Effect of Ball Burnishing on Fretting at Elevated Temperatures.

The influence of ball burnishing on friction and wear at elevated temperatures under fretting conditions has not yet been reported. Fretting experiments were conducted using the Optimol SRV5 tester (Optimol Instruments, Munich, Germany) under dry gross fretting conditions. A ball of WC ceramic was pressed against a disc from the titanium alloy Ti6Al4V. Experiments were carried out at elevated temperatures of 100, 200, and 300 °C. The displacement frequency was 50 Hz, the stroke was 0.1 mm, and the test duration was 15 min. The normal loads used were 40, 60, and 80 N. Ball burnishing led to a substantial reduction in the roughness height and an increase in the microhardness of samples from the titanium alloy. Burnishing, in most cases, caused an improvement in the friction resistance of sliding assemblies. Ball burnishing also led to wear reduction compared to the turned disc sample. The best tribological performance of the sliding pair was achieved for the disc sample burnished with the highest pressure of 40 MPa. An increase in temperature from 100 to 200 °C caused small changes in disc wear volumes and coefficients of friction. A further increase in temperature to 300 °C led to an increase in disc wear rates and friction coefficients.