Aluminum and materials like CFRP (Carbon Fiber Reinforced Plastic) and even titanium to a lesser degree are susceptible to catastrophic failure caused by minor surface damage like nicks and scratches.
This is especially so since many the products made from those materials employ cutting edge design technology utilizing material properties such as weight reduction.
deux jambes Those bars appear to have been exposed to a corrosive atmosphere such as salt air or have may even been submerged. Also it appears that there could be some surface delamination caused by flaws in the aluminum billet that the tubing was drawn from.
In any case, the aluminum alloys used in a lot of the low cost bars BITD, especially during the bike boom era were low strength. They started to sag or droop after a few years of hard riding ending up in unexpected catastrophic failure!
Bars like these should be
IMMEDIATELY replaced and preferably cut in half so that no one can try to reuse them!
verktyg