[lmilcin]

I took liberty to look through the literature and it seems change of physical and chemical properties of material due to all types conditions (including physical stresses) is covered by the term.

I am not into mechanical science that much, I have always treated degradation as a kind of surface or volume phenomena where the material looses its properties due to temperature, radiation, age, chemical reaction, etc. For mechanical effects there are already very good terms like metal fatigue and stress induced cracking.