JPS58136772A - Gas softnitriding and austempering method - Google Patents

Abstract

PURPOSE:To subject a steel material easily to softnitiding and austempering without using any salt bath agent, by cooling the steel material quickly to a softnitriding temp. from the austenitizing temp. thereof, holding the same at said temp., and subjecting the material to austempering and softnitriding simultaneously. CONSTITUTION:Steel materials 2 are introduced with a meashed belt type conveyor 4 into a heating furnace 1 kept in a non-oxidative atmosphere where the materials are heated to the austenitizing temp. thereof, and are then charged into a powder fluidized layer 5A in a cooling tank 3. The layer 5A is constituted of powder of Al2O3, etc. and is kept fluidized by non-oxidative gases 6 introduced through a blow pipe 9 from the outside so that the materials 2 are quickly cooled from the austenitizing temp. to a softnitriding temp. and are held at said temp. The materials 2 are introduced with a meshed belt type conveyor 7 into a gas softnitriding furnace 8A, where the materials are held at a softnitriding temp. in an atmosphere of gaseous ammonia or the like. The softenitrided mateials 2 are discharged to the outside of the furnae with a meshed belt type conveyor 10.

Description

[Detailed Description of the Invention] This invention is a method of manufacturing steel
This invention relates to a soft nitriding A-1 damping method in which the soft nitriding temperature t is rapidly cooled and held, and the soft nitriding process and the soft nitriding process are performed simultaneously.

In conventional nitrocarburizing and o-tempering treatment methods, the quenching J3 from the austenitizing temperature to 1-1 and the nitrocarburizing were usually carried out in a salt bath. However, if a salt bath is used, please take precautions against pollution, such as how to dispose of the salt bath after use.
-It is necessary to pay sufficient attention/> (and the reality is that these require considerable expense.Also, if a salt bath is used, continuous operation is difficult, which makes it difficult to produce large clay. There are issues such as whether it is appropriate or not.

On the other hand, in the case of only soft nitriding treatment, a gas soft nitriding method using gas without using a salt bath is known. However, the steel material is not rapidly cooled to the soft-nitriding wet trot, and the high deep hardness that is the aim of the soft-nitriding process cannot be obtained. Applying this was considered rotation.

This invention was made in view of the following considerations, and allows practical application of the gas soft-nitriding method to soft-nitriding austempering treatment instead of the salt bath, which has troublesome problems such as pollution and single-method treatment. The object of the present invention is to provide a nitrocarburizing austempering treatment that reduces the problem of ``pollution countermeasures'' and facilitates mass production.

The nitrocarburizing austempering treatment method of the first invention involves putting a steel material heated to an austenitizing temperature into a powder fluidized bed maintained at a nitrocarburizing temperature ra and rapidly cooling it to the nitrocarburizing temperature. , followed by soft nitriding treatment.

Further, in the soft nitriding method of the second invention, the steel l heated to the austenitizing temperature is put into a powder fluidized bed maintained at the soft nitriding temperature and into which soft nitriding gas is introduced. Therefore, austempering treatment and soft nitriding treatment are done in the same way.
1.1 and 16().

Hereinafter, the process of this invention will be described as follows,
Tomorrow 1.

FIG. 1 shows an example of a small-sized 11-1 apparatus for carrying out the gas nitrocarburizing ausnon-var treatment method of the '1st invention. In Fig. 1, ++n heat is used to heat the treatment (J) steel material, that is, the material to be treated 2, to a temperature of A-7. The material is equipped with a mesh belt type conveyor 4 to convey the material in a fixed direction.The material 2 to be treated is heated to the temperature of Ausbuna-f1 by the heating furnace 1.
The powder is put into the fluidized bed 5A in the cooling tank 3. This powder flow 1flJ layer 5Δ is caused by the gas 6 introduced from the outside through the blowing pipe 9, and the powder such as AO flows and returns to the J state, and the temperature of the fluid powder reaches the nitrocarburizing temperature. It is something that has been held and is being treated with embarrassment 1t1442 let 7
1- The stenitized warm melon is rapidly cooled to the nitrocarburizing temperature. It should be noted that it is desirable to use a non-oxidizing gas such as RX gas for the gas 6 for powder fluidization to prevent oxidation of the limb treatment H and In21 beauty. It is desirable that a similar non-oxidizing gas be introduced into the furnace 1 as well. Said cold) J
In the powder fluidized bed 5) A of tank 3, Metschpel 1 to Formula 21 cabinets A77 are arranged. quenched to temperature 1
The 9 pieces are conveyed to the gas nitrocarburizing furnace E3△ by a belt conveyor 7. In this gas soft-nitriding furnace 8A, a soft-nitriding atmosphere gas such as ammonia gas or a mixed gas mainly consisting of ammonia gas is introduced and maintained at the soft-nitriding temperature, so that the material 2 to be treated is soft-nitrided. Ru. The material to be treated 2 which has been subjected to soft-nitriding treatment is carried out of the furnace by a Messhicobel I complete set 710. It is desirable to provide a partition wall 11 between the J3 heating furnace 1 and the gas soft-nitriding furnace 8A to prevent the atmospheres of the two from mixing.

In this series of methods, since the heat capacity of the powder fluidized bed 5A is significantly larger than that of the primary gas, the powder fluidized bed 5A is
The material 2 to be treated that has been put into the chamber is immediately rapidly cooled down to the nitrocarburizing temperature up to the inside thereof, and subsequently to the nitrocarburizing furnace 8A, the material 2 is subjected to nitrocarburizing treatment at J3.

Although the apparatus shown in Fig. 1 is a series of MEC bells 1, an elevator is installed between the heating furnace 1 and the June 1 tank 3, and between the cold FJI tank 3 and the sludge soft-nitriding furnace 8△. Depending on the installation, it can also be used as a continuous furnace with a tray set.

FIG. 2 shows an example of an apparatus for carrying out the gas soft-nitriding austempering treatment method of the second invention. 1 In the apparatus shown in FIG. 2, the gas soft-nitriding furnace 813 itself is
It is composed of 3 and -C. Rinawachiko powder fluidized bed 513
In this case, powder such as AO is brought into a fluidized state by a soft nitriding atmosphere gas 14, for example, a mixed gas of ammonia gas and RX gas, and is maintained at the soft nitriding treatment temperature. has been done. Therefore, the material to be treated 2 heated to the austenitizing temperature in the heating furnace 1 is put into the powder fluidized bed 5B having a large heat capacity, where it is rapidly cooled to the soft nitriding temperature and simultaneously subjected to gas soft nitriding treatment. In the powder fluidized bed 51 of the gas soft-nitriding furnace 8B, a mesh belt-type conveyor 13 is installed, and the soft-nitriding process 1!
The processed material 2 is conveyed out of the furnace continuously by this conveyor r13.

In this case as well, the 1111 thermal furnace 1 oxidizes the material 2 to be treated.
It is desirable to introduce a non-oxidizing gas such as RX gas in order to prevent decarburization. Furthermore, in the case of the apparatus shown in Fig. 2, it is of course possible to use a 1-ray continuous furnace.
It is υ.

As is clear from the above explanation, in the method of the first invention, the material to be treated is rapidly cooled from the A-stenitizing temperature to the soft nitriding temperature (the constant temperature I!I! temperature as austempering treatment). In the method of the second invention, a powder fluidized bed having a large heat capacity is used as a temperature medium.
This is because the powder fluidized bed is used as a temperature medium to rapidly cool the material to be treated from the austopitization temperature to the nitrocarburizing temperature, and subsequently the material to be treated is subjected to gas nitrocarburizing treatment (and isothermal treatment for austempering). By using a powder fluidized bed with a large heat capacity, gas soft-nitriding, which was conventionally considered difficult to apply to soft-nitriding austempering, can now be applied. It has become.

Unlike the salt bath used in conventional nitrocarburizing austempering treatment, the powder fluidized bed is less likely to cause pollution [problems], however, the first and second inventions of this application
According to the soft nitriding A-sumpper processing method of the invention, compared to the conventional soft-nitrided austomer processing method, the cost required for countermeasures against -C pollution is significantly reduced, and the working environment is also improved. What's more, it's different when using a salt bath, and continuous operation is not possible. Since it is cheap, mass production can be easily carried out, and furthermore, since the operating conditions are easy, the quality of steel H is stable, etc., which has 1q effects.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an example of an apparatus for carrying out the gas nitrocarburizing A-sumper treatment method of the first invention;
FIG. 2 shows an example of an apparatus for carrying out the gas nitrocarburizing aus-jumper treatment method of the second invention. It is a schematic cross-sectional view. 1... Heating furnace, 2... Material to be treated (steel material), 5A, 5
B... Powder fluidized bed, 8A, 813... Gas soft nitriding furnace. Applicant: Toyota Motor Corporation Ne1 Agent: Patent Attorney Yutaka 1) Hisashi Take (and 1 other person) 9-136: Written amendment to the procedure (spontaneous) 1982 Patent Application No. 19505 2, Name of the invention: Gas Soft-nitriding austempering treatment method 3, relationship with the amended case Patent applicant address 1, Toyota-cho, Toyotafu, Aichi Prefecture Name (
320j Toyota Motor Corporation 4, Agent address: 803 Futaba Pill, 3-4-18 Mita, Minato-ku, Tokyo Telephone: (453) 65915, Column 6 for detailed description of the invention in the specification to be amended, Contents of the amendment 364- on page 4, line 16 of the specification, and on page 6, line 13 of the specification.

Claims (2)

[Claims] (1) After heating the L material to its austenitizing temperature,
In the soft-nitriding austempering treatment method, in which the steel material is rapidly cooled to the soft-nitriding temperature and immediately subjected to soft-nitriding, the steel material heated to a temperature of 1 to the soft-nitriding temperature is put into a powder fluidized bed maintained at the soft-nitriding temperature, and then soft-nitrided. A gas nitrocarburizing austempering treatment method characterized by rapid cooling to a temperature followed by gas nitrocarburizing. (2) After heating the steel material to its austenitizing temperature,
In the soft-nitriding austempering treatment method, in which the steel material is rapidly cooled to the soft-nitriding temperature and immediately subjected to soft-nitriding, the steel material heated to the austenitizing temperature is heated to the soft-nitriding temperature in a powder fluidized bed in which the soft-nitriding temperature is maintained and a soft-nitriding atmosphere gas is introduced. 1. A gas soft-nitriding austempering treatment method characterized by charging the powder into a powder fluidized bed, rapidly cooling it to a soft-nitriding temperature, and performing gas soft-nitriding treatment in the powder fluidized bed.