Welding Structures in Gas Tungsten Arc-Welded Zircaloy-4

Abstract

Microstructures were obtained by the gas tungsten arc welding of tubes to end caps in Zircaloy-4 fuel elements and analyzed metallographically. This article characterizes the structures and the relationships between the operative variables and structural elements and properties. The final joint properties are shown to be greatly influenced by the different structural elements, including microstructure, porosity, and inclusions. The secondary structure found after welding is Widmanstätten, varying from a parallel-plate to a basketweave pattern. Welding thermal cycles are inherently inhomogeneous, affecting both plate width and β primary grain.