JPH06106337A - Method for joining cemented carbide and steel - Google Patents

Abstract

PURPOSE:To provide the method for joining cemented carbide and steel suitable for joining the parts to be joined to the steel particularly requiring wear resistance in a technique for joining the cemented carbide and the steel. CONSTITUTION:An inserted silver brazing filler metal is held for 20 minutes at the solidus temp. or below and >=727 deg.C and thereafter, the inserted silver brazing filter metal is melted by heating in the heating stage in the method of inserting the silver brazing filler metal between the cemented carbide and the steel and melting the brazing filler metal by heating thereby joining the cemented carbide and the steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining technique for cemented carbide and steel, and more particularly, it is suitable for joining parts to be joined to steel particularly requiring wear resistance, for example, hammer parts such as a crusher. The present invention relates to a method for joining cemented carbide and steel.

[0002]

2. Description of the Related Art Conventionally, cemented carbide has a wide range of uses such as cutting tips, drawing dies, crushers, wear resistant and impact resistant tool parts, and is often used as a steel joining part. As a typical method for joining the cemented carbide and the steel, there is a brazing method using an Ag-based brazing material (hereinafter referred to as silver brazing material) or a copper brazing material.

For example, when a cemented carbide is used as a hammer for a crusher, flux brazing in which silver brazing is inserted using copper as a stress relaxation material is generally performed. In the publication, the superiority of the method of brazing in a furnace using silver braze containing Ti is proposed.

[0004]

As described above, a method for joining cemented carbide and steel using copper as a stress relaxation material and silver brazing material as an insert material in the above-mentioned conventional technique is also used.
It has an advantage that it can be easily used and is effective, or by using a clad material in which an insert material is laminated in advance, it is easier and easier to handle.

However, a method of inserting a silver brazing material and brazing in a furnace using the stress relaxation material as in the above-mentioned conventional technique is to bond both the cemented carbide and the stress relaxation material and the steel and the stress relaxation material. All must be sound. However, when brazing is actually performed in a furnace, a defect may occur between steel and copper as a stress relaxation material. This is particularly noticeable when the joint surface is inclined, and in that case, there is a problem that a large defect occurs and a sound joint cannot be obtained.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for joining cemented carbide and steel which solves the above-mentioned problems with a simple structure and obtains a sound joined body. There is.

[0007]

The above object can be achieved by the method of joining cemented carbide and steel described in the claims. That is, during the heating in the method of inserting the silver brazing filler metal into the cemented carbide and the steel, heating and melting it, the temperature is kept below the solidus temperature of the inserted silver brazing filler metal and at a temperature of 727 ° C. or higher for 20 minutes or more. However, the gist is a method of joining a cemented carbide and steel in which the silver brazing material that has been inserted is then heated and melted. Hereinafter, the operation and the like of the present invention will be described based on Examples.

[0008]

EXAMPLE In the present invention, a method of joining a cemented carbide and a steel by inserting a silver brazing filler metal and heating and melting the brazing filler metal is used.
By holding at a temperature of 7 ° C. or higher for 20 minutes or longer, and then reheating the melted insert material to join it, it is possible to obtain a sound joined body without defects.

FIG. 1 shows the above-mentioned joining method. In FIG. 1, the horizontal axis represents time and the vertical axis represents temperature, and heating is started from the position of the intersection of the horizontal axis and the vertical axis. Temperature below solidus temperature of material and above 727 ° C (A
When it reaches the junction temperature (point B), it is held at that temperature for 20 minutes or longer, and when it reaches the joining temperature (point B), it is joined again at that temperature. Lower.

The reason why the temperature of the insert material is kept below the solidus temperature of the insert material and above 727 ° C. for 20 minutes or more during heating is as follows. That is, when the temperature reaches 727 ° C. or higher during heating, the temperature rise of the steel becomes slow due to the heat absorption by the Al transformation. Such a phenomenon does not occur in the cemented carbide or the copper of the stress relaxation material and the temperature rises as it is, so that a temperature difference occurs between the cemented carbide or the steel and the steel.

When the heating is continued with the temperature difference kept, the cemented carbide and the stress relaxation material reach the melting temperature of the insert material faster than the steel. When the insert material melts, the temperature of the steel is low, so that the difference in the wettability between the stress relaxation material and the steel with respect to the insert material becomes large, and the insert material does not wet the steel side and causes defects. Defects become noticeable when joining inclined surfaces because the flow occurs in the insert material.

However, by maintaining the temperature below the solidus temperature of the insert material and above 727 ° C. for 20 minutes or more during heating, the transformation of steel was completed and the temperature difference was eliminated. Even if it is heated thereafter, a temperature difference does not occur, and it becomes possible to obtain a sound joint.

The inventors of the present application conducted the following comparative test in order to confirm the above description. First of all,
Between the cemented carbide 1 and the steel (S45C) 4 in the shape shown in
The insert material (silver braze containing Ti) 2a / stress relaxation material (oxygen-free copper 0.5t) 3 / insert material 2b were laminated and heated in a vacuum. At that time, the temperature and time held during heating were changed, and finally heated to 850 ° C. for joining. Table 1 shows the holding temperature and holding time at that time. Ultrasonic flaw detection was performed on the obtained bonded body, and the results are also shown in Table 1 as the bonding rate.

FIG. 3 is a diagram for explaining the procedure for measuring the temperature of the test body in the above comparative test. As shown in FIG. 3, R thermocouples 5 and 6 were resistance-welded to the respective members of the cemented carbide 1 and the steel 4, and the temperature change was recorded in the recorder 7. The temperature was controlled by measuring the furnace temperature with a thermocouple attached to the furnace.

The sample 11 in Table 1 was joined without holding the temperature during the temperature rise, and the samples 7 to 10 were held at a temperature of 727 ° C. or lower. In all of these cases, there was a temperature difference between the cemented carbide or the stress relaxation material and the steel at the melting temperature of the insert material, and the joining rate of the obtained joined body was low.

[0016]

[Table 1]

In Samples 3 to 6, there is no temperature difference between the cemented carbide and the stress relaxation material and the steel at the melting temperature of the insert material, and the bonding rate of the obtained bonded body is high and sound bonding is performed. I was able to. Further, as a result of using these bonded bodies as a hammer of a crusher, samples 3 to 6 did not crack or peel, but samples 1, 2 and 7 to 11 crack or peel in several hours after use. That caused a problem.

[0018]

As described above, according to the present invention, as described in detail in the above embodiment, it becomes possible to provide a technique for producing a sound joined body in joining a cemented carbide and steel. Produce an effect.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a joining method according to the present invention.

FIG. 2 is a diagram for explaining the shape and position of each member when joining cemented carbide and steel for comparison.

FIG. 3 is a diagram illustrating a procedure for measuring a temperature of a test body during a comparative test.

[Explanation of symbols]

 1 Cemented Carbide 2a, 2b Insert Material 3 Stress Relaxation Material 4 Steel 5,6 R Thermocouple 7 Recorder 8, 9 Resistance Welding

Claims (1)

[Claims] 1. A temperature not higher than the solidus temperature of the inserted Ag-based brazing material and not lower than 727 ° C. in a heating process in a method of joining a cemented carbide and steel by inserting an Ag-based brazing material and heating and melting. The method for joining cemented carbide and steel, characterized in that the Ag-based brazing filler metal is held for 20 minutes or more and then melted by heating.