P. Delobelle et al., A MODEL TO DESCRIBE THE ANISOTROPIC VISCOPLASTIC BEHAVIOR OF ZIRCALOY-4 TUBES, Journal of nuclear materials, 238(2-3), 1996, pp. 135-162
Citations number
38
Categorie Soggetti
Nuclear Sciences & Tecnology","Mining & Mineral Processing","Material Science
With the aid of multiaxial tests under monotonic and cyclic loadings (
tension, torsion and internal pressure), the anisotropic viscoplastic
properties of Zircaloy-4 tubes in two metallurgical states can be stud
ied. The anisotropic behavior at a temperature of 350 degrees C has be
en thoroughly quantified. The results obtained at room temperatures as
well as the independence of the ratio R(p)=epsilon(theta theta)(p)/ep
silon(zz)(p) with respect to the temperature would seem to indicate th
at the set of anisotropy coefficients do not depend on the temperature
. However, the viscosity of this alloy possesses a clearly marked mini
mum in the neighborhood of 300 degrees C, a behavior which is probably
due to the dynamic strain aging frequently observed in solid insertio
n solutions. This material also presents a slight supplementary harden
ing during out-of-phase cyclic loading (tension-torsion with a 90 degr
ees phase lag). It is proposed to extend the formulation of a viscopla
stic model, developed and identified elsewhere for other initially iso
tropic materials, to the case of Zircaloy-4. Generally speaking, aniso
tropy is introduced into this model through fourth order tensors which
affect the flow directions [M], the linear kinematical hardening comp
onents [N], as well as the dynamic and static recoveries, [Q] and [R]
respectively, of the forementioned hardening variables. The identifica
tion of this model is performed at 350 degrees C. It is shown that the
formulation is capable of describing the set of mechanical characteri
stics of this alloy.