JP2003320460A - Method for mig welding titanium and titanium alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for MIG welding which can stably and efficiently weld titanium and a titanium alloy. <P>SOLUTION: The method for MIG welding the titanium and the titanium alloy by using a pure titanium welding wire or a titanium alloy welding wire (sectional outer diameter of 1.6 to 2.0 mm) comprises a step of continuously or intermittently supplying Al or an Al alloy into a welding arc for bringing about a pulse welding current for satisfying the current conditions of 300A≤(peak current)≤500A, 2.0≤(peak current)/(base current)≤5.0, in any state of a wire, a hoop, a tube, a foil and a twist line, or any state of a particle, a wire piece, a hoop piece, a tube piece, and a foil piece, and a supply speed VA (g/s) satisfying formula of 10VA≤ρT×(ϕT/2)<SP>2</SP>×π×VT≤200VA (ρT: the specific gravity (g/mm<SP>3</SP>) of the welding wire, ϕT: outer diameter (mm) of the welding wire, VT: the feeding speed (mm/s) of the welding wire). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an M excellent in arc stability used for MIG welding of titanium or titanium alloy structural materials in the field of structures such as ships and building structures.
The present invention relates to an IG welding method.

[0002]

2. Description of the Related Art Conventionally, titanium or titanium alloy materials have been used for structural materials such as ships, building structures, automobiles, motorcycles, etc., which require high corrosion resistance. The TIG welding method (tungsten inert gas metal welding method), which is one of the non-consumable electrode welding methods, is mainly used.

In addition, as a typical welding method, there is a consumable electrode type welding method such as MIG welding method (inert gas metal arc welding method). This MIG welding method uses T
Compared with the IG welding method, it is a welding method that can obtain welding efficiency of several times or more, but when using pure Ti welding wire and welding titanium and titanium alloys with this method, the welding arc becomes unstable. , Weld beads with good appearance cannot be obtained.

This is because during welding, the arc moves violently between the oxide films present on the surface of the material to be welded (titanium or titanium alloy) in order to secure the cathode spot and maintain the arc, and the arc is rampant. It is thought to be due to the wandering phenomenon.

That is, this wandering phenomenon causes the welding bead to meander and a large amount of welding spatter to adhere to the surface of the material to be welded (titanium or titanium alloy).

As described above, in MIG welding of titanium and titanium alloys using a pure Ti welding wire, the weld bead meanders and spatter adheres due to the wandering phenomenon, resulting in a poor appearance of the welded portion. .

On the other hand, in the TIG welding method, an arc is generated using a non-consumable electrode having a high melting point, and a welding wire is supplied to a molten pool generated in a material to be welded for welding, so that spatter does not occur. Also, since the electrode side has a negative polarity (the welded side has a positive polarity), a cleaning action occurs in which the oxide film on the surface of the welded material is removed during welding, and as a result, the wandering phenomenon does not occur. The weld bead does not meander, and a weld having a good appearance is obtained.

For this reason, the TIG welding method is exclusively used when welding the structural material of titanium or titanium alloy.

For example, Japanese Patent Publication No. 59-226159 discloses a method in which two titanium strips having a worked structure are abutted with each other in the longitudinal direction and TIG-welded to soft-anneal the base metal portion in the vicinity of the welded portion. There is disclosed a method of connecting titanium strips for a connection that does not break.

However, in TIG welding, it is necessary to hold the welding torch and the welding wire in proper positions, and it is preferable that a device for holding the welding torch and the welding wire can be used in a factory or the like. In the case of a large structure, the welding operator has to move with the progress of welding while holding the welding torch and the welding wire, which increases the work load on the welding operator.

In order to reduce this work load, it is conceivable to incorporate a guide device for feeding the welding wire into the welding torch. A welding torch provided with such a device is
It is more expensive than a semi-automatic welding torch for MIG welding.

Further, in the TIG welding, the welding heat input is smaller than that in the MIG welding, so that the welding time is unavoidably long, and therefore the work efficiency is poor. Furthermore, TI
In G welding, since the welding time is long, the amount of gas used as the shield gas is inevitably large and the welding cost is high.

As an alternative welding method to the TIG welding method, Japanese Patent Laid-Open No. 2000-280076 uses a shield gas in which a trace amount of an oxidizing gas is added to an inert gas and a consumable electrode of titanium or a titanium alloy. The arc welding method for titanium and titanium alloys in which a pulse welding current is applied to perform welding is disclosed.

However, when oxygen or oxide is supplied from the shield gas as in the above welding method, the welding arc is stabilized, while a large amount of oxygen is mixed in the weld metal. It hardens and causes deterioration of mechanical properties such as reduction of elongation.

[0015]

In view of the above problems in the prior art, the present invention enables stable and high-efficiency MIG welding of titanium and titanium alloys, and further enables on-site welding by semi-automatic welding. MIG enables cost reduction by reducing the amount of shielding gas used by shortening the welding time
It is intended to provide a welding method.

[0016]

[Means for Solving the Problems] The root cause of the wandering phenomenon is an oxide existing on the surface of the material to be welded and acting as a cathode spot. If the oxide is constantly and intensively formed, the welding arc can be stably maintained and continued, and the wandering phenomenon can be suppressed.

However, according to the results of experiments conducted by the present inventor, even if the material to be welded contains an element that easily forms an oxide, it is not always the case that the surface of the material to be welded closest to the tip of the welding wire is Oxides are not always formed in a concentrated manner.

Therefore, the present inventor, if an element that easily forms an oxide is fed directly into the welding arc together with the feeding of the welding wire, the oxide acting as a cathode spot is brought into closest contact with the tip of the welding wire. The idea that it can be constantly and intensively formed on the surface of the material to be welded and the welding arc can be stably maintained and continued during welding, and the means for realizing this idea were studied.

The inventor of the present invention uses Al as an element that easily forms an oxide and a pure titanium welding wire as a welding wire, and uses Al powder for the amount of feeding Ti (the feeding speed of the welding wire). Titanium was welded by changing the supply amount and the supply amount of Ti (the supply speed of the welding wire) with respect to the supply amount of Al powder, and the external shape of the welding bead was observed.

As a result, the inventors of the present invention have found that the welding bead having a good appearance in a predetermined relationship between the Ti feed rate (welding wire feed rate) and the Al powder feed rate (Al feed rate). Found that you can get.

Further, the present inventor has found that, in the above-mentioned predetermined relationship, when a pulse welding current satisfying a predetermined current condition is used as the welding current, a welding bead having a better appearance can be obtained. .

The present invention has been made based on the above findings, and the gist thereof is as follows.

(1) In a method of MIG welding titanium or a titanium alloy using a pure titanium welding wire or a titanium alloy welding wire, Al or Al alloy is supplied at a supply rate V _A (g / sec) satisfying the following formula: A method for MIG welding titanium or a titanium alloy, which comprises supplying into a welding arc.

10 V _A ≤ρ _T × (φ _T / 2) ² × π × V _T ≤
200V _A where ρ _T : Specific gravity of welding wire (g / mm ³ ) φ _T : Outer diameter of welding wire (mm) V _T : Feeding speed of welding wire (mm / sec) (2) Pure titanium welding wire Alternatively, in a method of MIG welding titanium or a titanium alloy using a titanium alloy welding wire, Al or an Al alloy is generated at a supply speed V _A (g / sec) satisfying the following formula and a pulse welding current satisfying the following current condition. The method of MIG welding titanium or titanium alloy, characterized in that the titanium or titanium alloy is supplied into the welding arc.

10 V _A ≤ρ _T × (φ _T / 2) ² × π × V _T ≤
200 V _A where ρ _T : specific gravity of welding wire (g / mm ³ ) φ _T : outer diameter of welding wire (mm) V _T : feed rate of welding wire (mm / sec) 300 A ≦ peak current ≦ 500 A 2 0.0 ≦ peak current / base current ≦ 5.0 (3) The pure titanium welding wire or the titanium alloy welding wire has a cross-sectional outer diameter of 1.6 mm or more and 2.0 mm or less (1) Alternatively, the MIG welding method for titanium or titanium alloy according to (2).

(4) The above-mentioned (1), characterized in that the Al or Al alloy is continuously or intermittently supplied in the form of any one of a wire, a hoop, a tube, a foil and a twisted wire. The method for MIG welding titanium or a titanium alloy according to (2) or (3).

(5) The titanium or titanium alloy according to (4), wherein the wire, the hoop, the tube, the foil, and the twisted wire have a cross-sectional area of 0.01 to 25.0 mm ^2. MIG welding method.

(6) Particles of the Al or Al alloy,
Titanium according to the above (1), (2) or (3), characterized in that it is continuously or intermittently supplied in the form of any one of a wire piece, a hoop piece, a tube piece, and a foil piece. Titanium alloy MIG welding method.

(7) The particles, wire pieces, hoop pieces,
The average particle diameter or equivalent circle diameter of the tube piece and foil piece is 0.01 to
It is 2 mm, The MIG welding method of the titanium or titanium alloy as described in said (6) characterized by the above-mentioned.

(8) The MIG welding method for titanium or titanium alloy according to any one of the above (1) to (7), wherein the Al alloy is an alloy containing Al as a main component.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail. FIG. 1 schematically shows the appearance of the MIG welding device.

A torch 2 for MIG welding is made to face the material to be welded 1 and a welding wire 3 is fed by a wire feeding device (not shown), while a direct current pulse welding power source (not shown) is used.
An arc 4 is generated between the material 1 to be welded and the welding wire 3 to form a molten pool 5 in the material 1 to be welded.

Then, the welding torch 2 is moved in the direction of the arrow to form the welding bead 6. At this time, as shown in FIG. 1, the tip of the welding torch 3 and the rear of the welding arc 4 are also shielded by an inert gas such as Ar gas.

Titanium and titanium alloys are more likely to oxidize at a lower temperature than steel or the like. Therefore, if only the tip of the welding torch is gas shielded (steel is sufficient), the weld metal is oxidized and hardened. However, good elongation cannot be obtained.

Therefore, MIG of titanium and titanium alloys
In welding, a shield box 7 is attached to the rear of the welding torch 2 to shield the rear of the welding arc 4 with an inert gas such as Ar gas.

At this time, in order to uniformly supply the shield gas to the surface of the weld bead 6, a suitable number of gas outlets 9 are provided in the shield box 7 in parallel with the welding direction and on the side opposite to the weld bead. Arrange the pipe 8 and the gas outlet 9
A method is generally adopted in which the shield gas ejected from the above is first applied to the upper wall in the shield box and then applied to the lower welding bead 6.

FIG. 2 shows a welded material 1 having a groove 11 formed therein.
1 schematically shows a mode of forming the welding bead 6 in the case of welding with a MIG welding apparatus as shown in FIG.

The welding torch 2 is moved in the direction of the arrow (welding direction) to form the welding bead 6 behind the molten pool 5, but at this time, normally, due to the wandering phenomenon of the welding arc 4, it is relatively Large spatter 12 adheres to the surface of the material to be welded and the surface of the weld bead.

FIG. 3 schematically shows the appearance of a welding bead formed by conventional MIG welding. The welding bead 6 meanders due to the wandering phenomenon, and a trace of the wandering phenomenon is left around the welding bead 6.

The degree of meandering of the weld bead is defined by the bead meandering width, which is the straight line passing through the position 14 where the starting end of the welding bead is most recessed, parallel to the welding direction (arrow in the figure), and the starting end of the welding bead being most protruding. It is indicated by the shortest distance (mm) (Wb in the figure) from a straight line passing through the position 15 and parallel to the welding direction.

The meandering width Wb of the bead is preferably about 0 mm, but when it is difficult to set it to about 0 mm, up to 0.6 mm is acceptable.

The trace of the wandering phenomenon remains as a trace of the arc moving and protruding to the outside of the welding bead start end portion when the wandering phenomenon occurs violently.

If the trace is hidden by the weld bead, there is no problem in appearance, but if it remains outside the weld bead, it naturally damages the external appearance of the material to be welded, so it should not be left in the welded part. Is.

The degree of the wandering phenomenon is defined by the width of this trace as the wandering phenomenon width, and the maximum distance (mm) from the beginning and end of the welding bead to the outermost position of the trace where the welding arc has moved due to the wandering phenomenon. Indicated by value (W in the figure
w).

Since no trace of the wandering phenomenon should be left in the welded portion, the width Ww of the wandering phenomenon should be 0 mm. However, even if the welding conditions aiming at 0 mm are selected, the wandering phenomenon occurs severely, and Ww is 2 to 3 m.
It may reach m.

Further, in FIG. 3, a relatively large spatter 12 is formed on the surface of the material to be welded and the surface of the weld bead.
Many are attached. Thus, the external shape of the weld bead formed by conventional MIG welding is poor.

The present inventor has made the above idea in order to improve the appearance shape of the above-mentioned weld bead, and as a result of diligent study on means for realizing this idea, the feed amount of Ti and Al
Or, in relation to the supply amount of Al alloy, supply rate V _A (g / sec) of Al or Al alloy satisfying the following formula
It was found that, when supplied into the welding arc, the welding arc is stable and the wandering phenomenon does not occur, and as a result, welding beads with extremely low spatter adhesion and an extremely good appearance are obtained. It was

10 V _A ≤ρ _T × (φ _T / 2) ² × π × V _T ≤200 V _A where ρ _T : Specific gravity of welding wire (g / mm ³ ) φ _T : Outer diameter of welding wire (mm ) V _T : Welding wire feeding speed (mm / sec) The present invention is based on the above idea.

Here, the supply rate of Al or Al alloy (V
_The technical reason for defining _A ) by the above equation is that when the supply rate ( _VA ) is less than {ρ _T × (φ _T / 2) ² × π × _VT } / 200, a Insufficient supply of Al,
Not enough cathode spots could be formed to stabilize the welding arc, while the feed rate (V _A ) was {ρ _T ×
When (φ _T / 2) ² × π × V _T } / 10 is exceeded, the amount of Al supplied into the welding arc becomes excessive, and as a result, a large amount of Al remains in the weld zone as Al oxide, This is because the toughness of the welded portion is deteriorated.

As the source of Al, an Al alloy can be used in addition to Al. The Al alloy is preferably an alloy containing 50% by mass or more of Al from the viewpoint of an Al supply source, but an alloy containing Al as the main component may be used even if it is less than 50% by mass.

FIG. 4 shows the welding method of the present invention (the method of the present invention).
The appearance of the weld bead obtained in 1. is schematically shown. As shown in the figure, the bead meandering width Wb≈0, the wandering phenomenon width Ww
≈0, and there is no spatter adhesion.

In the method of the present invention, the welding power source is
Use a DC welding power source or a DC pulse welding power source.

It is generally known that when a pulse welding current is used, droplet transfer during welding is performed regularly and smoothly. In the method of the present invention, the DC pulse welding power source is also used in view of the above equation. As a result of the experiment, it was found that the use of the alloy reduces the width of the wandering phenomenon and / or the meandering width of the bead, and makes the appearance of the weld bead extremely excellent.

A combination of a peak current value and a base current value,
In relation to the external shape of the weld bead, a weld bead with a wandering phenomenon width of about 0 mm and a meandering width of the bead of 0.6 mm or less is used as a weld bead with a good external appearance (○),
Among them, FIG. 5 shows the results of organizing the welding beads having a meandering width of 0.2 mm or less as the welding beads (⊚) having an “excellently good” appearance.

From FIG. 5, when a DC pulse welding power source of 300 A ≦ peak current ≦ 500 A 2.0 ≦ peak current / base current ≦ 5.0 is used, the welding arc is further stabilized and the appearance shape is extremely good. It turns out that a weld bead can be obtained.

When the method of the present invention is carried out under the above-mentioned current conditions (see FIG. 5), the welding arc becomes extremely strong during welding in combination with the effect of supplying Al or Al alloy into the welding arc. It is possible to stabilize and obtain a weld bead having a better appearance (see FIG. 4).

In the method of the present invention, A into the welding arc
It is preferable that the 1 or Al alloy is supplied continuously or intermittently in the form of any one of a wire, a hoop, a tube, a foil and a twisted wire. At this time, the cross-sectional area is 0.01 to
Choosing a wire, hoop, tube, foil or twisted wire of 25.0 mm ² will further stabilize the welding arc and provide a weld bead with a better appearance.

If the cross-sectional area is less than 0.01 mm ² , no matter which form is adopted, the cross-section becomes too thin or too thin to cause buckling, which makes it impossible or impossible to feed. In some cases, the feeding speed must be increased, and as a result, the frictional resistance generated during feeding increases, the feeding speed becomes unstable, and the welding arc becomes unstable.

On the other hand, when the cross-sectional area exceeds 25.0 mm ² ,
When the rigidity of the welding wire is increased and a larger correction force is required for the welding wire, resulting in increased feeding resistance, unstable wire feeding speed, and unstable arc. There is. Although increasing the capacity of the wire feeding motor can improve the instability of the wire feeding speed, it is not a good idea because the wire feeding device becomes large.

In the method of the present invention, Al or Al
The alloy can be supplied in the form of any one of particles, wire pieces, hoop pieces, tube pieces, and foil pieces.
At this time, if particles having an average particle diameter or equivalent circle diameter of 0.01 to 2 mm, wire pieces, hoop pieces, tube pieces, or foil pieces are selected, the welding arc is further stabilized, and a more excellent appearance shape is obtained. Weld beads can be obtained.

If the average particle diameter or the equivalent circle diameter is less than 0.01 mm, the weight Al per unit becomes small, and when supplied to the welding arc, a part of the weight Al is blown by the flow of the shield gas to cause arcing. May not be supplied during. In such a case, the welding arc becomes unstable and a good bead cannot be obtained.

On the other hand, if the average particle diameter or the equivalent circle diameter exceeds 2 mm, the volume per unit becomes large, and when it is supplied into the welding arc, the time for melting all is long, and the arc The stabilizing effect may not be sufficiently obtained, and the arc may become unstable. In addition, when the particle size becomes large, when the supply is performed intermittently, the supply interval becomes long and the arc becomes unstable for some time. As a result, the weld bead becomes partially unstable, and it may not be possible to obtain a good bead as a whole.

Wires, hoops, tubes, foils, and twisted wires are produced by using a feeding device having a feeding speed control mechanism, and particles, wire pieces, hoop pieces, tube pieces, and foil pieces are
A jetting device having a jetting speed control mechanism is used to continuously or intermittently feed or jet into a welding arc. In this case, it is preferable to control the feeding device and the jetting device in conjunction with the arc control device.

Al or A supplied into the welding arc
The form of the l alloy is not limited to the above-mentioned form,
Of course, other forms can be adopted depending on the situation.

The cross-sectional outer diameter of the welding wire used in the method of the present invention is 1.6 mm in order to further stabilize the welding arc.
It is preferably not less than 2.0 mm.

The inventors of the present invention have found that the MI of titanium and titanium alloys.
We conducted extensive research into the droplet transfer mode in G welding, and on the low current side, the droplet became a globular and the droplet became large, and spatter easily occurred. On the other hand, on the high current side, the droplet was in a sprayed state. It became clear that the spatter was suppressed and the spatter was suppressed.

Generally, in MIG welding, increasing the diameter of the welding wire is preferable in that the maximum welding current can be increased and the range of selection of the optimum welding conditions can be widened compared with the case where it is small. If constant, the welding current density in the arc becomes small, it is preferable in that the welding arc is stabilized, but increasing the diameter of the welding wire has a limit in terms of smooth feeding of the wire, The present inventor has further investigated the optimum range of the wire diameter that can secure the smooth feeding of the welding wire even at a high current and can ensure the stable generation and continuation of the arc.

As a result, it was found that the cross-sectional outer diameter of the wire is preferably 1.6 mm or more and 2.0 mm or less. If the cross-sectional outer diameter of the wire is less than 1.6 mm, the welding current density in the arc becomes large and the welding arc becomes unstable, resulting in a poor bead appearance. On the other hand, if the cross-sectional outer diameter of the wire exceeds 2.0 mm, fluctuations in the feed rate of the welding wire have a large effect on the stability of the welding arc, which is not preferable.

In the method of the present invention, when the cross-sectional outer diameter of the welding wire is set to 1.6 mm or more and 2.0 mm or less, the welding arc is extremely generated during welding in combination with the supply of Al or Al alloy into the welding arc. Since it is stabilized, it is possible to obtain a welded portion having an excellent external shape shown in FIG.

[0070]

EXAMPLES Examples of the present invention will be described below.
The conditions used in the examples are examples, and the present invention is not limited to the conditions.

(Example 1) Using a pure titanium welding wire having a wire diameter of 1.6 mm, under the welding conditions shown in Table 1, the peak current of the pulse welding current was 250 to 550 A and the base current was 60 to 300 A. The current value was changed, MIG welding was performed, and the welded portion was observed and evaluated.

The results are shown in Table 2 and FIG. In Table 2,
Ww is the wandering phenomenon width, Wb is the bead meandering width,
Those having Ww = 0 mm and Wb ≦ 0.6 mm are evaluated as “good”,
Among them, those having Wb ≦ 0.2 mm were evaluated as “extremely good”.

[0073]

[Table 1]

[0074]

[Table 2]

From Table 2, when welding is performed under the conditions within the scope of the present invention, the wandering phenomenon width Ww and the bead meandering width Wb.
It can be seen that the weld bead having a good appearance is obtained.

Also, under the peak current of 300 to 500 A and the current condition of 2.0 ≦ peak current / base current ≦ 5.0, the wandering phenomenon width Ww and the bead meandering width Wb are further reduced, and the appearance is excellent. It can be seen that a weld bead was obtained.

(Example 2) Table 3 shows the appearance evaluation of the welding state when MIG welding was performed using pure titanium welding wires having wire diameters of 1.2 mm and 1.6 mm. When a welding wire with a wire diameter of 1.2 mm is used, the wandering phenomenon width Ww is 0 mm, but the bead meandering width Wb is 0.4 mm.
Thus, it is twice as large as 0.2 mm when the wire diameter is 1.6 mm.

From these results, it is possible to maintain a stable arc at a high current by using a welding wire having a wire diameter of 1.6 mm.
It can be seen that it is possible to obtain a weld bead that can be continued and has a very good appearance.

[0079]

[Table 3]

[0080]

According to the present invention, in MIG welding of titanium or titanium alloy, the welding arc is stabilized to suppress the wandering phenomenon, and the appearance of the welding bead is good.
In addition, it is possible to obtain a welded part without deterioration of mechanical properties.

Therefore, the present invention makes it possible to efficiently construct a large outdoor structure or an industrial machine structure with a titanium or titanium alloy structural material, and greatly contributes to the development of industry. .

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an appearance of a MIG welding device.

FIG. 2 is a diagram schematically showing a formation mode of a weld bead.

FIG. 3 is a diagram schematically showing the appearance of a weld bead obtained by conventional MIG welding.

FIG. 4 is a diagram schematically showing the appearance of a weld bead obtained by MIG welding according to the present invention.

FIG. 5 is a diagram showing a preferable range of pulse welding current in the present invention.

[Explanation of symbols]

1 ... Material to be welded 2 ... Welding torch 3 ... Welding wire 4 ... Welding arc 5 ... Welding pool 6 ... Weld beads 7 ... Shield box 8 ... Gas supply pipe 9 ... Gas outlet 10 ... Shield gas flow direction 11 ... groove 12 ... Spatter 13 ... Trace of wandering phenomenon Ww ... Wandering phenomenon width Wb ... Bead meander width

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Taiji Hase             7-6-1 Higashi Narashino, Narashino City, Chiba Prefecture             Welding Industry Co., Ltd.             Within the corporation F-term (reference) 4E001 BB08 CB04 DC01 DC03 DC09                       DE04 EA01 EA04 EA05

Claims (8)

[Claims] 1. A method of MIG welding titanium or a titanium alloy using a pure titanium welding wire or a titanium alloy welding wire, wherein Al or Al alloy is welded at a supply rate V _A (g / sec) satisfying the following formula. A method for MIG welding titanium or a titanium alloy, which is characterized by supplying into an arc. 10 V _A ≤ρ _T × (φ _T / 2) ² × π × V _T ≤200 V _A where ρ _T : Specific gravity of welding wire (g / mm ³ ) φ _T : Outer diameter of welding wire (mm) V _T : Feeding speed of welding wire (mm / sec) 2. A method of MIG welding titanium or a titanium alloy using a pure titanium welding wire or a titanium alloy welding wire, wherein Al or Al alloy is supplied at a feed rate V _A (g / sec) satisfying the following formula: A MIG welding method for titanium or titanium alloy, characterized by supplying into a welding arc generated by a pulse welding current satisfying a current condition. 10 V _A ≤ρ _T × (φ _T / 2) ² × π × V _T ≤200 V _A where ρ _T : Specific gravity of welding wire (g / mm ³ ) φ _T : Outer diameter of welding wire (mm) V _T : Feeding speed of welding wire (mm / sec) 300A ≦ peak current ≦ 500A 2.0 ≦ peak current / base current ≦ 5.0 3. The MIG of titanium or titanium alloy according to claim 1 or 2, wherein the pure titanium welding wire or the titanium alloy welding wire has a cross-sectional outer diameter of 1.6 mm or more and 2.0 mm or less. Welding method. 4. The Al or Al alloy is continuously or intermittently supplied in the form of any one of a wire, a hoop, a tube, a foil and a twisted wire.
Or the MIG welding method for titanium or titanium alloy according to item 3. 5. The titanium or titanium alloy M according to claim 4, wherein the wire, the hoop, the tube, the foil, and the twisted wire have a cross-sectional area of 0.01 to 25.0 mm ^2.
IG welding method. 6. The Al or Al alloy is continuously or intermittently supplied in the form of any one of particles, wire pieces, hoop pieces, tube pieces, and foil pieces. 2. The MIG welding method for titanium or titanium alloy according to 2 or 3. 7. The particles, wire pieces, hoop pieces, tube pieces,
Also, the average particle diameter or equivalent circle diameter of the foil pieces is 0.01 to 2 mm.
The method of MIG welding titanium or a titanium alloy according to claim 6, wherein 8. The MIG welding method of titanium or a titanium alloy according to claim 1, wherein the Al alloy is an alloy containing Al as a main component.