Enhanced creep parameters of Al–Zn alloy induced by cyclic stress reduction

Transient and steady state creep parameters, β, n and ε ′ s were measured for Al–12.6 wt.% Zn alloy samples at static condition and superimposed (stress reduction and frequency) in the temperature range from 443 to 503 K. The static stress was 8.86 MPa and the stress reduction σ cy ranged from 1.28 to 2.99 MPa. The applied frequency ranged from 0.12 to 0.35 Hz. Increased temperature T, stress reduction σ cy and frequency ν decreased the parameter n but increased both β and ε ′ st . The activation energy decreased with increasing σ cy and/or ν due to Zn precipitation. The ratio γ showed high values relating the transient and steady creep stages.