Originally Posted by
lebowitz
the problem with aluminum is that is actually can not bend much over time without failing. It can bend very little before deforming permanently (like an aluminum can) and never returning to the original shape. So the failure case is usually one traumatic incident that wrecks it structually.
Steel can bend and be bent back and that is essentially what makes it resilient and desirable as a frame material (along with its vibration absorption property)
You are confusing stiffness (the ability to resist bending) and elastic deformation (stress that doesn't permanantly bend a structure) with ductility (the ability to bend permanantly without failure).
What you are incorrectly describing is "fatigue life" which is how many stress cycles, at a stress level below that needed to permanantly deform the material, a given material will take before it fails.
Steel and Ti, if kept below a stress threshold, have an effectively infinite fatigue life. Aluminum, even at low stress, has a finite fatigue life and will crack sooner or later. That said, the practical life of most aluminum frames is so long that failure is a non-issue unless the frame is badly abused. BTW, you can also ruin a steel frame if you are abusive enough.
To the OP: as the others have said, your frame is a high strength steel and the "butting" means the tubing wall thickness is varied to reduce weight while maintaining strength where needed. It is not aluminum in any way.