Effects of Strain Rate and Temperature on Tensile Properties, Deformation and Dynamic Strain Ageing Behavior of Ni-Base Superalloy Superni 263

Tensile studies on Superni 263 superalloy were carried out by employing various strain rates and temperatures in the range of (298–923 K), to explore the tensile deformation and fracture characteristics. It is found that Superni 263 alloy was sensitive to strain rate and peak value in yield strength was obtained at intermediate strain rate 1.3 × 10−3 S−1 and 673 K. The alloy exhibited serrated plastic flow, anomalous variations in tensile properties, minimum in ductility, work hardening rate and negative strain rate sensitivity which are the important manifestations of dynamic strain ageing (DSA) in the intermediate temperature range. The species responsible for the occurrence of DSA were identified as Cr and Mo with the activation energy measurements of 68–74 kJ/mol, indicating the pipe diffusion in austenite matrix. The alloy exhibited mixed ductile and intergranular mode of fracture in the entire temperature range. Few grains exhibited transgranular quasi-cleavage facets in the DSA range.