Ultrasonic impact treatment

Ultrasonic impact treatment (UIT) is a metallurgical processing technique, similar to work hardening, in which ultrasonic energy is applied to a metal object. This technique is part of the high-frequency mechanical impact (HFMI) class of processes. Other terms include ultrasonic needle peening (UNP) and ultrasonic peening (UP). Ultrasonic impact treatment can result in controlled residual compressive stress, grain refinement, and grain size reduction. Low- and high-cycle fatigue are enhanced and have been documented to provide increases up to ten times greater than non-UIT specimens.