If the titanium absorbs either gas it becomes brittle and will crack over time. This crack is right near the BB at the seat of two major welds. The tube would have been very hot there and if it was not properly shielded by argon during welding and cooling, it could have absorbed air during that period.

How long will a titanium bike frame last?

Depending on the frame material, how well it is maintained, and how hard it is used, bike frames last anywhere from 6 to 40 years. Carbon and titanium bike frames will last the longest with proper care, with some even outlasting their riders.

Can titanium frame break?

Titanium frames are durable and very flexible, but when they break, there is not much you can do. Titanium can be spot-welded easily, and no argon cover is needed to protect the weld.