Flux-cored wire for different-material bonding and method of bonding different materials

Abstract

There are provided a flux cored wire for joining dissimilar materials with each other, capable of enhancing a bonding strength upon joining an aluminum-base material with a steel-base material, and excellent in bonding efficiency, a method for joining the dissimilar materials with each other, and a bonded joint obtained by the method. In particular, there is provided a method for joining dissimilar materials with each other, in the case of melt weld-bonding of high-strength dissimilar materials with each other, that is, the high-strength steel member with the high-strength 6000 series aluminum alloy member and in the case of the steel member being a galvanized steel member. In one mode, use is made of a flux cored wire wherein the interior of an aluminum alloy envelope is filled up with a flux, the flux has fluoride composition containing a given amount of AlF 3 without containing chloride, and the aluminum alloy of the envelope contains Si in a range of 1 to 13 mass %. If such a flux cored wire is use, it is possible to obtain a high bonding strength in the case of melt weld-bonding of high-strength dissimilar materials with each other, that is, the high-strength steel member with the high-strength 6000 series aluminum alloy member.

1 - 7 . (canceled) 
     
     
         8 : A method for joining dissimilar materials together comprising:
 a step of an AC-MIG welding for directly joining an aluminum member or an aluminum alloy member with a steel member by use of a flux cored wire wherein a flux containing potassium fluoride, aluminum fluoride, and at least one fluoride selected from the group consisting of fluorides of elements of the Group IIA of the Periodic Table is coated with aluminum or an aluminum alloy.   
     
     
         9 : A method for joining dissimilar materials together comprising:
 a step of an AC-MIG welding for directly joining an aluminum member or an aluminum alloy member with a steel member by use of a flux cored wire formed by coating a flux containing potassium fluoride, aluminum fluoride, and at least one fluoride selected from the group consisting of magnesium fluoride, calcium fluoride, strontium fluoride, and barium fluoride with aluminum or an aluminum alloy, as a filler metal.   
     
     
         10 : A bonded joint wherein an aluminum member or an aluminum alloy member is joined with a steel member by the method for joining dissimilar materials together, according to  claim 8 . 
     
     
         11 : A method for joining dissimilar materials together comprising:
 a step of joining an aluminum member or an aluminum alloy member with a steel member by either an AC-MIG welding or a MIG welding by DC reversed polarity with the use of a flux cored wire, wherein the flux cored wire is formed by filling up the interior of an envelope made up of an aluminum member or an aluminum alloy member with a flux, the flux for filling up is mixed with aluminum fluoride, and potassium fluoride to be turned into a mixed flux, and a loading weight of the mixed flux is in a range of 0.1 to 24 mass %, against the total mass of the flux cored wire.   
     
     
         12 : The method for joining dissimilar materials together, according to  claim 11 , wherein the mixed flux has a melting point in a range of 560 to 700° C., and the flux cored wire is not more than 1.6 mm Φ in diameter. 
     
     
         13 : The method for joining dissimilar materials together, according to  claim 8 , wherein the steel member is a galvanized steel member.