Limitations of double compression to determine static recrystallization fraction

It is well known that double deformation method is widely used to determine static recrystallization volume fraction. And static recrystallization volume fraction for many materials have ever been evaluated by the methods, as 0.2% offset, 2% offset, back-extrapolation, 5% total strain, mean flow stress and area (strain energy) methods. These methods are based on characteristic stress or strain energy (CS). However, materials can exhibit different flow behaviors during hot working process, which results in a difficulty to designate CS. Therefore, there are some limitations for the methods. In the present work, these six methods were divided into two groups: group I, the CS designated on experimental curves and group II, CS designated on semi-experimental curves. And typical curves were analyzed to find out the limitations of the methods, which can be used to rationalize the method selection to evaluate static recrystallization volume fraction.