Abstract
Serrated flow in Inconel 625 was investigated in solution treated tensile specimens at strain rates between 4.17×10−5 s−1 and 4.17×10−3 s−1 at temperatures between 498 K and 923 K.
The strain for the onset of Type A serrations and that for the gradual development of Type B serrations were able to be related, by the same form of equation, to strain rate, temperature, and the activation energy for solute migration. The equation was derived from the Cottrell-Bilby’s ageing model and from the concept of ageing at obstacles between dislocation flights. The obstacle distance in Type B serrations was taken as traveling distance of Lüders bands associated with each serration.
The activation energies for the onset of Type A serrations and for the amplitude growth of Type B serrations were both 100 kJ/mol, which is Mo solute migration energy to mobile dislocations. In the temperature and strain rate ranges for higher work hardening, larger strain prior to necking was obtained, which was explained by a longer traveling distance of Lüders bands associated with a larger amplitude of Type B serrations.
