Recovery and Recrystallization during High Temperature Deformation

A simplified phenomenological model for non-elastic deformation: Predictions of pure aluminum behavior and incorporation of solute strengthening effects

The emergence in the deforming material of local strain patterns (self excited waves), which are ordered in space and evolve with time, has been investigated for a wide range of metals and alloys. The main parameters of these waves, i.e. propagation rate against work hardening coefficient, dispersion law and wavelength against specimen length and grain size, have been defined. The possibility of treating plastic flow localization as a process of plastic flow occurring in a deforming medium is considered. A set of equations has been developed, which is appropriate for the description of the evolution of local strain domains. The changes in the type of local strain pattern observed in the various stages of flow are examined. A model is proposed to account for the large-scale periodicities exhibited by the distribution of localized deformation.

On the waves of plastic flow localization in pure metals and alloys

The effect of solutes on the strength and strain hardening behavior of alloys

Deformation behaviour of zircaloy-4 between 77 and 900 K

The deformation of α-zirconium has been studied between 375 and 625°C and at strain rates from 5 × 10−6 to 10−1 s−1 by compression testing. The yield stress at the lower temperatures was relatively insensitive to strain rate and temperature, whereas at the higher temperatures, it was highly sensitive to strain-rate and temperature.Various mechanisms are considered as being responsible for the athermal range of behaviour and it is concluded that the Orowan stress required to bow out segments of the Frank network is most likely to be controlling in this region. Similar considerations applied to the rate-sensitive range of behaviour suggest that the unpinning of nodes in the dislocation network is ratecontrolling above the transition temperature. In the transition region between the athermal and thermally activated ranges of flow, a maximum in flow stress was observed that is attributed to a dynamic strain-ageing effect caused by the presence of interstitial oxygen.

J. J. Jonas

Papers

The Transition Between Thermally Activated and Athermal Flow in Polycrystalline Alpha-Zirconium