JPH02160188A - Method for joining intermetallic compound of ti-al system and ti-based alloy - Google Patents

Abstract

PURPOSE:To allow easy joining of an intermetallic compd. of a Ti-Al system and a Ti-based alloy 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 1 to 6kgf/mm<2> friction pressure P1, 1 to 4 seconds time t1 for impartation the friction pressure, and <=10kgf/mm<2> upset pressure P2 are satisfied at the time of joining the intermetallic compds. of the Ti-Al system and the Ti-based alloy 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 enable in this way and the excellent characteristics of the intermetallic compd. are effectively utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of joining a Ti-Al intermetallic compound and a Ti-based alloy by friction welding.

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

However, because of its low plastic deformability, it is extremely 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, T1-Al intermetallic compounds are difficult-to-cut materials, and manufacturing complex-shaped parts by cutting increases manufacturing costs and has disadvantages because the yield from material to product is low. 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
i-AJJ intermetallic compounds have high deformation resistance at high temperatures;
Due to its low deformability, it is difficult to apply large deformations, and there are many technical problems involved in molding complex-shaped parts, including constant temperature forging dies and mold release agents.

To solve these problems, manufacturing each part of complex-shaped parts individually and joining them together using friction welding is an effective method to reduce the difficulty of forming and processing, and to reduce the difficulty of forming parts. If the properties required for the part are satisfied by partially using Ti-based alloy, Ti-A
It is an advantageous method in terms of manufacturing cost to manufacture complex-shaped parts by joining an 11-based intermetallic compound and a Ti-based alloy.

However, although research and development of Ti-Afi intermetallic compounds has recently become active, there is currently no study on friction welding of Ti-Al intermetallic compounds and Ti-based alloys. .

[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(e) 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). 3.4 is a bearing.

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(e) shows the friction pressure P1 and its application time 11,
FIG. 3 is a diagram showing the upset pressure P2 and its application time t2.

However, when brittle materials such as Ti-Al) based 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, Ti-Al intermetallic compounds have high high-temperature strength and low deformability, so they are heated during friction welding and deformed as if expelled from the joint, causing cracks to form. There were problems such as penetrating 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 an i-Al1-based intermetallic compound and a Ti-based alloy by friction welding.

[Means for Solving the Problems] The joining method according to the present invention reduces manufacturing costs and improves manufacturing efficiency by joining complex-shaped parts with Ti-based alloys that take advantage of the excellent properties of Ti-Al intermetallic compounds. In order to solve the problem, parts of each part are joined using friction welding.
The conditions for joining are: Friction pressure Pl: 1 to 6 kgf/me2
This is a welding method using friction welding, in which a good welding state can be obtained by setting the friction pressure application time t1: 1 to 4 sec, and the upset pressure P: 10 kgf/s+a2 or less.

Furthermore, if necessary, the bonding method is capable of preventing deterioration of the heat-affected zone and obtaining a good bonding state by performing a subsequent structure stabilizing heat treatment.

Incidentally, these are T 1-Al intermetallic compounds and Ti-based alloys that are targeted in the present invention.

Regarding Ti-Al1-based intermetallic compounds, specifically T
iA1. TL AI, Al3Ti, Ti.

chT iA R (The amount of Ti is higher than the chemical composition of T t A II, and its main component is Ti Al)
, 1, 1c h T iA I (the amount of Al is higher than the chemical composition of T iA D, mainly composed of TiAjl), TirichTi AD (Ti3A
There is more Tijl than in the chemical composition of II, and the main component is T.
ia A 1), AM Ti An
(It has a larger amount of 1 than the chemical composition rich 3 of Ti3Al, and is mainly composed of T ia AR). It is a compound whose main compositional elements are Ti and Afl.

Regarding Ti-based alloys, existing Ti-based alloys such as
Specifically, Ti-6Ail-4V alloy.

TiTi-6Al-2Sn-42r-2 alloy.

T1-6Af! -2Sn-4Z r-6Mo alloy.

T t-6Aj-6V-2Sn alloy, Ti-8Ag-I
M o -IV alloy, Ti-5Al-2,5Sn alloy, Ti-3AjJ-2,5V alloy, Ti-10V-2
Fe-3Al alloy, Ti-5A, 77-2Sn77-2
Sn-2Zr-4 alloy, Ti-15V3Cr-3Sn-
This is an alloy targeted for 3Aj1 alloy, etc.

[Function] The friction welding of the Ti-Al7-based intermetallic compound and the Ti-based alloy in the present invention can achieve T 1-
Since Al-based intermetallic compounds have poor workability and many technical problems related to melting and casting, we have solved these technical problems by joining a part of them into a Ti-based alloy using friction welding. This solves the problem and further reduces manufacturing costs.

The reason why the range of friction welding conditions was determined so that a good bonding state between the T1-Al1-based intermetallic compound and the Ti-based alloy of the present invention can be obtained will be described below.

If the friction pressure P is less than 1 kgf/Tsuru2, the temperature of the friction surface will not rise and no bonding will occur; if it exceeds 6 kgf/Tsuru2, the friction pressure P will be too strong and Cracks occur at the joints between the intermediate compounds. Therefore, the range of friction pressure P1 is set to 1 to 6 kg.
It was set to f7.12.

In principle, the upset pressure P2 takes a larger value than the friction pressure P1, but if it exceeds 10 kg rims 2.
Cracks occur on the rt1 alloy side and the Ti-Al intermetallic compound. For this reason, the upset pressure P2 is set to 10 kgr/m.
It was set to be less than 2 servings.

Regarding the lower limit of the upset pressure P2, the friction pressure P
■ It is desirable to set the value to 1 kgf/2, which is the same as the lower limit of .

Furthermore, if the application time 11 of the frictional pressure P is less than 1 sec, the friction surfaces will not be heated enough and will not be joined, and the 4 s
If it exceeds ec, the heat affected zone deteriorates and the strength decreases.

For this reason, the application time t1 of friction pressure was set to 1 to 4 seconds.

Furthermore, if necessary, heat treatment is performed to stabilize the structure of the joint and the heat-affected zone in its vicinity, thereby preventing deterioration due to the heat-affected zone and providing good joint strength.

Next, examples of the present invention will be described.

[Example] (Example 1) TiAl, which is one of the T1-Al based intermetallic compounds, was cast, and a round bar with a diameter of 10 mm was prepared from it, and this round bar and the T1-6Al-4V alloy were cast. A round bar with a diameter of 10 mmφ is attached to a brake method friction welding machine, the planes are butted together, and the friction welding conditions are friction pressure P and friction pressure application time t.
, upset pressure 1 [by varying the force P2, respectively, T i A, 17 vs. Ti-6
A joining test was conducted using friction welding of 1-4V alloy.

The rotation speed at this time is 1200.3050.3600 rpm
The three conditions were as follows, and the upset time t2 was 5 seconds.

Thereafter, a portion of the sample was heat-treated to stabilize the structure by heating at 950°C and holding for 10 minutes, followed by air cooling.

The cross-sections of these joints were observed with an optical microscope and the joints were subjected to a tensile test to evaluate the joint state.

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

In this example, the bonded state was good in all cases, and no cracks were observed in the cross section of the bonded portion.

Furthermore, the tensile strength of the joint is 40 kgf/u+2 or more, and there is no deterioration of the joint.

However, as shown in the comparative example, the friction pressure P1 is 1 kgf.
lII is smaller than 112 (Magic 13), or when the friction pressure application time t1 is shorter than 1 sec (Magic 14).
) is not joined.

This was the part closest to the joint surface of part 1.

In addition, f subjected to structure stabilization heat treatment in the example of the present invention
lJ (seed 1O-12) has a tensile strength of 40kgr/m
m2 or more, but when the friction pressure application time t1 exceeded 4 sec in the comparative example (fill
1g), the tensile strength remains low even when subjected to structure stabilization heat treatment.

or when the upset pressure P exceeds 10 kg rhm (NlllL17), the intermetallic compound T i
Cracks occur in the Al joint, especially when the upset pressure P2
If it is 10 kgr/am2'Ir (k17)
Cracks also occurred on the Ti-6A1-4V alloy side.

If the friction pressure application time t1 exceeds 4 seconds (klB, 1B'), the temperature will rise too much due to heat generation, and the microstructure of the joint and heat-affected zone will change, especially the heat on the Ti-based alloy side. The crystal grains became coarse in the affected zone and the tensile strength decreased.

The fracture position during the tensile test was determined by processing the hot type (Example 2) on the Ti-based alloy side.The joint surface was processed into convex and concave shapes, and 11 tM pressure P l: 2) tgi'/+n2 Friction pressure application time t: Table 2 shows examples of friction welding under the friction welding conditions of 4 sec upset pressure P2: 4 kgf/mm2.

The joint surface is processed into convex surfaces A and B shown in Fig. 1(a) and (b) for Ti-6AJ-4V alloy, and T
i Al was processed into concave surfaces A and B shown in FIGS. 2(a) and 2(b).

Some of these were subjected to structure stabilization heat treatment (950°C
nAC) was applied, and the tensile strength of all bonded examples was measured.

By changing the shape of the joint, the Paris shape has been improved,
Good bonding strength was obtained in all cases with the combinations shown in Table 2.

The table 2 bar and the circular cross section of a Ti-6Afi-4V alloy round bar with a diameter of 10 mm were vacuum-brazed and joined together, and the tensile strength of the joint surface after that was determined.

Table 3 shows the relationship between the brazing filler metal, brazing temperature, brazing time, and tensile strength of the joint surface.

T i AII and T 1-6Al -4V alloy are joined by halo welding, but the joining strength is at a low level of 1/2 or less compared to the joining method using friction welding of the present invention.

Table 3: * indicates tissue stabilization treatment < 950℃ x 10m1nAC
) has been applied.

(Example 3)
The bonding surfaces of Examples 1 and 2 above were finished by machining, and as a comparative example, a Ti AII diameter of 10 mm was used. Even if finished, it can be joined by the present invention.

[Effects of the Invention] According to the method for joining a Ti-Al intermetallic compound and a Ti-based alloy of the present invention, the Ti-Al intermetallic compound and a Ti-based alloy can be easily joined by using friction welding. , when manufacturing complex-shaped parts that take advantage of the excellent properties of Ti-Al intermetallic compounds, friction welding can be used to join and integrate each part of the parts, reducing manufacturing problems. This has the effect of lowering manufacturing costs.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) show Example 2, which is an embodiment of the present invention.
Schematic diagrams of the bonding surfaces (convex surfaces A and B) of the Ti-based alloy test material in Figure 2 (a) and (b) are the same <Example 2
Joint surfaces of Ti-Al1 specimens (concave surfaces A and B) in
The schematic diagrams of 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. P is the friction pressure, P2 is the upset pressure, t1 is the friction pressure application time, and t2 is the upset pressure application time.

Claims (1)

[Claims] When joining a Ti-Al intermetallic compound and a Ti-based alloy by friction welding, friction pressure P_1: 1 to 6 kgf/mm^2 Friction pressure application time t_1: 1 to 4 seconds Upset pressure P_2 A method for joining a Ti-Al intermetallic compound and a Ti-based alloy, characterized by applying a condition of 10 kgf/mm^2 or less.