Effects of ultrasonic nanocrystalline surface modification on the high-frequency fretting wear of CP titanium and Ti-6Al-4V alloy

The probability of encountering fretting in machines and engineering structures is extremely high, and it is well known that titanium alloys have poor fretting wear resistance. Titanium specimens which are made of commercially pure titanium (CP Ti) and Ti-6Al-4V alloy were treated by ultrasonic nanocrystalline surface modification (UNSM) treatment in order to strengthen fretting wear resistance. Lubricated high-frequency fretting wear tests were performed with a nanocrytalline twin system surface layer of both CP Ti and Ti-6Al-4V alloy fabricated by means of UNSM treatment, in comparison with untreated surface specimens. Knowing the corresponding loads and constant displacement that induce mixed fretting conditions will allow for the predetermination of wear regime. The fretting tests have been carried out on both CP Ti and Ti-6Al-4V alloy under normal loads in the range from 10 to 80 N, displacement amplitude of 30 μm and high-frequency of 20 kHz.