FR2984785A1 - Filled yarn, useful in connection between aluminum alloy material and steel material for welding materials, comprises sheath with aluminum alloy that contains silicon and zirconium, and flow filling arranged in interior of sheath - Google Patents

Abstract

The filled yarn (1) comprises a cylindrical sheath including an aluminum alloy that contains silicon (1.5-2.5 wt.%), zirconium (0.05-0.25 wt.%) and remaining inevitable aluminum impurities, and a flow filling that is arranged in an interior of the sheath and includes cesium fluoride (20-60 wt.%) and aluminum fluoride (7-15 wt.%), where a content of the flow filling is 4-20 wt.% of the total weight of the yarn. An independent claim is included for a method for welding different materials by laser.

Description

The present invention relates to a flux-cored wire for soldering, and to a method for welding different materials in the process and to a process for welding different materials. (1) FIELD OF THE INVENTION different materials that can be used for welding different materials, for example, transport machines such as motor vehicles and components of building materials and so on, and a process of laser welding materials different and to a MIG welding process of different materials using the cored wire for welding different materials, it relates more particularly to a cored wire for welding different materials suitable for use in a welding operation between an aluminum material or aluminum alloy and a galvanized steel sheet, a laser welding process of my different materials and a MIG welding process of different materials. (2) Description of the state of the art So far, in transport machines such as motor vehicles, steel materials are used as vehicle body materials and the like. Since the steel materials used as components of transporting machines and the like are exposed to rainwater, and so on, during their use, rustproof galvanizing is performed on their surfaces. As a result, an oxide film formed on the galvanized surface provides a water resistance effect, whereas zinc corrodes preferably (sacrificial protection) to iron even in the presence of surface-like defects, voids or the like. a steel material. Recently, for reasons of environmental protection, R & D in the field of hybrid motor vehicles, electric vehicles and the like has intensified, reducing the weight of vehicle bodies, and so on, of these motor vehicles being necessary to improve energy efficiency and for other reasons. In addition, in order to reduce the weight of vehicle bodies and other parts, the replacement of steel parts used as material with aluminum materials or aluminum alloy materials has been studied. after, the term aluminum materials and aluminum alloy materials are both referred to as aluminum alloy materials). Therefore, the production of vehicle bodies and the like requires the realization of a connection between different materials involving a steel material and an aluminum alloy material. Examples of different material bonding techniques between a steel material and an aluminum alloy material include a method of bonding by MIG welding or laser welding between base materials while feeding a flux-cored wire ( Non-Examined Publication of Japanese Patent Application No. 2008-68290).

In the prior art, the compositions of the outer sheath of the cored wire are defined as follows: 1 to 13% Si, and a fluoride-based flux containing no chloride is loaded into the outer sheath with a filling fraction which is between 0.3 and 20% by weight. In addition, in order to improve the cohesion of a bonded structure made of different materials, it has been suggested that a filler metal containing an amount of Si of 1.5 to 6.0%, and in addition containing Zr in the form of additive in an amount of from 0.1 to 0.2% by weight (Non-Examined Publication of Japanese Patent Application No. 2006-22445). MIG (Metal Inert Gas) welding is a method of supplying an inert gas such as argon or helium near a site to be bonded as a shielding gas. and generating an arc between a welding wire and the site to bond a steel material and an aluminum alloy material. This MIG welding is characterized in that the welding operation is performed in an isolated state of the atmosphere, the welding therefore continues without being affected by the oxygen present in the air. In contrast, laser welding comprises feeding a solder wire to a joining portion while the solder wire and the joining portion are irradiated with a laser light causing the solder wire and the joining portion to thermally fusing under the effect of laser light. However, the aforementioned prior art poses the following problems: in a structure such as the bodywork of a motor vehicle, in the case where a steel material and an aluminum alloy material are welded end to end, a stress of traction acts between the base materials when an external force is applied to the welded joint portion. On the other hand, in the case where, for example, a steel material and an aluminum alloy material are superimposed and welded, and when an external force is applied to the welded joint portion, a tensile stress acts between them. base materials, and at the same time a peel stress that moves the two base materials away from each other acts on the welding interface. Therefore, when different materials are welded, the welded joint portion must not only have tensile and shear strength but also high peel strength (peel strength). However, when a steel material and an aluminum alloy material are bonded by welding as in a conventional case, a highly brittle intermetallic compound is produced at the bonded portion, which poses the following problem: the tensile and shear strength and the peel strength of the bonded part are lower than in the case where the same type of component is welded. On the other hand, in the case where welding between different materials is carried out using the cored wire disclosed in Japanese Unexamined Publication No. 2008-68290, this highly fragile intermetallic compound is no longer produced, and the thickness of the the layer of the intermetallic compound can be reduced. However, post-weld tensile and shear strength increases in an area where the amount of Si contained in the filler metal is high, but unfortunately the peel strength decreases. On the other hand, although the peel strength improves in a zone with a small amount of Si and the detachment does not occur in the layer of the intermetallic compound, when there is a large difference in thermal expansion between the material aluminum and steel material (for example, in the case where the thickness of the aluminum material is greater than that of the steel material, etc.), cracks unfortunately occur in the welded part (welded metal part) due to the thermal shrinkage of the welded part. On the other hand, as in the Unexamined Publication of Japanese Patent Application No. 2006-224145, it is also possible to keep the amount of Si in a solid filler metal at a relatively low level between 1.5 and 6%. and add, if necessary, Zr as an optional component.

However, when the amount of Si is relatively high, or according to the main compositions and the filling fraction of the flux in the flux-cored wire, the formation of an intermetallic compound layer can not be effectively avoided, and one can not succeed in high detachment resistance. SUMMARY OF THE INVENTION In order to solve these problems, the present invention proposes to provide a cored wire for welding different materials, a laser welding process of different materials and a MIG welding process of different materials which, when an aluminum or aluminum alloy material and a steel material are welded, can improve the tensile and shear strength of a welded joint portion and the release resistance of an interface of the welded portions, and can give a welded metal part free of cracks. The cored wire for welding different materials according to the present invention is a cored wire for welding different materials for use in bonding different materials between an aluminum or aluminum alloy material and a steel material, the wire filled article comprising a cylindrical sheath made of an aluminum alloy which contains Si in an amount which is between 1.5 and 2.5% by weight and Zr in an amount which is between 0.05 and 0.25% by weight, the remainder being aluminum and unavoidable impurities, and a flow filling the interior of this sheath and containing cesium fluoride in an amount which is between 20 and 60% by weight, and the filling fraction of flux of between 5 and 20% by weight of the total weight of the yarn. Furthermore, another flux-cored wire according to the present invention suitable for welding different materials is a flux-cored wire for welding different materials to be used in the connection between different materials involving an aluminum or aluminum alloy material and a a steel material, the cored wire having a cylindrical sheath made of an aluminum alloy which contains Si in an amount of between 1.5 and 2.5% by weight and Zr in an amount of between 0, 0.5 and 0.25% by weight, the remainder being aluminum and unavoidable impurities, and a flow filling the interior of this sheath and containing AlF3 in an amount which is between 7 and 15% by weight, and the flux filling fraction of between 4 and 20% by weight of the total weight of the yarn. The method of laser welding different materials according to the present invention comprises the use of the above cored wire for welding different materials, forming a joining portion by an aluminum or aluminum alloy material and a steel material, and bonding the aluminum material or aluminum alloy material and steel material by feeding the cored wire for welding different materials while irradiating this joining portion with laser light. The method of MIG welding of different materials according to the present invention comprises the use of the above cored wire for welding different materials, the constitution of a joining portion by an aluminum or aluminum alloy material and a material in steel, forming an arc between the joining portion and the flux-cored wire for welding different materials, feeding an inert gas around the arc, and simultaneously bonding the aluminum or alloy material of aluminum and steel material. In the flux-cored wire for welding different materials of the present invention, the amounts of cesium fluoride contained in the flux and Si contained in the sheath are suitably defined. Therefore, the use of the wire in the laser welding of different materials or the MIG welding of different materials between an aluminum or aluminum alloy material and a steel material can improve the tensile and shear strength of the material. a welded joint portion and the release resistance of an interface of the welded portions.

Further, since the Zr is added in a predetermined amount as an essential composition in addition to the Si, a welded metal portion may be free of cracks even when the difference in thermal expansion between the steel material and the aluminum material is significant because the effect of refining the grains of Zr. On the other hand, the addition of Zr improves the junction strength as compared to a filler metal with added Si only. On the other hand, since the flux filling fraction is suitably defined, the flow reduction effect can be effectively obtained, and the tensile and shear strength of the welded joint portion and the level of the welding interface can be more effectively improved. It should be noted that the flow reduction effect is likely to be such that in laser welding of different materials or MIG welding of different materials between an aluminum or aluminum alloy material and a steel material, the reduction and the removal of an oxide film on the surface of the aluminum and a galvanized layer and a surface oxide film of the steel material are obtained more easily thanks to the activation of the flux by the heat Welding. In this way, in laser welding of different materials or MIG welding of different materials, by removing plated layers of base materials to be bonded and oxide films on the surfaces of the base materials, the metal interfaces freshly generated take place on the outermost layers of the basic materials. As a result, the base materials are well bonded together, and the tensile and shear strength and peel strength of the welded joint portion are improved. When the steel sheet is a non-galvanized steel sheet, the oxide film on the surface of the steel sheet can be removed by a predetermined amount of the stream having a predetermined chemical composition. As a result, the base materials of an aluminum material or an aluminum alloy material are well bonded together, and the tensile and shear strength and peel strength of the welded joint portion are improved. According to the method of laser welding or MIG welding of different materials of the present invention, when bonding between different materials involving an aluminum or aluminum alloy material and a steel material, the resistance to traction and shearing of the welded joint portion and the release resistance at the interface of the welded portions can be improved, and the formation of cracks in a portion of molten metal which occurs when the expansion difference can be avoided thermal between a steel material and an aluminum material is important. On the other hand, in the method of laser welding different materials of the present invention, the use of a semiconductor laser as a laser source reduces the irregularity of the extruded bead, thereby obtaining a good and beautiful welding structure. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a lap welding by the laser welding process of different materials of the present invention; Fig. 2 is a block diagram illustrating butt welding by the laser welding process of various materials of the present invention; Fig. Fig. 3 is a block diagram illustrating MIG weld overlay welding of various materials of the present invention; Fig. 4 is a block diagram illustrating butt welding by the MIG welding process of different materials of the present invention; Figs. 5A to 5D are drawings illustrating an example of the cored wire for welding different materials; Fig. 6 is a drawing which illustrates a test of tensile and shear strength of a joining portion according to an embodiment of the present invention; and FIG. 7 is a drawing which illustrates a peel strength test of an interface of the welded portions according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below. Fig. 1 is a schematic diagram illustrating overlap welding by the laser welding process of different materials of the present invention; FIG. 2 is a block diagram illustrating butt welding by the laser welding process of different materials of the present invention; and Figs. 5A-5D are drawings which illustrate an example of the cored wire for welding different materials. When the lap welding is performed by the laser welding process of different materials of the present invention, as shown in FIG. 1, for example, an aluminum alloy material 2 is disposed on the laser light side, and a plate-shaped aluminum alloy material 2 and a steel material 3 overlap. An overlap portion 4 of the aluminum alloy material 2 and the steel material 3 is irradiated by the laser light while a cored wire for welding different materials 1 is fed to the overlap portion 4 to effect welding laser, whereby the aluminum alloy material 2 and the steel material 3 are bonded. When butt welding is performed by the laser welding process of different materials of the present invention, as shown in FIG. 2, the plate-shaped aluminum alloy material 2 and the steel material 3 are placed end-to-end, and their abutment portion 6 is irradiated by the laser light while the cored wire 1 of the laser welding of different materials is fed to the abutment portion 6 to perform the laser welding. Among the laser light emitting devices that can be used are the YAG laser, the CO2 laser and the fiber laser, the semiconductor laser and various other devices, the semiconductor laser being the most preferable from the point of view of the appearance of the weld bead. Examples of aluminum alloy material 2 that can be used include those in accordance with JIS class A1000, class A2000 (alloy based on Al-Cu), class A3000 (alloy based on Al -Mn), class A4000 (alloy based on Al-Si), class A5000 (alloy based on Al-Mg), class A6000 (alloy based on Al-Mg-Si) and class A7000 (alloy based on Al Zn-Mg, alloy based on Al-Zn-Mg-Cu). Furthermore, a plate material whose thickness is for example between 0.5 and 4.0 mm, can be used as aluminum alloy material 2.

Examples of steel materials that can be used include SPCC (low carbon cold rolled steel sheet), high tensile strength steel, and various other steel materials. In particular, a preferable steel material is a galvanized steel sheet treated by hot-dip galvanizing (GA sheet steel, GI sheet steel). Like the steel material 3, for example, a plate material having a thickness of 0.5 to 4.0 mm may be used, where the thickness may be different from that of the aluminum alloy material 2. As shown in Figs. 5A to 5D, the cored wire for welding different materials 1 is, for example, a cylindrical sheath 1a made of aluminum alloy which is filled with a flux 1b, and the outer diameter of the wire 1 is, for example, between 0.8 and 1.6 mm. In the present invention, the filling fraction of the flux 1b in the yarn 1 is between 5 and 20% by weight of the total weight of the yarn. In addition, flux lb of the present invention contains cesium fluoride in an amount of 20 to 60% by weight. On the other hand, the flux of the flux-cored wire according to a second invention of the present invention has a flux containing AlF 3 in an amount of 7 to 15% by weight, and the filling fraction of the flux being from 4 to 20% by weight of the total weight. some thread. The aluminum sheath of the above-mentioned cored wires contains Si in an amount of 1.5 to 2.5% by weight and Zr in an amount of 0.05 to 0.25% by weight, the remainder being formed from an aluminum alloy comprising aluminum and unavoidable impurities. Examples of unavoidable impurities in this aluminum sheath are Mg, Mn, and Fe, and are contained in amounts each of which is 0.1 wt.% Or less of the total sheath weight. The reasons for limiting numerical values in the chemical composition of the cored wire for welding different materials of the present invention will now be discussed. "The amount of cesium fluoride contained in the flux: 20 to 60% by weight of the total weight of the flux" Cesium fluoride is intended to suppress the generation of a highly brittle intermetallic compound between an aluminum alloy material and a galvanized steel material during laser welding. When the amount of cesium fluoride contained in the stream is less than 20% by weight, the effect of suppressing the generation of the highly fragile intermetallic compound is low, leading to the reduction of tensile and shear strength and peel strength. On the other hand, when the amount of cesium fluoride contained in the flux is greater than 60% by weight, the effect of improving the suppressive function of the generation of the highly fragile intermetallic compound saturates, while the increase the amount of expensive cesium content increases the production costs of the cored wire for welding different materials. Therefore, in the present invention, the amount of cesium fluoride contained in the stream is defined to be between 20 and 60% by weight of the total weight of the stream. Examples of compositions which may be contained in combination in the stream other than cesium fluoride include aluminum fluoride, potassium fluoride, aluminum and potassium fluoride, lanthanum fluoride and so on. right now. Aluminum fluoride, potassium fluoride and aluminum and potassium fluoride are thus called: aluminum and potassium fluoride compounds, they are considered to have functions such as the removal of a aluminum oxide film, favoring the melting of the wire at a low melting point, ensuring wettability and forming a barrier to suppress diffusion at the interface between the steel material and the aluminum material. "The amount of AlF3 contained in the stream: from 7 to 15% by weight of the total weight of AlF3 flux serves to suppress the generation of the highly brittle intermetallic compound between an aluminum alloy material and the galvanized steel material during the laser welding and MIG welding. Examples of compositions in the stream other than AlF3 include a suitable combination of KA1, KF and the like. When the amount of AlF3 contained in the stream is less than 7% by weight, the effect of suppressing the generation of the highly fragile intermetallic compound is low, which leads to a decrease in tensile and shear strength and resistance to peeling. On the other hand, when the amount of AlF3 contained in the flux is greater than 15% by weight, the effect of improving the generation-suppressing function of the highly fragile intermetallic compound saturates, and the peel strength also decreases. . Therefore, in the present invention, the amount of AlF3 contained in the stream is defined to be between 7 and 15% by weight of the total weight of the stream. The amount of Si contained in the aluminum alloy constituting the sheath: 1.5 to 2.5% by weight, the amount of Zr contained: 0.05 to 0.25% by weight. The aluminum alloy constituting the sheath is a composition which is essential for improving the tensile and shear strength of the welded joint portion. When the amount of Si contained in the aluminum alloy is less than 1.5% by weight, the peel strength improves to a certain extent, but the effect of improving the tensile strength and shearing of the welded joint portion is insufficient. In addition, when the amount of Si is less than 1.5% by weight, the occurrence of a break at the interface of the bonded part is unlikely (fragile intermetallic compound), but if the difference in expansion thermal between the steel material and the aluminum material is important, the aluminum in the welded metal part becomes more sensitive to cracks, and the cracks do not occur at the interface of the bonded part but in a metal part welded. On the other hand, when the amount of Si contained in the aluminum alloy is greater than 2.5% by weight, a lower toughness of the parts close to the bonded portion reduces the peel strength. Therefore, in the present invention, the amount of Si contained in the aluminum alloy constituting the sheath is set between 1.5 and 2.5% by weight, to which is additionally added a predetermined amount of Zr. Consequently, the amount of Si being between 1.5 and 2.5%, the amount of Zr contained, with which it is possible to avoid cracks in the welded metal part and with which the peel strength can be improved, is between 0 , 05 and 0.25% by weight. More preferably, the amount of Zr contained is between 0.07 and 0.20% by weight.

It should be noted that the Mn, Mg or Fe may further be contained in the sheath as unavoidable impurities each in an amount of 0.1 wt% or less of the total weight of the sheath. "Flux filling fraction: 5 to 20% by weight of the total weight of the wire" The flux has a reducing effect on the aluminum alloy material and the steel material. When the flux filling fraction is less than 5% by weight of the total weight of the yarn, the flow reduction effect decreases, and the tensile and shear strength and peel strength decrease. On the other hand, when the filling fraction of the flux is greater than 20% by weight of the total weight of the yarn, the reduction action becomes excessively high, and on the contrary, the tensile and shear strength and the tensile strength. detachment decrease. Therefore, in the present invention, the fill fraction of the flux is between 5 and 20% by weight of the total weight of the yarn.

It should be noted that in the aforementioned chemical compositions of the stream, the remainder other than the specified residues is essentially composed of KA1F, but this means that a KA1F-based flux is used as the main composition. Examples of these KA1F-based fluxes (aluminum fluoride and potassium fluoride) include streams containing 75% by weight of KA1F4 and 25% by weight of K3A1F6. Otherwise, there are other streams containing the aluminum fluoride and potassium compounds that are partially replaced by K2A1F6. On the other hand, it is also possible to cite flows containing no Al, such as KF. Accordingly, a stream composed essentially of KA1F normally means, when a compound containing K, Al and F in an amount of 95% or more, the streams that may contain KF and the like, such as other fluorides. . The method of laser welding different materials using the cored wire for welding different materials of this embodiment will now be described. First, a joining portion is made of the aluminum alloy material 2 and the steel material 3. For example, when the joining portion is produced by lap welding, as shown in FIG. 1, the plate-shaped aluminum material 2 and the steel material 3 are superimposed, and, for example, the aluminum alloy material 2 is arranged on the laser light side. In this way, the arrangement of the aluminum alloy material 2 laser light side causes the aluminum alloy material 2 having a low melting point to be melted earlier than the steel material 3. Then, since one can partially melting the steel material 3 disposed under the aluminum alloy material 2, then the molten metal drip of the melt can be prevented more effectively and the lap welding can be performed more easily than in the case where the steel material 3 is arranged on the laser light side and subjected to overlap welding. When the joining portion is produced by butt welding, as shown in FIG. 2, the aluminum material 2 and the steel material 3 are end to end. Subsequently, when bathing the welded joint portion in an atmosphere where shielding gas, for example, helium and argon, is present, a position of the focal point of the laser light is adjusted, and the laser light condenses near the overlap portion 4 or the abutment portion 6 of the base materials. The flux-cored wire 1 of laser welding of different materials is then fed near the overlap portion 4 or the abutment portion 6 of the base materials. When the aluminum alloy material 2 and the steel material 3 are bonded through lap welding, the aluminum alloy material 2 can be actively melted since it is arranged on the laser light side. The surface oxide film on the surface of the steel material 3 is then reduced through the flux, and the steel interface is placed in contact with the molten metal of the aluminum alloy, so that the alloy material aluminum 2 and the steel material 3 are bonded by braze welding. It should be noted that the braze welding between the aluminum alloy material 2 and the steel material 3 means the melting of the aluminum alloy material 2 having a low melting point and the bonding of the aluminum alloy material 2 to the steel material 3 using the molten aluminum alloy as filling material. When the aluminum alloy material and a steel material are connected by butt welding, the aluminum alloy material 2 and the steel material 3 are bonded by braze welding by feeding the flux-cored wire 1 for laser welding the different materials to the abutting portion 6, adjusting the position of the focal point of the laser light to the abutting portion 6 and irradiating the abutment portion 6 with the laser light with the position of the focal point. As a result, the formation of a hole by the molten metal can be avoided. The aluminum alloy material 2 having a low melting point melts first by irradiating the laser light. The steel material 3 is then melted, where the surface layer on the steel sheet melts first. Subsequently, the cored wire 1 for laser welding of different materials which was also melted by irradiating the laser light is fed into these molten metal compositions. The radiation position of the laser light is then moved along a weld line, whereby in a state where the composition of the molten aluminum alloy, plating compositions if the steel material is plated, the steel compositions and the flux-cored compositions are mixed, the molten metal solidifies sequentially behind the radiation position of the laser light along the welding direction to form a bead. At this stage, an intermetallic compound is produced between the aluminum alloy material 2 and the steel material 3 to be bonded. The cored wire 1 for laser welding different materials of this embodiment has a quantity of cesium fluoride content set to an appropriate value. Alternatively, the amount of AlF3 contained is also fixed at an appropriate value.

Therefore, the amount of intermetallic compound generated in the welded portion is larger, for example, with FeAl, Fe3A1 and the like, which do not decrease brittleness, than with highly fragile FeA13 and Fe2A15. Therefore, the tensile and shear strength and peel strength of the welded joint portion can be improved for the former. Furthermore, in the cored wire 1 for laser welding different materials, the amount of Si contained in the aluminum sheath is defined in a suitable range, and therefore the tensile and shear strength can be improved without reduce the peel strength of the welded joint portion.

On the other hand, the cored wire 1 for laser welding different materials of this embodiment has a flux-filling fraction Ib defined in an appropriate range, and therefore the flow-reducing action can be effectively achieved without reducing tensile and shear strength and peel strength. In this embodiment, as previously mentioned, when the aluminum alloy material 2 and the steel material 3 are bonded through lap welding, it is desirable that the aluminum alloy material 2 be arranged on the laser light. However, in the present invention, the radiation position of the laser light and the feed position of the flux-cored wire 1 are not limited so long as the base materials can be fused together and an appropriate amount of flux-cored wire 1 can be fed into the melt of the molten metal by melting the wire.

Embodiments of the MIG welding process of different materials according to the present invention will now be described. A solder wire used in MIG welding is the same as solder wire 1 used in the laser welding process of different materials. In addition, conditions, etc., for MIG welding are similar to those of normal MIG welding. Fig. Figure 3 is a schematic diagram illustrating a welding process in the case of lap welding. First, a joining portion is made of the aluminum alloy material 2 and the steel material 3. When the joining portion is produced through lap welding, as shown in FIG. 3, the plate-shaped aluminum material 2 and the steel material 3 are superimposed, and, for example, the aluminum alloy material 2 is disposed on the side of a torch 7. In this way, by arranging the aluminum alloy material 2 torch side 7, the aluminum alloy material 2 having a low melting point can melt earlier than the steel material 3, and subsequently the steel material 3 disposed under the material in Aluminum alloy 2 can partially melt. As a result, drip of molten metal from the molten bath can be prevented more effectively and overlap welding can be performed more easily than in the case where the steel material 3 is disposed on the torch side 7 to perform lap welding. When the joining portion is produced by butt welding, as shown in FIG. 4, the aluminum material 2 and the steel material 3 are end to end. In both cases Figs. 3 and 4, an inert gas such as argon gas or helium gas is supplied close to the solder wire 1 to be supplied from the torch 7 to the joining portion and the melt, so that the oxygen in the air can not enter the melt and the oxidation of the molten metal is eliminated. The MIG welding process of different materials using the cored wire for welding different materials of the present invention also has effects similar to those produced by the laser welding process of different materials using the cored wire for soldering different materials of the present invention. [Examples] (First Example) Examples which show the effects of flux cored wire for laser welding of different materials of the present invention will be described below more specifically in comparison to Comparative Examples.

A plate material (e.g., 100 mm wide, 300 mm long) comprising AA6022 alloy (JIS class A6000 alloy) and having a plate thickness of 1.0 mm is used as the alloy material. aluminum 2. In addition, 980 MPa cold-rolled steel sheet having a plate thickness of 1.4 mm (eg, width: 100 mm, length: 300 mm) and two types of steel plate which are produced by treating the same steel sheet by hot-dip galvanizing are used as steel material 3. Just like the test materials to be welded, aluminum alloy materials 2 and steel materials 3 which are materials in untreated plate, and plate materials bent at 90 degrees at positions at an appropriate distance from their edges (for aluminum alloy materials 2, 10 mm from their edges; steel 3, 60 mm from their edges), are used. Subsequently, these aluminum alloy material 2 and galvanized steel material 3 are superimposed; the aluminum alloy material 2 is arranged on the laser light side as shown in FIG. 1; and the surroundings of the overlap portion 4 are bathed in a protective gas atmosphere. An argon gas is used as the shielding gas. The laser light is irradiated on the overlap portion 4 while each of the cored wires for soldering different materials (1.2 mm in diameter) of the Examples and Comparative Examples is fed to the overlap portion 4, performing the soldering. laser. The lasers irradiated on the overlap portion 4 are a YAG laser (yttriumaluminum garnet) of continuous wave oscillation type (laser power: 4.0 kW) and a semiconductor laser (laser power: 4.0 kW) . The welding speed is 1.2 m / min with the YAG laser, while it is 1.5 m / min with the semiconductor laser. In addition, the wire feeding speed is 4.8 m / min with the YAG laser, while it is 3 m / min with the semiconductor laser.

When plate materials are used as components to be welded, as shown in FIG. 6, they are arranged so that the length of the overlap portion 4 of the overlapping components is 50 mm. In addition, when the folded sheet materials are used as components to be welded, as shown in FIG. 7, the components 2 and 3 are arranged so that the folded positions of the components 2 and 3 coincide, and so that the length of the overlap portion 4 of the components is 10 mm.

With respect to the cored wires for welding different materials used for Comparative Examples and Examples used in this Example, the chemical compositions of the cladding, the chemical compositions of the fluxes and flux-filling fractions are shown in the Table. 1 below. In addition, the presence or absence of cracks in the welded metal part when welding is performed using these wires, the tensile strength and the peel strength are shown in Tables 2 to 5 below. Tables 2 and 4 show the results when the YAG laser is used to weld a non-galvanized steel sheet, while Tables 3 and 5 show the results when the semiconductor laser is used to weld a metal sheet. non-galvanized steel. The aluminum alloy material to be welded is AA6022. The steel material to be welded is a non-galvanized steel sheet in Tables 1 and 2, whereas it is the GA980 in Tables 3 and 4. The thickness of the aluminum alloy material is 1.0 mm, and the thickness of the steel material is 1.4 mm. In the case of the YAG laser, the power is 4 kW; the welding speed is 1.2 m / min; and the thread feeding speed is 4.8 m / min. In the case of the semiconductor laser, the power is 4 kW; the welding speed is 1.5 m / min; and the unwinding speed is 3 m / min. In Table 1, the amount of CsF contained in the flow composition varies, but the remainder of this flow is essentially composed of a KA1F-based flux (aluminum and potassium fluoride). Examples of these KAlf-based fluxes include streams containing 75% by weight of KA1F4 and 25% by weight of K3A1F6. Alternatively, there are also flows in which these compounds based on aluminum fluoride and potassium are partially replaced by K2A1F6. On the other hand, compounds containing no Al, such as KF, may also be included in some cases. Accordingly, a stream that is composed essentially of KA1F means a compound comprising the three elements, K, Al and F, and a compound that is composed of two elements, K and F, or mixtures of these compounds. It should be noted that the indication tr in Table 1 indicates a quantity in the form of traces.

TABLE 1 Sheath Flux Si Zr OsF Filling Fraction Comparative Example 1 1.45 tr Comparative Example 2 1.45 0.2 Comparative Example 3 1.50 tr Example 1 1.50 0.2 30 10 Example 1 Comparative 4 1.75 tr Example 2 1.75 0.07 Example 3 1.75 0.1 Example 4 1.75 0.25 Comparative Example 5 1.75 0.3 30 Example Comparative 6 2.00 tr Example 5 2.00 0.07 30 Example 6 2.00 0.1 30 10 Example 7 2.00 0.25 30 Comparative Example 7 2.00 0.3 30 10 Example Comparative 8 2.50 tr Example 8 2.50 0.2 Comparative Example 8 2.75 tr Comparative Example 9 2.75 0.2 Comparative Example 10 2.00 0.25 15 Example Comparative 11 2.00 0.25 65 10 Comparative Example 12 2.00 0.25 30 3 Comparative Example 13 2.00 0.25 30 Example 9 2.50 0.2 30 10 Example 10 1.50 0.2 Comparative Example 14 2.00 0.25 _ TABLE 2 Non-Galvanized Steel Sheet / AA6022 YAG Laser Cracks in Welded Metal Part TSS PS Overall Evaluation Comparative Example 1 Comparative Example 2 D 189 33 Poor Comparative Example 3 D 188 27 Poor Example 1 B 205 21 Good Comparative Example 4 D 199 24 Poor Example 2 B 203 Good Example 3 B 211 38 Excellent Example 4 B 211 29 Good Comparative Example 5 B 197 14 Poor Comparative Example 6 C 212 13 Poor Example 5 A 211 38 Excellent Example 6 A 213 Excellent Example 7 B 213 18 Good Comparative Example 7 B 198 12 Poor Comparative Example 8 B 213 13 Poor Example 8 A EXAMPLE 8 Comparative Example 8 B 210 9 Poor Comparative Example 9 B 213 12 Poor Comparative Example 10 B 187 11 Poor Comparative Example 11 B 191 10 Poor Comparative Example 12 B 195 8 Poor Comparative Example 13 B 180 7 Poor Example 9 B 202 17 Good Example 10 B 202 18 Good Comparative Example 14 A 97 3 Poor5 TABLE 3 Non-Galvanized Steel Sheet / AA6022 Semiconductor Laser Cracks in the TSS Part PS Overall Welded Metal Evaluation Comparative Example 1 E 186 34 Poor Comparative Example 2 E 191 2 Poor Comparative Example 3 E 187 27 Poor Example 1 B 205 22 Good Comparative Example 4 D 202 25 Poor Example 2 B 204 26 Good Example 3 B 206 27 Good Example 4 B 208 24 Good Comparative Example 5 B 189 11 Poor Comparative Example 6 C 209 Poor Example 5 A 210 Example 6 6 Excellent Example 7 B 212 35 Excellent Comparative Example 7 B 196 13 Poor Comparative Example 8 B 211 11 Poor Example 8 A 209 23 Good Comparative Example 8 B 208 12 Poor Example Comparative 9 B 207 8 Poor Comparative Example 10 B 174 21 Poor Comparative Example 11 B 123 20 Poor Comparative Example 12 B 158 9 Poor Comparative Example 13 B 168 1 Poor Example 9 B 202 17 Good Example 10 B 207 16 Good Comparative Example 14 A 102 3 Poor TABLE 4 AA6022- GA980 YAG laser Cracks in the TSS part PS Overall Al welded metal evaluation Comparative Example 1 E 192 31 Poor Comparative Example 2 D 187 34 Poor Comparative Example 3 D 191 26 Poor Example 1 B 205 21 Good Example Comparative 4 D 202 24 Poor Example 2 B 203 22 Good Example 3 B 208 25 Good Example 4 B 207 22 Good Comparative Example 5 B 190 12 Poor Comparative Example 6 C 204 9 Poor Example 5 B 212 Excellent Example 6 A 215 32 Excellent Example 7 B 211 Good Comparative Example 7 B 189 11 Poor Comparative Example 8 B 210 9 Poor Example 8 A 213 Good Comparative Example 8 B 212 8 Poor Comparative Example 9 B 214 10 Poor Comparative Example 10 B 191 3 Poor Comparative Example 11 B 190 9 Poor Comparative Example 12 B 180 8 Poor Comparative Example 13 B 180 2 Poor Example 9 B 203 17 Good Example 10 B 205 16 Good Comparative Example 14 A 70 1 Poor TABLE 5 AA6022- GA980 YAG Laser 29 Cracks in Part TSS PS Overall Assessment Al welded metal Comparative Example 1 E 187 29 Poor Comparative Example 2 E 192 31 Poor Comparative Example 3 D 192 28 Poor Example 1 B 203 21 Good Comparative Example 4 D 201 24 Poor Example 2 B 204 25 Good Example 3 B 207 28 Good Example 4 B 210 24 Good Example C Comparative Example 5 B 195 14 Poor Comparative Example 6 C 214 13 Poor Example 5 A 214 21 Good Example 6 A 214 31 Excellent Example 7 B 213 22 Good Comparative Example 7 B 198 12 Poor Comparative Example 8 B 213 11 Poor Example 8 A 214 23 Good Comparative Example 8 B 212 9 Poor Comparative Example 9 B 213 12 Poor Comparative Example 10 B 185 5 Poor Comparative Example 11 B 189 6 Poor Comparative Example 12 B 179 4 Poor Comparative Example 13 B 180 3 Poor Example 9 B 201 16 Good Example Good Comparative Example 14 A 98 0 Poor The plate material shown in FIG. 6 and the folded plate material shown in FIG. 7 are folded through lap welding using the cored wires of the Examples and Comparative Examples. The tensile and shear strength (TSS) and peel strength (PS) of the welded portion 5 are measured. Evaluation of Tensile Strength and Shear Strength Tensile and shear strength is evaluated using a plate material subjected to lap welding shown in FIG. 6. This plate material after being welded is processed into a JIS No. 5 compliant sample as defined in JIS Z 2201-1998. At this point, the welded portion 5 is adjusted to be in the center of the parallel portion. Each of the plate materials is then pulled in the direction of the arrow in FIG. 6 using a modulometer (manufactured by Shimadzu Corporation, RS-2 uniaxial tester), and the tensile and shear strength of the welded portion 5 is measured. The tensile and shear strength of the welded portion 5 as in the case where the flux-cored wire of each of the Examples and Comparative Examples is used to effect a weld, is shown in Tables 2 to 5. Evaluation of the resistance to peeling Peel strength is evaluated using a folded sheet material after being subjected to the overlap welding shown in FIG. 7. The plate material after being welded is treated in a 25 mm wide band. Each of the plate materials is then pulled in the direction of the arrow in FIG. 7 using a modulometer (manufactured by Shimadzu Corporation, RS-2 uniaxial tester), and the peel strength of the welded portion 5 is measured. The peel strength of the welded portion 5 as in the case where each of the cored wires of the Examples and Comparative Examples are used to effect the welding, is shown collectively in Tables 2 to 5.

In the evaluation of cracks, it is judged to be test material A when no crack is found; B when there is no crack but co-crystals are present at the grain boundaries; C when a crack that is equivalent to a grain boundary is present; D when cracks that are equivalent to several grain boundaries are present, and E when large cracks are generated. In an overall evaluation, each of the samples of the Examples and Comparative Examples is judged to be excellent when the tensile and shear strength is 210 [N / mm] or more, the peel strength is 30 [N / mm] or more, and no crack is found; good when the tensile and shear strength is 200 [N / mm] or more, the peel strength is 15 [N / mm] or more, and no crack is present but co-crystals are generated at grain boundaries (B); poor when the tensile and shear strength is less than 200 [N / mm] or the peel strength is less than 15 [N / mm] or a crack equivalent to a single grain boundary (C) or equivalent cracks at multiple grain boundaries (D) or large cracks (E) are generated. As shown in Tables 2 to 5, in Examples 1 to 10, in both cases the YAG laser and the semiconductor laser, cesium fluoride in the flux, the filling fraction of the flux, and the amounts of If and Zr in the sheath are within the range of the present invention, and therefore their tensile strength, shear strength, and peel strength are better than in Comparative Examples 1 to 14 which are not in the range. of the present invention, and no cracks are generated in their welded metal parts. In addition, in the case of the semiconductor laser, cords are formed by being better and more uniform than in the case of a YAG laser. (Second Example) Examples of the MIG welding process of different materials using cored wires for welding different materials of the present invention will now be specifically described by comparing to Comparative Examples. A plate material (eg, 100 mm wide, 300 mm long) comprising AA6022 alloy (JIS A6000 compliant alloy) and having a 2.0 mm plate thickness is used as the aluminum alloy material. 2. In addition, a 980 MPa cold-rolled steel sheet having a plate thickness of 1.4 mm (for example, width: 100 mm, length: 300 mm) or galvanized steel sheet produced by galvanizing the same steel sheet is used as galvanized steel sheet. As are the test materials to be welded, aluminum alloy materials 2 and steel materials 3 which are untreated sheet materials, and folded sheet materials which are bent at 90 degrees at positions at one end. appropriate distance from their edges (in the case of aluminum alloy materials 2, 10 mm from their edges, in the case of steel materials 3, 60 mm from their edges) are used. These aluminum alloy materials 2 and steel material 3 are subsequently superimposed, and as shown in FIG. 3, the aluminum alloy material 2 is disposed on the MIG torch side 7, and the surroundings of the overlap portion 4 are placed in a shielding gas atmosphere. An argon gas is used as the shielding gas. The overlap portion 4 is then energized using each of the cored wires for welding materials different from the Examples and Comparative Examples (diameter: 1.2 mm), and overlapping MIG welding is performed. As a MIG welding machine for welding the overlap portion 4, a DC pulse MIG welding power source is used. The amperage is 90A, its voltage is 16V, and the welding speed is 0.5m / min. When plate materials are used as components to be welded, as shown in FIG. 6, the components are arranged so that the length of the overlap portion 4 of the components is 50 mm. In addition, when folded sheet materials are used as components to be welded, as shown in FIG. 7, the components 2 and 3 are arranged so that the folded positions of the components 2 and 3 coincide, and so that the length of the overlap portion 4 of the components is 10 mm. For flux-cored wires for bonding dissimilar materials of the Examples and Comparative Examples used in this Example, the flow chemistries, flux fill fractions, and sheath chemical compositions are shown in Table 6 below. -Dessous. It should be noted that the indication tr in Table 6 describes a quantity in the form of traces. On the other hand, the plate material shown in FIG. 6 and the folded plate material shown in FIG. 7 are bonded through lap welding using the cored wires of the Examples and Comparative Examples. The tensile and shear strength and peel strength of the welded portion produced by lap welding are measured. The presence or absence of cracks, the tensile strength and the peel strength of this welded portion are shown in Table 7 below. TABLE 6 Sheet Sheath (% by weight) Flux (% by weight) of steel Si Zr AIF Filling fraction Comparative example 1 Steel sheet GA 1.45 tr 10 12 Comparative Example 2 1.45 0.2 Comparative Example 3 1.50 tr Example 1 1.50 0.2 Comparative Example 4 1.75 tr Example 2 1.75 0.07 Example 3 1.75 0.1 Example 4 1.75 0.25 Comparative Example 5 1.75 0 Comparative Example 6 1.75 tr non-galvanized steel sheet Example 5 1.75 0.07 Example 6 1.75 0.1 Example 7 1.75 0.25 Comparative Example 7 1.75 0.3 Example Comparative 8 Steel Sheet GA 2.00 tr Example 8 2.00 0.07 Example 9 2.00 0.1 Example 10 2.00 0.25 Comparative Example 9 2.00 0.3 Comparative Example 10 2.00 Example 11 2.00 0.2 7 Example 12 2.00 0.2 Comparative Example 11 2.00 0.2 17 Comparative Example 12 2.00 0.2 10 3 Example 13 2.00 0, Example 14 2.00 0.2 19 Comparative Example 13 2.00 0.2 21 Comparative Example 14 2.50 tr 12 Example 15 2.50 0.2 Comparative Example 15 2.75 tr Comparative Example 16 2.75 0.2 TABLE 7 Sheet steel galvanized or GA980 / AA6022, DC MIG welding Cracks TSS PS Overall Evaluation Comparative Example 1 E 270 12 Poor Comparative Example 2 C 275 12 Poor Comparative Example 3 D 280 11 Poor Example 1 B 310 18 Good Comparative Example 4 D 290 Poor Example 2 B 340 21 Good Example 3 A 350 23 Excellent Example 4 A 360 26 Excellent Comparative Example 5 A 280 7 Poor Comparative Example 6 D 300 17 Poor Example 5 B 350 23 Good Example 6 A 365 Excellent Example 7 A 370 Excellent Example Comparative Example 7 A 290 8 Poor Comparative Example 8 D 290 16 Poor Example 8 B 310 Good Example 9 A 360 Excellent Example 10 A 365 22 Excellent Comparative Example 9 C 320 Poor Comparative Example 10 A 290 9 Poor Example 11 A 340 Good Example 12 A 335 18 Good Comparative Example 11 A 295 8 Poor Comparative Example 12 A 245 5 Poor Example 13 A 310 18 Good Example 14 A 330 Good Comparative Example 13 A 290 7 Poor Comparative Example 14 C 280 16 Poor Example 15 A 300 18 Good Comparative Example 15 C 270 14 Poor Comparative Example 16 B 275 Poor (Evaluation of tensile and shear strength) Tensile and shear strength is evaluated using the plate material shown in FIG. 6 subjected to lap welding. The plate material after being welded is processed into a JIS No. 5 compliant sample as defined in JIS Z 2201-1998. At this point, the welded portion 5 is adjusted to be in the center of the parallel portion. Each of the plate materials is then pulled in the direction of the arrow in FIG. 4 using a dynamometer (manufactured by Shimadzu Corporation, uni-axial RS2 tester), and the tensile and shear strength of the welded portion 5 is measured. The tensile and shear strength of the welded portion in the case where the welding is performed using each of the cored wires of the Examples and Comparative Examples is set forth in Table 7. Evaluation of peel strength Peel strength is evaluated using the folded plate material after being subjected to the lap welding shown in FIG. 7. The plate material after being welded is treated in a 25 mm wide band. Each of the plate materials is then pulled in the direction of the arrow in FIG. 7 using a dynamometer (manufactured by Shimadzu Corporation, uni-axial RS-2 tester), and the peel strength of the welded portion 5 is measured. The peel strength of the welded portion in the case where each of the cored wires of the Examples and Comparative Examples is used to effect the welding is set forth in Table 7 collectively. As in Example 1, in the evaluation of cracks, it is judged to be the test material A when no crack is found; B when no crack is generated but co-crystals are present at the grain boundaries; C when a crack that is equivalent to a single grain boundary is present; D when large cracks are generated; and E when large cracks are generated. In an overall evaluation, each of the samples of the Examples and Comparative Examples is considered excellent when the tensile and shear strength is 350 [N / mm] or more, the peel strength is 20 [N / mm] or more, and no cracks are found (A); good when the tensile and shear strength is 300 [N / mm] or more, the peel strength is 10 [N / mm] or more, and no crack is generated but co-crystals are generated at grain boundaries (B); and poor when the tensile and shear strength is less than 300 [N / mm] or the peel strength is less than 10 [N / mm] or a crack equivalent to a single grain boundary (C) or cracks equivalent to several grain boundaries (D) or large cracks (E) are generated. As shown in Table 7, the amounts of AlF3 in the flow, the fill fraction of the flow, and the chemical compositions of Si and Zr in the sheath in Examples 1 to 15 are within the scope of the present invention, and therefore their tensile and shear strength and peel strength are better and no cracks are generated in their welded metal part. In contrast, Comparative Examples 1 to 16 which are not within the scope of the present invention had cracks, low tensile strength or low peel strength.

Claims (7)

REVENDICATIONS1. Filled wire for welding different materials for use in a bond between different materials involving an aluminum or aluminum alloy material and a steel material, the flux-cored wire comprising a cylindrical sheath comprising an aluminum alloy which contains Si in an amount of between 1.5 and 2.5% by weight and Zr in an amount of between 0.05 and 0.25% by weight, the remainder being aluminum and unavoidable impurities, and flux filling the interior of this sheath and containing cesium fluoride in an amount of between 20 and 60% by weight, andthe flux filling fraction of between 5 and 20% by weight of the total weight of the wire. Filled yarn for welding different materials for use in a connection between different materials involving an aluminum or aluminum alloy material and a steel material, the cored wire comprising a cylindrical sheath comprising an aluminum alloy which contains Si in an amount of between 1.5 and 2.5% by weight and Zr in an amount of between 0.05 and 0.25% by weight, the remainder being aluminum and unavoidable impurities, and a flow filling the interior of this sheath and containing AlF3 in an amount of between 7 and 15% by weight, and the filling fraction of the flux being between 4 and 20% by weight of the total weight of the wire. A method of laser welding dissimilar materials which uses the cored wire for soldering different materials according to claim 1 or 2, the method comprising: - forming a joining portion by an aluminum or alloy material aluminum and a steel material; and - bonding the aluminum or aluminum alloy material and the steel material by feeding the flux-cored wire for welding different materials while irradiating this joining portion with a laser light. A method of laser welding different materials according to claim 3, wherein the aluminum or aluminum alloy material and the steel material are superimposed so that the aluminum or aluminum alloy material is side of the laser light, and the aluminum or aluminum alloy material and the steel material are welded through a lap welding. A method of laser welding different materials according to claim 3 or 4, wherein the laser welding is performed by means of a semiconductor laser. A method of MIG welding of different materials, the method comprising: - using the cored wire for welding different materials according to claim 1 or 2; the fact of constituting a joining part by an aluminum or aluminum alloy material and a steel material; and - forming an arc between the joining portion and the flux-cored wire for welding different materials, feeding an inert gas around the arc, and simultaneously welding the aluminum material or aluminum alloy and the steel material. A method of MIG welding of different materials according to claim 6, wherein the aluminum or aluminum alloy material and the steel material are superimposed so that the aluminum or aluminum alloy material is placed on the side. flux-cored wire for welding different materials, and the aluminum or aluminum-alloy material are welded through lap welding.