Creep-resistant steels

Creep is a plastic deformation process (occurring at above-ambient temperatures) whose main characteristic is that it can develop over time, eventually to failure, while both temperature and applied stress (below the tensile strength at the temperature in question) remain constant. This makes it one of the so-called "time-dependent" failure modes (along with fatigue and corrosion).

A steel must resist creep whenever it is subjected to mechanical stress at a temperature significantly higher than the ambient temperature.