JP6263296B2 - Wire for welding dissimilar materials and manufacturing method thereof - Google Patents

Description

  The present invention relates to a dissimilar material welding wire for welding an Fe-based workpiece and an Al-based workpiece and a method for manufacturing the same.

  In Japanese Patent No. 5688492 (Patent Document 1), in the joining of different materials between an aluminum material or an aluminum alloy material and a steel material, joint strength can be increased and cracking of the joint portion can be suppressed, and further, breakage can be caused during wire drawing. Dissimilar material joining filler material (dissimilar material welding wire) is disclosed. This conventional wire for welding dissimilar materials has at least Si: 1.0 to 6.0 mass%, Ti: 0.01 to 0.30 mass%, and Zr: 0.01 to 0.30 mass%. The powdery flux is tubular in a skin material made of aluminum alloy containing aluminum and unavoidable impurities in the balance so that the filling rate is 2.0 to 20.0% by mass with respect to the mass of the whole wire. The metal shell is filled.

In Japanese Patent No. 4256886 (Patent Document 2), as a flux in a flux cored wire for joining different materials of a steel material and an aluminum alloy material, AlF ₃ is 0.1 to the total mass of the flux cored wire. It is disclosed that a fluoride composition containing -15% by mass and not containing chloride is filled with 0.3-20% by mass with respect to the total mass of the flux cored wire. This flux cored wire is manufactured by filling a powdered flux in a tubular metal sheath. In addition, in the paragraph [0066] of this document, “when the amount of flux in the flux cored wire is 1% by mass or less with respect to the total weight of the flux cored wire, the metal powder is commonly added. The metal powder is commonly an aluminum alloy powder (particle size 150 μm) having the same composition as A4047 as the outer skin, and 20 mass% is added to the total weight of the flux cored wire. ” As a method of adding a flux when the amount is reduced, it is described that it is possible to fill the flux by adding metal powder to the flux to increase the apparent amount.

 Recently, there has been a demand for realizing low-current joining of Fe-based welded materials and Al-based welded materials. And in order to implement | achieve this request, it turned out that a preferable welding result will be obtained, if the penetration of an Al type welding material is prevented and a Fe type welding material is joined in a brazing state (nonpatent literature 1). ).

 Further, Japanese Patent No. 4263879 (Patent Document 3) discloses a welding wire in which a flux exists between a tubular metal sheath and a conductive core wire, and flux filling of the welding wire is disclosed. The rate is 6.5-30%, preferably 15.5-19.5%. Japanese Patent No. 5444293 (Patent Document 4) discloses a manufacturing method thereof. In this prior art, the diameter of the conductive core wire is smaller than the inner diameter of the tubular metal sheath, and the flux is in the form of powder in the tubular metal sheath as in the prior art described in Patent Documents 1 and 2. Filled with flux.

Japanese Patent No. 5688492 Japanese Patent No. 4256886 Japanese Patent No. 4263879 Japanese Patent No. 5444293

Technical Paper Nippon Steel Technical Report No. 393 (2012) Dissimilar Metal Joining Technology between Steel Sheet and Aluminum Alloy Plate in Automobile Body / Nippon Steel & Sumitomo Metal Research Institute Joint Research Center

 Conventional welding wire fluxes are used to stabilize the arc and shield the molten pool from the atmosphere. Therefore, in order to achieve the purpose of this flux, it is necessary to fill the metal shell with a certain amount of flux. However, Patent Document 1 does not disclose any relationship between the flux filling rate and the penetration. This is only disclosed in Patent Document 1 that an effect is obtained in an embodiment in which the flux filling rate is 5% by mass with respect to the mass of the entire wire, and the flux specified in the claims. This is supported by the fact that it is not disclosed that the effect is obtained in the entire range of the filling rate (2 to 20%).

  Although it is also described in Patent Document 2, in the case of performing welding at a low current, in order to prevent excessive penetration of the Al-based welded material and join the Fe-based welded material in a brazed state, There is a fact that the amount of flux used in welding is preferably small. Particularly in high-speed welding by laser, if the amount of flux is large, unmelted flux may remain at the time of welding, so it is necessary to reduce the amount of flux also in this respect. In Patent Document 2, when the flux amount is 1% by mass or less with respect to the total weight of the flux cored wire, metal powder is added to increase the apparent amount, and the flux is filled in the metal sheath. It is described that it can be made possible. However, when the present inventor actually conducted a confirmation test, in order to suppress the occurrence of uneven filling of the flux even when the flux of about 5% by mass, which is greater than 1% by mass, is filled in the tubular metal shell. It was found that it was necessary to increase the apparent amount by adding metal powder to the powdery flux.

  Further, the inventor has reduced the flux filling rate by causing the flux to exist between the tubular metal sheath and the conductive core wire as in the conventional techniques described in Patent Documents 3 and 4. Tried. However, even if this conventional technique is used, if the filling rate of the flux is reduced, a state in which the flux is locally present between the tubular metal sheath and the conductive core wire is generated, which is large in the entire circumferential direction of the wire. Flux could not be present without causing variation. This is because the conventional techniques described in Patent Documents 3 and 4 are based on a region where the flux filling rate is higher than that of the present invention.

  An object of the present invention is to provide a method for manufacturing a wire for welding dissimilar materials that makes it possible to reduce the flux filling rate and at the same time suppress the occurrence of filling unevenness.

  Another object of the present invention is to provide a welding wire for dissimilar materials with a small amount of flux that can realize the joining of an Fe-based welded material and an Al-based welded material with a low current.

  The dissimilar material welding wire manufactured by the manufacturing method of the dissimilar material welding wire for welding the Fe-based welded material and the Al-based welded material of the present invention is formed in a tubular metal sheath made of aluminum or aluminum alloy. A conductive core wire made of aluminum or an aluminum alloy is disposed, and a flux having at least a function of removing an oxide film from the surface of the material to be welded exists between the metal sheath and the conductive core wire. Is. And the filling rate of a flux is 4.9 mass% or less with respect to the mass of the whole wire.

  In the first manufacturing method of the present invention, a coating conductive material provided with a coating layer by applying a flux paste obtained by kneading a flux material and a solvent onto the surface of a conductive core material for forming a conductive core wire. A core material is formed. Next, a wire for drawing is formed by forming a tubular metal sheath material for forming a tubular metal sheath on the outside of the coated conductive conductor material so that the coated conductive core material is located at the center. To do. Then, the drawing operation is performed until the drawing wire has a predetermined outer diameter.

  Further, in the second manufacturing method of the present invention, a coating layer is provided by applying a flux paste obtained by kneading a flux material and a solvent to the inner surface of a metal skin material having a circular cross section perpendicular to the longitudinal direction. Forming a coated metal skin material. Next, in a state where the conductive core material for forming the conductive core wire is disposed inside the coated metal sheath material, the coated metal sheath material is molded and the tubular metal sheath is formed outside the conductive core material. A wire for drawing is formed by forming the material. Then, the drawing operation is performed until the drawing wire has a predetermined outer diameter.

  In the production method of the present invention, a flux paste is applied to the surface of the conductive core material to form a coated conductive core material having a coating layer, or a flux paste is applied to the inner surface of the metal skin material. A wire for drawing is formed by forming a coated metal skin material with a coating layer and then forming a tubular metal skin material. In this way, as a result of the coating layer being formed over the entire circumferential direction of the wire, even when the flux filling rate is low, after the solvent in the coating layer is exhausted, the flux is distributed in the entire length direction and the circumferential direction of the wire. It will be distributed.

  In any case, according to the manufacturing method of the present invention, even when the flux filling rate is reduced, it is possible to manufacture a wire for welding dissimilar materials in which a large bias of the flux is not locally generated in the wire.

  In addition, it is preferable to form a tubular metal shell material after the coating layer is dried to such an extent that a part of the solvent remains. In this way, a large deviation in the thickness of the coating layer is not caused.

  In the dissimilar material welding wire for welding the Fe-based welded material and the Al-based welded material of the present invention, a conductive core wire made of aluminum or aluminum alloy is formed in a tubular metal sheath made of aluminum or aluminum alloy. Is arranged. And the flux which has at least the function to remove an oxide film from the surface of a to-be-welded material exists between a metal shell and a conductive core wire. The filling rate of the flux is as small as 4.9% by mass or less with respect to the mass of the whole wire for welding different materials. In the present invention, the flux between the metal skin and the conductive core wire exists as a dry coating layer.

  In the specification of the present application, the “dry coating layer” means “a powder powder formed by drying a coating layer formed by applying a flux paste kneaded with a flux material and a solvent. The part where the flux exists is the powder of the flux ". When the flux is provided in the form of a dry coating layer, a small amount of flux can be disposed without a large deviation over the entire circumferential direction of the wire.

  According to the wire for welding dissimilar materials of the present invention, even when the amount of flux is reduced, the flux can be stably supplied to the weld during welding. As a result, according to the wire for dissimilar material welding of the present invention, since the arc is stable even in a low current region, it is possible to prevent the excessive penetration of the Al-based welded material and join the Fe-based welded material in a brazed state. Became possible.

  The thickness of the coating layer is determined by the amount of the flux. When the filling rate of the flux is 0.2 to 4.9% by mass, the thickness is 200 μm or less at the maximum.

  The outer diameter of the wire for dissimilar material welding is preferably about 1.0 mm to 2.0 mm, similar to the outer diameter of a wire that can be used in a welding machine currently used in the market.

  When used for MIG welding, if the Fe welded material is carbon steel or stainless steel and the Al welded material is made of an aluminum alloy, it is made of aluminum or an aluminum alloy having a lower solidus temperature than the metal shell. It is preferable to use a conductive core wire. By encapsulating a conductive core wire with a melting point lower than that of the metal sheath, it becomes a droplet transfer that does not generate a thin and elongated liquid column as seen when a solid wire is welded with an inert shielding gas. This is because the obtained arc is obtained.

  When the dissimilar material welding wire of the present invention is used for MIG welding, the outer diameter of the dissimilar material welding wire is 1.0 mm to 1.6 mm, and the flux filling rate is the mass of the entire dissimilar material welding wire. It is preferable that it is 0.2-1.8 mass% with respect to. If the flux filling rate is within this range, the arc is stable even in a low current region in MIG welding, so that it is possible to prevent excessive penetration of the Al-based welded material and join the Fe-based welded material in a brazed state. it can.

  In addition, when used for MIG welding, if the flux filling rate is 1.0 to 1.8% by mass relative to the mass of the entire wire for dissimilar material welding, the arc stability is further increased, and spatter is reduced accordingly. The effect that a bead is formed is obtained.

  When the dissimilar material welding wire of the present invention is used in laser welding, the outer diameter of the dissimilar material welding wire is 1.0 mm to 2.0 mm, and the flux filling rate is the mass of the entire dissimilar material welding wire. It is preferable that it is 1.0-4.9 mass% with respect to. If the flux filling rate is within this range, in laser welding, unmelted flux does not remain, the molten state is stable, a good bead is formed, and an excessive penetration of the Al-based workpiece is prevented, Fe-based workpieces can be joined in a brazed state.

  In addition, when used for laser welding, if the flux filling rate is 1.3 to 4.4% by mass with respect to the total mass of the wire for welding different materials, the melted state becomes more stable and the compatibility is further improved. The effect that a good bead is formed is obtained.

For the purpose of removing the oxide film, the flux is mainly composed of KAlF-based metal fluoride, and one or more metal fluorides such as CsAlF ₄ , CsF, KF, NaF, LiF, CeF, AlF ₃ are added. There is a case. Furthermore, what added any 1 or more types of metal powder of Al, Si, Cu, Zn, and Mn can also be used. One or more metal fluorides such as CsAlF ₄ , CsF, KF, NaF, LiF, CeF, and AlF ₃ may not be added to the flux.

(A) is a figure which shows the outline of the apparatus which manufactures the wire for drawing, (B) is an expanded sectional view of a part of this apparatus. (A) is a photograph showing an example of a cross section of a wire for welding dissimilar materials manufactured by drawing a wire for drawing manufactured using the apparatus of FIG. 1 (A), and (B) is shown in Patent Document 4. A photograph showing an example of a cross section of a wire for welding dissimilar materials manufactured by drawing a wire for drawing manufactured by filling a powder flux between a metal sheath and a conductive core wire using a conventional manufacturing method. It is. (A) is a figure which shows the outline of the other apparatus which manufactures the wire for drawing, (B) is a partial expanded sectional view of this apparatus. It is a simulation cross section of the wire for dissimilar material welding of this Embodiment. It is a figure which shows Table 1 which displayed the wire structure of the Example and the comparative example, the metal outer sheath, the kind of electroconductive core wire, the solidus temperature difference, the flux filling rate, the flux supply method, and the kind of inclusion flux. It is a figure which shows Table 2 which shows the evaluation result of the evaluation test using the wire for dissimilar material welding of an Example and a comparative example. (A) thru | or (C) is a figure which shows the joint shape of the test piece used by the tension test.

[Description of manufacturing method]
Hereinafter, an embodiment of a method for manufacturing a wire for welding different materials of the present invention and a wire for welding different materials manufactured by the method will be described in detail. FIG. 1A is a diagram showing an outline of a part of a manufacturing apparatus for carrying out the first manufacturing method of the present invention. FIG. 1B is a view of a portion B surrounded by a circle in FIG. It is a general | schematic expanded sectional view.

A method of manufacturing a wire for welding dissimilar materials including a dry coating layer of a flux (embodiment of the first method invention) will be described. First, an elongated metal skin material 101 made of aluminum or an aluminum alloy fed from a metal plate feed coil (not shown) is formed by a primary forming roll device 102 so that a cross section in the width direction becomes an arc shape. A conductive core wire 201 made of aluminum or an aluminum alloy fed from a wire delivery coil (not shown) is fed to the coating device 204 via guide rollers 202 and 203. In the coating apparatus 204, a flux paste is applied to the conductive core wire 201 that passes between the pair of felts F1 and F2, as shown in FIG. The flux paste is a liquid mixture of a powder flux material and a solvent [for example, ethyl alcohol (C ₂ H ₅ OH)]. The flux paste is supplied from the applicator 205 to the felts F1 and F2. On the outer peripheral surface of the conductive core wire 201 that has passed between the felts F1 and F2, a flux paste is applied as a whole to form a coating layer C. Before the coated conductive core material 206 provided with the coating layer C reaches the guide roller 207, the coating layer C is partially left with a solvent (that is, the flux does not fall off) by a drying device (not shown). Dried. In this state, the coating layer does not fall off the conductive core wire 201. In the present embodiment, the coated conductive core material 206 is formed using the applicator 205, but the coating layer is formed by immersing and passing the conductive core material 201 into the immersion tank in which the flux paste is stored. May be formed.

  Next, the coating conductive core material 206 is inserted into a region surrounded by the arc-shaped metal sheath material 103, and the coating conductive core material 206 and the metal sheath material 103 are merged. When the final wire diameter is 1.2 mm which is the standard dimension, the metal sheath material 101 and the conductive material are conductive so that the ratio of the cross-sectional area of the conductive core wire to the cross-sectional area of the wire obtained after the drawing process is 10 to 40%. The material and dimensions of the core wire 201 are selected. Next, the metal forming material 103 is formed by the secondary forming roll device 301 so as to reduce the distance between the joints of the metal covering material 103, and the outer periphery of the coated conductive core material 206 is formed into a tubular metal. A wire 208 for drawing is formed by enclosing it with a skin material. Thereafter, the drawing wire 208 is drawn using a known drawing device. When drawing, almost no solvent is present in the coating layer, and the coating layer is a dry coating layer. In the wire drawing operation, the cross-sectional area of the wire is gradually reduced, the powder powder of the dry coating layer is densified by pressurization, processed to a predetermined wire diameter, and then dried to complete. In addition, the said manufacturing process can be divided | segmented suitably.

  FIG. 2A is a photograph showing an example of a cross section of a wire for welding dissimilar materials manufactured by drawing a wire for drawing manufactured using the apparatus of FIG. FIG. 2 (B) is manufactured by drawing a wire for drawing manufactured by filling a powder flux between a metal sheath and a conductive core wire using the conventional manufacturing method shown in Patent Document 4. It is the photograph which shows an example of the cross section of the wire for welding dissimilar materials. 2A and 2B, the flux filling rate is about 4.7% by mass with respect to the mass of the entire wire. A dissimilar material welding wire 1 manufactured in the present embodiment shown in FIG. 2A includes a flux layer 7 formed of a dry coating layer between a metal sheath 3 and a conductive core wire 5. In FIG. 2 (B), the same reference numerals as those shown in FIG. As can be seen from the cross section of the wire manufactured using the conventional method of FIG. 2B, when the flux filling rate is reduced, the flux is placed between the tubular metal sheath 3 'and the conductive core wire 5'. The existing flux layer 7 ′ has a local bias in the abundance. On the other hand, when the flux layer 7 is provided in the form of a dry coating layer like the wire shown in FIG. 2A manufactured by the method of the present embodiment, a small amount over the entire circumferential direction of the wire. The flux can be arranged without a large deviation.

  FIG. 3 (A) is a diagram showing an outline of a part of a manufacturing apparatus for carrying out the second manufacturing method of the present invention, and FIG. 3 (B) is a portion B surrounded by a circle in FIG. 3 (A). FIG. 3A and 3B, the same members as those shown in FIGS. 1A and 1B are denoted by the same reference numerals as those shown in FIGS. 1A and 1B. It is. Compared with the manufacturing apparatus of FIG. 1 (A), in the manufacturing apparatus of FIG. 3 (A), a flux material and a solvent are applied to the inner surface of the metal skin material 103 whose cross-sectional shape perpendicular to the longitudinal direction has an arc shape. The kneaded flux paste is applied to form the coated metal skin material 104 having the coating layer C. Next, in a state where the conductive core wire material 201 for forming the conductive core wire is disposed inside the coating metal shell material 104, the coating metal shell material 104 is formed by the secondary forming roll device 301, The wire for drawing 208 is formed by forming a tubular metal sheath material outside the conductive core material. Even in the second manufacturing method, the coating layer C is not shown to the extent that the solvent remains in part before entering the secondary forming roll device 301, that is, the flux does not fall off the inner surface of the metal skin material. It is dried by a drying device. Even when the second manufacturing method is used, the flux layer 7 is provided in the form of a dry coating layer as in the first manufacturing method, so that a small amount of flux is arranged without a large deviation over the entire circumferential direction of the wire. can do.

[Dissimilar material welding wire of this embodiment]
The dissimilar material welding wire of the present embodiment manufactured by the above manufacturing method is a dissimilar material welding wire for welding an Fe-based welded material and an Al-based welded material. The dissimilar material welding wire 1 of the present embodiment has a tubular metal sheath made of aluminum or an aluminum alloy, as shown in a simulated cross section (cross section cut in a direction perpendicular to the longitudinal direction of the wire) shown in FIG. 3, a conductive core wire 5 made of aluminum or an aluminum alloy is disposed, and has at least a function of removing an oxide film from the surface of the material to be welded between the metal sheath 3 and the conductive core wire 5. A flux layer 7 containing metal powder as an alloying element of molten metal or a metal fluoride flux layer 7 containing no metal powder is present in the form of a dry coating layer. And the outer diameter dimension of the wire 1 for dissimilar material welding of this Embodiment is 1.0-2.0 mm. This dimension is a general wire diameter dimension of a welding wire used in an existing welding machine. Moreover, a flux filling rate is 0.2-4.9 mass% with respect to the mass of the whole wire 1 for different material welding.

  A small amount of flux 7 having fine particles and inferior fluidity, such as a metal fluoride flux, used in the wire 1 of the present embodiment is used as a metal sheath as in the conventional welding wire described in Patent Document 1. If a structure wrapped in a wire is adopted, a small amount of flux cannot be present in the longitudinal direction and the circumferential direction of the wire without great variation. Therefore, in this embodiment, since a small amount of flux is present in the form of a dry coating layer inside the wire 1, the flux layer 7 is elongated between the tubular metal sheath 3 and the conductive core wire 5. There is no great variation in the direction and circumferential direction.

(Flux type)
In joining aluminum or an aluminum alloy, the aluminum oxide film on the surface of the base material needs to be removed to inhibit the flow and spread of the molten metal. For this reason, the oxide film on the surface of the base material is removed by flux. In particular, the flux of alkali metal fluoride has the effect of dissolving the aluminum oxide film on the surface of the base material with molten alkali to activate the surface and facilitate wetting with the molten metal.

As the flux used in the present embodiment, for example, a flux containing any one or more of metal fluorides such as KAlF metal fluoride, CsAlF ₄ , AlF ₃ , CsF, NaF, KF, LiF, and CeF. Alternatively, a flux obtained by adding at least one metal powder of Al, Si, Cu, Zn, and Mn to those fluxes can be used.

In this particularly preferred embodiment, for the purpose of giving good wettability and reducing blowholes, in MIG welding, as a flux, KAlF-based metal fluoride is used as a main component, and AlF ₃ , CsF, LiF, It is preferable to use a flux containing one or more metal fluorides such as NaF and CeF. In laser welding, it is preferable to use a flux containing KAlF metal fluoride as a main component, CsAlF ₄ as an essential component, and one or more metal fluorides such as NaF and KF added.

(Examples and comparative examples)
Hereinafter, the result of having carried out the welding test using the Example and comparative example of the wire for dissimilar materials welding of this invention is demonstrated. Table 1 shown in FIG. 5 shows the structure of Examples 1 to 20 of the welding wires for different materials according to the present invention including a dry coating layer as a flux layer, the metal sheath, the type of the conductive core wire, and the solid phase. The line temperature difference, flux filling rate, flux supply method, and type of inclusion flux are displayed. Table 1 also shows Comparative Example 1 in which the flux filling rate was increased using a dry coating layer to compare and confirm the effects of the present invention, and Comparative Example 2 in which powdery flux was filled without using a dry coating layer. And the structure of the comparative examples 3-5 of a flux cored wire, the metal shell, the kind of electroconductive core wire, the solidus temperature difference, the flux filling rate, the flux supply method, and the kind of inclusion flux were shown. In the following Examples 1 to 20 and Comparative Example 1, the outer diameter of the wire for welding different materials 1 is 1.2 mm or 1.6 mm, the inner diameter of the metal sheath 3 and the outer diameter of the conductive core wire 5. The flux filling rate is changed by changing the size of the slight gap formed between the metal sheath 3 and the conductive core wire 5 by changing the flux and filling the flux as a dry coating layer. About Comparative Examples 3-5, like the wire shown to patent documents 1 and 2, only the powdery flux is filled into the inside of a metal shell, without using a conductive core wire.

  In Table 1 shown in FIG. 5, each row includes the structure of the different material welding wires of Examples 1 to 20 and Comparative Examples 1 to 5, the metal sheath, the type of the conductive core wire, the solidus temperature difference, the flux The filling rate, the flux supply method, and the type of inclusion flux are shown. Each of the wires for welding dissimilar materials of Examples 1 to 19 uses aluminum for the metal sheath and an Al-Si alloy for the conductive core so that the solidus temperature of the conductive core is lower than that of the metal sheath. In Example 20, aluminum is used for the metal sheath and the conductive core, and a flux is present as a dry coating layer between the metal sheath and the conductive core. In Example 19, since the core wire obtained by applying Cu plating to the conductive core wire was used, no metal powder was added to the flux.

In addition, the fluxes used in the welding wires for different materials in Examples 1 to 20 are all metal fluoride fluxes such as KAlF, CsAlF ₄ , AlF ₃ , CsF, NaF, KF, LiF, and CeF. In any one or more fluxes, one or more metal powders of Al, Si, Cu, Mn, and Zn are added, or no metal powder is added. In the welding wires of Examples 1 to 18, after containing Si as a chemical component of the conductive core wire, at least one element out of three alloy elements composed of Cu, Mn and Zn is fluxed. And the balance consists of Al and inevitable impurities.

(Chemical composition of welding wire)
Hereinafter, chemical components contained in the welding wire will be described.

  Si: In joining aluminum or aluminum alloy and steel, Si forms a thin FeSiAl layer at the joining interface on the steel side and suppresses interdiffusion of Fe and Al. Therefore, a brittle intermetallic compound (IMC) made of FeAl is used. It is effective for suppressing generation and greatly contributes to improvement of joint strength. It also improves wettability and improves the conformability and shape of the bead. However, when the addition amount is small, a sufficient effect cannot be obtained. When the addition amount is large, the form of the FeSiAl-based layer at the steel-side joint interface changes, and the effect of suppressing mutual diffusion between Fe and Al is reduced. Since the brittle IMC of the system grows and decreases the joint strength, it contains an appropriate amount.

  Cu: Cu dissolves in the matrix and contributes to strength improvement. Moreover, when Cu more than a solid solubility limit is added, it contributes to strength improvement by precipitation strengthening. However, when the addition amount is small, a sufficient effect cannot be obtained, and when the addition amount is large, the weld cracking sensitivity is remarkably increased, resulting in a decrease in toughness due to an increase in CuAl-based intermetallic compounds. In joining steel materials, an appropriate amount is contained to promote the formation of FeAl-based intermetallic compounds at the steel material-side joining interface.

  Mn: Mn dissolves in the matrix and contributes to strength improvement. However, when the addition amount is large, the strength and toughness decrease due to the coarsening of crystal grains and the generation of coarse intermetallic compounds, so an appropriate amount is contained.

  Zn: Zn improves the conformability of the bead, and further contributes to suppressing the formation of FeAl-based IMC at the steel-side joint interface in the joining of aluminum or an aluminum alloy to a steel material, but improves the joint strength. In order to reduce the joint strength by increasing the number of blowholes, and to increase the amount of fumes generated during welding, an appropriate amount is contained.

(Evaluation results)
Table 2 shown in FIG. 6 shows the evaluation results of the evaluation tests using the different material welding wires of Examples 1 to 20 and Comparative Examples 1 to 5 shown in Table 1. In the evaluation test, depending on the joint shape, base material combination (combination of aluminum alloy and carbon steel and stainless steel) and the joining method, the arc of MIG welding when produced in one pass by MIG welding and laser welding. Stability, molten state in laser welding, spatter generation state, bead shape of the prepared specimen, presence or absence of cracks in weld metal part, breaking load in tensile test, steel material side interface (carbon steel and stainless steel side interface) A confirmation test of the thickness of the intermetallic compound (IMC) layer was performed. As a joint test piece, a flare welded joint test piece produced in one pass [FIG. 7A], a lap weld joint test piece [FIG. 7B], or a butt weld joint test piece [FIG. 7]. (C)] was used.

  Moreover, the test piece of the flare welded joint of FIG. 7 (A) is an aluminum alloy A6061 (JIS H 4000) and an electrogalvanized steel sheet (JIS G 3313, SECCT) or an aluminum alloy A6022 and an alloyed hot-dip galvanized steel sheet (GA270 MPa). It was set as the combination. The plate thickness was 1.2 or 1.5 mm for an aluminum alloy and 0.8 mm for a galvanized steel plate.

  The test pieces of the lap weld joint of FIG. 7B are aluminum alloys A5052, A6061, A7N01 (JIS H 4000) and carbon steel plate (JIS G 3141, SPCCT and JIS G 3135, SPFC590) or hot dip galvanized steel plate (GI 270 MPa). And a 980 MPa grade steel plate. The plate thickness was 1.2 or 2.0 mm for an aluminum alloy and 0.8 or 1.0 mm for a carbon steel plate.

  The test piece of the butt weld joint shown in FIG. 7C is a combination of an aluminum alloy A6061 (JIS H 4000) and a 1200 MPa class steel plate or SUS304 (JIS G 4305), and the thickness of the aluminum alloy is 1.0 mm. The 1200 MPa grade steel plate and SUS304 were 1.6 mm. The back plate was a carbon steel plate (JIS G 3141, SPCCT), and the plate thickness was 1.2 mm.

(Welding conditions)
In MIG welding, dissimilar material welding wire with a diameter of 1.2 mm is used, and AC pulse welding or DC pulse welding is used in a downward posture, current 65 to 122 A, voltage 12.0 to 16.2 V, welding speed 600 to 2000 mm. / Min. On the other hand, laser welding was performed using dissimilar material welding wires having diameters of 1.2 and 1.6 mm with a fiber laser in a downward posture under conditions of a laser output of 2 to 4 kW and a welding speed of 500 to 1000 mm / min. . The test conditions actually employed in each example and comparative example were selected as the best conditions from the above range. Moreover, argon was used as a shielding gas in any welding method.

(Arc stability in MIG welding)
In the evaluation of arc stability in MIG welding, mainly the arc transfer mode, the presence or absence of fluctuations in arc length, and the concentration of arc (presence or absence of deviation of arc on one side base metal) were confirmed. A case where a concentrating and stable spray transfer arc was obtained was evaluated as ◯ (good), and when any one of the arcs was inferior, Δ (tolerable range) or x (defective) depending on the degree.

(Molten state in laser welding)
In the evaluation of the melting state in laser welding, the melting state of the welding wire for different materials under laser irradiation is observed with a high-speed camera, and the metal shell, conductive core wire, and flux are normally melted to form a molten pool. ◯ (good), if any of them is supplied to the molten pool in an unmelted state, or a stable molten pool is not formed, △ (tolerable range) or × (bad) depending on the degree .

(Spatter generation state)
When evaluating the spatter generation state, visually observe the spatter generation state during welding and observe the spatter adherence to the surface of the test specimen after welding. Although the occurrence is slight, the extent that can be removed is indicated by Δ (allowable range), and the occurrence is high and the adherence is indicated by × (defect).

(Bead shape)
In the evaluation of the bead shape of the joint produced by MIG and laser welding, the bead shape on the surface of the joint was confirmed by visual observation, and the cross-sectional shape of the weld bead was also enlarged and observed about 15 times using an optical microscope. In addition, the sample for optical microscope observation performed the buffing finishing by embedding the cross section of the welded joint cut out from the joint in resin.

  As for the bead shape of the joint surface, it is preferable that there is no fusion failure with a uniform bead width over the entire length, and there is no excessive penetration, and the cross-sectional shape of the weld bead is on the surface of the aluminum alloy base material, carbon steel and stainless steel plate. It is preferable that the bead spreads and the flank angle is large, the carbon steel and stainless steel plate sides are joined by brazing, and the aluminum alloy side is not excessively melted or undercut. A case where all of these conditions are met is marked as ◎ (very good), while a fusion defect and other evaluation items that have significant defects are marked as x (defective), and other than that, it is marked as ◯ or △ depending on the degree. .

(Crack of weld metal part)
In the evaluation of cracks in weld metal parts of joints produced by MIG and laser welding, the weld metal cross section was magnified about 15 to 400 times using an optical microscope, and the presence or absence of cracks in the weld metal parts was confirmed. The case where there was no crack was evaluated as ◯ (good), and the case where the weld metal part was cracked was rated as x (defective).

  In addition, the sample for optical microscope observation was confirmed by embedding the cross section of the welded joint cut out from the joint in a resin, buffing the finish, and performing no etching.

(Tensile test)
In the tensile test of joints produced by MIG and laser welding, a tensile test piece with a width of 20 mm was taken from the welded joint shown in FIGS. 7A to 7C at right angles to the welding direction, and a Tensilon universal material testing machine was used Then, a tensile load was applied to the aluminum alloy base material, the carbon steel, and the stainless steel plate, and the breaking load was measured.

Tensile test evaluations of flare welded joints and lap welded joints were taken from flare welded joints and lap welded joints based on a measured rupture load of 270 MPa or more, which is the tensile strength rule of galvanized steel sheet (JIS G 3313 SECCT). Since the cross-sectional area of the galvanized steel sheet of the tensile test piece thus processed was 16 mm ² , it was judged as ◯ (good) if it exceeded 4320 N as the breaking load, and x (defect) if not exceeded.

In addition, the tensile test evaluation of the butt welded joint is a tensile test in which the measured rupture load is taken from the butt welded joint and processed based on the aluminum alloy (JIS H 4000 A6061P-T4) tensile strength regulation of 205 MPa or more. Since the cross-sectional area of the piece of aluminum alloy was 20 mm ² , it was judged as ◯ (good) if the breaking load exceeded 4100 N, and x (bad) if not exceeded.

(IMC width)
In the evaluation of the intermetallic compound (IMC) of the joint produced by MIG and laser welding, the cross section of the weld joint was magnified about 400 times using an optical microscope, The thickness was measured. In the joining of aluminum or aluminum alloy and steel sheet, the FeAl-based IMC layer generated at the steel sheet side interface significantly reduces the joint strength. Therefore, it is preferable to keep the layer thickness low, and the maximum width is 4 μm or less. The case of good (◯) and 5 μm or more was evaluated as x (defect).

(Test results)
(Explanation of results: Mig-arc stability / Laser melting state / sputtering state)
Based on each test result shown in Table 2 of FIG. 6, the effect of this Embodiment is demonstrated concretely. In Examples 1 to 7, 9, and 14 to 18, aluminum was used for the metal sheath, and an Al—Si alloy was used for the conductive core, and the solidus temperature of the conductive core was lower than that of the metal sheath. In these examples, in MIG welding, the unstable behavior of the liquid column (molten column) is suppressed even in the low current range of 65 to 122 A, the arc length does not vary, the arc concentration is good, and the spray is stable. A transition arc has been obtained. In Example 20, aluminum was used for the metal sheath and the conductive core, and since there was no difference in the solidus temperature between them, no effect was obtained in MIG welding, and the arc concentration was slightly weak.

  Moreover, Examples 8, 10-13, and 19 satisfy | fill the regulation range of the flux filling rate of this invention, and are performing laser welding. In these examples, the metal shell, the conductive core wire, and the flux were normally melted, and a healthy molten pool with good wettability was formed.

  On the other hand, Comparative Examples 1 and 2 each have a high flux filling rate of 5.1% by mass and do not satisfy the specified range of the flux filling rate of the present invention. In Comparative Example 1, since the flux layer was formed by the dry coating layer, the molten state was stable, but the amount of spatter was increased. In Comparative Example 2, since the powder was added, the molten state was poor, the amount of spatter was increased, and a healthy molten pool was not formed.

(Result explanation: Bead shape)
In the bead shape evaluation results, Examples 1 to 7, 9, and 14 to 18 are for MIG welding, and are combinations in which the solidus temperature of the conductive core wire is lower than that of the metal sheath. And it is adjusted to an appropriate flux filling rate, flux supply method, type of flux, and chemical composition, and a good bead shape is obtained. Among these, since Examples 1-5, 7, 9, 14, 15, 17, and 18 have a flux filling rate in the range of 1.0 to 1.8%, the arc stability is further increased. Furthermore, the effect that a favorable bead is formed is acquired. In Example 20, there was no solidus temperature difference between the metal sheath and the conductive core, and the arc stability in MIG welding was slightly inferior, so the bead width was slightly disturbed.

  On the other hand, Examples 8, 10 to 13, and 19 are for laser welding, and are adjusted to an appropriate flux filling rate, a flux supply method, a kind of flux, and a chemical component, and a good bead shape is obtained. Among these, Examples 11 to 13 and 19 have a flux filling rate in the range of 1.3 to 4.4%. Therefore, the molten state is more stable, the conformability is further improved, and good beads are obtained. The effect that is formed is obtained.

  In contrast, Comparative Examples 3 to 5 are not the multilayer cross-section wire of the present invention [FIG. 2 (A) or FIG. 4], but are flux cored wires shown in Patent Documents 1 and 2, and flux is added as a powder. In Comparative Examples 4 and 5, the flux filling rate exceeds the range of the present invention. For this reason, in Comparative Examples 4 and 5, the influence of the flux became strong, and an undercut occurred on the aluminum base material side. Further, in Comparative Example 3, in the flare joint, burn-out due to excessive melting occurred over almost the entire length on the aluminum alloy side, and the bead shape was rejected.

  In Comparative Examples 3 to 5 using the conventional method, metal fluorides having fine powder particles and poor fluidity could not be stably supplied. However, in Examples 1 to 20, 0.2 to 4.9% of the flux supply method to the wire of the present invention can be obtained by using a conductive core wire or a metal sheath in which a flux coating layer of a flux paste is formed in advance. Since the flux can be supplied without variation in the flux filling rate region, the effect of the flux is stably obtained, and a better bead shape is obtained.

(Explanation of results: cracks in weld metal)
In the crack confirmation result of the weld metal part, Examples 1 to 20 are the flux filling rate, the flux supply method, and the type of flux within the scope of the present invention, and contain appropriate amounts of Si, Cu, Mn, and Zn. Since the balance was composed of Al, the matrix was not excessively hardened by precipitates, and no cracks were observed in the weld metal.

(Result explanation: Breaking load, IMC width)
In the joint tensile test results, Examples 1 to 13 and 16 to 20 are the flux filling rate, the flux supply method, the type of the flux within the scope of the present invention, and the Al-Si-Cu based chemical composition. In both cases, the thickness of the IMC layer was suppressed to 4 μm or less due to the effect of suppressing the generation of IMC by Si, and a sufficient breaking load was obtained by solid solution strengthening and precipitation strengthening of Cu.

  Example 14 is a flux filling rate, a flux supply method, and a kind of flux within the scope of the present invention, and has an Al—Si—Mn-based chemical composition. A sufficient breaking load was obtained by solid solution strengthening and precipitation strengthening of Mn after the thickness was suppressed to 4 μm or less.

  Example 15 is a flux filling rate, a flux supply method, and a type of flux within the scope of the present invention, and is an Al—Si—Zn-based chemical composition. While the thickness was suppressed to 4 μm, the conformability of the beads and the penetration shape were improved by the effect of Zn, and a sufficient breaking load was obtained.

  In Comparative Examples 1 and 2, the flux filling rate is 5.1% by mass, does not satisfy the specified range of the flux filling rate of the present invention, the influence of the flux becomes excessive, and deep penetration occurs in laser welding. Melting-off occurred on the aluminum alloy side, and a sufficient breaking load could not be obtained. Further, the Fe content in the weld metal increased, and the thickness of the IMC layer at the carbon steel plate side interface became 5 μm or more.

  In Comparative Examples 4 and 5, the flux filling rate is 5.9% by mass, 6.7% by mass, and the addition of powder does not satisfy the flux filling rate and the flux supply method of the present invention. In welding, an undercut occurred on the aluminum alloy side, and fractured from the undercut part, so that a sufficient breaking load could not be obtained. Further, the Fe content in the weld metal increased, and the thickness of the IMC layer at the carbon steel and stainless steel plate side interface became 5 μm or more.

  Comparative Example 3 is a powder addition, does not satisfy the flux supply method of the present invention, and in the flare joint, burn-out due to excessive melting occurs over almost the entire length on the aluminum alloy side, and a sufficient breaking load is obtained. There wasn't.

  Generally, in brazing, a flux is applied to the surface of a base material in advance, and the molten flux removes an oxide film on the surface of the base material. The molten metal then flows over it and joins the interface. However, when brazing with the flux cored wires having the conventional structures of Comparative Examples 3 to 5, the flux is arranged at the center of the wire, so that the flux is hardly melted and the original effect of brazing is difficult to obtain. On the other hand, in the multilayer cross-section structure wires of Examples 1 to 20 of the present invention in which the flux is arranged near the surface of the wire, the time when the flux melts out is fast, and the original effect of brazing is easily obtained.

  As described above, the dissimilar material welding wire of the present invention includes a flux layer composed of a dry coating layer, so that welding can be performed in dissimilar material joining of an Fe-based welded material and an Al-based welded material by MIG and laser welding. It was confirmed that the fabrication of a high-strength joint with excellent workability and bead shape and no weld crack was realized.

  According to the method of the present invention, a flux paste is applied to the surface of the conductive core material to form a coated conductive core material having a coating layer, or a flux paste is applied to the inner surface of the metal skin material. Then, a coated metal hull material having a coating layer is formed, and then a tubular metal hull material is formed, and a conductive wire is disposed therein to form a wire for drawing. In this way, the coating layer is formed over the entire length and circumferential direction of the wire. As a result, even when the filling rate of the flux is low, after the solvent in the coating layer is removed, the flux It will be distributed and arranged in the entire circumferential direction.

  According to the wire for welding dissimilar materials manufactured by the method of the present invention, even when the flux filling rate is low, the flux layer exists as a dry coating layer over the entire length direction and circumferential direction, so that an arc is generated even in a low current region. It was possible to stabilize and prevent excessive melting of the Al-based welded material, and to join the Fe-based welded material in a brazed state.

1 Wire for welding dissimilar materials 3 Metal sheath 5 Conductive core wire 7 Dry coating layer

Claims (13)

A conductive core wire made of aluminum or aluminum alloy is disposed in a tubular metal sheath made of aluminum or aluminum alloy,
A flux having at least a function of removing an oxide film from the surface of the material to be welded exists between the metal sheath and the conductive core wire,
A method for producing a wire for welding dissimilar materials for welding an Fe-based welded material and an Al-based welded material in which the filling rate of the flux is 4.9% by mass or less based on the mass of the entire wire
Applying a flux paste obtained by kneading the flux material and a solvent to the surface of the conductive core material for forming the conductive core wire to form a coated conductive core material having a coating layer;
A wire for drawing is formed by forming a tubular metal sheath material for forming the tubular metal sheath on the outside of the coated conductive conductor material so that the coated conductive conductor material is located at the center. And
A method for producing a wire for welding dissimilar materials, wherein the wire drawing operation is performed until the wire has a predetermined outer diameter.   The method for producing a wire for welding dissimilar materials according to claim 1, wherein the tubular metal outer material is formed after the coating layer is dried to such an extent that the solvent remains partially. A conductive core wire made of aluminum or aluminum alloy is disposed in a tubular metal sheath made of aluminum or aluminum alloy,
A flux having at least a function of removing an oxide film from the surface of the material to be welded exists between the metal sheath and the conductive core wire,
A method for producing a wire for welding dissimilar materials for welding an Fe-based welded material and an Al-based welded material in which the filling rate of the flux is 4.9% by mass or less based on the mass of the entire wire
A flux paste obtained by kneading the flux material and a solvent is applied to the inner surface of the metal shell material having a circular cross section perpendicular to the longitudinal direction to form a coating metal shell material having a coating layer,
In the state where the conductive core wire material for forming the conductive core wire is disposed inside the coated metal sheath material, the coated metal sheath material is formed and a tubular metal is formed outside the conductive core wire material. Forming a wire for drawing by forming a skin material;
A method for producing a wire for welding dissimilar materials, wherein the wire drawing operation is performed until the wire has a predetermined outer diameter.   The method for producing a wire for welding dissimilar materials according to claim 3, wherein the tubular metal outer material is formed after the coating layer is dried to such an extent that the solvent remains partially. A conductive core wire made of aluminum or aluminum alloy is disposed in a tubular metal sheath made of aluminum or aluminum alloy,
A flux having at least a function of removing an oxide film from the surface of the material to be welded exists between the metal sheath and the conductive core wire,
In the wire for welding dissimilar materials for welding the Fe-based welded material and the Al-based welded material whose filling rate of the flux is 4.9% by mass or less with respect to the total mass of the wire,
The wire for welding dissimilar materials, wherein the flux between the metal sheath and the conductive core wire is present as a dry coating layer. The Fe-based workpiece is carbon steel or stainless steel,
The wire for welding dissimilar materials according to claim 5, wherein the conductive core wire is made of an aluminum alloy having a solidus temperature lower than that of the metal sheath. The filling rate of the flux is 0.2 to 4.9% by mass,
The wire for welding dissimilar materials according to claim 5, wherein the dry coating layer has a thickness of 200 μm or less at the maximum. The welding is MIG welding;
The outer diameter of the wire for welding different materials is 1.0 mm to 1.6 mm,
The wire for welding dissimilar materials according to claim 6 or 7, wherein a filling rate of the flux is 0.2 to 1.8% by mass with respect to a mass of the whole wire for dissimilar materials welding.   The wire for welding dissimilar materials according to claim 8, wherein a filling rate of the flux is 1.0 to 1.8% by mass with respect to a mass of the whole wire for welding dissimilar materials. The welding is laser welding;
The outer diameter of the wire for welding different materials is 1.0 mm to 2.0 mm,
The wire for welding dissimilar material according to claim 7, wherein a filling rate of the flux is 1.0 to 4.9% by mass with respect to a mass of the entire wire for dissimilar material welding.   The wire for welding dissimilar materials according to claim 10, wherein a filling rate of the flux is 1.3 to 4.4% by mass with respect to a mass of the whole wire for welding dissimilar materials.   The wire for welding dissimilar materials according to any one of claims 5 to 11, wherein the flux contains metal powder as an alloy element of molten metal. The flux is mainly composed of KAlF based metal _{fluorides, CsAlF 4, KF, NaF,} LiF, CeF, CsF, 1 or more or a metal fluoride of Al F ₃ are added, further Al, Si The wire for welding dissimilar materials according to claim 5, wherein at least one metal powder of any one of Cu, Zn, and Mn is added.