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The property of a metal that allows it to be permanently deformed when subject to stress (e.g., turbine blades that operate at temperatures at which creep can become serious). Creep increases with temperature, duration, and magnitude of force.
Primary creep, stage 1, is a period of decreasing creep rate. Primary creep is a period of primarily transient creep. During this period deformation takes place and the resistance to creep increases until stage 2. Secondary creep, stage 2, is a period of roughly constant creep rate. Stage 2 is referred to as steady state creep. Tertiary creep, stage 3, occurs when there is a reduction in cross sectional area due to necking or effective reduction in area due to internal void formation.

Aviation dictionary. 2014.