Abstract: A method of welding dissimilar metal materials, wherein a high melting-point material and a low melting-point material which are dissimilar metal materials having melting points different from each other are positioned to a planned welding position, and a rotatable tool is pressed to and then inserted into the high melting-point material to thereby perform a friction-stir-welding between the high melting-point material and the low melting-point material to each other. The friction-stir-welding between the high melting-point material and the low melting-point material is performed by disposing an intervening piece made from a same material as the high melting-point material between the rotatable tool and the high melting-point material.

Abstract: A method of welding dissimilar metal materials, wherein a high melting-point material and a low melting-point material which are dissimilar metal materials having melting points different from each other are positioned to a planned welding position, and a rotatable tool is pressed to and then inserted into the high melting-point material to thereby perform a friction-stir-welding between the high melting-point material and the low melting-point material to each other. The friction-stir-welding between the high melting-point material and the low melting-point material is performed by disposing an intervening piece made from a same material as the high melting-point material between the rotatable tool and the high melting-point material.

Abstract: A method of bonding dissimilar metal materials each having a different melting point, including: positioning a steel member and an aluminum member to a bonding position; press-contacting a rotation tool to the steel member while the rotation tool is rotated, and inserting the rotation tool into the steel member; controlling an insertion position of the rotation tool to a position where the rotation tool does not break through the steel member; producing a friction heat at a portion between the steel member and the rotation tool; partially softening the steel member and the aluminum member by a conduction heat conducted from the friction heat thereby to allow the two members to cause a plastic flow; and partially stirring the steel member and the aluminum member by the rotation tool thereby to friction-stir weld the steel member and the aluminum member.