Zirconium based alloys have been widely used in light water reactors due to their small neutron absorption cross sections, good corrosion resistance and excellent creep strength. Zircaloy-4 is a zirconium based Zr-Sn alloy, which is found in many applications in structural components such as fuel cladding tubes and pressure tubes.
Zircaloy-4 alloys are fabricated by several hot working methods such as hot rolling and hot extrusion, and numerical simulations are used to optimize and design the hot working process. So, predicting the hot flow stress evolution of Zircaloy-4 is of great importance for the numerical simulation of hot working processes.
Kim Hyok Song, a student at the Faculty of Material Science and Technology, constructed a modified Johnson-Cook model, a strain compensated Arrheniustype model, a modified Zerilli-Armstrong model and a microstructure-based model to predict the flow stress behavior of Zircaloy-4 in hot working. For this purpose, isothermal uniaxial compression tests had been conducted in the range of strain rates and deformation temperatures of 0.001-1s-1 and 750-1 000°C. Then, he compared the prediction accuracy of the proposed constitutive models in terms of correlation coefficient and average absolute relative error.
The results showed that the microstructure-based model is the most suitable for accurately predicting the hot deformation behavior of Zircaloy-4.
You can find the details in his paper “Constitutive Models for Predicting Flow Stress Behavior of Zircaloy-4 in Thermo-Mechanical Processing” in “Physics of Metals and Metallography” (SCI).