The hull consisted of a carbon fiber tube with titanium endcaps, one of which served as a door (which could not be opened from inside) and contained the porthole.
I watched this that shows the making of the hull. So it seems that it's carbon fibre over a metal cylinder. I don't know if that cylinder is titanium but it doesn't seem like the hull was pure carbon fibre. That cylinder is nowhere near thick enough for anything but the base for the carbon fibre though so it's not like it would offer anything but squish in an emergency. But I did find this very interesting (and terrifying somehow):
The hull consisted of a carbon fiber tube with titanium endcaps, one of which served as a door (which could not be opened from inside) and contained the porthole.
I watched this that shows the making of the hull. So it seems that it's carbon fibre over a metal cylinder. I don't know if that cylinder is titanium but it doesn't seem like the hull was pure carbon fibre. That cylinder is nowhere near thick enough for anything but the base for the carbon fibre though so it's not like it would offer anything but squish in an emergency. But I did find this very interesting (and terrifying somehow):
https://youtu.be/4O5F4ZVlIac?t=660
The tube section was carbon fiber only, no metal. The endcaps were titanium. Many thanks for the link, I will take a look!
Hmmm.... still not sure....
The Titan Tragedy—A Deep Dive Into Carbon Fiber, Used for the First Time in a Submersible
OceanGate shows a metal tube around which the carbon fiber filament is wound but it may be a mandril removed after hardening of the composite.
I'll be damned, you're right, the carbon fiber was wound around a metal tube. My bad.