactured, and the resulting Fe-based alloy powders 1 to 10 all inhibit sinterability when a sintered body is manufactured using this as a raw material powder. Since the hard oxide particles are sealed inside the powder, good sinterability can be ensured, making it possible to manufacture a high-strength sintered body. When a sintered body manufactured using powders 1 to 1O is placed in an abrasion environment, the annular layer of hard oxide particles appearing on the worn surface acts as one hard particle, that is, the annular layer Because it acts as a hard particle with a size equivalent to the outer diameter of It is clear that in all of the sintered bodies 1 to 3, since the hard oxide particles have poor adhesion to the base material, they tend to fall off easily and wear progresses quickly.

As described above, according to the method of the present invention, it is possible to produce Fe-based alloy powder in which fine oxide hard particles form a layer inside the powder and are confined in a shell shape, and therefore, the produced Fe-based alloy powder has extremely good sinterability, and sintered bodies manufactured using it have high strength. Because it is formed by a reaction, it has high adhesion to the Fe or Fe-based alloy substrate, and in addition, in the sintered body, it acts as hard particles with dimensions equal to the outer diameter of the annular layer, making it an excellent material. In addition to exhibiting wear resistance, the center of the annular layer suppresses the aggressiveness of the opponent, and these characteristics are required for various drives such as sintered bearings, block rings, rocker arm tips, brake butts, and clutch plates. It brings about industrially useful effects, such as exhibiting excellent performance when used as a raw material powder for manufacturing structural members of devices.

Claims (7)

[Claims] (1) On a substrate made of Fe or Fe-based alloy, there is an annular layer composed of aggregates of fine oxide hard particles between the powder center and the powder periphery in every cross section passing through the powder center. An Fe-based alloy powder characterized in that it exists. (2) the oxide hard particles form a solid solution with Fe;
The Fe-based alloy powder according to claim 1, wherein the Fe-based alloy powder is made of an oxide of an oxidizing element that has a greater affinity with oxygen than Fe. (3) The oxide hard particles include Al, Si, Ti, V,
The Fe-based alloy powder according to claim (1), characterized by comprising one or more of oxides of Cr, W, Be, Th, Y, and Zr. (4) An Fe-based alloy powder material containing 1 to 30% by weight of oxidizing elements is subjected to oxidation treatment under the conditions of holding at a temperature of 1000 to 1300°C for a predetermined time in an oxidizing atmosphere, so that the main component is iron oxide. In every cross section passing through the center of the powder, between the center of the powder and the periphery of the powder, there is an annular layer composed of aggregates mainly composed of fine Fe and composite oxides of the above-mentioned oxidizing elements. The oxide powder is then heated to 200 to 500 ml in a reducing atmosphere.
Reduction treatment is performed under the conditions of holding at a temperature of ℃ for a predetermined time,
While reducing the matrix mainly composed of iron oxide to Fe or Fe-based alloy, the annular layer composed of aggregates mainly composed of the above-mentioned composite oxide is converted into a fine oxide mainly composed of oxides of the above-mentioned oxidizing elements. A method for producing Fe-based alloy powder, characterized by forming an annular layer composed of hard particles. (5) Production of the Fe-based alloy powder according to claim (4), wherein the oxidizing element is an element that forms a solid solution with Fe and has a greater affinity for oxygen than Fe. Method. (6) The oxidizing element is Al, Si, Ti, V, Cr
, W, Be, Th, Y, and Zr. , W, Be, Th, Y, and Zr. (7) The method for producing Fe-based alloy powder according to claim (4), wherein the oxidation treatment is performed while fluidizing the Fe-based alloy powder material.