Abstract
AbstractHigh‐cycle‐fatigue/creep experiments were performed on a 9%Cr‐1%Mo temperered marten‐site ferritic steel at 873 K in air. The stress ratio R=σmin/σmax ranged from‐1 (“pure” fatigue) to 1 (“pure” creep). The maximum stress σmax was kept constant at 240 MPa. The lifetime depends on the stress ratio R in a non‐monotonic way.In the stress ratio interval 0.6 < R < 1.0 both the creep strain rate and the lifetime are controlled by mean stress σmassof the stress cycle. In the stress ratio interval — 1 < R < 0.2 the lifetime is controlled by the stress amplitude na. The fatigue/creep interaction occurs in between these intervals.The fatigue/creep loading induces transformation of the tempered martensite ferritic structure into an equiaxed subgrain structure. The resulting subgrain size depends strongly on the stress ratio.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have