JP3987771B2 - MIG welding method of titanium or titanium alloy and weld metal - Google Patents

Description

【００１７】
【表２】

【００１８】
なお、表２において、ワンダリング現象幅とは、ワンダリング現象によりアークが不安定となってワンダリング現象が大きくなり、溶接ビード始端部の外側にワンダリング現象の痕跡が残る幅をいい、溶接ビード蛇行幅とは、溶接ビード始端部が最も凹んでいる位置を通って溶接方向に平行な直線と、溶接ビード始端部が最も出っ張っている位置を通って溶接方向に平行な直線との最短距離をいう。（図３参照）
【００１９】
【発明の効果】
以上述べたように、本発明は、チタン又はチタン合金をＭＩＧ溶接方法を用いて、安定、かつ高能率に、かつ半自動溶接による現場溶接を可能とし、溶接時間短縮によるシールドガス使用量低減によるコスト削減を図ったＭＩＧ溶接用チタン合金溶接ワイヤ、溶接方法および溶接金属の提供を可能にする。
【図面の簡単な説明】
【図１】 ＭＩＧ溶接装置の外観模式図。
【図２】 ＭＩＧ溶接法の外観模式図。
【図３】 従来のＭＩＧ溶接による溶接ビードの平面模式図。
【図４】 本発明によるＭＩＧ溶接による溶接ビードの平面模式図。
【図５】 パルス溶接時の適正溶接電流範囲を示す図。
【符号の説明】
１…被溶接材
２…ＭＩＧ溶接用トーチ
３…シールドガス供給装置
３−１…シールドガス供給パイプ
３−２…シールドボックス
３−３…ガス供給パイプ
３−４…ガス出口
４、４’…シールドガス
５…溶融池
６…溶接ビード
７…スパッタ
８…溶接ワイヤ [0001]
BACKGROUND OF THE INVENTION
The present invention relates to a titanium or titanium alloy MIG welding method and weld metal used for welding titanium or titanium alloy members used in ships, building structures, and the like.
[0002]
[Prior art]
Conventionally, titanium or a titanium alloy has been used for ships, building structures, automobiles, motorcycles, and the like that require high corrosion resistance, and recently, the amount of use has been increasing. At the time of welding titanium or a titanium alloy, a TIG welding method (tungsten inert gas metal welding method), which is one of non-consumable electrode type welding methods, is currently employed. On the other hand, the MIG welding method (inert gas metal arc welding method) which is a consumable electrode type welding method has an advantage that a welding efficiency several times or more can be obtained as compared with the TIG welding method, but is made of pure titanium. When MIG welding is performed using a welding wire, the welding arc becomes extremely unstable. This is because, when titanium and a titanium alloy are welded by the MIG welding method, the arc violently moves to the position where the surface oxide film of the material to be welded of titanium and titanium alloy remains in order to maintain the cathode spot. Since the wandering phenomenon occurs, a large amount of welding spatter is generated, and the spatter adheres to titanium and titanium alloy as a base material. Further, there is a problem that the weld bead meanders due to the wandering phenomenon, and the appearance defect of the welded portion frequently occurs. For this reason, the danger of welding titanium and titanium alloys by the MIG welding method has been avoided as much as possible.
[0003]
On the other hand, when the TIG welding method is adopted, an arc is generated using a non-consumable electrode having a high melting point, and sputtering is performed in order to perform welding while supplying a welding wire to the molten pool generated in the base material. There is no occurrence. In addition, since the electrode side is negative and the welded side is positive, the wandering phenomenon does not occur because there is no cleaning action to remove the oxide film formed on the surface of the material to be welded. The bead does not meander and a good weld appearance shape is obtained. For this reason, the TIG welding method has been exclusively employed for welding titanium and titanium alloys.
[0004]
In TIG welding, it is necessary to hold the welding wire in an appropriate position while holding the welding torch in an appropriate position. Therefore, if it is possible to prepare a device that can hold the welding torch and welding wire in an appropriate position at a factory, etc., but if the non-welded product is a large structure, the welding operator can The burden on the welding operator cannot be imagined because the wire or the like must be moved as the welding progresses while being held in an appropriate position. Furthermore, the one in which the guide device for feeding the welding wire is incorporated in the welding torch is extremely expensive as compared with the semi-automatic welding torch for MIG welding. In addition, TIG welding has a problem that welding time is long because welding heat input is smaller than MIG welding, and therefore welding efficiency is poor. Further, since the welding time is long, the amount of gas used for the shield gas becomes large, resulting in an increase in cost.
[0005]
For example, in Japanese Patent Application Laid-Open No. 59-226159, the end surfaces in the length direction of two titanium strips forming a processed structure are brought into contact with each other, and TIG welding is performed to soften and anneal the base metal portion in the vicinity of the welded portion. There is disclosed a method for connecting a titanium strip without any problems. As described above, conventionally, when the titanium strip is welded, welding is performed exclusively by the TIG welding method. Japanese Patent Laid-Open No. 2000-280076 discloses a shield gas in which a trace amount of an oxidizing gas is added to an inert gas, and titanium or titanium that is welded by applying a pulse welding current using a consumable electrode of titanium or a titanium alloy. A method for arc welding of a titanium alloy is disclosed. However, when oxygen or oxide is supplied from the shielding gas, not only the welding arc is stabilized, but also a large amount of oxygen is mixed in the weld metal, so that the welded part is hardened and the elongation is reduced. Will lead to deterioration.
[0006]
On the other hand, with regard to MIG welding using an alternating current, for example, there is a technique in which an alternating current of 200 to 400 A is applied and a workpiece such as titanium material is manually welded in a sealed chamber filled with an inert gas. This is disclosed in Japanese Patent Laid-Open No. 63-101079. In addition, as an AC arc welding method, there is a method in which positive polarity welding and reverse polarity welding are alternately repeated. However, the ratio between the positive polarity period and the reverse polarity period is difficult and is not practically used. Therefore, a means for forming an arc by applying a DC voltage between the consumable electrode and the base material and reversing the polarity of the consumable electrode has been proposed. MIG welding has not been put to practical use.
[0007]
[Problems to be solved by the invention]
In view of the above-mentioned problems of the prior art, the present invention enables stable and highly efficient on-site welding by semi-automatic welding in titanium or titanium alloy by alternating current, and uses shield gas by shortening the welding time. It is an object of the present invention to provide a MIG welding method of titanium or a titanium alloy and a deposited metal which are intended to reduce the cost by reducing the amount.
[0008]
[Means for Solving the Problems]
The present invention has been made to solve the above-mentioned problems, and the gist of the present invention is a composition of a welding wire having a cross-sectional outer diameter of 1.6 mm or more and 2.0 mm or less in a MIG welding method of titanium or a titanium alloy. However, Al: 0.5 to 10% by mass, preferably O ≦ 1.0% by mass, using a titanium alloy wire consisting of the remaining titanium and unavoidable impurities, and MIG welding, the AC pulse satisfying the following current conditions A titanium or titanium alloy MIG welding method characterized by welding a titanium base material or a titanium alloy base material with a welding current;
200A ≦ positive current peak current ≦ 500A
-50 A ≧ negative peak current 1.0 ≦ | positive polarity peak current / negative polarity peak current of |
In the present invention, the composition of the weld metal obtained by the above welding method is Al: 0.5 to 10% by mass, O ≦ 1.0% by mass, the balance titanium and inevitable impurities,
It is.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
First, a welding apparatus used for MIG welding will be described with reference to FIG. In Figure 1, relative to the material to be welded 1, directly above the welding site, welding the center wire ya 8, a shielding gas 4 supplied from the shielding gas feeding device 3 provided separately on the outer periphery toward the molten fabric 5 injection A torch 2 for MIG welding having an injection port is arranged, and welding work is performed by applying a welding current to form a weld bead 6. In general, titanium or a titanium alloy is easily oxidized at a low temperature as compared with steel and the like, and in a gas shield having only a welding torch tip used in steel, the weld metal is oxidized and hardened, and good elongation of the weld metal cannot be obtained. Therefore, a shield box is provided behind the welding torch immediately after welding, and the rear of the welding arc point is also shielded with an inert gas such as Ar gas. The shield gas supply device 3 used in the present invention temporarily takes the shield gas supplied from the shield gas supply pipe 3-1 into the shield box 3-2, and the shield gas is welded to the shield bead 3-2. The gas supply pipe 3-3 is arranged in parallel with the welding direction so as to be uniformly supplied to the surface of the gas 6, and a plurality of gas outlets 3-4 are provided at the outlet opposite to the weld bead 6 and injected from the gas outlet. A method is adopted in which the shield gas 4 ′ is applied to the upper wall in the shield box 3-2 and then applied to the weld bead 6 on the lower surface.
[0010]
FIG. 2 shows the spatter scattering state due to the wandering phenomenon in the case of performing MIG welding by the conventional method, and FIG. 3 shows a schematic diagram of the appearance of the weld bead. As shown in FIG. 2, in conventional MIG welding of titanium and titanium alloys, the arc remains at the cathode spot, so that the welding arc becomes extremely unstable, and the arc is placed at the position where the surface oxide film of the work piece remains. As a result of the wandering phenomenon, the spatter 7 is scattered and adheres to the surface of the base material. Further, as shown in FIG. 3, in addition to the scattering and adhesion of the spatter, the weld bead meanders due to the wandering phenomenon, resulting in the appearance defect of the weld and the strength of the weld metal. In FIG. 3, when the wandering phenomenon occurs, a trace of the arc moving in the waviness width direction due to the wandering phenomenon remains outside the weld bead starting end portion, resulting in a very poor weld bead shape.
[0011]
On the other hand, in gas shielded arc welding, the direct-current MIG welding method with a torch (rod) plus has a cleaning action that removes the oxide film on the surface of the base material, but this cleaning action is too large and the wandering phenomenon becomes large. With the same heat input, there is a disadvantage that the penetration is deeper than the torch minus and the amount of deposited metal is small. In addition, AC MIG welding has both torch plus and torch minus. In the former, there is a cleaning action of the base material, and in the latter, the cleaning action of the base material is suppressed, and the wandering phenomenon is reduced. Compared with the plus, there is an advantage that the penetration becomes shallower and the amount of deposited metal increases. In particular, this AC MIG welding has the advantage that it will be difficult to melt through the welding of thin plates, but the welding efficiency will be lower because the amount of deposited metal will be less than that of direct torch plus with the same heat input in the welding of thick plates. There is a disadvantage of doing.
[0012]
The above-described cleaning operation of the base material will be described in detail. This cleaning action of the base material occurs with a torch plus polarity, but does not occur with a torch minus polarity. Generally, when welding an aluminum material, the oxide film (Al ₂ O ₃ ) having a small electrical conductivity existing on the surface is removed to stabilize the arc, and oxygen becomes difficult to enter the weld metal, thereby improving joint characteristics. . On the other hand, TIG welding of titanium material has the same effect as the aluminum material described above. However, in MIG welding of a titanium material, since the welding current to be used is large, the cleaning action is also increased, and a wandering phenomenon occurs. Therefore, by performing MIG welding using alternating current, the wandering phenomenon can be suppressed, and an excellent bead shape can be obtained.
[0013]
Therefore, the present invention is based on the above knowledge, and in the MIG welding method of titanium or titanium alloy, the composition of the welding wire contains Al: 0.5 to 10% by mass, and optionally O ≦ 1.0% by mass. Using a titanium alloy wire having a cross-sectional outer diameter of 1.6 mm or more and 2.0 mm or less, consisting of the remaining titanium and unavoidable impurities, during MIG welding, as a current condition,
200A ≦ positive current peak current ≦ 500A
-50 A ≧ negative peak current 1.0 ≦ | positive polarity peak current / negative polarity peak current of |
By welding the titanium base material or titanium alloy base material with an AC pulse welding current that satisfies the above conditions, the wandering phenomenon can be suppressed and MIG welding of titanium or titanium alloy having an excellent bead shape has become possible. It is.
[0014]
When such a welding wire is used and when the welding conditions specified above are adopted and titanium or a titanium alloy is MIG welded, the composition of the welded portion of titanium or the titanium alloy is expressed by mass%, Al: 0.00. A weld metal that is 5 to 10%, O: 0 to 1.0%, and the balance titanium can be obtained.
[0015]
【Example】
As a material to be welded, a pure titanium material having a V groove (90 °) with a plate thickness of 12.7 mm is used as an AC pulse welding current, and a positive peak welding current value is 150 to 550 A, and a negative peak welding current value is MIG welding with a welding wire having a cross-sectional outer diameter of 1.2 mmφ and 1.6 mmφ using Ar gas with a welding speed of 100 cm / min and a flow rate of 25 l / min as a shielding gas, with a range of −30 to −550 A. Went. Table 1 shows the AC pulse welding current and bead appearance evaluation used in the present invention. 5 shows the evaluation of Table 1 as it is. In FIG. 5, the negative peak welding current value is plotted on the horizontal axis and the positive peak welding current value is plotted on the vertical axis. The case of “very good” is indicated by ◎, and the case of “good” is indicated by ○. As can be seen from Table 1, an excellent bead appearance can be obtained by appropriately selecting the values of the positive peak welding current and the negative peak welding current, or the ratio thereof (see FIG. 4) . Table 2 shows the results of the welding wire diameter, welding state, and appearance evaluation. As can be seen from Table 2, it was excellent in using a welding wire having a positive peak welding current, a negative peak welding current value, and a diameter of 1.6 mm or more and 2.0 mm or less as defined in the present invention. A bead appearance can be obtained.
[0016]
[Table 1]

[0017]
[Table 2]

[0018]
In Table 2, the width of the wandering phenomenon means a width in which the wandering phenomenon becomes large due to the unstable arc due to the wandering phenomenon, and the trace of the wandering phenomenon remains on the outside of the weld bead starting end. The meandering width of the bead is the shortest distance between the straight line parallel to the welding direction through the position where the weld bead start end is most recessed and the straight line parallel to the weld direction through the position where the weld bead start end protrudes most. Say. (See Figure 3)
[0019]
【The invention's effect】
As described above, the present invention enables stable and highly efficient on-site welding by semi-automatic welding using titanium or a titanium alloy by using the MIG welding method, and reduces the amount of shielding gas used by shortening the welding time. It is possible to provide a titanium alloy welding wire for MIG welding, a welding method, and a weld metal that are reduced.
[Brief description of the drawings]
FIG. 1 is a schematic external view of a MIG welding apparatus.
FIG. 2 is a schematic external view of the MIG welding method.
FIG. 3 is a schematic plan view of a weld bead formed by conventional MIG welding.
FIG. 4 is a schematic plan view of a weld bead by MIG welding according to the present invention.
FIG. 5 is a diagram showing an appropriate welding current range during pulse welding.
[Explanation of symbols]
1 ... Material to be welded
2 ... MIG welding torch
3 ... Shield gas supply device
3-1. Shield gas supply pipe
3-2 ... Shield box
3-3 ... Gas supply pipe
3-4 ... Gas outlet
4, 4 '... shield gas
5 ... molten pool
6 ... Weld beads
7 ... Spatter
8 ... welding wire

Claims (4)

In the MIG welding method of titanium or a titanium alloy, the composition of the welding wire is Al: 0.5 to 10% by mass, the titanium alloy wire consisting of the remaining titanium and unavoidable impurities is used, and the following current conditions are satisfied during MIG welding. A titanium or titanium alloy MIG welding method comprising welding a titanium base material or a titanium alloy base material with an AC pulse welding current.
200A ≦ positive current peak current ≦ 500A
-50 A ≧ negative peak current 1.0 ≦ | positive polarity peak current / negative polarity peak current of |   The titanium or titanium alloy MIG welding method according to claim 1, wherein the titanium alloy wire further contains O ≦ 1.0 mass%.   3. The titanium or titanium alloy MIG welding method according to claim 1, wherein the titanium alloy wire has a cross-sectional outer diameter of 1.6 mm or more and 2.0 mm or less.   A weld metal in which the composition of the weld metal welded by the welding method according to any one of claims 1 to 3 is Al: 0.5 to 10% by mass, O ≦ 1.0% by mass, the remaining titanium and unavoidable impurities.

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