JPH10147855A - Production of high lubricity nitriding treated ferrous structural parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce high lubricity nitriding treated ferrous structural parts in which the lubricity of the surface is improved to prevent wear in the initial stage and capable of attaining the prolonged service life by subjecting ferrous structural parts to nitriding treatment and impregnating lubricating oil into a porous layer formed on a compound layer precipitated on the surface. SOLUTION: A ferrous structural parts such as SNC631 is subjected to nitriding treatment at about 570 deg.C in a gaseous mixture, e.g. of NH3 and C3 H8 . In this way, on the surface of the ferrous structural parts, a compound layer 1 composed of ε phases 2 and γ<1> phases 3 is formed, and a porous layer 4 is formed on the layer. At this time, it is preferable that the porous layer 4 is formed by 1 to 20μm thickness and by 10 to 50% to the thickness of the compound layer 1. Next, this nitriding treated part is charged to a vacuum furnace 6, air in the porous layer 4 is removed, and after that, it is impregnated with lubricating oil in a vacuum. In the case this lubricating oil has high viscosity, a heating impregnating method can be adopted, or a vacuum impregnating method can jointly be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a highly lubricated, nitriding-treated iron-based mechanical component in which a lubricating oil is impregnated during nitriding to extend the life.

[0002]

2. Description of the Related Art Conventionally, there are various nitriding treatment methods. Among them, gas nitrocarburizing treatment is a method of nitriding iron nitride or the like by heating steel in a mixed gas of ammonia and hydrocarbon to diffuse nitrogen. Precipitates substances, forms a high-hardness compound layer on the surface, imparts wear resistance, corrosion resistance, and heat resistance. Have been. In order to improve the lubricity of the surface, there is a sulfide-nitriding method in which sulfide is added to a salt bath to precipitate iron sulfide on the surface of the compound layer. In addition, a technique has been established in which a vapor film treatment is performed to improve their corrosion resistance, and an oxide is formed on the surface. However, since the compound layer in the high hardness region is as shallow as several μm to several tens μm and the internal diffusion layer has low hardness, when the compound layer on the surface disappears, abrasion proceeds at a stretch. Therefore, lubricating oil is indispensable on the sliding surface, and it is necessary to supply the lubricating oil to the entire sliding surface.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a high lubrication nitrided iron-based mechanical component which prevents early wear.

[0004]

SUMMARY OF THE INVENTION The present invention provides an iron-based mechanical component which is usually subjected to a nitriding treatment and then impregnated with a lubricating oil in a porous layer formed on a surface compound layer. This makes it possible to impart high lubricity.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] FIGS. 1 and 2 are schematic views showing a method of manufacturing an iron-based mechanical component subjected to a gas soft nitriding treatment in the present invention. The material of the iron-based mechanical component uses SNC631 to promote nitriding and to secure the internal strength. The processing conditions are a mixed gas of ammonia and propane at a mixing ratio of 1: 1, and the processing temperature and time are 570. C. and 5 hours. As a result, a compound layer 1 of about 20 μm is formed on the surface as shown in FIG. This compound layer 1 has Fe _2-3 N called ε phase 2 and Fe ₄ N iron nitride and FeC, CrN, CrC called γ 'phase 3 in the outermost layer.
Etc. and a mixture of carbides and nitrides.
On the surface of the ε-phase 2, Fe containing a porous layer 4 of 5 μm
O and FeC-based iron compounds are formed. In the present invention, in order to impregnate the porous layer 4 with the lubricating oil 5, a vacuum impregnation process is performed in the vacuum furnace 6. The degree of vacuum is 667 Torr
The processing time was 20 minutes at room temperature. As a result, as shown in FIG. 2, the lubricating oil 5 forcibly enters the porous layer 4 from which the air has been removed, and the lubricating oil impregnation can be performed.
However, since lubricating agents such as grease having a high viscosity are difficult to be vacuum impregnated at room temperature, an appropriate heating temperature must be set according to grease characteristics.

Here, the lubricating oil impregnation method according to claim 3 is specified because the pores of the outermost layer obtained by nitriding treatment are small, so that when the lubricating oil is impregnated at normal temperature and atmospheric pressure, it enters the pores. This is because it is difficult to sufficiently infiltrate the lubricating oil 5 due to the surface tension of the air, and uniform lubricity cannot be imparted to the surface.

[Embodiment 2] Next, the present invention will be described with reference to FIGS. 1 and 2 in which the present invention has a layer form similar to that of a gas nitrocarburized product by taking nitrosulphurizing as an example. Nitrogen, carbon, and sulfide are added to sulfides in an acid-based salt bath to allow S to penetrate into a high-hardness compound layer obtained by nitridation.
This is a process in which solid lubricity is imparted and wear resistance is improved as compared with gas nitrocarburizing. As the processing conditions, SCM435 was used as the material to promote nitriding, and the processing temperature and time in a salt bath were 565 ° C. and 1.5 hours. Although the thickness of the compound layer is about 20 μm, a very porous layer 4 is formed on the outermost layer of about 5 μm as compared with the gas nitrocarburizing treatment. This is F
This is a layer in which e ₃ N and FeS are mixed, and the hardness is low because it is porous. However, the presence of FeS improves the self-lubricating property. In the present invention, since the nitrosulphurizing treatment using a salt bath is more porous than the gas nitrocarburizing treatment, the lubricating oil 5 is heated in the atmosphere to lower the viscosity in order to impregnate the porous layer 4 with the lubricating oil 5. Impregnation treatment. Processing condition is lubricating oil 5
At a heating temperature of 120 ° C. and a treatment time of 30 minutes. As a result, impregnation equivalent to the gas nitrocarburizing treatment of Example 1 can be performed as shown in FIG.

[0008] In the present invention, the porous layer 4 is the compound layer 1.
The reason why the thickness of the compound layer is 20%
μm, the porous layer 4 has a thickness of 2 to 10 μm,
If it is less than 5, even if the lubricating oil 5 is impregnated, the lubricating effect cannot be secured because the content is very small. The porous layer 4 is 1
When the thickness exceeds 0 μm, the lubricating effect is sufficient, but the notch sensitivity of the surface layer of the compound layer having high hardness and brittleness is increased, which causes a decrease in mechanical properties. Further, the present invention is applicable to all iron-based mechanical parts that can be nitrided.

[0009]

The method of the present invention for producing a highly lubricated nitrided iron-based component is a conventional compounding technique, and can be processed in the same process as the conventional treatment. Further, it is possible to prevent early wear of the iron-based mechanism parts.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an outline of a production method of the present invention.

FIG. 2 is a schematic cross-sectional view of a highly lubricated nitriding material obtained by the present invention.

[Explanation of symbols]

1 is a compound layer, 2 is an ε phase, 3 is a γ 'phase, 4 is a porous layer,
5 is a lubricating oil.

Claims (3)

[Claims] 1. A highly lubricated nitriding iron-based mechanism characterized by impregnating a porous layer formed on the surface of a compound layer with a lubricating oil to improve lubricity when nitriding the iron-based mechanism part. The method of manufacturing the part. 2. The method according to claim 1, wherein the thickness of the porous layer is 1 to 20 μm.
2. The method according to claim 1, wherein the thickness of the compound layer is 10 to 50% of the thickness of the compound layer. 3. The method according to claim 1, wherein the impregnation is performed by a vacuum impregnation method or a heat impregnation method.