In , Chris Phillipo wrote:

If they actually brazed them instead of welding then that might be the
problem right there. I'm not familiar witht he brand but unless it came
from Walmart, this sort of quality is not acceptable.

Plenty of top notch bicycle frames are brazed. I think the problem was
a design flaw. The frame designer may have underestimated or failed to
realize some stresses. As I remember how this frame was described a few
posts ago, I could see how it could have craked in normal use, whether it
was brazed or welded.
Normally the seat stays are attached to the seat tube at the same height
at which the top tube is attached, forming a distinct "seat cluster"
joint. If I remember correctly, the seat stays and the top tube were
attached at different heights, and the way I see it this can flex the seat
tube in a way that can cause cracks in the rear end of the top
tube or where the seat stays are atached, maybe elsewhere in that area.
And most brazed frames have lugs. (The frame in question here does
not.) You can make good lugless brazed frames, but it's trickier, among
other things requiring built-up braze joints that typically require brass
braze which requires a higher brazing temperature (than silver brazes)
that weakens most of the higher-strength steels used in lighter weight
steel frames. A good steel for brass brazed bicycle frames is Reynolds
531, which seems to have been falling out of fashion the last time I paid
much attention in this area.
There were good brazed bicycle frames before there were good welded
ones. In the 1970's and early 1980's, the usual road racing bicycle frame
had steel tubing and steel lugs and was brazed.

- Don Klipstein )