Method of forming bimetallic transition joints

Claim 1

The method of claim 1 wherein: the reducing step is performed by rotary swagging until the desired amount of reduction is achieved.

Claim 5

A method of joining two metals having different coefficients of thermal expansion comprising: positioning a rod formed of a first metal within a cylinder which is formed of a second metal and is longer than said rod, positioning first and second plugs formed of said second metal at least partially within opposed ends of said cylinder and in abutting contact with said rod, welding each plug to said cylinder, and forming a metallurgical bond between said two metals by heating the assembled rod, plugs and cylinDer, and reducing the cross-sectional area of said assembly by 10 to 50 percent, cooling the assembly subsequent to the rotary swagging cutting away the original cylinder and the outer portion of the plugs so that the final diameter of the assembly is reduced to the final diameter of the rod, drilling an axial bore throughout the length of the assembly, and transversely cutting the drilled assembly at a position between the ends of the rod portion to thereby form two tubular transition joints each having tubular sections of dissimilar metals joined together by a metallurgical bond at a butt joint.

Claim 6

A method of joining two metals having different coefficients of thermal expansion comprising: positioning a rod formed of a first metal within a cylinder which is formed of a second metal and is longer than said rod, positioning first and second plugs formed of said second metal at least partially within opposed ends of said cylinder and in abutting contact with said rod, welding each plug to said cylinder, and forming a metallurgical bond between said two metals by heating the assembled rod, plugs and cylinder, and reducing the cross-sectional area of said assembly by 10 to 50 percent, cooling the assembly subsequent to rotary swagging transversely cutting the assembly near the midpoint of the rod to make two sections, drilling an axial bore in one end of each section to a depth and diameter so as to remove all of the rod along a portion thereof less than one-half the length of the section, cutting away the second metal from the outer diameter of the other end of each section along a portion thereof which is less than one-half the length of the section and, drilling an axial bore through the sections to form two transition joints each having two tubular sections of dissimilar metals joined together by a lapjoint at which is formed a metallurgical bond.