Effect of Temperature on the Structure and Mechanical Properties of Zr–2.5% Nb Alloy Processed by Rotary Forging

The influence of the temperature of the rotary forging process as well as the temperature of the post-deformation annealing on the microstructure and mechanical properties of the Zr–2.5% Nb zirconium alloy was studied. The mechanical properties were measured at both 23 and 300 °C. It was found that rotary forging of the alloy at both 200 and 300 °C forms a highly inhomogeneous ultrafine-grained structure with elongated crystallites and a high dislocation density. Some equiaxed crystallites with high-angle boundaries were found in the structure. The amount of the regions with the small-angle misorientation in the alloy structure after rotary forging at 300 °C is higher than after rotary forging at 200 °C. The structure of the alloy after forging at 300 °C is more stable to heating than at 200 °C. The best balance of strength and ductility of the alloy is provided by rotary forging at 200 or 300 °C followed by annealing at 400 °C.