Abstract
The deformation behaviour of an Fe-3Si (wt-%) steel was studied in the temperature range 400-900°C over six orders of magnitude of strain rate. It was found that the Fe-3Si steel exhibits a threshold behaviour. A correlation between the deformation behaviour and the temperature dependence of the threshold stress was etermined. An analysis in terms of the threshold stress showed that two modes of deformation behaviour exist in the power law creep regime. At normalised strain rate ϵkT/(D 1 Eb) ranging from 2 × 10-6 to 10-3, the value of the true stress exponent n is equal to 7, and at lower values of ϵkT/(D 1 Eb) the value of n is ∼ 5. The true activation energy for plastic deformation Q c increases from 250 ± 15 to 290 ± 30 kJ mol-1 with increasing temperature from 550 to 700°C, and remains virtually unchanged at high temperatures. The relationship between rate controlling mechanisms of plastic deformation and mechanisms of interaction between lattice dislocations and dispersoids is discussed.
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