Ultrasonic Vibration Influences on the Flow Stress Behavior of a Ferrite-Perlite and Austenite Stainless Steel

In times of energy scarcity and global warming, simple but efficient smart processes are needed to reduce the need for natural resources and the production of climate changing gases. Therefore, ultrasonic vibrations in deformation processes could be a possibility because ultrasonic vibrations can reduce the flow stresses, decrease friction, increase the forming limit, produce heat, and increase the process efficiency of metallic materials, but until today the mechanism and the influences are not well understood, especially not for steels. The common ferritic-pearlitic C15E and austenitic X6CrNiMoTi17-12-2 steels are investigated in compression tests with additional different ultrasonic vibration amplitudes and durations in view of residual effects. Both steels showed residual softening after ultrasonic vibrations depending on the ultrasonic vibration duration and the ultrasonic vibration amplitude. The austenite showed a higher sensitivity to the ultrasonic vibration in terms of a higher residual softening and a higher temperature increase. Based on the mean flow stress, the temperature increase, the strain hardening rate, and the strain hardening exponent are discussed in the context of dislocation reactions.