Development and validation of a processing map for zirconium alloys

Abstract

For the development of processing maps to zirconium alloys, a simple instability condition based on the Ziegler's continuum principles as applied to large plastic flow is extended for delineating the regions of unstable metal flow/occurrence of fracture or defects, utilizing the flow stress data of Zr-2.5Nb-0.5Cu. An attempt is made to fit the measured flow stress data in a constitutive equation, useful in the finite element process models. Instability maps at different strain levels were superimposed while delineating the unstable regions in the processing maps. This phenomenon takes into account the dependence of strain rate sensitivity and strain hardening coefficient of the material on the plastic instability during hot deformation. The applicability of the developed processing map has been examined by comparing with the reported microstructural observations of the deformed compression specimens of various zirconium alloys. It is found that the processing map is practically usable in the real fabrication process for the zirconium alloys.

Hot Deformation Behavior and Microstructure Evolution of a TiBw/Near α-Ti Composite with Fine Matrix Microstructure

“…The power dissipation map represents how the material dissipates power through the microstructure evolution [38]. Based on the extremum principle of irreversible thermodynamics, the flow instability map is constructed by continuous instability criterion and applied to the large plastic flow, and the instability criterion is derived by [39]:…”

Microstructural characterization of creep anisotropy at 673 K in the M5® alloy

“…In consequence, thermal creep mechanisms have been widely studied during the past 50 years [1][2][3][4][5]. Although there is no consensus concerning the physical mechanisms involved, creep anisotropy of zirconium alloy tubing is generally accepted [6][7][8][9][10][11]. A better understanding of this phenomenon would lead to improvements in modeling and predictions of the creep behavior of core structures.…”

Processing Map Development through Elaborating Phenomenological and Physical Constitutive Based Models

“…The dynamic material models (DMM) suggested by Prasad [34] and later modified by Murty and Rao, [35] have been hired to develop the processing maps. According to these well-known models, the workpiece under hot-working conditions is considered as a power dissipater, where at any strain and temperature the power P (per unit volume) consists of two complementary parts: G content and J co-content.…”