TRANSIENT AND STEADY-STATE CREEP OF AL-4.5 WT-PERCENT MG DURING PHASE-TRANSFORMATION

Transient and steady state creep of Al–4.5 wt% Mg alloy is studied under various constant stresses ranging from 91 to 117 MPa in the temperature range from 473 to 553 K. The results of creep characteristics show two deformation temperature regions, (below and above 513 K). Peak values of transient creep parameters B and n are obtained at 493 K. The transient creep parameter B is related to the steady state creep rate ϵst through the exponent γ which is found to range from 0.85 to 0.5. The strain rate sensitivity parameter m of the steady state creep is 0.3 ± 0.01 at the steady state strain peaks, which is characteristic of dislocation climb along the grain boundaries. Microstructural analysis confirms that the above mentioned mechanism take place in the disolution region of the β‐phase. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA