Been riding steel, carbon and titanium frames. Steel failed the most, especially after many years (+30) of service. Weldings doesn't last.

Carbon frames and forks I have seen in freak accidents. Like snap-cracking by not even hitting some hard. This too me has been pure structural issues, since with metal, it has always been the weldings.

Titanium I have seen tore apart as well, again all about the weldings.

As for component failures, I have experienced rim-walls explode due to brake heat, rimes fall apart on flat tires, chain snapping and seat post clamps suddenly break and riders losing their saddle :)

I am going for a ride in a few hours. Can't wait!