JPH1034340A - Welding method of ti-al alloy, and composite wire for welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of cracks and peeling of the weld metal, and to provide high bonding strength at a low cost. SOLUTION: In a welding method of the Ti-Al alloy containing 40-50atm.% Al, welding is performed by the gas shielded metal arc welding method or the plasma arc welding method using a composite wire 1 for welding in which a core 3 made of aluminum or aluminum alloy is filled in an outer shell 2 made of titanium or titanium alloy. The composite wire 1 contains (X-5) to (X+5)atm.% Al based on the whole atomic weight of the composite wire where X (atm.%) is the Al content based on the whole atomic weight of Ti-Al alloy which is the base metal in welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for welding a lightweight, high-strength, high-heat-resistant structure made of a Ti--Al alloy material and a composite wire for welding, and more particularly to the occurrence of cracks and peeling of a weld metal. The present invention relates to a method for welding a Ti—Al-based alloy material and a composite wire for welding, which can prevent the occurrence of a high bonding strength at low cost.

[0002]

2. Description of the Related Art In recent years, Ti-Al-based alloy materials having an intermetallic compound having a single structure of TiAl (γ phase) or a mixed structure of TiAl and Ti ₃ Al as constituent phases have excellent strength and heat resistance. Therefore, it is attracting attention as a new material used for lightweight, high-strength, high-heat-resistant structures. And T
For example, i-Al-based alloy materials are being developed for practical use in turbine parts for aircraft, engine parts for automobiles, and the like, and some have already been put to practical use as lightweight heat-resistant parts.

[0003] In a Ti-Al-based alloy material that has been put to practical use as a lightweight heat-resistant part, ductility at room temperature, which is a drawback of an intermetallic compound, is improved by controlling the crystal grains of the structure. As described above, the Ti—Al-based alloy material having a controlled structure of the crystal grains, light weight, and excellent strength and heat resistance is obtained from the Al contained in the alloy material.
The amount is 40 to 50 atomic% based on the total atomic weight of the alloy material.

[0004] As a method of joining Ti-Al alloy materials having such a composition ratio to each other, for example, Ti-A
(1) There is a solid-state welding method in which a mixed green compact is used as an insert metal and high-temperature welding is performed by a direct electric current method, or a fusion welding method in which a Ti-Al sintered body is used as a solid wire.
Using Ti-Al mixed compact as insert metal,
In the solid-state joining method in which a Ti-Al-based alloy is hot-pressed, Al in the insert metal is preferentially melted into a liquid phase in a temperature rising process. Therefore, surface treatments such as smoothing and cleaning of the surface of the base material, which are usually required in the solid phase diffusion bonding method, can be simplified. Further, the insert metal can be easily manufactured in accordance with the composition of the base material.

[0005]

However, the diffusion bonding method using an insert metal has a problem that the bonding site is limited. Also, there is a problem that the joining requires a relatively long joining time and pressure for the joining, and the equipment cost increases.

In the fusion welding method using a Ti-Al sintered body as a solid wire, the ductility of the Ti-Al intermetallic compound at a room temperature is relatively low, so that the Ti-Al intermetallic compound becomes brittle and draws a wire for manufacturing a wire. There is a problem that processing becomes extremely difficult. Therefore, the manufacturing cost of the wire increases. Furthermore, if a welding wire made of a Ti-Al intermetallic compound is used as it is, the arc will not be stable during welding and an uneven welding structure will be formed.

The present invention has been made in view of the above problems, and it is possible to prevent the occurrence of cracks, peeling, and the like of a weld metal, and to obtain a Ti-Al alloy that can obtain high bonding strength at low cost. An object of the present invention is to provide a method for welding a system alloy material and a composite wire for welding.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a Ti-Al alloy.
The method of welding a Ti-Al-based alloy material containing 40 to 50 atomic% of Al is a method of welding a Ti-Al-based alloy material, wherein an outer shell made of titanium or a titanium alloy is filled with a core material made of aluminum or an aluminum alloy. The Ti-A
Assuming that the Al content relative to the total atomic weight of the l-based alloy material is X atomic%, Al is (X−
5) Use of a composite wire containing at least (X + 5) atomic%.

[0009] The composite wire for welding a Ti-Al alloy material according to the present invention is a Ti wire containing 40 to 50 atomic% of Al.
A composite wire for welding an Al-based alloy material, wherein a sheath made of titanium or a titanium alloy is filled with a core material made of aluminum or an aluminum alloy;
When the Al content with respect to the total atomic weight of the i-Al alloy material is X atomic%, the Al content with respect to the total atomic weight of the composite wire is (X-5) to (X + 5) atomic%.

The composite wire for welding is obtained by wrapping the core material while forming the material of the outer skin in a curved shape, welding the outer skin butt portion, and repeatedly drawing and annealing. Is preferred.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive experiments and research conducted by the present inventors to solve the above-mentioned problems, a composite wire in which a shell made of titanium or a titanium alloy is filled with a core material made of aluminum or an aluminum alloy is used. And Ti-A
It has been found that by welding an l-based alloy material by a gas shielded arc welding method or a plasma arc welding method, the equipment cost for welding can be reduced.

This welding composite wire wraps a core material made of Al or an Al alloy while forming a hoop (skin) material made of Ti or a Ti alloy in a curved shape, welds a skin butt portion, draws and anneals. Can be repeatedly produced. By producing in this manner, a wire having an arbitrary composition of Ti-Al can be easily produced without generating a Ti-Al intermetallic compound having low ductility at room temperature. In addition, Ti-
Compared with a solid wire using an Al sintered body, a wire having a long strip length can be easily manufactured, so that the wire manufacturing cost can be reduced.

Further, at the time of welding, the outer skin of Ti or Ti alloy and Al or Al alloy are melted,
A stable Ti-Al intermetallic compound can be formed.

Hereinafter, the reasons for limiting the composition of the Ti—Al alloy material and the composite wire for welding which are the objects of the present invention will be described.

Al in Ti—Al alloy material: 40 to 5
As 0 atomic% described above, in order to apply the Ti-Al alloy material as high strength and high heat resistance component lightweight improves ductility properties at room temperature is a drawback of the Ti-Al intermetallic compound, the strength and It is necessary to improve heat resistance. The ductility characteristics are improved by controlling the crystal grains of the structure. In order to control the crystal grains of the structure and to improve the strength and heat resistance, it is necessary to adjust the composition of the Ti-Al-based alloy material as the welding base metal. There is. The Al content in the Ti-Al-based alloy material is less than 40 at% or 50 at% based on the total atomic weight of the alloy material
When the ratio exceeds, a single phase of the γ phase or a mixed structure of the α ₂ phase and the γ phase is hardly formed, and a target lightweight, high-strength, high-heat-resistant material cannot be obtained.

Therefore, the Al content of the Ti—Al alloy material targeted by the present invention is set to 40 to 50 atomic% based on the total atomic weight of the alloy material.

Al in the composite wire for welding: (X-5)
(X + 5) atomic% (X: Al in Ti-Al alloy material
Content) Assuming that the Al content in the welding base metal (Ti-Al-based alloy material) targeted in the present invention is X atomic%, the Al content in the composite wire for welding is expressed by ( X-
5) When the content is less than atomic%, the arc in gas shielded arc welding or plasma arc welding is not stable, so that the shape of the welded portion becomes unstable. Furthermore, in addition to Al content of the weld metal obtained by welding becomes large alpha ₂ phase missing, boundary alpha ₂ phase and Ti-Al-based alloy material as the matrix is formed preferentially organized not The uniformity increases, and the strength of the weld and the boundary decreases. On the other hand, if the Al content in the composite wire for welding exceeds (X + 5) atomic%, the Ti content of the weld metal obtained by welding becomes insufficient and the structure tends to have a γ-phase single-phase structure. -Cracks easily occur at the boundary with the Al-based alloy material, and the strength at the boundary decreases. Therefore, assuming that the Al content in the Ti-Al alloy material is X atomic%, the Al content in the composite wire for welding is (X-5) to (X + 5) with respect to the total atomic weight of the wire.
Atomic%. In the present invention, since the Al content in the target welding base metal is 40 to 50 atomic%, the Al content in the composite wire is 35 to 55 atomic%.

[0018]

EXAMPLES Examples of the composite wire for welding a Ti-Al alloy material according to the present invention will be specifically described below in comparison with comparative examples.

First, composite wires having various Ti / Al ratios were produced by using a skin made of titanium and a core material made of aluminum.

FIG. 1 is a sectional view showing a composite wire according to an embodiment of the present invention. As shown in FIG. 1, in the composite wire 1, the surface of a core material 3 made of aluminum is covered with a hoop (outer skin) 2 made of titanium.

The composite wire 1 wraps the core material 3 while forming the hoop 2 into a curve, and welds the outer butt portion,
It is manufactured by repeating drawing and annealing.

Next, using these composite wires, Ti
-Butt welding of Al-based high-strength materials was performed.

FIG. 2 is a perspective view showing the shape of the base material and the welding method when performing butt welding using the composite wire according to the embodiment of the present invention. The two plate-shaped welding base materials 4 are formed with notches 4a inclined from the upper surface to the end surface and from the back surface to the end surface, leaving a root portion 5 at the center of the end surface. The root portions 5 formed on the two plate-shaped welding preforms 4 are arranged so as to abut each other, and a double-sided V-shaped welding groove portion 6 is formed.

With respect to the welding base material 4 arranged as described above, the wire 1 is used to attach MI to the groove portions 6 on both sides of the base material 4.
Both were joined by forming the weld metal 7 by G welding.

In this embodiment, a pure titanium tape of JIS H 4600 TR270C is used as the outer sheath of the composite wire, and JIS H 4040 A is used as the core material.
A composite wire having a diameter of 2.0 mm was manufactured using a 1050 W pure aluminum rod. In addition, as a welding base material, a 100 mm × 100 mm × 10 mm Ti—
An Al alloy plate was used, and the Al content was set to 40 at%, 45 at%, and 50 at% with respect to the total atomic weight of the alloy plate. Table 1 below shows these welding conditions.

[0026]

[Table 1]

Next, a tensile test was performed to observe the bead shape and the occurrence of defects in the formed weld metal and to measure the strength of the joined joint. However, the tensile test was evaluated by pulling both base materials at a speed of 10 mm / min in opposite directions with respect to the weld metal, and observing the position where the fracture occurred. Tables 2 and 3 show the conditions and evaluation results of the composite wire and the base material.
Shown in

[0028]

[Table 2]

[0029]

[Table 3]

As shown in Tables 2 and 3 above, Example N
o. In Nos. 1 to 12, the amount of Al in the composite wire is within the range of the present invention, and the amount of Al in the composite wire with respect to the amount of Al in the welding base metal is appropriately regulated. No peeling, cracking, etc. occurred at the joint. In addition, in the tensile tests, fractures occurred in all the welding base metals, and the joints had excellent strength.

On the other hand, in Comparative Example No. For 15, 16, and 18 to 22, the amount of Al in the composite wire is within the range of the present invention, but the amount of Al in the composite wire with respect to the amount of Al in the welding base metal is outside the range of the present invention. In some cases, the shape of the welded portion was defective, and peeling or cracking occurred. Comparative Example No. Also for 13, 14, 17, 23 and 24, the ratio of the amount of Al in the composite wire to the amount of Al in the composite wire and the amount of Al in the welding base metal is outside the range of the present invention. Some of them had a bad shape, and peeling or cracking occurred. Further, in the tensile tests of all the comparative examples, fracture occurred at the boundary between the welded portion and the base material or at the welded portion, and the strength of the joint or the weld metal was lower than that of the examples.

In the present invention, pure titanium is used as the material of the outer skin constituting the composite wire, and pure aluminum is used as the material of the core material. However, a titanium alloy is used as the outer material, and an aluminum alloy is used as the material of the core material. Can also. That is, in the case of a titanium alloy, for example, Si, Ni,
Zr, Cr, Co, V, Nb, Mo, Ta, Sn, M
n, Fe and Al, etc., and in the case of an aluminum alloy, for example, Si, Cu, Mg, Ni, M
It may contain n, Ti, Cr, Fe and the like.

Further, as the core material, a wire or a pipe whose cross section perpendicular to the longitudinal direction is, for example, a circle, an ellipse or a rectangle can be used.

[0034]

As described in detail above, according to the present invention,
Using a welding composite wire in which a core made of Al or an Al alloy is filled in an outer shell made of Ti or a Ti alloy, the amount of Al in this wire is regulated to an appropriate amount with respect to a welding base material, and a gas shield is formed. Since welding is performed by the arc welding method or the plasma arc welding method, it is possible to prevent the occurrence of cracks, peeling, and the like of the weld metal, and to obtain high joining strength at low cost. In addition, when the method of manufacturing the wire is appropriately selected, the manufacturing cost of the wire can be further reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a composite wire according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a shape of a base material and a welding method when performing butt welding using a composite wire according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; Composite wire 2; Hoop 3; Core material 4; Welding base material 5; Root part 6;

Claims (3)

[Claims] 1. Ti containing 40 to 50 atomic% of Al
In the method for welding an Al-based alloy material, a shell made of titanium or a titanium alloy is filled with a core material made of aluminum or an aluminum alloy, and the Al content of the Ti-Al-based alloy material with respect to the total atomic weight is X atomic%. When using a composite wire containing Al (X-5) to (X + 5) atomic% with respect to the total atomic weight of the composite wire,
A welding method for a Ti-Al-based alloy material, wherein the welding is performed by a gas shielded arc welding method or a plasma arc welding method. 2. T which contains 40 to 50 atomic% of Al
In a composite wire for welding an i-Al alloy material, an outer shell made of titanium or a titanium alloy is filled with a core material made of aluminum or an aluminum alloy, and the Al content with respect to the total atomic weight of the Ti-Al alloy material is contained. Amount X
A composite wire, characterized in that the content of Al with respect to the total atomic weight of the composite wire is (X-5) to (X + 5) atomic% when the content is expressed as atomic%. 3. The composite according to claim 2, wherein the core material is wrapped while the material of the outer skin is formed in a curved shape, and the outer skin butt portion is welded, and then repeatedly drawn and annealed. Wire.