Surface Nanocrystallization Induced by Ultrasonic Shot Peening and Its Effect on Corrosion Resistance of Ti–6Al–4V Alloy

Abstract

Alloy Ti–6Al–4V was subjected to ultrasonic shot peening (USP) for 1 min (min) and 5 min to examine the effect of surface nanostructure on corrosion resistance of this alloy in simulated body fluid (SBF). USPed samples were also subjected to stress relieving (SR) treatment at 400 °C for 1 h in the argon atmosphere (AR). The surface nanostructure and constituted phases were characterized by TEM, and the effect of USP was examined on electrochemical corrosion resistance in SBF solution. It has been observed that corrosion resistance is enhanced due to USP. The development of the resistance to corrosion is attributed to the quick formation of protective oxide scale due to extensive increase in number of grain boundaries and the associated compressive residual stress induced by USP. The relatively lower corrosion resistance and higher tendency of pitting following SR treatment of the USPed specimens are due to decreasing the associated residual stress. © 2018, The Indian Institute of Metals - IIM.