The knowledge of the flow behavior of metallic all oys subjected to hot forming operations is of particular interest for designers and engineers in the practice of industrial forming processes simulations (i.e. rolling mill). Nowadays dynamic recrystallization (DRX) is recognized as one of the most relevant and meaningful mechanis ms available for the control of microstructure. This mechanism occurs during hot forming operations over a wide range of metals and alloys and it is known to be as a powerful tool which can be used to the control of the microstructure and properties of alloys. Therefore is important to kno w, particularly in low stacking fault energy (SFE) materials, the precise time for which DRX is availa ble to act. At constant strain rate such time is defined by a critical strain, . Unfortunately this critical value is not directly measurable on the flow curve; as a result different methods have been developed to derive it. Focused on steels, in the present work the state of art on the critical strai n for the initiation of DRX is summarized and a review of the different methods and expressions for determining is included. The collected data is suitable to feeding constitutive models.

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