Stress Reduction Ratio Research Articles

Effect of stress reduction ratio on the creep behavior of an Al-5wt.%Ag alloy

Uninterrupted and stress reduction tests were conducted on an Al-5wt.%Ag alloy in the temperature range of 640–873 K and at a normalized stress range extending from 10 −5 to 3×10 −4. The experimental data in uninterrupted creep tests show that the creep behavior of Al-5wt.%Ag is similar to that reported for pure aluminum and that under the present experimental conditions, the alloy behaves as a metal class alloy (class II). A comparison between the stress exponent n determined from uninterrupted and the stress exponent n ∗ inferred from stress reduction experiments indicates the presence of two types of behavior, depending on the temperature: normal and mixed behavior. The normal behavior exists at 873 K and is characterized by close correspondence between n and n ∗ for all stress reduction ratios used. The mixed behavior is noted at 780 and 640 K and is manifested by the presence of a reproducible difference between n and n ∗ for lower values of the stress reduction ratio; for the higher values, n ∗ = n . The discrepancy between n and n ∗ in the region of mixed behavior is discussed in the light of results reported for the creep behavior of aluminum after stress reductions.

Effect of stress reduction ratio on the creep behaviour of Al

Abstract Stress-reduction and uninterrupted experiments have been conducted on Al in the temperature range 573–923 K; in performing stress-reduction experiments, stress-reduction ratios (τ1-τ2)/τ1, (where τ1 is the initial shear stress and τ2 is reduced shear stress) ranging from 0.05 to 0.75 were used. The stress exponent inferred from stress-reduction experiments, n∗, was compared with that obtained from uninterrupted tests, n. On the basis of this comparison three regions of behaviour, depending on temperature, were identified. At high temperatures (T≥673K), n∗ = n regardless of the value of the stress-reduction ratio. At intermediate temperatures (600K n for small reduction ratios (≤0.15); for small reductions, the lower the reduction ratio, the larger the discrepancy between n∗ and n. At low temperatures (T n for all stress-reduction ratios used (whether small or large). It is suggested that the discrepancy between n∗ and n at ...