JPH03174981A - Production of wear resistant sliding member - Google Patents

Abstract

PURPOSE:To improve a sliding characteristic while lowering of sliding member strength being prevented by cladding metal powder formed of one at least of molybdenum, vanadium, chromium and tungsten having limited component composition and limited components and iron for a remaining component on iron-based base material. CONSTITUTION:The cladding metal powder in which carbon percentage content, silicon percentage content, manganese percentage content, phosphorus percentage content and sulfur percentage content are regulated to 3.0-3.9w%, <=3.5w%, <=1.5w%, <=0.1w% and <=0.05w%, respectively and which is formed of 5.0-10.0w% molybdenum, 0.3-5.0w% vanadium, 0.3-3.0w% chromium, 0.5-2.0w% tungsten as temper softening resistance elements with the remaining component formed of iron is molten by high output energy and then, solidified and clad on the iron-based base material, by which a sliding layer containing chilled structure is formed on the base material and then, nitrided. At this time, even when the temperature of the sliding layer becomes high and then, it is cooled and tempered, hardness of the sliding layer is not lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a wear-resistant sliding member in which a wear-resistant sliding layer is formed on an iron base material.

[Prior Art] Generally, in a method for manufacturing a sliding member that is required to have good sliding properties such as wear resistance and scuff resistance, for example, an apex seal for a rotary piston engine,
The base material (main body) is formed of a common iron-based material, and a sliding layer is formed by melting and overlaying an appropriate metal powder on this base material. A ferrous metal powder material containing various components that enhance dynamic properties is melted using high-power energy (e.g., plasma generated by arc discharge), and this molten metal material is used to melt the ferrous metal powder material, which contains components that enhance dynamic properties. It is cooled and solidified on the base material to form a chilled alloy layer (sliding layer) mainly consisting of del structure on the base material, and then quenched and low-temperature tempering is performed to form a sorbite structure on the base of the chilled alloy layer. A method of manufacturing a wear-resistant sliding member (apex seal) is known (for example, Japanese Patent Laid-Open No. 624590
(See Publication No. 1).

[Problem to be solved by the invention] In order to further improve the sliding properties (wear resistance, scuff resistance, etc.) of the sliding layer, a wear-resistant sliding material is provided in which a chill alloy layer is subjected to nitriding treatment. A method of manufacturing the member has been proposed.

In such nitriding treatment, the sliding member is heated at a high temperature (for example, 550 to 600°C) for a predetermined period of time in an appropriate nitrogen atmosphere.
) and then air-cooled to form a hard iron nitride near the surface of the chilled alloy layer, thereby improving the sliding properties of the chilled alloy layer.

However, when such a nitriding treatment is applied to a sliding member, although the hardness of the surface of the chilled alloy layer increases, the entire chilled alloy layer is heated to a high temperature (550 to 600°C) during the nitriding treatment, so the base of the del alloy layer ( The structure (other than near the surface) is decomposed by heat, that is, tempering occurs, and the hardness of the chilled alloy layer decreases, reducing the strength of the sliding member (e.g. flexural strength)
There are problems such as a decrease in

The present invention was made in view of the above-mentioned conventional problems, and consists of forming a chill alloy layer (sliding layer) by melting and overlaying metal powder on a base material, and applying nitriding treatment to the layer. In the method for manufacturing a wear-resistant sliding member, the sliding layer cb of the chilled alloy layer (sliding layer) can be increased, and the strength of the base of the del alloy layer or the sliding member can be increased by the nitriding treatment. It is an object of the present invention to provide a method for manufacturing a wear-resistant sliding member that can effectively prevent f1 from decreasing.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for manufacturing a wear-resistant sliding member in which a wear-resistant sliding layer is formed on an iron base material, comprising: ■ Carbon content is 30 to 3.9 weight percent, silicon content is 3.5 weight percent or less, manganese content is 1.5 weight percent or less, phosphorus content is 0.1 weight percent or less, and the sulfur content is 0.
05% by weight or less, and contains at least one element of molybdenum, vanadium, chromium, and tungsten as a tempering softening resistance element, and if these are included, the content is higher than that of molybdenum. 5.0 to 10.0 weight percent, 0.3 to 50 weight percent for vanadium, 0.3 to 3.0 weight percent for chromium, and 0.5 to 2 weight percent for tungsten. .0 weight percent, and the remaining component is iron. After melting this metal powder for overlay with high output energy, it is melted on the iron base material. Solidify base material 1-IA
1++t h+su-3-+,-) r M, M kl
- To provide a method for manufacturing a wear-resistant sliding member, characterized in that a sliding layer is formed that meets the sheep II/button trout book, and (2) the sliding layer is then subjected to a nitriding treatment.

The basis for the above configuration and preferred processing conditions will be shown below.

(1) Composition of metal powder for build-up ■ Carbon; 3.0 to 3.9% When the metal powder for build-up and the base material in the part that comes into contact with it are melted and then rapidly cooled and solidified, mainly A chilled alloy layer consisting of a chilled structure is formed. At this time, carbon combines with various metal elements to produce metal carbides, and in particular, combines with iron to produce hard cementite (Fe3G). Here, if the carbon content of the metal powder is less than 3.0wL%, cementite is not sufficiently generated, so the hardness of the chill alloy layer decreases and the wear resistance deteriorates. On the other hand, when the carbon content exceeds 3.9 vt%, residual graphite is generated in the chill structure, reducing the strength of the chill alloy layer and causing problems such as pitting.

■Silicon: 3.5 wt% Silicon is a chilling inhibiting element, so if it exceeds 3.5 wt%, a good chill structure will not be formed in the del alloy layer, and the wear resistance of the chill alloy layer will deteriorate. Become.

■Manganese: 1.5wt% or less Manganese is an element that improves the hardness of the base, but 1.
If it exceeds 5 wt%, it may cause quench cracking.

■Phosphorus: 0.1 wt% or less Phosphorus exists as an impurity. The phosphorus content of the metal powder is 0.
When it exceeds 1 wt%, steadite is generated in the chilled alloy layer, and the chilled alloy layer becomes brittle.

■Sulfur: 0.05 wt% or less Sulfur exists as an impurity like phosphorus. Considering mechanical properties, etc., the content is set to 0.05 wt% or less.

■Molybdenum; 5.0~IO, Owt% Molybdenum improves the tempering softening resistance of the base of the chilled alloy layer (the effect of suppressing softening due to tempering), and
It has the effect of preventing tempering brittleness (a decrease in impact value that occurs when tempered to a certain temperature). It also combines with carbon to produce molybdenum carbide. Here, if the molybdenum content of the metal powder is less than 5.0% by weight, the tempering softening resistance of the base of the chilled alloy layer cannot be sufficiently improved, and the hardness of the base decreases at around 550 to 600 °C. do. This reduces the strength and wear resistance of the Dell alloy layer. On the other hand, molybdenum content or IO
, Od%, molybdenum cannot be sufficiently dissolved into the structure of the matrix and remains as carbide, which may reduce the toughness of the chilled alloy layer.

(2) Vanadium: 03 to 50 wt% Vanadium is dissolved in the base, and when tempering is performed, it causes secondary hardening of the base and improves its hardness. It also combines with carbon to produce bananuno/carbide. Here, the vanadium content of the metal powder is 0,
If the amount is less than 3 wt%, the softening resistance of the base of the chill alloy layer cannot be sufficiently improved, and when tuftride treatment (limb nitriding treatment) is performed at 500 to 600°C, the hardness of the base decreases and the chill Reduces the strength of the alloy layer. On the other hand, if the vanadium content exceeds 5.0% by weight, vanadium carbide may crystallize in the matrix of the chilled alloy layer, which may reduce the toughness of the chilled alloy layer.

■Chromium: 0.3-3, Owt%Chromium has the effect of improving the tempering softening resistance of the base and preventing graphitization. 1. Chromium combines with carbon to form chromium carbide.

Here, the chromium content of the metal powder is 0.3wE%
If it is less than 50°C, the tempering softening resistance of the base of the chilled alloy layer cannot be sufficiently improved, and the hardness of the base decreases by heat treatment at 500 to 600°C. This reduces the strength and wear resistance of the chill alloy layer. On the other hand, the chromium content is 3. When Ovt% is exceeded, since chromium is a strong carbide-forming element, the whitening of the chilled alloy layer is promoted, resulting in a complete white iron structure. For this reason, cracks are likely to occur during cooling of the molten build-up.

■Tungsten: 0.5-2, Owt% Tungsten is dissolved in the matrix and has the effect of increasing the resistance to tempering and softening, and also combines with carbon to form carbide. Here, the tungsten content of the metal powder is 0, 5
When it is less than wt%, as in the case of molybdenum and vanadium, the softening resistance of the base of the chill alloy layer cannot be sufficiently improved, and the strength of the chill alloy layer decreases. on the other hand,
When the tungsten content exceeds 2.0% by weight, unmelted tungsten remains in the chilled structure, reducing the strength of the chilled alloy layer. Additionally, it combines with carbon to produce tungsten carbide, which may increase wear on the mating material.

Among the nine ingredients listed in ``Two Feet■~■, ■molybdenum, ■vanadium, ■chromium, and ■tungsten are elements that resist tempering and softening, and it is most preferable to add these four elements in sequence. Even if you do not add all of these elements, and even if you only add at least one of these elements, it will not be as good as adding all four of the above elements, but
Furthermore, the tempering softening resistance can be effectively increased.

(II) Particle size of metal powder for build-up The particle size of metal powder for build-up is preferably set in the range of 50 to 150 μm. If the particle size is less than 50t1m,
The metal powder supply device may become clogged, and a good chilled alloy layer (built-up layer) may not be obtained. On the other hand, if the particle size exceeds 150 μm, unmelted metal powder will remain in the chilled alloy layer, which is not preferable.

(III) Overlay treatment For the overlay treatment, it is preferable to use a commonly used plasma powder overlay welding device. The processing conditions were: current of 40 to 80 A, processing speed of 50 to 150 mm/min,
Preferably, the powder feed rate is 6-209/min.

If the current is less than 40A, the melting of the base material and metal powder will become unstable due to insufficient output, while if the current exceeds 8OA, the weld zone will become hot, resulting in what is called a state where hot water is too hot, resulting in blowholes and rough beats. It becomes easier to invite people.

(IV) Nitriding Treatment As the nitriding treatment, it is preferable to use salt bath nitriding or gas soft nitriding.

In the case of salt bath nitriding, it is preferable to use a cyanide compound such as NaCN or KCN as a salt bath agent, and to set the treatment temperature to 500 to 630° C. and the treatment time to 0.5 to 3 hours. If the treatment temperature is less than 500° C., the reaction is slow and a sufficient nitride layer cannot be obtained. On the other hand, if the processing temperature exceeds 630° C., a problem arises in that the hardness of the sliding member decreases.

Furthermore, if the treatment time is less than 0.5 hours, the formation of the nitride layer will be insufficient and the layer thickness will become thin. On the other hand, even if the treatment is carried out for more than 3 hours, the thickness of the nitride layer hardly increases and becomes saturated, which is economically disadvantageous.

According to the present invention, the metal powder for overlay contains molybdenum, vanadium, which is a tempering softening resistant element that prevents the chilled structure of the sliding layer (Dell alloy layer) from decomposing due to heat. Since at least one element of chromium and tungsten is added, even if the sliding layer (chill alloy layer) reaches a high temperature during the nitriding process and is subsequently cooled and tempered, the sliding layer will essentially remain intact. The hardness of R (chill alloy layer) does not decrease. Therefore, the sliding properties (wear resistance, scuff resistance, etc.) of the sliding layer can be sufficiently improved while effectively preventing a decrease in the strength of the sliding member as a whole.

[Example] Hereinafter, an example of the present invention will be specifically described in accordance with the flowchart shown in FIG. 1, taking as an example the case of manufacturing a test piece of a sliding member.

In step Sl, a base material of a test piece of a sliding member on which a chilled alloy layer (sliding layer) will be formed by melt build-up and metal powder for build-up are prepared. The base material is 4+nm long, t
'& 10 (1+m, height 10mm formed into a rectangular parallelepiped. Six test pieces were prepared, and the first to fifth test pieces were subjected to a build-up process using the method according to the present invention. For comparison, the sixth test piece was subjected to a build-up process using a conventional method that is not based on the present invention.

Table 1 shows the composition of the base material, and Table 2 shows the composition of the metal powder for build-up used in the build-up process for the first to sixth test beads.

In step S2, each base material of the first to sixth test pieces is subjected to a melt build-up process using the corresponding metal powder for build-up, and a chilled alloy layer is formed on the base material.

The overlay device is a 7If type which melts metal powder for overlay using plasma generated by arc discharge and solidifies it on the surface of the base material, so a description thereof will be omitted. The overlay processing conditions are as follows.

■Voltage 30V ■Ilt flow 60A ■Processing speed 80mm/min ■Plasma gas argon gas flow rate 3.5 (/min) ■Nold gas argon gas flow rate 2512/min ■Layer 11th 3~3.5 questions In step S3, chill In order to make the base of the alloy layer martensite and increase its strength, the first to sixth test pieces are subjected to a quenching treatment.

Here, each test piece was held at 850°C for 3 minutes and then cooled in oil.

In step S4, in order to prevent processing cracks in the first to sixth test pieces, each test piece is subjected to low-temperature annealing treatment. Here, each test piece was held at 400° C. for 2 hours and then air cooled.

In step S5, the first to sixth test pieces are machined and molded into a predetermined shape.

In step S6, in order to improve the sliding properties of the chilled alloy layer, the first to sixth test pieces are subjected to soft nitriding treatment using a salt coating. Here, each test piece was immersed in a salt bath made of a Noan compound at 580° C. for 2 hours, and then air-cooled.

Table 3 shows the results of measuring the hardness, bending strength, and abrasion resistance of the first to sixth test pieces manufactured in this way.

Here, the wear resistance is evaluated by processing each test piece (sliding member) into a pin shaped as shown in Figure 2, and sliding this pin against the circumferential surface of a rotating disk for a certain period of time. The so-called pin-wear method is used to measure the amount of pin wear.
I went up to the disc type wear test. The specifications and test conditions of the above disc are as follows.

■Disc shape: Disc-shaped surface with outer diameter 200++un and plate thickness 20mm; Hard chrome plating) (V880~920.Thickness 200μ ■Test conditions Lubrication: None Load: 5 kg (0, 5 kg/mm) Peripheral speed: 5
m/s (at the pin contact surface) Test time: 20 minutes In addition, in the bending test, each test piece was processed into the shape shown in Fig. 3, and then the test piece was cut into the shape shown in Fig. 4. The lower surface near both ends of the test piece was supported at two points, a downward force F was applied to the upper surface of the center part of the test piece, and this force was gradually increased to measure the strength of the force when the test piece broke. .

As is clear from Table 3, the first example showing the embodiment of the present invention is
~The fifth test piece showed significantly improved hardness after overlaying, hardness after nitriding, bending strength, and abrasion resistance compared to the sixth test piece produced using the conventional method. There is.

As described above, according to the present invention, it is possible to improve the sliding properties such as wear resistance and scuff resistance while increasing the strength of the chilled alloy layer of the sliding member.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the first step in manufacturing a test piece of sliding portion 10 using the manufacturing method according to the present invention. FIG. 2 is a perspective explanatory view of a pin subjected to a pin-disk type wear test. FIG. 3 is a perspective explanatory view of a test piece subjected to a bending test. FIG. 4 is a diagram showing how to apply a load in a bending test.

Claims (1)

[Claims] (1) A method for manufacturing a wear-resistant sliding member in which a wear-resistant sliding layer is formed on an iron-based base material, the method comprising: [1] having a carbon content of 3.0 to 3.9 weight percent; To,
The silicon content is 3.5% by weight or less, the manganese content is 1.5% by weight or less, and the phosphorus content is 0.1% by weight.
weight percent or less, and the sulfur content is adjusted to 0.05 weight percent or less, and contains at least one element of molybdenum, vanadium, chromium, and tungsten as a tempering softening resistance element, and when these are included. The content of molybdenum is 5.0 to 10.0% by weight, vanadium is 0.3 to 5.0% by weight, and chromium is 0.3 to 3.0% by weight. Prepare a metal powder for build-up which is adjusted to 0 weight percent, and 0.5 to 2.0 weight percent for tungsten, and the remaining component is iron, [2] This metal powder for build-up After melting the powder with high output energy, it is solidified on an iron base material and built up on the base material to form a sliding layer containing a chilled structure on the base material, [3] After this sliding A method for manufacturing a wear-resistant sliding member, characterized in that the dynamic layer is subjected to nitriding treatment.