RETRACTED ARTICLE: Experimental and Numerical Investigation of VMR and HPTR Pilgering of Zr–1.5%Nb Tubes

Abstract

Due to role of the sequence of cold pilger rolling processes with intermediate heat treatments in regular Zr cladding tube productions, the precise study of such processes and their effects on the material properties, geometry and deformation behavior of the tube can be very important. Therefore, a unique set of experimental and finite element simulation examinations were carried out to investigate the mechanical properties, microstructure, hydrides fraction (F) and deformation behavior of Zr–1.5%Nb by employing a series of vertical mass ring die mill and roll cold reduction mill (Holodnoj Prokatki Trub Rolikami: HPTR) processes. Furthermore, it was important to optimize the process parameters and the resulting mechanical properties of the cold-rolled cladding tubes. Therefore, the effects of the main process parameters (feed rate and turn angle) on the damage build-up during the pilgering process were also studied. To determine the optimum process parameters, a new revised Latham–Cockcraft damage was calculated for different conditions by introducing the new subroutine, which considered the compressive stresses on the formula. It is shown that the proposed model is completely reliable. Then, based on its results, the optimum values of process parameters could be obtained. Besides, it is concluded that the annealing process could change the orientations of zirconium hydrides from the radial direction to the circumferential one. The different Fn values in the internal and external surfaces of the samples were related to the basal planes orientations at these two layers.