JP4606751B2 - Plasma arc hybrid welding method - Google Patents

Description

  The present invention relates to a welding method for obtaining an excellent bead shape with high efficiency by combining a gas shielded arc welding method and a plasma welding method.

  The gas shielded arc welding method is roughly classified into a fused electrode type and a non-fused electrode type depending on whether the electrode is melted or not melted. Furthermore, the steel melt electrode type gas shielded arc welding method is roughly classified into a MIG welding method in which the arc point is shielded with an inert gas and a MAG welding method in which the arc point is shielded with an active gas, and is used as a melting electrode. There are two types of welding wires: solid wire and flux-cored wire (hereinafter referred to as FC wire). The most common steel electrode type gas shielded arc welding method uses a welding wire to stabilize the arc. This is a reverse polarity MAG welding method using an anode.

On the other hand, the non-melting electrode type gas shielded arc welding method includes a TIG welding method and a plasma welding method, and a tungsten (W) electrode having a small diameter is used for both electrodes. Furthermore, the electrode is used with a positive polarity in order to take advantage of the cooling action by electron emission at a high temperature. In TIG welding, the tungsten electrode is open, whereas in plasma welding, the tungsten electrode is surrounded by a water-cooled Cu tip, which has a long life, and the Cu tip diameter and plasma gas flow rate. It is possible to adjust the arc force. An inert gas such as Ar, He, or Ar—H ₂ is used for the shielding gas of these non-melting electrode type gas shielded arc welding methods in order to prevent the tungsten electrode from being consumed due to oxidation.

In the plasma welding method, in addition to this plasma gas, Ar or Ar—H ₂ gas is used as a shielding gas so as to wrap the Cu chip in order to suppress oxidation of the weld metal.

Various types of gas are used for the shield gas for the gas electrode arc welding of the melting electrode type by appropriately selecting components that do not adversely affect the behavior of the droplets and the characteristics of the weld metal. In particular, carbon dioxide shielded arc welding using CO ₂ gas as the shielding gas is widely used for welding steel materials because CO ₂ gas is inexpensive and is an efficient welding method.

  Electrodes (that is, welding wires) used in carbon dioxide shielded arc welding are roughly classified into solid wires and FC wires.

  The solid wire is a welding wire made of a steel wire, and there is a wire in which the surface of a steel wire that is a material is plated or a lubricant is applied. This solid wire is known to provide a weld metal having excellent strength and toughness. On the other hand, the FC wire is a wire in which a welding flux is filled inside a steel outer shell, and an excellent bead shape is obtained.

  The reason why the FC wire has an excellent bead shape is that the droplets that move from the tip of the welding wire to the molten metal of the steel sheet are fine, so that the surface fluctuation of the molten metal is kept small and slag is included in the welding flux in a large amount This is because the slag generated by the agent covers the bead.

  In a solid wire, since the droplets transferred from the tip of the welding wire to the molten metal of the steel sheet are rough and irregular, the surface fluctuation of the molten metal is large and the deoxidizing element contained in the steel wire (ie, Slag is formed by oxidation of Si, Mn, Ti, Zr, Al, etc.). As a result, the slag is unevenly distributed and does not completely cover the bead. Further, in carbon dioxide shielded arc welding using a solid wire, slag accumulates at the end of the bead. Therefore, when a solid wire is used in carbon dioxide shielded arc welding, the bead shape becomes unstable.

  Solid wire is less expensive than FC wire, so when performing carbon dioxide shielded arc welding using solid wire, in addition to the original properties of weld metal being superior in strength and toughness, it is equivalent to FC wire. If an excellent bead shape can be obtained, the construction cost can be reduced by using a solid wire.

  Usually, not only carbon dioxide shielded arc welding but also molten electrode type gas shielded arc welding is performed using one electrode (that is, a welding wire). On the other hand, if a plurality of heat sources are used, it is possible to increase the efficiency of welding. Therefore, various highly efficient welding construction techniques using multipolarization have been proposed. Among them, there is a laser arc hybrid welding method that combines a high-speed and heat-saving heat welding characteristic of the laser welding method and a versatile arc welding method (see Patent Document 1). Since this method uses expensive laser equipment, a large initial investment is required.

In addition, a high-efficiency welding method in which the electrode type gas shielded arc welding method is made into multiple electrodes has been developed (see Patent Document 2). The weld bead shape obtained by this method is not greatly improved as compared with high-current welding with one electrode, and arc instability is likely to occur due to mutual interference.
JP 2002-288734 A Japanese Patent Laid-Open No. 7-256455

An object of the present invention is to provide a welding method that solves the above-described problems and performs fillet welding by combining a gas shielded arc welding method and a plasma welding method to obtain a bead shape with high efficiency. .

When performing fillet welding , the present inventors diligently studied a welding method excellent in high-speed and weld bead shape by using a plurality of heat sources based on a melted electrode type gas shielded arc welding method. At that time, it changed the viewpoint from the conventional examination subject greatly, and the trace element added to the steel wire for gas shielded arc welding (hereinafter referred to as the welding steel wire) called solid wire which does not have the welding flux built in and welding. We investigated in detail about the polarity of and obtained the following knowledge.

  (1) Welding method (hereinafter referred to as “plasma arc”), which combines a hot electrode type gas shielded arc welding method with positive polarity (ie, a welding steel wire with a negative pole) and a non-melting type plasma welding method with positive polarity. By adopting a hybrid welding method, an excellent bead shape can be obtained even at a high speed.

  (2) Both the plasma welding method and the molten electrode type gas shielded arc welding method are positive, and the distance between the electrodes (that is, between the electrode for plasma welding and the electrode for gas shielded arc welding) is 50 mm or less. The molten metal formed on the steel plate side can be made into one pool. Furthermore, the molten pool and bead shape can be controlled by the shift amount (distance) of each electrode from the weld line.

   (3) In a combination of a galvanic positive gas shielded arc welding method and a non-molten positive plasma welding method, from a steel wire containing 0.0150 to 0.100% by mass of rare earth element (hereinafter referred to as REM) By using the welding steel wire to be used as an electrode for the melting electrode type gas shielded arc welding, the arc is concentrated and the arc can be stabilized.

  (4) More stable plasma arc hybrid welding by using welding steel wire with REM and Al, Ti, Zr, O, and Ca added to the steel wire for hot electrode gas shielded arc welding Is possible.

(5) The construction cost of plasma arc hybrid welding can be reduced by using a gas containing 60% by volume or more of CO ₂ as a shielding gas for the melting electrode type gas shielded arc welding. The balance of the shielding gas (that is, 40% by volume or less) is preferably mixed with one or more of Ar, He, H ₂ and O ₂ . It should be noted that there is no problem even if a shield gas of 100 volume% CO ₂ is used.

  The present invention has been made based on these findings.

That is, the present invention provides a plasma arc hybrid welding method using a combination of a non-melting-type plasma welding method and a melting-electrode type gas shielded arc welding method, wherein both the plasma welding method and the gas shielded arc welding method are positive. The distance between the electrode of the plasma welding method and the electrode of the gas shielded arc welding method is 50 mm or less, the electrode of the gas shielded arc welding is the leading electrode, and the welding steel wire used as the melting electrode in the gas shielded arc welding method is A steel wire containing 0.015 to 0.100% by mass of rare earth elements is used, and the plasma welding electrode is used as the trailing electrode, and only the trailing electrode is shifted from the end of the upper plate to the lower plate by 2 to 10 mm. This is a plasma arc hybrid welding method in which fillet welding is performed.

In the plasma arc hybrid welding method of the present invention, the steel wire of the steel wire for welding used in the hot electrode type gas shielded arc welding method includes Ti: 0.02 to 0.50 mass% and Zr: 0.02 to 0.50 mass in addition to REM. It is preferable to contain 1 type or 2 types of%, and O: 0.0080 mass% or less, Ca: 0.0008 mass% or less. Furthermore, it is preferable that a steel strand contains Al: 0.005-3.00 mass% in addition to an above described composition.

Moreover, it is preferable that the shielding gas used in the melting electrode type gas shielded arc welding method is a gas containing 60% by volume or more of CO ₂ . The shielding gas may be 100 volume% CO ₂ , or contains 60 volume% or more of CO ₂ and contains one or more of Ar, He, H ₂ and O _{2 in} a total volume of 40 volume% or less. A mixed gas may be used.

  The steel wire for gas shielded arc welding (namely, the steel wire for welding) which consists of a steel strand refers to the wire (what is called a solid wire) which does not carry the welding flux internally and mainly has the steel strand used as a raw material. The present invention can also be applied to a welding steel wire in which the surface of the steel wire is plated or a lubricant is applied without any trouble.

According to the present invention, when performing fillet welding by combining the melting electrode type gas shielded arc welding method and the non-melting electrode type plasma welding method, an excellent bead shape can be obtained with high efficiency.

  First, in the plasma arc hybrid welding method in which the non-melting electrode type plasma welding method and the melting electrode type gas shielded arc welding method of the present invention are combined, both the plasma welding method and the gas shielded arc welding method are made positive. The reason for limiting the distance between the electrodes (that is, between the plasma welding electrode and the gas shielded arc welding electrode) to 50 mm or less will be described.

  In the laser arc hybrid method disclosed in Patent Document 1, the laser apparatus is expensive and lacks versatility. In addition, the use of multiple electrodes in the melting electrode type gas shielded arc welding method disclosed in Patent Document 2 does not have an effect of improving the weld bead shape, and has a large merit as compared with the case where a single electrode is used for a high current. Absent.

  On the other hand, the plasma welding method has an advantage that a thick steel plate can be efficiently joined by keyhole welding as in the laser welding method. However, there is a defect that defects are easily involved due to deep penetration, and further, there is a defect that a weld metal is insufficient due to not using a molten material, and a bead appearance defect is likely to occur. Therefore, it is considered that the plasma welding method can be improved by combining with the gas shielded arc welding method in the same manner as the laser welding method.

  However, the plasma welding method is positive (that is, the plasma electrode has a negative polarity), whereas the gas shielded arc welding method has a reverse polarity (that is, a welding steel wire has a positive polarity). When the positive polarity welding method and the reverse polarity welding method are performed at close positions, the electric currents discharged between the electrode and the steel sheet flow in opposite directions, so that the arc interferes. As a result, it was considered difficult to perform plasma welding and gas shielded arc welding simultaneously and stably.

  On the other hand, the present inventors examined the optimization of the polarities of the non-melting electrode type plasma welding method and the melting electrode type gas shielded arc welding method, and confirming that arc interference can be prevented by setting both to positive polarity. I found it.

  Furthermore, if the distance between the electrodes exceeds 50 mm, the molten metal on the steel plate side becomes two pools, and there is no effect of improving the weld bead shape. Therefore, the distance between the electrodes needs to be 50 mm or less. Preferably it is 20-30 mm.

  Next, in the plasma arc hybrid welding method of the present invention, the reason for limiting the components of the steel wire used as the material of the steel wire for welding used for gas shielded arc welding will be described.

  In addition, it is preferable to apply this invention to the steel wire for welding which consists of a steel strand which contains C, Si, Mn, P, and S as a basic component as follows.

C: 0.20% by mass or less C is an important element for securing the strength of the weld metal, and has an effect of improving fluidity by reducing the viscosity of the molten metal. However, when the C content exceeds 0.20% by mass, not only the behavior of the droplets and molten metal becomes unstable in positive gas shielded arc welding, but also the toughness of the weld metal decreases. Therefore, preferably, the C content needs to satisfy 0.20% by mass or less.

  On the other hand, if the C content is excessively reduced, the strength of the weld metal cannot be ensured. Therefore, the range of 0.01 to 0.10% by mass is more preferable.

Si: 0.05-2.5 mass%
Si has a deoxidizing action and is an indispensable element for deoxidizing weld metals. If the Si content is less than 0.05% by mass, deoxidation of the molten metal is insufficient, and blow holes are generated in the weld metal. Furthermore, it has the effect of suppressing the spread of the arc in positive polarity gas shielded arc welding, making the droplets finer and stabilizing the behavior. On the other hand, if it exceeds 2.5% by mass, the toughness of the weld metal is significantly reduced. Therefore, it is preferable that Si should satisfy the range of 0.05 to 2.5% by mass. However, if the Si content exceeds 0.65% by mass, a tendency to increase the spatter of small grains appears, so that the range of 0.05 to 0.65% by mass is more preferable.

Mn: 0.25 to 3.5% by mass
Mn, like Si, has a deoxidizing action and is an indispensable element for deoxidizing molten metal. If the Mn content is less than 0.25%, deoxidation of the molten metal is insufficient, and blow holes are generated in the weld metal. On the other hand, if it exceeds 3.5% by mass, the toughness of the weld metal decreases. Therefore, Mn preferably satisfies the range of 0.25 to 3.5% by mass. In order to promote deoxidation of molten metal and prevent blowholes, 0.45% by mass or more is desirable. Therefore, the range of 0.45 to 3.5% by mass is more preferable.

P: 0.05% by mass or less P is an element that lowers the melting point of steel and improves electrical resistivity and improves melting efficiency. Furthermore, in positive polarity gas shielded arc welding, it has the effect | action which refines | miniaturizes a droplet and stabilizes an arc. However, if the P content exceeds 0.05% by mass, the viscosity of the molten metal in positive gas shielded arc welding is remarkably lowered, the arc becomes unstable, and a large amount of small-sized spatter is generated. Also, the risk of hot cracking in the weld metal increases. Therefore, P is preferably 0.05% by mass or less. In addition, 0.03 mass% or less is more preferable. On the other hand, since it takes a long time to reduce P in the steelmaking stage where the steel material of the steel wire is melted, 0.002% by mass or more is desirable from the viewpoint of improving productivity. Therefore, the range of 0.002 to 0.03 mass% is more preferable.

S: 0.02% by mass or less S lowers the viscosity of the molten metal, promotes the detachment of the droplet suspended from the tip of the welding steel wire, and stabilizes the arc in positive polarity gas shielded arc welding. In addition, S has a function of smoothing the bead by spreading the arc in the positive gas shielded arc welding and lowering the viscosity of the molten metal. When the S content exceeds 0.02% by mass, not only the spatter of small grains increases, but also the REM precipitates become coarse, the workability in the manufacturing stage of the steel strand deteriorates and the yield decreases. Therefore, S is preferably 0.02% by mass or less. On the other hand, since it takes a long time to reduce S in the steelmaking stage where the steel material of the steel wire is melted, 0.002% by mass or more is desirable from the viewpoint of improving productivity. Therefore, the range of 0.002 to 0.02% by mass is more preferable.

REM: 0.015-0.100 mass%
Rare earth elements (that is, REM) are useful elements for finer inclusions and improved toughness during steelmaking and casting. In gas shielded arc welding, it has the effect of suppressing the occurrence of spatter. In particular, in positive gas shielded arc welding, it is an element indispensable for fine transfer of droplets. In addition, in normal multi-electrode welding, the arc interferes and becomes unstable, but by adding REM to the steel wire, the arc can be concentrated and the arc directivity can be improved to prevent arc interference, Moreover, deep penetration can be obtained.

In the plasma arc hybrid welding method of the present invention, the molten electrode type gas shielded arc welding method is used as the leading electrode, and the plasma welding method is used as the trailing electrode, thereby forming the steel plate side by the molten electrode type gas shielded arc welding method . The shape of the molten pool and the shape of the weld bead can be controlled by reheating the shape of the molten pool by the plasma welding method of the trailing electrode. In particular, in fillet welding, a weld bead having a wide width and a small wetting angle can be obtained by shifting the bottom plate (web) side by 2 to 10 mm. If the REM amount is less than 0.015% by mass, the effect of reducing the amount of spatter generated by the stabilization of the arc and the effect of preventing the interference of the arc due to the strong directivity of the arc are not exhibited.

  On the other hand, addition exceeding 0.100% by mass causes cracks in the manufacturing process of the welding steel wire and decreases the toughness of the weld metal. Therefore, the REM amount preferably satisfies the range of 0.015 to 0.100 mass%. More preferably, it is 0.025 to 0.050 mass%.

  Here, REM is a general term for elements belonging to Group 3 of the periodic table. In the present invention, it is preferable to use an element having an atomic number of 57 to 71, and Ce and la are particularly preferable. When Ce and La are added to the steel strand, Ce or La may be added alone, or Ce and La may be used in combination. In addition, when adding both Ce and La, it is preferable to use the mixture obtained by mixing beforehand in the range of Ce: 40-90 mass% and La: 10-60 mass%.

  Furthermore, in the present invention, in addition to the above-described composition, the steel strand preferably contains Ti, Zr, O, Ca, Al.

One or two of Ti: 0.02-0.50 mass% and Zr: 0.02-0.50 mass%
Ti and Zr are elements that both act as strong deoxidizers and increase the strength of the weld metal. Furthermore, it has the effect | action which lowers | hangs a viscosity by deoxidation of molten metal, stabilizes the behavior of a droplet, and stabilizes a bead shape (that is, suppresses a humping bead). Since it has such an effect, it is an effective element in high current welding of 350 A or more, and is added as necessary. If Ti is less than 0.02 mass% and Zr is less than 0.02 mass%, this effect cannot be obtained. On the other hand, when Ti exceeds 0.50 mass% and Zr exceeds 0.50 mass%, the droplets become coarse and a large amount of large spatter is generated. Therefore, when Ti and Zr are contained, it is preferable to satisfy the ranges of Ti: 0.02 to 0.50 mass% and Zr: 0.02 to 0.50 mass%.

O: 0.0080% by mass or less O is an effect of destabilizing the arc point generated in the droplet suspended from the tip of the welding steel wire in positive gas shielded arc welding and destabilizing the behavior of the droplet. There is. However, if the O content exceeds 0.0080% by mass, the effect of REM addition, which is the stability of arc in high-current positive gas shielded arc welding with a current of 350A or more, is impaired, and the fluctuation of droplets increases and spattering occurs. It occurs in large quantities. In addition, O has a property of reacting violently with REM to form slag at the stage of melting the steel material of the steel wire, and when the O content exceeds 0.0080% by mass, the yield of REM decreases significantly. To do. Therefore, O is preferably 0.0080% by mass or less. However, if the O content is less than 0.0010% by mass, the effect of O addition cannot be obtained sufficiently. Therefore, the range of 0.0010 to 0.0080 mass% is more preferable, and the range of 0.0010 to 0.0050 mass% is more preferable.

Ca: 0.0008 mass% or less
Ca is mixed into the molten steel as an impurity during steelmaking and casting, or adheres to the steel wire as an impurity during wire drawing. In positive gas shielded arc welding, if the Ca content exceeds 0.008% by mass, the arc stabilization effect of REM addition in high current welding is impaired. Therefore, Ca is preferably 0.0008% by mass or less.

Al: 0.005 to 3.00 mass%
Al is an element that acts as a strong deoxidizer and further increases the strength of the weld metal. Furthermore, there is an effect that the viscosity due to deoxidation of the molten metal is lowered and the bead shape is stabilized (that is, the humping bead is suppressed). In gas shielded arc welding of reverse polarity, no clear droplet stabilization effect is observed, but in positive polarity gas shielded arc welding, the effect of stabilizing droplet transfer is prominent in high current welding at 350A or higher. Is done. On the other hand, in low current welding, the number of short circuit transitions can be increased to achieve uniform droplet transfer and improved bead shape. It also has the effect of reducing the REM oxidation loss in the manufacturing stage of welding steel wires due to its affinity with O. When Al is less than 0.005% by mass, such an effect cannot be obtained. On the other hand, when Al exceeds 3.00 mass%, the crystal grain of a weld metal will coarsen and toughness will fall remarkably. Therefore, Al preferably satisfies 0.005 to 3.00 mass%.

  Furthermore, the effects of the present invention are not reduced by adding the following elements as necessary.

Cr: 0.02 to 3.0 mass%, Ni: 0.05 to 3.0 mass%, Mo: 0.05 to 1.5 mass%, Cu: 0.05 to 3.0 mass%, B: 0.0005 to 0.015 mass%, Mg: 0.001 to 0.20 mass%
Cr, Ni, Mo, Cu, B, and Mg are all elements that increase the strength of the weld metal and improve the weather resistance. When the content of these elements is very small, such an effect cannot be obtained. On the other hand, when it adds excessively, the toughness fall of a weld metal will be caused. Therefore, when Cr, Ni, Mo, Cu, B, and Mg are contained, Cr: 0.02 to 3.0 mass%, Ni: 0.05 to 3.0 mass%, Mo: 0.05 to 1.5 mass%, Cu: 0.05 to 3.0 mass, respectively. %, B: 0.0005 to 0.015% by mass, Mg: 0.001 to 0.20% by mass are preferably satisfied.

Nb: 0.005 to 0.5 mass%, V: 0.005 to 0.5 mass%
Nb and V are elements that improve the strength and toughness of the weld metal and improve the stability of the arc. When the content of these elements is very small, such an effect cannot be obtained. On the other hand, when it adds excessively, the fall of the toughness of a weld metal will be caused. Therefore, when Nb and V are contained, it is preferable to satisfy the ranges of Nb: 0.005 to 0.5% by mass and V: 0.005 to 0.5% by mass.

  The balance other than the components of the steel strand described above is Fe and inevitable impurities. For example, it is a typical inevitable impurity, and is inevitably mixed in the stage of melting a steel material or the stage of manufacturing a steel wire. N is preferably reduced to 0.0200% by mass or less.

  Next, the manufacturing method of the steel wire for welding used with the gas shielded arc welding method of the plasma arc hybrid welding method of this invention is demonstrated.

  Using a converter or an electric furnace, molten steel having the above composition is produced. The melting method of the molten steel is not limited to a specific technique, and a conventionally known technique is used. Next, a steel material (for example, billet) is manufactured from the obtained molten steel by a continuous casting method, an ingot-making method, or the like. After this steel material is heated, hot rolling is performed, and dry cold rolling (that is, wire drawing) is further performed to manufacture a steel strand. The operating conditions for hot rolling and cold rolling are not limited to specific conditions, and may be any conditions as long as they produce a steel wire having a desired size and shape.

  Further, the steel wire is sequentially subjected to annealing, pickling, copper plating, wire drawing, and lubricant application as necessary to form a predetermined product, that is, a steel wire for welding. In the present invention, it is not always necessary to apply copper plating to the steel wire, and even a steel wire for welding in which a lubricant is applied to the surface of the steel wire can be used without any problem.

  In order to stably adhere the lubricant to the surface of the steel wire and improve the stability of power feeding, it is preferable that the flatness (= actual surface area / theoretical surface area) of the steel wire is 1.005 or more and less than 1.0100. The flatness of the steel wire can be maintained in the range of 1.0005 or more and less than 1.0100 by strictly controlling the dies used for wire drawing.

  When copper plating is applied to the surface of the steel wire, the instability of the arc due to poor power feeding of the welding steel wire can be prevented by performing copper plating with a thickness of 0.6 μm or more. In addition, it is more preferable that the thickness of the copper plating is 0.8 μm or more because the effect of preventing power feeding failure is remarkably exhibited. By making the copper plating thicker in this way, there is also an effect that the wear of the power supply tip can be reduced.

  A suitable welding condition when performing positive polarity and melted electrode type gas shielded arc welding using the steel wire for welding thus manufactured will be described below.

As the shielding gas, a gas containing 60% by volume or more of CO ₂ may be used. The balance of the shielding gas (that is, 40% by volume or less) is preferably mixed with one or more gases of Ar, He, H ₂ and O ₂ . Even if CO ₂ gas is used alone (that is, CO ₂ mixing ratio: 100% by volume) as a shielding gas, plasma arc hybrid welding can be performed without any trouble.

  Further, it is preferable that the welding current of the melted electrode type gas shielded arc welding is 200 to 350 A, the welding voltage is 25 to 38 V (increases with the current), the protruding length is 15 to 30 mm, and the wire diameter is 0.8 to 1.6 mm.

On the other hand, the plasma gas in the plasma welding, using 100 vol% Ar gas, He or H ₂ is 4 vol% or less of Ar-H ₂ mixed gas. The welding current of positive plasma welding is preferably 100 to 300 A, the voltage is 12 to 20 V, the plasma gas is Ar, and the flow rate is preferably 0.6 to 2.0 liter / min.

  The type of steel of the base material to be welded (that is, steel) is not particularly limited, but rolled steel for welded structure (SM material) specified in JIS G3106 of Si-Mn series, and steel for building structure specified in JIS G3136 ( It is preferable to apply to SN materials.

  The billet manufactured by continuous casting was hot-rolled into a wire having a diameter of 5.5 to 7.0 mm. Next, the steel strand having a diameter of 2.0 to 2.8 mm is formed by cold rolling (that is, wire drawing). If necessary, the steel strand is annealed, pickled, and plated with Cu in a nitrogen atmosphere. As a result, a steel wire for welding with a diameter of 1.4 mm was produced. The components (including Cu plating) are shown in Table 1.

  Table 2 shows the conditions of the lap fillet welding in the case where the melting electrode type gas shielded arc welding is the leading electrode and the plasma welding method is the trailing electrode. FIG. 1 is a diagram schematically showing the joint shape and electrode arrangement, where (a) is a side view and (b) is a front view.

  Plasma arc hybrid welding was carried out in a Cu collection vessel using a steel wire for welding with steel wire number 3 in Table 1. Under condition 1 in Table 2, the polarity and the distance between the electrodes were changed to investigate the spatter generation amount, the bead shape, and the deterioration of the plasma welded tungsten electrode.

  Spatter generation rate is good (○) when the welding time is 0.3 g / min or less per minute, good (0.3) or more than 0.3 g / min or less (△), and over 1.5 g / min Was evaluated as impossible (×).

  FIG. 2 is an enlarged cross-sectional view of the vicinity of the bead of the lap fillet weld joint. As shown in FIG. 2, the contact angle θ (°) of the bead toe was measured. A contact angle θ of 20 ° or less was evaluated as good (◯), a value exceeding 20 ° to 45 ° or less was acceptable (Δ), and a value exceeding 45 ° was evaluated as unacceptable (×). Further, the melted part length of the tip of the tungsten electrode having a tip angle of 60 ° used for plasma welding was measured, and the melted part length of 2 mm or less was evaluated as good (◯), and the melted part length exceeding 2 mm was evaluated as impossible (x). These results are shown in Table 3.

  Using the plasma arc hybrid welding method of the present invention in which the positive electrode gas shielded arc welding of the melting electrode type is the leading electrode, the positive electrode plasma welding method is the trailing electrode, and the distance between the electrodes is adjusted to 25 to 27 mm, Table 1 Plasma arc hybrid welding was performed in a Cu collection vessel using the welding steel wire having the composition shown in Fig. 1 to investigate the influence of the composition of the welding steel wire. The results are as shown in Table 4.

Table 3, 4 or al apparent, the examples of the invention, the amount of sputtering is small, excellent bead shapes, weld defects is small, deterioration of tungsten electrodes was small. In Test Nos. 1 and 2 of the comparative example, spattering could not be reduced because the electrode of the molten electrode type gas shielded arc welding method had a reverse polarity with the negative electrode. In the test numbers 1 and 3 of the comparative examples, the bead shape could not be improved because the polarities of the melting electrode type gas shielded arc welding method and the non-melting electrode type plasma welding method were not the same. In the test numbers 2 and 3 of the comparative examples, the tungsten electrode was melted because the polarity of the non-melting electrode type plasma welding method was reversed. In Test No. 9 of the comparative example, the bead shape could not be improved because the distance between the electrodes was 50 mm or more.

It is a figure which shows a joint shape and electrode arrangement typically, (a) is a side view, (b) is a front view. It is sectional drawing to which the bead vicinity of the lap fillet welded joint of FIG. 1 was expanded. It is a figure which shows a joint shape and electrode arrangement | positioning typically, (b) is a front view, (a) is sectional drawing of an AA arrow.

Explanation of symbols

1 Plasma Torch 2 Steel Wire for Welding 3 Bead 4 Upper Plate 5 Lower Plate

Claims (6)

In a plasma arc hybrid welding method using a combination of a non-melting electrode type plasma welding method and a melting electrode type gas shielded arc welding method, both the plasma welding method and the gas shielded arc welding method are positive, and the plasma welding is performed. The distance between the electrode of the method and the electrode of the gas shielded arc welding method is 50 mm or less, the electrode of the gas shielded arc welding is a leading electrode, and the welding steel wire used as the molten electrode in the gas shielded arc welding method is A steel wire containing 0.015 to 0.100% by mass of a rare earth element is used, and the plasma welding electrode is used as a trailing electrode, and only the trailing electrode is disposed from the end of the upper plate to the lower plate side. A plasma arc hybrid welding method characterized in that fillet welding is performed with a shift of 10 mm. The steel strand contains one or two of Ti: 0.02-0.50 mass% and Zr: 0.02-0.50 mass% in addition to the rare earth element, and O: 0.0080 mass% or less, Ca: The plasma arc hybrid welding method according to claim 1 , wherein the plasma arc hybrid welding method has a composition containing 0.0008 mass% or less. The plasma arc hybrid welding method according to claim 2 , wherein the steel wire contains Al: 0.005 to 3.00 mass% in addition to the composition. Shielding gas used in gas-shielded arc welding method of the consumable electrode type A plasma arc hybrid welding method according to claim 1, 2 or 3, characterized in that the CO ₂ is a gas containing more than 60 vol% . The plasma arc hybrid welding method according to claim 4 , wherein the shielding gas is 100 volume% CO ₂ . The shielding gas is a mixed gas containing 60% by volume or more of CO ₂ and containing one or more of Ar, He, H ₂ and O ₂ in total of 40% by volume or less. 4. Plasma arc hybrid welding according to 4.

Images