Comparison of ultrasonic equipment for surface finishing of titanium products

This paper compares three types of ultrasonic equipment used for surface finishing Ti6Al4V alloy samples. High-frequency mechanical impact (HFMI) technique suitable for local and high-coverage treatment is compared with two self-made ultrasonically driven systems allowing high-frequency hardening of complex surfaces by metallic/ceramic balls positioned in the vibrating chambers. Hardening balls acquired their kinetic energy either from the tip of an ultrasonic sonotrode (surface mechanical attrition treatment – SMAT) or from a whole ultrasonic chamber oscillating at a frequency of ~20 kHz. Finishing efficiency was compared based on the microhardness changes and XRD-based data on microstructure, residual stress, microhardness, and other mechanical properties (yield strength, ultimate strength, and Yu.V. Milman’s plasticity characteristics) of Ti6Al4V alloy surfaces.