In most industrial applications, this process is also known as ultrasonic peening (UP)/ultrasonic impact treatment(UIT). The beneficial effect of UIT/UP is achieved mainly by relieving of harmful tensile residual stresses and introducing of compressive residual stresses into surface layers of materials, decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the material.
The UIT/UP produces a number of beneficial effects in metals and alloys. Foremost among these is increasing the resistance of materials to surface-related failures, such as fatigue and stress corrosion cracking. The fatigue testing of large-scale parts and welded specimens showed that the UIT/UP is the most efficient improvement treatment as compared with traditional techniques such as heat treatment, TIG-dressing, hammer peening and shot peening.
