JPH0813124A - Nitriding method and ion nitriding method for metallic member - Google Patents

Abstract

PURPOSE:To enable uniform nitriding for a metallic member having a complicated surface shape, long and nallow pores, dense slits or the like by bringing the specified surface part of a metallic member into contact with a metal subjected to nitriding treatment with a shape corresponding to the shape of the same or holding it to the almost vicinity of the same and executing nitriding treatment. CONSTITUTION:The specified surface part of a metallic member, particularly the part having close grooves and nallow and deep pares and slits is brought into contact with a metal or metal powder or metallic nitride powder or holding it to the same or filling it with the same. Then, the metallic member and the same metal or the same powder are held in a vacuum or in an atmosphere of a reduced gass to 300 to 650 deg.C and is subjected to nitriding treatment or ion nitriding treatment. By this method, the purpose can be attained with hardly changing the surface roughness of the member, and without masking, only the required part can locally be subjected to nitriding treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for nitriding the entire surface of a metal member or a specific surface portion, particularly a portion having a fine groove, a narrow deep hole or a slit, or a nitriding-treated metal member. The present invention relates to a method of performing a nitriding treatment and an ion nitriding treatment with almost no change in surface roughness.

[0002]

2. Description of the Related Art It is known to nitride or ion-nitride a metal surface to form a metal nitride layer on the surface to improve the wear resistance and corrosion resistance of the metal surface.

Among various nitriding methods, the ion nitriding method can be used to ion nitrid the surface of a metal member having a relatively simple shape such as a crank pin or a crank without fine irregularities. Further, according to the ion nitriding method, it is possible to easily perform the nitriding treatment on the necessary portion by masking the necessary portion.

However, when the ion nitriding method is used, the portion of the metal member to be treated, which has fine slits, holes, grooves, etc., cannot be sufficiently treated or cannot be treated. was there.

Among various nitriding methods, gas nitriding, salt bath nitriding, and the like can process metal members having fine slits, holes, grooves, etc., but inside deep holes or slits Since the raw material gas and the like cannot be sufficiently distributed and exchanged, it is not easy to uniformly perform nitriding treatment. Further, it is not easy to partially prevent the nitriding treatment by masking. Further, there is also a problem that the surface roughness is increased by the treatment, and it is necessary to polish or chemically clean the surface after the treatment, if necessary.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a metal member having a complicated surface shape or a metal member having elongated holes or minute slits is uniformly nitrided without nitriding treatment, or particularly without masking. A method of locally nitriding only the portion to be treated, or a method of nitriding while maintaining the surface state of the metal member by nitriding treatment,
An object of the present invention is to propose a method for ion-nitriding a metal member having a complicated surface shape while making use of excellent characteristics such as masking of the nitriding treatment by the ion-nitriding method.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a metal having a shape that matches the shape of a specific surface portion of the surface of a metal member that is to be nitrided and that has been previously nitrided. The surface of the member is brought into contact with or held in close proximity to a specific surface portion to be subjected to the nitriding treatment, and the metal member and the metal are kept in a vacuum or a reduced pressure gas atmosphere for 300 to 300
A nitriding method for a metal member characterized by performing a nitriding treatment at a temperature of 650 ° C. (first invention), a specific surface portion of the surface of the metal member subjected to the nitriding treatment, or the entire surface of the metal member. The nitriding treatment is performed by contacting or filling a metal powder or a metal nitride powder that has been subjected to a nitriding treatment in advance and maintaining the metal member and the metal powder at a temperature of 300 to 650 ° C. in a vacuum or reduced pressure gas atmosphere. A method of nitriding a metal member (second invention), which has a shape that matches the shape of a specific surface portion of the surface of the metal member to which the nitriding treatment is applied, and which has been pre-nitrided While contacting or holding in close proximity to a specific surface portion to be subjected to nitriding treatment on the surface of the metal member, the metal member and the metal are maintained at a temperature of 300 to 650 ° C. An ion nitriding method of a metal member (third invention), a specific surface portion of the surface of the metal member to be subjected to nitriding treatment, or the entire surface of the metal member being subjected to nitriding treatment in advance. An ion nitriding method for a metal member, which comprises contacting or filling a powder or a powder of a metal nitride, and performing an ion nitriding treatment while maintaining the metal member and the metal powder at a temperature of 300 to 650 ° C (fourth invention). ) Is the gist.

[0008]

In the present invention, the material of the metal member to be used in the present invention is mainly a case hardening steel such as SI15CK, a structural steel such as S45C, a spring steel such as SUP10, a bearing steel such as SUJ2, a nitrided steel such as SACM1 and SKD61. Hot working steels such as SKD11, cold working steels such as SKD11, high speed steels such as SKH51, heat resistant steels such as SUS301, steels for machine parts such as SCr20, heat resistant and acid resistant steels such as SUS410.

The metal member of the present invention having a complicated surface has a metal mold for machine parts, a gear for automobiles, and the like. Further, as the metal member having the slit, there are various dies for extruding aluminum, a knitting machine, and the like. Examples of those having holes include resin extrusion nozzles and fuel injection nozzles for marine engines.

In the present invention, it is necessary to heat the metal base material to a reaction temperature at which the reaction can be carried out at a yield that is economical, and for that purpose, it is necessary to maintain the temperature of the metal base material at 300 to 650 ° C. . The reason is that if the temperature is lower than 300 ° C., the nitriding reaction is extremely slow, while if it exceeds 650 ° C., the nitride once formed is decomposed and nitriding does not occur.

As the heating means, there are electric heating, gas heating, etc., but electric heating is easy to use. If the heating source is placed in a vacuum chamber for nitriding treatment or placed outside the heating chamber to perform heating, programmed temperature rise and temperature maintenance can be easily performed in combination with an automatic control system.

The inside of the vacuum chamber in which the nitriding treatment is performed may be in a vacuum exhaust state or in a reduced pressure gas atmosphere. However,
The gas supplied into the vacuum chamber is hydrogen gas, nitrogen gas, other inert gas such as argon, or a mixed gas thereof, and it is preferable that the gas does not promote the surface oxidation of the metal member. The pressure in the vacuum chamber is preferably 10 Torr or less.

The metal which is used for nitriding the metal member and which has been previously subjected to nitriding treatment is SACM1 which is a structural steel such as S45C capable of sufficiently absorbing and desorbing nitrogen.
Various steels such as nitriding steels such as, steels for hot working such as SKD61, steels for machine parts such as SCr are desirable. Other metal nitrides may be used.

The metal powder or metal nitride powder which is used for nitriding the metal member and which is previously subjected to nitriding treatment is
It is desirable that the average particle size is fine particles of 1 mm or less, and particularly when the metal member to be subjected to the nitriding treatment has pores, slits, etc., it is particularly fine particles of 0.2 mm or less. desirable.

As the nitriding method of the metal or the metal powder which is previously subjected to the nitriding treatment, any one of ion nitriding, gas nitriding, salt bath nitriding and the like may be adopted.

It is desirable that the metal powder used for nitriding the metal member and previously subjected to the nitriding treatment should be subjected to the nitriding treatment as sufficiently as possible. A powder of iron nitride (Fe ₂ N or Fe ₄ N) is desirable.

When it is necessary to perform the nitriding treatment over the entire surface of the metal member to be subjected to the nitriding treatment, the metal powder or the metal nitride powder which has been subjected to the nitriding treatment is filled with the nitriding treatment. It is desirable to be processed in. When nitriding only the inner surface such as holes and slits,
It is desirable that the portion is filled with a metal powder or a metal nitride powder that has been previously subjected to a nitriding treatment, and then treated.

The metal which is used for nitriding the metal member and which is previously subjected to the nitriding treatment has a shape of the surface portion of the metal member which is difficult to be nitrided by the ion nitriding method, such as a narrow groove, a slit or an elongated hole. It is desirable that the shapes match.

Even if the entire surface of the metal member to be subjected to the nitriding treatment is filled with the metal powder or the metal nitride powder subjected to the nitriding treatment in advance, or the ion nitriding of holes or slits is performed. Depending on the method, only the surface portion of the metal member, which is difficult to be nitrided, may be filled with the metal powder or the metal nitride powder that has been previously nitrided.

Of the metal that has been previously nitrided, or the metal powder or metal nitride powder that has been previously nitrided, it has the role of supplying nitrogen atoms to the surface of the metal member that is nitrided. It is desirable that the metals are in contact with each other or that they are close to each other at an interval of 1.0 mm or less, and the metal powder or the metal nitride powder that has been subjected to the nitriding treatment is packed in the necessary portion as closely as possible. It is desirable that it is in the state of being kept.

In the ion nitriding apparatus of the present invention, a pipe for supplying a raw material gas used for ion nitriding and a vacuum pump for exhausting the inside of the vacuum chamber are connected in the vacuum chamber, and a power source for generating plasma used for the ion nitriding. As long as the electrode for installing the metal member or the like connected to is installed in the vacuum chamber, its structure, form, etc. do not matter.

The gas supplied to the vacuum chamber of the ion nitriding apparatus is not particularly limited as long as it causes an ion nitriding reaction such as hydrogen gas, nitrogen gas or ammonia gas. Further, it does not matter if an inert gas such as argon is added. The plasma generation method may be any method as long as it produces an ion nitriding reaction, such as direct current glow discharge and high frequency glow discharge.

[0023]

FIG. 1 is a schematic view showing an example of an external heating furnace type nitriding apparatus for carrying out the first and second inventions of the present invention, and FIG. 2 is also for carrying out the third and fourth inventions. FIG. 3 is a schematic view showing an example of an external heating furnace type ion nitriding device of FIG.
1 is an enlarged schematic vertical sectional view showing a processed member corresponding to the invention and the third invention, and FIG. 4 is an enlarged schematic longitudinal sectional view showing a processed member corresponding to the second invention and the fourth invention.
Is a vacuum chamber, 2 is a heater, 3 is a metal member support, 4 is an exhaust pipe, 5 is an exhaust valve, 6 is a vacuum pump,
Reference numeral 7 is a raw material gas introduction nozzle, 8 is a mass flow controller, 9 is a valve, 10 is a raw material gas introduction pipe, 11 is a DC power source, 12 is an electrode, 13 and 14 are members to be treated, 13a,
14a is a fuel injection nozzle for a marine engine, 13b, 14
b is a knitting machine.

That is, in the external heating furnace type nitriding apparatus shown in FIG. 1, the heater 2 is installed on the outer wall of the vacuum chamber 1, and the metal member support 3 for fixing the member 13 to be processed is arranged inside the chamber. ing. The inside of the vacuum chamber 1 is configured to be evacuated by the vacuum pump 6 through the exhaust valve 5 and the exhaust pipe 4, and the source gas (H ₂
Gas, Ar gas) is configured to be supplied into the chamber from the nozzle 7 via the mass flow controller 8, the valve 9 and the introduction pipe 10.

Among the materials 13 and 14 to be treated, the fuel injection nozzles 13a and 14a for a marine engine have metal rods that have been previously nitrided in the pores 13a-1 and 14a-1 as shown in FIGS. 13a-2 and a metal powder 14a-2 are respectively inserted, and a plurality of slits 13b-1 are pre-nitrided on a metal plate 13b in the kama 13b of the knitting machine.
2 is inserted, and the kama 14b of the knitting machine has a crucible-shaped metal container 14b-3 filled with a metal powder 14b-2 that has been subjected to nitriding treatment in advance. It is embedded so as to touch the metal powder 14b-2.

The external heating furnace type ion nitriding apparatus shown in FIG. 2 is used to generate a direct current glow discharge by applying an electrode 12 for installing a material to be treated, which is disposed in the vacuum chamber 1, to this electrode. Except for the DC power supply 11, it has the same structure as the nitriding apparatus shown in FIG.

Example 1 An example corresponding to the first aspect of the present invention (claim 1) is shown below. The material to be processed on the metal member support 3 is die steel (SKD61) and has an inner diameter of 0.6 mm and a length of 50.
Fuel injection nozzle for marine engine having 13 mm pores
The same material as a, width 0.8 mm, depth 12 mm, length 3
A knitting machine comb 13b provided with a large number of 0 mm slits was installed. The pores 13a-1 of the fuel injection nozzle 13a for the marine engine and the slits 13b- of the knitting machine comb 13b-
1 is a nitrided steel (SACM having a compound layer of about 15 μm and a diffusion layer of 550 μm formed in advance by an ion nitriding method.
In 1), a metal rod 13 having a diameter of 0.55 mm and a length of 55 mm
a-1 and a plate 13b having a thickness of 0.75 mm and a length of 15 mm
-2 is inserted.

In the nitriding treatment, first, the vacuum chamber 1 was evacuated to 10 ⁻³ Torr by the vacuum pump 6, H ₂ gas was supplied at 1000 ml / min while continuing the evacuation, and the valve 9 was used.
Was adjusted to maintain the chamber at 1 torr. At the same time, the metal member support 3 and the member to be treated 13 are heated by the heater 2 until the temperature is made uniform to 550 ° C., the state is maintained for 3 hours, and the inner surface of the hole of the fuel injection nozzle 13a for the marine engine and the braid 13b of the knitting machine are held. The inner surface of the slit was nitrided.
Then, the heater 2 was turned off, and the metal member support 3 and the member 13 to be processed were cooled to room temperature. Thereafter, the fuel injection nozzle 13a for the marine engine and the braid 13b of the knitting machine are taken out from the vacuum chamber, cut and cut, and a cross-section of each portion of the inner surface of the hole 13a-1 of the fuel injecting nozzle for the marine engine and the slit 13b-1 of the braid 13b of the braiding machine. As a result of observing with a microscope, the thickness of all the treated members is approximately 120 μm evenly on the surface.
m diffusion layer was formed. The hardness of the surface of the holes and slits of these members to be processed is Hv = 1020.
Met. Further, the surface roughness of the holes and slits subjected to the nitriding treatment is 0.03 μm in average roughness Ra before the treatment.
However, the same value was shown after the treatment, and it was confirmed that the surface roughness did not change due to the nitriding treatment.

Embodiment 2 An embodiment corresponding to the second invention (claim 2) of the present invention will be shown below. The material to be processed on the metal member support 3 is die steel (SKD61) and has an inner diameter of 0.6 mm and a length of 50.
Fuel injection nozzle for marine engine having 14 mm pores
The same material as a, width 0.8 mm, depth 12 mm, length 3
A knitting machine 14b equipped with many 0 mm slits was installed. The pores 1 of the fuel injection nozzle 14a for the marine engine
4a-1 is a nitrided steel (SAC) in which a compound layer of about 15 μm and a diffusion layer of 550 μm were previously formed by a gas nitriding method.
It is filled with powder 14a-2 of M1) having an average particle size of about 0.1 μm. The kama 14b of the knitting machine is filled with the powder 14a-2 having the average particle diameter of about 0.1 μm of the nitrided steel (SACM1) having the compound layer of about 15 μm and the diffusion layer of 550 μm formed by the same gas nitriding method as described above. In a metal container 14b-3 made of stainless steel (SUS304), the entire surface of the sill is buried so as to come into contact with the powder 14a-2.

In the nitriding treatment, as in Example 1, first, the vacuum chamber 1 was evacuated to 10 ⁻³ Torr by the vacuum pump 6, H ₂ gas was supplied at 1000 ml / min while the evacuation was continued, and the valve 9 was adjusted. The chamber was maintained at 1 torr. At the same time, the heating member 2 heats the metal member support 3 and the member to be processed 14 to 550 ° C. until they are homogenized.
The state was maintained for 3 hours, and the inner surface of the hole of the fuel injection nozzle 14a for a marine engine and the entire surface of the top 13b of the knitting machine were nitrided.

After the nitriding treatment, as in the first embodiment, the holes of the fuel injection nozzles 14a for the marine engine and the braces 14b of the knitting machine.
As a result of observing the cross section of each of the inner and outer surfaces of the slit with a microscope, the thickness of all the treated members is approximately 90 μm evenly on the surface.
The diffusion layer was formed. The hardness of the surface of the holes and slits of these members to be treated was Hv = 980. Further, the surface roughness of the holes and slits subjected to the nitriding treatment is the average roughness R before the treatment also in this embodiment.
Although a was 0.03 μm, it showed the same value after the treatment, and it was confirmed that the surface roughness did not change due to the nitriding treatment.

Example 3 An example corresponding to the third aspect of the present invention (claim 3) is shown below. The material to be processed on the electrode 12 is a die steel (SKD61), which is a ship engine fuel injection nozzle 13a having an inner diameter of 0.6 mm and a length of 50 mm, and the same material, a width of 0.8 mm, and a depth of 12 mm. A knitting machine comb 13b provided with a large number of slits having a length of 30 mm was installed. The pores 13a- of the fuel injection nozzle 13a for the marine engine
1 and the slit 13b-1 of the braid 13b of the knitting machine, a compound layer of about 15 μm and 550 μm were previously prepared by ion nitriding.
A metal rod 13a-1 having a diameter of 0.55 mm and a length of 55 mm and a plate 13b-2 having a thickness of 0.75 mm and a length of 30 mm are respectively inserted in a nitrided steel (SACM1) having a diffusion layer of m. ing.

In the ion nitriding process, first, the vacuum chamber 1
The inside was evacuated to 10 ⁻³ Torr by the vacuum pump 6, H ₂ gas was supplied at 1000 ml / min and N ₂ gas was supplied at 500 ml / min while the evacuation was continued, and the inside of the chamber was maintained at 2 Torr by the valve 5. Heater 2 and electrode 1 at the same time
The electrode 12 and the member to be treated 13 are heated to 550 ° C. by the DC glow discharge generated by the DC voltage of −500 V applied to the electrode 2.
By heating for 3 hours until it is uniformized, and maintaining the state for 3 hours, the entire surface including the surface of the fuel injection nozzle 13a for a marine engine and the inner surface of the hole, and the inner surface of the slit of the comb 13b of the knitting machine is subjected to ion nitriding treatment.

After the ion nitriding treatment, the surface and holes of the fuel injection nozzle 14a for the marine engine, the surface of the knitting machine 14b and the cross-sections of the inner and outer surfaces of the slit were observed under a microscope as in Example 1. A diffusion layer having a thickness of about 140 μm was uniformly formed on the surface of the member to be treated. Further, the hardness of the surface portion of these processed members is Hv
= 1020. Further, the surface roughness of the holes and slits subjected to the nitriding treatment was 0.03 μm in average roughness Ra before the treatment also in this example, but the same value is shown after the treatment. It was confirmed that the surface roughness did not change.

Example 4 An example corresponding to the fourth aspect of the present invention (claim 4) is shown below. The material to be processed on the electrode 12 is die steel (SKD61), which is a ship engine fuel injection nozzle 14a having an inner diameter of 0.6 mm and a length of 50 mm, and the same material as a width of 0.8 mm and a depth of 12 mm. A knitting machine 14b provided with a large number of slits having a length of 30 mm was installed. In the pores 14a-1 of the fuel injection nozzle 14a for a marine engine, a compound layer of about 15 μm and 5
It is filled with powder 14a-2 of nitrided steel (SACM1) having a diffusion layer of 50 μm and having an average particle size of about 0.1 μm. The knitting machine 14b has a mean particle diameter of about 0.1 μm of a nitrided steel (SACM1) in which a compound layer of about 15 μm and a diffusion layer of 550 μm are formed by the same gas nitriding method as described above.
m powder 14a-2 filled with stainless steel (SUS
304) made of a metal container 14b-3, and the whole surface of the kettle is buried so as to come into contact with the powder 14a-2.

In the ion nitriding treatment, as in the third embodiment, the inside of the vacuum chamber 1 is first evacuated to 10 ⁻³ Torr by the vacuum pump 6, and H ₂ gas of 1000 is supplied while the evacuation is continued.
ml / min and N ₂ gas of 500 ml / min, and valve 5
The chamber was maintained at 2 torr. At the same time, the electrode 12 and the member to be treated 13 are heated to a uniform temperature of 550 ° C. by a DC glow discharge generated by a DC voltage of −500 V applied to the heater 2 and the electrode 12, and the state is maintained for 3 hours. , The surface of the fuel injection nozzle 13a for the marine engine and the inner surface of the hole, and the knitting machine 1
The entire surface including the inner surface of the slit 3b was subjected to ion nitriding treatment.

After the ion nitriding treatment, as in Example 1, the surface and holes of the fuel injection nozzle 14a for the marine engine, the surface of the knitting machine 14b and the cross-sections of the inner and outer surfaces of the slit were observed under a microscope. A diffusion layer having a thickness of about 140 μm was uniformly formed on the surface of the engine fuel injection nozzle 14a. The surface hardness of that portion is Hv =
It was 1070. Further, a diffusion layer of about 120 μm was formed in the holes of the fuel injection nozzle 14a for a marine engine, the surface of the knitting machine 14b and the slit portion. The surface hardness of that portion was Hv = 1020. Further, the surface roughness of the holes and the slits subjected to the nitriding treatment is 0.
Although it was 03 μm, the same value was shown after the treatment, and it was confirmed that the surface roughness did not change due to the nitriding treatment.

[0038]

As described above, according to the method of the present invention, nitriding treatment and ion nitriding treatment are uniformly performed on a metal member having a complicated surface shape or a metal member having elongated holes or fine slits on the surface. It can be performed, and it is possible to locally perform only the portion requiring the nitriding treatment without masking, and to perform the nitriding treatment and the ion nitriding treatment while maintaining the surface state of the metal member. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an external heating furnace type nitriding apparatus for carrying out the first invention and the second invention of the present invention.

FIG. 2 is a schematic view showing an example of an external heating furnace type ion nitriding apparatus for carrying out the third invention and the fourth invention.

FIG. 3 is an enlarged schematic vertical sectional view showing a member to be processed corresponding to the first invention and the third invention.

FIG. 4 is an enlarged schematic vertical sectional view showing a member to be processed corresponding to the second invention and the fourth invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Heater 3 Metal member support 4 Exhaust pipe 5 Exhaust valve 6 Vacuum pump 7 Raw material gas introduction nozzle 8 Mass flow controller 9 Valve 10 Raw material gas introduction pipe 11 DC power supply 12 Electrode 13, 14 Processed material 13a, 14a Ship Fuel injection nozzle for engine 13b, 14b Kama machine kneader 13a-1, 14a-1 Pore 13a-2 Metal rod 14a-2 Metal powder 13b-1, 14b-1 Slit 13b-2 Metal plate 14b-3 Metal container

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiro Ishii 3-18-5 Chugoku, Ichikawa, Chiba Sumitomo Metal Mining Co., Ltd. Central Research Laboratory

Claims (4)

[Claims] 1. A nitriding treatment is performed on the surface of a metal member, the metal having a shape that conforms to the shape of a specific surface portion to which the nitriding treatment is applied on the surface of the metal member and which has been subjected to the nitriding treatment in advance. A method of nitriding a metal member, which comprises contacting with a specific surface portion or holding the metal member in the immediate vicinity thereof, and performing nitriding treatment while maintaining the metal member and the metal at a temperature of 300 to 650 ° C. in a vacuum or reduced pressure gas atmosphere. . 2. A specific surface portion of the surface of the metal member to be subjected to a nitriding treatment, or the entire surface of the metal member is contacted or filled with a metal powder or a metal nitride powder which has been subjected to a nitriding treatment in advance. The metal member and the metal powder in a vacuum or reduced pressure gas atmosphere at 300 to 650 ° C.
A nitriding method for a metal member, which is characterized in that the nitriding treatment is performed while maintaining the temperature. 3. A nitriding treatment is performed on the surface of the metal member, the metal having a shape that matches the shape of a specific surface portion on which the nitriding treatment is performed on the surface of the metal member and which has been subjected to the nitriding treatment in advance. The metal member and the metal are kept in contact with the specific surface portion or kept in the immediate vicinity thereof in an amount of 300 to 65%.
An ion nitriding method for a metal member, which comprises performing an ion nitriding treatment while maintaining the temperature at 0 ° C. 4. A specific surface portion of the surface of the metal member to be subjected to nitriding treatment, or the entire surface of the metal member is contacted or filled with a metal powder or a metal nitride powder which has been previously subjected to nitriding treatment, 3 parts of the metal member and the metal powder
An ion nitriding method for a metal member, characterized by performing an ion nitriding treatment while maintaining the temperature at 00 to 650 ° C.