Originally Posted by
WVU_Engineer
It is not entirely out of the question that heat treating causing stresses at joints itself, .....
What does BB stand for by the way, been trying to figure that out for the last couple days.
Welded bicycle frames are heat treated to normalize the stresses introduced by welding. Bonded aluminum frames usually use T-6 tubing and are not heat treated after assembly.
Heat treatment may or may not be indicated for fabricated aluminum parts, but that's not the issue here.
BB is shorthand for
bottom bracket (either the shell, or the bearing/spindle unit) or
ball bearing. Usually which is made clear by the context.