JPH11131109A - Manufacturing method of wear-resistant parts - Google Patents

Abstract

(57) [Summary] When densifying powders or compacts, the atmosphere during heating and processing is set to nitrogen gas or air, and the powders are nitrided or oxidized to form powders or compacts. By utilizing the plastic deformation of the ingot, which is in contact with the ingot, at high temperature, it has a sintered part with a high compaction density to maximize the properties of the powder, and joins the base and the sintered part High strength parts can be manufactured at low cost. PROBLEM TO BE SOLVED: To efficiently and inexpensively produce a composite part having excellent wear resistance has been difficult by a conventional method. SOLUTION: A powder or a green compact and an ingot as a base material are mixed in a nitrogen gas atmosphere or the atmosphere by the melting point of a high alloy powder.
Heat to a temperature of 0.5 times or more in a short time without lowering the production efficiency, and simultaneously process (forging, pressing, rolling, extruding) to a shape close to the final part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite product comprising an ingot and a powder sintered part. When heating at a high temperature, the powder is heated in a nitrogen atmosphere or the atmosphere to nitride or oxidize the powder part. The powder and green compact are consolidated by utilizing the plastic deformation at high temperature of the ingot material used as the base, and the base and the powder are joined together. The present invention relates to a method for producing a composite characteristic component having excellent wear resistance, which can improve the wear resistance and reduce the production cost by reducing the amount of powder used and the number of steps.

[0002]

2. Description of the Related Art For the purpose of reducing the cost of wear-resistant parts, it is necessary to manufacture composite parts using inexpensive ingots as base materials by using powders having excellent wear resistance only in areas where wear resistance is required. Is being done. Here, hot isostatic pressing is applied to the sintering of the powder. For example, there are the following methods for producing a composite characteristic component in which a powder sintered body is arranged outside a cylindrical component by this method.

[0003] First, an ingot serving as a base is mounted in a metal container, and a high alloy powder is filled between the ingot and the metal container and canning is performed. This is sintered and diffusion-bonded by hot isostatic pressing. However, if the base is brought closer to the shape of the final component in advance, the process for removing the metal container used for canning becomes complicated. Further, when the substrate has a simple shape, the number of steps such as rolling, forging, and extrusion for increasing the final component shape is increased. Therefore, the production of the composite characteristic component using the hot isostatic pressing process requires a large amount of cost, and therefore, the components to which the process is applied are limited.

[0004] On the other hand, hot pressing, which is one of the prior arts, is also applied only to parts limited to special applications. This is because hot pressing involves sintering at a high temperature and for a long time in an inert gas device, which is not suitable for mass production of general-purpose parts because the equipment cost is high and the product output per unit time is low. Is one of the reasons that the range of application is narrow.

Further, as a method of plastically deforming an ingot material serving as a substrate, a method in which the ingot material and powder are pressed at room temperature and sintered at a high temperature has been devised. However, it is known that the compaction density after processing is not sufficiently high, and that the bonding strength between the powder and the ingot is low.

[0006] On the other hand, a high-alloy powder is filled in a metal tube of an ingot material serving as a base, and the mouth of the metal tube is sealed by welding.
A method of extruding after heating at a high temperature of 1000 ° C. or more for about 1 hour, further rolling at a temperature of 1000 ° C. or more, and then performing a softening heat treatment to process into a final part shape and refining is disclosed in JP-B-4-47022. Have been. According to this method, it is possible to manufacture a composite characteristic part, but the heating time before extrusion is long, and a plurality of steps are added until the final part shape is processed, so that the productivity is low. There is.

[0007]

As explained in the prior art, it has been difficult to efficiently produce a composite part having excellent wear resistance by the conventional method. The purpose of the present invention is
It is an object of the present invention to provide a method for efficiently and inexpensively manufacturing a composite part having excellent wear resistance due to a densified powder sintered part and high bonding strength between the powder sintered part and an ingot.

[0008]

The present invention utilizes plastic deformation at a high temperature of an ingot as a base material when densifying a powder or a green compact. That is, the powder or the green compact and the ingot material serving as the base are divided by the melting point of the powder × 0.5.
The powder was heated to twice or more the temperature in a short time without lowering the production efficiency, and in that case, the powder was heated in a nitrogen atmosphere or the air to perform nitriding or oxidation. Further, a step of performing sintering and diffusion bonding while causing plastic deformation of the substrate in a temperature range of the melting point of the powder × 0.7 or more according to the state of powder compaction is added. Then, at the time of processing, the powder portion and the base are simultaneously processed (forged, pressed, rolled, extruded) into a shape close to the final part without going through a sintering process or a hot isostatic pressing process, so that the powder or The present invention has been made by finding that a green compact can be uniformly densified, and a composite characteristic part having high bonding strength between a powder sintered part and a substrate and excellent wear resistance of the powder sintered part can be manufactured.

According to the present invention, the density of the powder sintered part of the component processed in this way is 98% or more. The joint strength between the powder sintered part of these composite characteristic parts and the base ingot is determined by the plastic deformation of the ingot and the mechanical caulking action due to the powder penetrating into the ingot, and the alloy elements in the powder and the ingot. Is significantly higher than the case where the ingot is joined to the powder without plastically deforming it, so that it can be applied to the production of various parts.

Further, by heating the component thus processed in a sintering furnace, it becomes possible to manufacture a composite characteristic component having a sintered portion having a sintered density of 99% or more. Alternatively, by subjecting the processed component to the hydrostatic pressure treatment, it becomes possible to manufacture a composite characteristic component having a sintered portion having a substantially true sintered density.

Here, the powder is desirably cold tool steel containing carbonitride, high-speed steel, or the like. It goes without saying that the type of powder is not limited as long as the powder has higher wear resistance than the ingot material of the substrate. Nor. In addition, since the wear resistance after sintering is improved by nitriding or oxidizing the powder sintered part, even if the amount of alloying elements used in the conventional high alloy powder is reduced, the wear resistance is reduced. Can be maintained. It is desirable that the powder has an average particle diameter of 100 μm or less, but even if it is larger, it can be used by adjusting the heating temperature. The state of the powder in contact with the substrate may be either powder or green compact. The base ingot is preferably an Fe-based material, but Ni-based or Ti-based materials can also be used in consideration of heat resistance, corrosion resistance, and weight reduction of manufactured parts.

The heating temperature must be at least 0.5 times the melting point of the powder. At a lower temperature, the deformation resistance of the powder itself is high and the amount of plastic deformation is small, so that the contact area between the powders during processing is not large, so that sintering does not proceed sufficiently, and , The deformation resistance of the substrate cannot be increased to the final part shape because the deformation resistance does not decrease, and efficient production becomes difficult because the life of the mold is reduced.

If the heating time up to the heating temperature exceeds 600 seconds, the production efficiency of the parts is remarkably reduced.
It is desirable to heat within 00 seconds. Low heating method
High frequency induction heating methods are suitable.

At this time, it is necessary to set the heating atmosphere to nitrogen or air. Here, when heated in a vacuum, the powder is not nitrided or oxidized, so that desired abrasion resistance cannot be obtained. In addition, in Ar gas or He gas, a large amount of closed pores are formed on the free surface side of the powder by these gases, and there is a problem that the surface of the sintered part has low hardness.

The working method is desirably the final part shape by forging or a shape similar thereto, but rolling, extrusion, or wire drawing may be used. At this time, processing strain is applied so that at least the powder or the green compact has a true density. After performing these processes, again, the melting point of the powder ×
When plastic deformation occurs in the substrate in a temperature range of 0.7 or more,
The powder sintering part and the joint part can be strengthened respectively. However, when processing is performed by heating to a temperature lower than the melting point of the powder × 0.7, the effect of the repetitive processing is not recognized.

[0016] The processed product having the final part shape formed as described above is subjected to a necessary heat treatment, and the processed product conforming to the final part shape is subjected to heat treatment after processing into the final part shape by cutting or grinding. Or after the necessary heat treatment, it can be processed into the final part shape by cutting or grinding. Here, the heat treatment includes quenching, tempering, annealing, sintering, HIP, and the like, and these may be combined.

[0017]

Example 1 Hot work tool steel (0.4% C-1.1% Si-
A base composed of 5.2% Cr-1.2% Mo-0.55% V) and a high-speed green compact (1.3% C-4.1% Cr-2.
0% Mo After being installed as shown in (1), carbon steel heated to 1200 ° C. was inserted into the hole of the base, and the temperature of the base reached 1000 ° C. (melting point ratio 0.74) in a nitrogen atmosphere (carbon steel). After 90 seconds have passed, the base was plastically deformed by press working in a closed mold.
The substrate was heated again to 0 ° C. (melting point ratio: 0.89) to plastically deform the substrate again to consolidate the green compact. This complex is
The high-speed steel was sintered by holding at 80 ° C. and 1000 kg / cm ² for 1 hour. Furthermore, quenching from 1150 ° C to 550
After tempering at ℃, a cutting tip was produced by grinding.

[0018]

Comparative Example 1 Hot work tool steel (0.4% C-1.1% Si-
A base composed of 5.2% Cr-1.2% Mo-0.55% V) and a high-speed green compact (1.7% C-4.1% Cr-2.
0% Mo-14.8% W-5.1% V-7.9% Co)
Is installed as shown in FIG.
Is inserted into the hole of the base, and when the temperature of the base reaches 500 ° C. (melting point ratio: 0.37) (30 seconds after the insertion of the carbon steel, pressing is performed in a closed mold). The substrate was plastically deformed, and the whole was heated to 1200 ° C. (melting point ratio: 0.89) to plastically deform the substrate again to consolidate the green compact. This complex was
The steel was sintered at a temperature of 1000 ° C. and 1000 kg / cm ² for 1 hour. Furthermore, after quenching from 1150 ° C. and tempering to 550 ° C., a cutting tip was produced by grinding.

[0019]

COMPARATIVE EXAMPLE 2 Table 1 shows the results of intermittent cutting using the tips shown in Example 1 and Comparative Example 1 and a general-purpose HSS tip: SKH51 (Comparative Example 2). It is clear that the examples have better characteristics than the comparative example of the slip despite the small amount of the alloy element used.

[0020]

[Table-1] Work material: SCM440 (hardness: 280 HV), work material shape: φ90 mm, 7 grooves of 10 mm width Cutting speed: 150 m / min, depth of cut: 1.5 mm,
Feed: 0.3 mm / rev Life criterion: Cutting time (min) until flank wear reaches 0.2 mm

[0021]

Example 2 A base made of a Ti alloy (6.2% Al-4.1% V-balance Ti) and a cold tool steel powder (2.8% C-
17% Cr-1.9% Mo-0.3% V, melting point: 127
0 ° C) The vicinity of the filling was heated to 1200 ° C. (melting point ratio 0.94) in 20 seconds by high-frequency induction heating, then pressed to deform the base body plastically, heated again to 1200 ° C., pressed, and subjected to cold tool steel. The powder was compacted. Then 120
Tapping was performed by quenching from 0 ° C. and tempering at 580 ° C., and grinding the sintered portion.

[0022]

Comparative Example 3 A base made of a Ti alloy (6.2% Ai-4.1% V-balance Ti) and a cold tool steel powder (2.8% C-
17% Cr-2.9% Mo-0.3% V) was installed as shown in FIG. ), The base was plastically deformed by press working, and the base was heated again to 1200 ° C., followed by press working to consolidate the cold tool steel powder. Then, quenching from 1200 ° C, 5
After tempering at 80 ° C., the sintered portion was ground to produce a tappet.

[0023]

Comparative Example 4 The tappets shown in Example 2 and Comparative Example 3
General-purpose sintered high-speed steel (2.1% C-4.0% Cr-5.9)
% Mo-14.0% W-5.5% V-11.9% Co)
The carburized case hardened steel (0.2% C-1.1% Cr-0.15%
The results of an abrasion test performed using a tappet brazed to Mo) (Comparative Example 4) are shown in Table-2. In addition, the roughness on the tappet crown surface was within 0.3a.

[0024]

[Table-2] Number of cam contacts: 5000 rpm, load surface pressure: 1.5 GP
a, Endurance time: 150 hours

[0025]

Embodiment 3 Ni alloy (18.2% Cr-2.9% Mo)
-52% Ni- balance Fe and high-speed green compact (1.3% C-4.1% Cr-5.0% Mo-2.3%)
W-1. After the installation, the substrate was heated to 1200 ° C. (melting point ratio: 0.88) in a nitrogen atmosphere by high-frequency induction heating in 10 seconds, and subjected to press working to plastically deform the base, thereby consolidating the HSS powder. Then, immediately after reheating to 1220 ° C. (melting point ratio: 0.90) in 5 seconds by high-frequency induction heating, the base was plastically deformed by press working to increase the compaction density of the HSS powder. Subsequently, quenching was performed from 1200 ° C. and tempered at 540 ° C., and the sintered portion was ground to obtain a cylindrical radial bearing shape.

[0026]

Comparative Example 5 Ni alloy (18.2% Cr-2.9% Mo)
-52% Ni- balance Fe and high-speed green compact (1.7% C-4.1% Cr-2.0% Mo-14.8)
% W-5.1% V-7.9% Co) as shown in FIG. 3 and then high-frequency induction heating in vacuum for 500 seconds in 10 seconds.
After heating to 0 ° C. (melting point ratio: 0.37), the base was plastically deformed by press working to consolidate the HSS powder. Then, immediately after reheating to 1200 ° C. (melting point ratio: 0.88) in 20 seconds by high-frequency induction heating, the substrate was plastically deformed by press working to increase the compaction density of the high-speed powder. Subsequently, it was quenched from 1200 ° C. and tempered at 540 ° C., and the sintered portion was ground to obtain a cylindrical radial bearing shape.

[0027]

Comparative Example 6 The radial bearing test pieces shown in Example 3 and Comparative Example 5 and M50 (0.78% C-0.3% Si-4.
The results of a rolling fatigue test performed using a radial bearing (Comparative 6) made of 1% Cr-4.2% Mo1.0% V) are shown in Table-3.

[0028]

[Table-3] Surface pressure: 5.2 GPa, number of revolutions: 1800 rpm, lubricating oil: automatic fluid, oil temperature: 180 ° C. Life judgment: number of repetitions leading to the establishment of 10% cumulative damage

[0029]

Embodiment 4 Carbon steel (0.2% C-0.25% Si-
0.5% Mn- balance Fe and a high speed green compact (1.5% C-0.2% Si-4.1% Cr-2.5%)
Mo-1. After installation, the vicinity of the powder filling was heated to 1200 ° C. (melting point ratio 0.89) in the atmosphere by high frequency induction heating in 90 seconds.
The base was plastically deformed by press working, and the high-speed powder was compacted. After that, immediately with high frequency induction heating for 1 in 15 seconds
After reheating to 200 ° C. (melting point ratio: 0.89), the base was plastically deformed by press working to increase the compaction density of the HSS powder. Subsequently, quenching was performed from 1180 ° C. and tempered at 540 ° C., and the sintered portion was ground to form a tooth profile of the gear.

[0030]

Comparative Example 7 Carbon steel (0.2% C-0.25% Si-
0.5% Mn-balance Fe and a high speed green compact (1.5% C-0.2% Si-4.1% Cr-5.0%)
Mo-3.1% V) was installed as shown in FIG. 4, the vicinity of the powder filling was heated to 600 ° C. (melting point ratio 0.44) in 10 seconds by high-frequency induction heating, and then pressed to form a base. High-speed powder was compacted by plastic deformation. After that, immediately after reheating to 1200 ° C. in 35 seconds by high-frequency induction heating,
The base was plastically deformed by pressing to increase the compaction density of the HSS powder. Furthermore, quenching from 1180 ° C
After tempering at ℃, the sintered portion was ground to form a gear tooth profile.

[0031]

Comparative Example 8 The gears shown in Example 4 and Comparative Example 4
Table 4 shows the results of a gear fatigue test performed using a gear carburized with M420 case-hardened steel (Comparative Example 8).

[0032]

[Table-4] Tooth profile: Normal tooth, Module: 2.5, Number of teeth: 28 Lubricating oil: Automatic fluid, Oil temperature: 90 ° C Fatigue limit: 10 Root bending stress of undamaged gear after repeated ⁷ times

[0033]

According to the present invention, it is possible to minimize the amount of expensive powder used, and to obtain a sintered part having a high compaction density and excellent wear resistance so that the properties of the powder can be maximized. And a component having high bonding strength between the base and the sintered portion can be manufactured at low cost. In addition, the application of such a composite characteristic component is achieved by, for example, reducing the size and weight of the component itself due to the excellent characteristics of the powder sintered part, thereby reducing the size of the mechanical structure to which the component is applied. Lightening is also possible. Furthermore, when applied to tools and the like, the effect is great from the viewpoint of economic efficiency and resource saving.

[Brief description of the drawings]

FIG. 1 is a diagram showing the appearance of a chip. (A) is a plan view and (b) is a side view.

FIG. 2 is a diagram showing an appearance of a tappet. (A) is a plan view and (b) is a side view.

FIG. 3 is a diagram showing an appearance of a radial bearing. (A)
Is a plan view thereof, and FIG.

FIG. 4

Claims (2)

[Claims] 1. A temperature range consisting of a powder or a green compact and an ingot serving as a base, in a temperature range of at least the melting point of the powder × 0.5 or more in a nitrogen atmosphere in a state where the powder or the green compact and the base are in contact with each other. After heating within 600 seconds, the powder or green compact is consolidated while causing plastic deformation of the base, and then sintered while causing plastic deformation of the base in the temperature range of the melting point of the powder x 0.7 or more. And a diffusion-bonding method. 2. A powder or green compact, which is made of an ingot material serving as a base, and in a state where the powder or green compact and the base are in contact with each other, is heated to a temperature range of at least the melting point of the powder × 0.5. 60
After heating within 0 seconds, the powder or green compact is consolidated while causing plastic deformation of the substrate, and sintering is performed while causing plastic deformation of the substrate in the temperature range of the melting point of the powder x 0.7 or more. A method for producing a wear-resistant part, characterized by diffusion bonding.