Fabrication Process of High Nodular Corrosion-Resistant Zircaloy-2 Tubing

Abstract

A new fabrication process of high nodular corrosion-resistant Zircaloy-2 tubing for boiling water reactors (BWRs) water rods has been developed. The main features and findings are: 1. Development of a new quenching machine and method, by which tube shell can be α + β through-wall quenched at a rapid cooling rate of >50 K/s from 1173 to 1073 K. 2. High nodular corrosion-resistant tube shells, quenched at both hollow billet and tube shell stages, have less deformability, especially in the circumferential compression direction. 3. Reduction in area in combination with Q-value affect crack sensitivity during pilgering. Area reductions greater than 80% at high Q-values were proved possible with minimal or no cracking. 4. Consequently, a new fabrication process, consisting of two cold reduction passes from tube shell to final product, has been successfully developed. The final tubing showed high nodular corrosion resistance, having no nodules in the high temperature (773 K) corrosion test.

Method of Evaluating Workability in Cold Pilgering of Zirconium Alloy Tube

“…6) Their compression test confirmed that the special heat treatment affected the deformability of the Zr alloy tube. In the present study, the validity of the compression test as a general method of evaluating cold workability is investigated.…”

Modeling of cold pilgering of stainless-steel tubes

“…The first arc, R in Figure 4, determines the base groove, which is calculated using Eq. 2 [10]. The other two arcs, Rx in Figure 4, evaluate the side relief clearances.…”

“…Abe et al [10] in 1994 performed cold pilgering trials for zircaloy-2 tubes with various Qfactors to examine crack formation on the tube surface in addition to numerical calculations using the model in [13]. They observed cracks on the tube surfaces that have a larger quotient between the circumferential compressive and radial tensile strains, i.e.…”