The study on surface strengthening technology of Ti-6Al-4V alloy used in Power Plants

This paper was mainly study on surface strengthening properties of HIP Ti-6Al-4V alloy treated by ultrasonic surface rolling. The effect of the different ultrasonic amplitudes on material surface modification properties was researched, and the strengthened mechanism of ultrasonic surface rolling was revealed. The test results indicated that the thicker plastic deformation layer and the finer composition phases could be produced by the large ultrasonic vibration amplitude, as well as the lower surface roughness and the better mechanical properties (residual stress and microhardness). The fretting friction and wear properties and fatigue performance of the material before and after ultrasonic surface rolling were further compared. Finally it could be found that the fretting friction and wear properties and fatigue performance of the material after ultrasonic surface rolling treatment were improved effectively. The samples showed the slight fretting wear scar and the low fretting friction coefficient. Moreover the high-cycle fatigue stress was obviously increased.