Tensile and Fracture Behaviour of Zr-4 Alloy Processed Through Swaging

Production of Zirconium alloys for nuclear power reactor comprises of a number of steps during swaging and each step influences microstructural and mechanical properties of the finished product. The Zircaloy-4 was subjected to cold swaging to reduce its cross section gradually from 23 to 16 mm diameter via several passes of swaging followed by intermediate vacuum annealing at 732 °C for 3 h. EBSD was carried out to study the influence of twinning in the Zr-4 alloy. Twinning is observed in swaged ({112 ¯ 2}〈112 ¯ 3 ¯ 〉) and annealed ({112 ¯ 1}〈112 ¯ 6 ¯ 〉) samples. TEM was done to substantiate the role of dislocation density. It is observed that several swaging and annealing treatments have improved tensile strength and fracture toughness of the Zr-4 alloy.