JPH02160187A - Method for joining intermetallic compound of ti-al system - Google Patents

Abstract

PURPOSE:To allow easy joining of intermetallic compds. of a Ti-Al system to each other without generating the deterioration in the joint part by executing the conditions of a specific friction stress, specific friction stress imparting time, and specific upsetting pressure at the time of joining the above-mentioned compds. to each other by friction pressure welding. CONSTITUTION:The conditions of 3 to 18kgf/mm<2> friction pressure P1, 5 to 24 seconds time t1 for impartation the friction pressure, and <=24kgf/mm<2> upset pressure P2 are satisfied at the time of joining the intermetallic compds. of the Ti-Al system to each other by friction pressure welding. The pressure P1 is applied to a material 1 to be rolled and a material 2 to be rolled is rotated by a motor and is supported by bearings 3, 4. The material 1 is held static during this time. Joining is not executed when the friction pressure P1 is lower than the specific range. The materials are burred or cracked if the pressure exceeds the range. The burred part is cracked if the upset pressure P2 exceeds the specific value. The coupling by the friction pressure welding is enabled in this way and the excellent characteristics of the intermetallic compds. are effectively utilized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a Ti-Al1-based intermetallic compound and a Tt-Ajl
The present invention relates to a method of joining intermetallic compounds by friction welding.

[Prior Art] T1-Al7-based intermetallic compounds are promising materials with low specific gravity, excellent high-temperature strength, creep resistance, and oxidation resistance.

However, because of its low plastic deformability, it is difficult to form parts into complex-shaped parts by plastic working. Therefore, methods of manufacturing complex-shaped parts using methods such as cutting, precision casting, constant temperature forging, etc. are being considered.

However, T L-AN intermetallic compounds are difficult-to-cut materials, and manufacturing complex-shaped parts by cutting is disadvantageous because the manufacturing cost is high and the yield from material to product is low. There are many.

Precision casting is an effective molding method when the plastic deformability is small, but it is prone to foreign matter inclusion and shrinkage pores.

There are problems such as contamination with impurities from the furnace wall during melting, and the difficulty increases as the shape becomes more complex and larger.

Isothermal forging is considered to be advantageous in terms of material yield, but T
Due to the high deformation resistance and low deformability of i-Al intermetallic compounds at high temperatures, it is difficult to apply large deformations, so it is necessary to use isothermal forging dies, mold release agents, etc. to form parts with complex shapes. There are many technical problems.

To solve these problems, a method of manufacturing each part of a complex-shaped part and joining and integrating them by friction welding is an effective method for reducing the difficulty of molding.

However, at present, no study has been conducted regarding the friction welding method between TL-Al based intermetallic compounds.

[Problems to be Solved by the Invention] Friction welding is a simple joining method mainly used for joining steels such as heat-resistant steel and tool steel.

Friction welding is one of the welding methods that uses mechanical energy, and is a method in which parts to be welded are butted against each other and subjected to relative rotational motion, and the frictional heat generated on the contact surfaces is used to perform pressure welding. .

During friction, the unevenness and oxide film on the groove surface are destroyed and discharged outside the surface as debris, so there is also the advantage that no pretreatment of the groove surface is required.

FIGS. 3(a), 3(b), and 3(c) are explanatory diagrams of the above-mentioned friction welding method.

In FIG. 3(a), the application time of the friction pressure P1, 1 is a material to be welded, the friction pressure P1 is applied in the direction of the arrow in the figure, for example, by a hydraulic cylinder (not shown), and 2 is another material to be welded. Rotation is applied by a motor (not shown). 3 and 4 are bearings.

During this time, the pressurized material 1 is held stationary by a rotation prevention device (not shown).

In FIG. 3(b), the upset pressure P2 application time,
For example, by a hydraulic cylinder (not shown), the pressure welded material 1 is
An upset pressure P2 is applied by a motor (not shown) in the direction of the arrow in the figure.

During this time, the material to be welded 2 is pressed by a brake device (not shown).
Rotating and stationary.

FIG. 3(C) shows the friction pressure P1 and its application time t1.
FIG. 3 is a diagram showing the upset pressure P2 and its application time t2.

However, when brittle materials such as Ti-Al intermetallic compounds are joined by friction welding, large shear stress and compressive stress are applied near the joint, so there is a high possibility that the materials will crack.

In addition, T1-Al intermetallic compounds have high high-temperature strength and low deformability, so they are heated during friction welding, and cracks occur in the formed part as it deforms as if expelled from the joint. There were problems such as the material getting inside the material.

That is, the present invention aims to solve the above-mentioned problems.
The object of the present invention is to provide a method for joining i-Al based intermetallic compounds by friction welding.

[Means for Solving the Problems] The joining method according to the present invention is suitable for manufacturing complex-shaped parts that take advantage of the excellent properties of TL-Al intermetallic compounds. In order to alleviate the above problem, each part is joined by friction welding, and the conditions for joining are as follows: Friction pressure P: 3 to 18 kgf/mm2
This is a welding method using friction welding, in which a good welding state can be obtained by setting the friction pressure application time t: 5 to 24 sec, and the upset pressure P: 24kzrl or less.

In addition, the Ti-Aj7-based intermetallic compounds targeted by the present invention are specifically T i Al , T i 3Ajl
.

An Ti, Ti TIAN (has a higher amount of Ti than the chemical composition of TiAj! and is mainly composed of Ti AJ), Aff TIAN (has a higher amount of Ag than the chemical composition of TIAN and is mainly composed of T L AN), Ti Ti Aj) (Ti3r1
The amount of Ti is higher than the chemical composition of ch 3 Ap, and the main component is Ti.
consisting of AI), AN Ti A13
rlch 3(Tia
Aj! The amount of Afi is larger than the chemical composition of
It is a compound whose main compositional element is

[Function] Ti-Al intermetallic compound and Ti-Al in the present invention
Friction welding of Ti-Ajl-based intermetallic compounds is used to manufacture complex-shaped parts that take advantage of the excellent properties of Ti-Ajl-based intermetallic compounds. Since there are many technical problems, the various parts of the parts are joined and integrated by friction welding, which solves the technical problems and further reduces the manufacturing cost.

The reason why the range of friction welding conditions was determined so that a good bonding state between the Ti-/l-based intermetallic compound and the Ti-AN-based intermetallic compound of the present invention can be obtained will be described below.

If the friction pressure P is less than 3 kgf/1lI2, the temperature of the friction surface will not rise, so no welding will occur, and the pressure will be 18 kgf'/u.
If it becomes larger than i2, too much paris will be generated and large cracks will occur at the paris, or the friction pressure P will be too strong and cracks will occur near the friction surface.

Therefore, the range of the friction pressure P1 was set to 3 to 18 kgf'/kai-.

In principle, the upset pressure P takes a value greater than the friction pressure P1, but if it exceeds 24 kgf/am2, large cracks will occur in the paring section.

For this reason, the upset pressure P2 was set to 24) cgf/m or less.

Regarding the lower limit of the upset pressure P, the friction pressure P
■ It is desirable to set the value to 3 kgf/am, which is the same as the lower limit of .

In addition, if the application time tl of the friction pressure P is less than 5 seconds, the friction surfaces will not be heated enough and will not be joined.
If it exceeds sec, the amount of heat generated becomes too large and a large amount of debris is generated, which tends to cause cracks.

Therefore, the time t1 for applying the friction pressure was set to 5 to 248 ec. Next, examples of the present invention will be described.

[Example] (Example 1) TiA9, which is one of the Ti-Ajl-based intermetallic compounds, was cast, and a round bar with a diameter of 10 mm was prepared.

This was attached to a brake method friction welding machine, and the friction welding conditions were friction pressure P and upset pressure P 2 .

A joining test by friction welding between TiAl and TiA1 was conducted while varying the application time t1 of friction pressure.

Three conditions were used for the rotation speed: 1200, 3050, and 380 rpm, and the upset time t2 was 5 sec.

To evaluate the joint condition, check for cracks in the paris.

The presence or absence of cracks by optical microscopic observation of the cross section of the joint.

And the tensile strength of the joint was investigated.

Table 1 shows the relationship between each friction welding condition and the welding state.

In this example, no large cracks in the paris or cracks in the cross section of the joints were observed.

The tensile strength of the joint is also 38) cgr/2, which is the same as that of the base material, so no deterioration of the joint is observed, indicating a good joint condition.

However, as shown in the comparative example, the friction pressure P1 is 3 kg1
'/If smaller than 2, or friction pressure application time 1
If 1 is smaller than 5 sec, no bonding is performed.

or when the upset pressure P2 is greater than 24 kgr/fin, it is observed that a large crack occurs in the paris part, that the crack extends to the joint part, and that cracks occur in the cross section of the joint part. Ta.

(Example 2) Cast T i Al, isothermal cast T i Al
In order to perform friction welding by processing the joining surfaces of cast Tia A II round bars with a diameter of 10+mφ into convex and concave shapes, the high-temperature strength of each material was measured by a high-temperature tensile test.

Casting T i AjJ, constant temperature casting T i AN, casting Ti3Al (D tensile strength mackerel, husband k 64 kgrhvr
, 56 kgr/n+2.41 kzr/2
The high-temperature strength is the highest for cast T LAN,
Next, T LAN was constant temperature cast.

Cast T is A J? The order was

Friction welding of cast T i AN and constant temperature cast TiAl3 was performed using the combinations shown in Table 2.

The shape of the joint surface is shown in Fig. 1 (a), (b), and Fig. 2 (
The measurements were carried out using the dimensions and shapes shown in a) and (b).

The friction welding conditions were a rotation speed of 305 rpm and a friction pressure P of 6 kgf/n+2. The application time t of friction pressure is 1
2See, upset pressure P to 12kgf/+n
, the abset time t2 is 4 seconds.

By processing the second surface joint surface into a concave or convex shape,
The shape of the cracks was improved, no cracks were observed, and good bonding strength was obtained as shown in Table 2.

(Example 3) Friction welding of cast T i Afl and cast T ia A I round bars with a diameter of 10 es was performed using the combinations shown in Table 3.

The friction welding conditions are: rotation speed 305 Orpm + friction pressure P 4 kgf/sl, friction pressure application time t1 1O
sec, upset pressure P 12 kgr/mm,
Abset time t2 is 3 seconds.

Part 3 table In this case as well, the shape of the joint surface is shown in FIG. 1(a).

As shown in (b) and Figures 2 (a) and (b), the shape of the paris was improved by machining it into a concave or convex shape, and no cracks occurred, as shown in Table 3. As shown in Figure 2, good bonding strength was obtained.

As described above, different Ti-AN intermetallic compounds have different high-temperature strengths due to differences in manufacturing conditions.
L-based intermetallic compounds are also bonded using the friction welding method of the present invention, and by processing the shape of the bonded surface into a convex or concave shape depending on the high-temperature strength, an excellent bonded state with improved Paris shape can be achieved. can get.

(Comparative example) As a comparative example, a cast TiAjJ with a diameter of 10111φ
The circular sections of the round bars were vacuum-brazed to each other and the tensile strength of the joint surfaces was determined.

Table 4 shows the relationship between the brazing filler metal, brazing temperature, brazing time, and tensile strength of the joint surface.

TiAg is joined by brazing, but the joining strength is at a low level, less than half that of the joining method using friction welding of the present invention.

The above joint surfaces were finished by machining and polishing.

Even if the bonding surfaces are finished by shot blasting, pickling, surface treatment, etc., bonding can be achieved according to the present invention.

[Effects of the Invention] According to the method for joining Ti-AΩ-based intermetallic compounds of the present invention, joining by friction welding of the Ti-A, Q-based intermetallic compound and the Ti-Al1-based intermetallic compound can be performed at the joint portion. When manufacturing complex-shaped parts that take advantage of the excellent properties of T1-Al1 intermetallic compounds, it is possible to easily join and integrate each part of the parts without causing deterioration using friction welding. This has the effect of alleviating manufacturing problems and lowering manufacturing costs.

[Brief explanation of the drawing]

Figures 1(a) and (b) are schematic diagrams of the bonding surfaces (convex surfaces A and B) of the test materials of Example 2 and Example 3, which are examples of the present invention; ) are the same <Example 2 and Example 3
A schematic diagram of the bonding surfaces (concave surfaces A and B) of the sample materials. FIGS. 3(a), 3(b), and 3(c) are explanatory diagrams of the friction welding method. In the figure, 1 and 2 are materials to be welded under pressure, and 3 and 4 are bearings. Pl is friction pressure, P2 is upset pressure, 11 is friction pressure application time, and t2 is upset pressure application time.

Claims (1)

[Claims] When joining Ti-Al based intermetallic compounds by friction welding, friction pressure P_1: 3 to 18 kgf/mm^2 Friction pressure application time t_1: 5 to 24 sec Upset pressure P_2
: A method for joining Ti-Al based intermetallic compounds, characterized by applying a condition of 24 kgf/mm^2 or less.