Originally Posted by
krome
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I think the only mass produced bikes with actual butt welds were the Electro-forged Chicago Schwinns. Not considered a top line bicycle, but I think history has proven the strength of the welds. Otherwise, the frames during that time were most likely TIG welded. Tig welding has a long history in aircraft structures. It is a proven joining technique.
You're mixing terms with different meanings.
Butt weld refers to the type of the joint, namely 2 members meeting end to end, or at an angle with no overlap or reinforcement save the weld itself.
TiG welding refers to the welding process itself, which uses an inert gas to protect the weld area from harmful exposure to the surrounding air.
Whether TiG welded or not, most modern welded frames are butt welded though it would probably to refer to the joints as "T" joints (though nobody I know in the bike world ever does).