JPS58107264A - Quick joining and carburizing method - Google Patents

Abstract

PURPOSE:To simplify stages and to imrpove working efficiency and productivity by subjecting ferrous members simultaneously to high frequency brazing and high frequency carburizing. CONSTITUTION:Articles 5 to be treated of cylindrical and disc shapes consisting of low carbon steel placed with a steel brazing filler metal 5' therebetween are placed on a receiving jig 4 for the articles to be treated in the furnace chamber 2 of a high frequency heating chamber 1. Gaseous nitrogen added with 0.5-30% gaseous hydrocarbon is fed through a feed port 6 into the chamber 2 and the articles 5, then the jig 4 is rotated. On the other hand, high frequency outputs are applied to a high frequency coil 3 to heat the articles to 1,100- 1,150 deg.C brazing and carburizing temps. Said temps. are held for 3-15 minutes to effect brazing of the articles 5 and cementation and diffusion of carbon into the surface layers thereof simultaneously. After the articles are slowly cooled from the carburizing temp. down to 850-800 deg.C hardening temp., the articles are immersed in a cooling medium 11 held at 60 deg.C in a hardening tank.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a short-time joint carburizing and quenching method that simultaneously performs high-frequency brazing and high-frequency carburizing treatment of iron-based members. High-frequency brazing is a method that can join a large number of workpieces, such as mechanical parts, in a short period of time. This high-frequency brazing method consists of heating the product and the filler metal to a temperature above the melting point of the filler metal in a protective gas atmosphere to prevent them from oxidizing and decarburizing. It varies depending on the brazing material used. For example, when using copper brazing filler metal, the heating temperature is 1100 to 1180°C. Further, as the protective atmosphere gas, endothermic shift furnace gas, ammonia decomposition gas, N2 gas, etc. are used.

On the other hand, in order to impart wear resistance, fatigue resistance, etc. to the surface of an iron-based member, a gas carburizing and quenching method is known in which carbon is permeated and diffused into the surface layer of the member to form a hardened skin. This gas carburizing and quenching method uses hydrocarbon gas as a carbon source,
For example, an iron-based workpiece is heated to 900° to 950°C in an atmosphere consisting of propane gas, hydrocarbon gas, endothermic shift furnace gas, exothermic shift furnace gas, N2 gas, etc. Form a carburized layer, then 8
It consists of slow cooling to 5σ to 800℃ and then immersing it in cooling fs (usually oil) to harden the surface layer, which improves the wear resistance, fatigue resistance, etc. of iron-based parts. There is.

However, the above-mentioned brazing and carburizing processes are usually performed separately as completely separate processes.

In other words, for iron-based components that require mechanical strength imparting and brazing metal treatment, the brazing metal treatment is performed separately as a brazing metal treatment.
Thereafter, the obtained brazed product was subjected to gas carburization treatment in a separate process. Since the reprocessing was performed using completely separate equipment, processes, and lines, the heating process had to be repeated.

In other words, since the above-mentioned two treatments were conventionally performed separately in separate processing departments, the respective processors, etc., after examining various treatments, decided to select an appropriate atmosphere gas for the carburizing treatment. It was discovered that by using this method, it can be effectively used for brazing bonding, and by making the temperature conditions common to both treatments, both treatments can be performed effectively at the same time C11 The object of the present invention is to The purpose of this invention is to improve work efficiency and productivity by simplifying the work steps of joining parts and carburizing.

The method of the present invention involves bringing two or more iron-based members to be joined into contact with each other in a carburizing gas atmosphere with a brazing filler metal interposed therebetween;
The member is heated and maintained at a temperature higher than the melting point of the brazing material and carburizing temperature using high-frequency heating means to perform bonding and carburizing at the same time, and then subjected to quenching treatment.

Here, the term "ferrous member" refers to a member made of steel, such as carbon steel or copper alloy, which is usually subjected to carburizing treatment.

The high-frequency heating temperature and holding time vary depending on the type of member to be treated and the brazing material, and the mechanical strength required for the product. The heating temperature can be appropriately selected so as to be within the normal carburizing temperature range and at or above the melting point of the brazing filler metal, but a temperature higher than the melting point of the brazing filler metal by about 30°C or more, particularly about 3σ to 100°C higher, is preferable. For example, when using copper brazing filler metal, 11
It is preferable to heat and hold at 00° to 1180° C. for 3 to 15 minutes.

As the brazing filler metal, it is possible to use a metal that is normally used for joining steel materials by brazing, but a metal whose melting point is approximately within the carburizing temperature range is preferable, such as copper, steel wire brazing filler metal, etc. It will be done.

The carburizing gas atmosphere includes 0.5 to 30 g of a hydrocarbon gas, such as propane gas, in the brazing atmosphere such as endothermic shift furnace gas, exothermic shift furnace gas, or phonetic gas, and particularly about Although it is advantageous to use carbonaceous materials doped with carbon dioxide, the process according to the invention can also be carried out in the atmospheres used in conventional carburizing processes.

In the quenching process, the workpiece is usually slowly cooled to a quenching temperature of 800° to 850°C [7], then a cooling medium such as water, oil, etc.
This is done by immersion in the water.

Next, an example of the present invention is shown in the figure. I will explain according to io.

In the eleventh step, f is provided in the furnace chamber 2 of the high frequency heating furnace 1.
On the Lfc treatment receiving jig 4, a circle f1 made of low carbon sandwiched between the brazing filler metal 5' and... 1 and disc-shaped workpiece 5 to be treated, etc., and 99% Nl gas as carburizing gas.
, a mixed gas consisting of 1% propane gas is fed into the furnace chamber 2 and the workpiece 5 from the casing inlet 6. Next, the receiver J44 is rotated in order to uniformly heat the product to be processed. The rotation of the receiving jig 4 is performed by transmitting the driving force of the motor 9 via the chain 8 to the slotted rod 7 provided at the lower part of the receiving jig 4. On the other hand, apply a 1w1bia wave output to the #+Rinba coil 3, heat it to a brazing and carburizing temperature of 1100 to 1150°C, hold it at that temperature for 3 to 5 minutes, and calculate the wax value of the processed product and its table. The permeation and diffusion of carbon into the parts is carried out at the same time.

Next, the quenching oil 11 was kept at 60°C in the quenching tank 10 after being gradually cooled to the quenching degree of 850 to 800°C.
Soak in.

The above thermal cycle is shown in FIG. In Figure 2, A is the force and temperature at the start of brazing carburization, B is the time and temperature at the end of carburizing, Q is the time at the end of slow cooling and the quenching temperature f&'r, and R is the time at the end of quenching and the quenching temperature. The input temperature is 723° C., and A1 is the Al transformation point of 723°C.

In the heat treatment cycle shown in Figure 2, the austenite grain size is JIB@F1! Since the number is very large (1 to 2), if specific properties are particularly required, the temperature is gradually cooled from the brazing carburizing temperature to below the -HAI transformation point, then heated again to the quenching temperature, and then quenched. I do. The thermal cycle in this case is shown in FIG.

In FIG. 3, A, B, A1, and RFi are as explained in FIG. 2, where C indicates the end point of slow cooling and the temperature, and Q indicates the quenching point and temperature.

The brazed joint Φ carburized product obtained in the above example and the product obtained by applying conventional carburizing and quenching to the same low carbon steel as used in the above example were heated without lubrication. The test pieces were subjected to the Okoshi type abrasion test under the following conditions: Ohkoshi type abrasion test: Non-lubricated load: 3.2 Kf Friction distance: 400 m (constant) The results are shown in Figure 4. In FIG. 4, curve A shows the wear amount of the product produced by the method of the present invention, and curve B shows the wear amount of the product produced by the conventional method.

According to the method of the present invention, brazing and carburizing can be performed simultaneously, which simplifies the process and improves work efficiency and productivity. This makes it possible to mass-produce and reduce costs for iron-based products that require brazing and carburizing.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a high-frequency heating furnace apparatus that can be used to carry out the method of the present invention, FIGS. 2 and 3 are graphs showing heat treatment cycles, and FIG. 4 is a diagram showing the method of the present invention and the conventional method. 1 is a graph showing the results of shore abrasion tests on products according to the method. In Fig. 1, l... High frequency heating furnace 3... High frequency coil 4... Workpiece receiving jig 5... Workpiece 6... ...Gas inlet lO...Quenching tank patent Output person Toyota Motor Corporation Fang 1
Figure 2 Figure 3 Figure 3

Claims (5)

[Claims] (1) Two or more iron-based members to be treated are brought into contact with each other with a brazing material interposed in a carburizing gas atmosphere, and the members are heated to a carburizing temperature equal to or higher than the melting point of the brazing material using high-frequency heating means. A short-time bonding and carburizing treatment method, which is characterized in that bonding and carburizing are carried out simultaneously while holding, followed by quenching. (2) The method according to claim 1, characterized in that high frequency heating is carried out in a nitrogen gas atmosphere to which 0.5 to 30 g of hydrocarbon gas is added. (3) Using copper brazing filler metal, 1100°
The method according to claim 1 or 2, characterized in that high frequency heating is carried out at a temperature of 3 to 15 minutes at a temperature of 1180°C to 1180°C. (4) After high-frequency heating, heat the workpiece to 800° to 800°
Any one of claims 1 to 3, characterized in that it is slowly cooled to 50'C and then immersed in a cooling medium.
The method described in section. (5) After high-frequency heating, the member to be treated is slowly cooled to below the A1 transformation temperature, then heated to 800° to 850°C, and then immersed in a cooling medium. The method according to any one of Item 4.