The paper presents an overview and significant improvement of one of the intensive quenching processes (namely, the IQ-3 process). The IQ-3 process is an interrupted quench method that is usually implemented in high-velocity single-part quenching IQ units. The IQ-3 process is often called a direct convection quenching since, due to a very high water flow rates through the quench chamber, both the film boiling process and the nucleate boiling process are eliminated completely, and convention

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... ess starts immediately after beginning of the quench. Different criteria of the IQ-3 process interruption are considered. Normally, the IQ-3 process is interrupted at a time when current surface compressive stresses are at their maximum value. After a conventional IQ-3 process, there is a mixed structure in the part core. The paper focuses on the IQ-3 method that provides a bainitic structure in the part core. A method for calculation of a required water flow rate for high-velocity IQ systems for providing the bainitic part core structure is discussed.