Texture Analysis and Fracture Behavior of Zircaloy-4 Processed Through Swaging

Abstract

Zirconium alloy (Zircaloy-4) was cold-worked using the swaging process and subsequently subjected to mechanical and microstructural characterization in the present work. The influence of feed rate (0.7, 1.25, 2 m/min) during swaging on phase analysis, tensile properties and fracture behavior of the alloy was investigated. The swaged Zircaloy-4 samples were annealed at 732 °C for 3 h holding time to study the microstructural evolution and changes in its fracture behavior. Tensile test results show the improved tensile strength and ductility in the case of 1.25 m/min feed rate. The three-point bend test was performed on swaged and annealed samples to study the fracture behavior of Zircaloy-4 alloys. The apparent fracture toughness value of swaged samples (76.20 MPa.m^0.5 for 0.7 m/min, 69.22 MPa.m^0.5 for 1.25 m/min, and 57.52 MPa.m^0.5 for 2 m/min) and annealed samples (45.12 MPa.m^0.5 for 0.7 m/min, 44.37 MPa.m^0.5 for 1.25 m/min and 41.81 MPa.m^0.5 for 2 m/min) are reported in this work. The result shows the higher fracture toughness for swaged samples due to higher dislocation density. The deformed and annealed Zircaloy-4 samples were characterized by scanning electron microscopy–electron backscattered diffraction (SEM–EBSD) to elucidate the fracture behavior as well as phase analysis of the alloy. Texture analysis was performed using EBSD on the samples subjected to swaging at different feed rates. It reveals different types of texture on swaged and annealed rod samples. The swaged samples show basal texture 〈0002〉, and annealed samples show combination of basal 〈0002〉 and prismatic $\langle 10\bar{1}0\rangle$. Different types of textures are observed with varying feed rates and are found to be directly correlated with tensile and fracture properties.