On Tue, 1 Jan 2008 21:16:41 -0500, "Charles P Lamb"
wrote:

How are commercial chain links welded? My first guess is using resistance
but I would guess the electricity would be more likely to take the path
around the link than across the touching faces.

It isn't an all-or-nothing situation. Some current will go 'round the
back way, but if the electrodes are close to the joint and the faces
makes good contact, then most of the current will go thru the joint.