Modified wear behavior of selective laser melted Ti6Al4V alloy by direct current assisted ultrasonic surface rolling process

作者：Wang, Zhen; Liu, Zhongqiang; Gao, Chaofeng; Wong, Kaho; Ye, Sujuan; Xiao, Zhiyu^*

来源：Surface and Coatings Technology, 2020, 381: 125122.

DOI：10.1016/j.surfcoat.2019.125122

• DC-USRP
• Friction and wear properties
• Ti6Al4V
• Selective laser melting

Ti6Al4V alloy samples prepared by selective laser melting were treated by three different post-treatments: namely heat-treatment, ultrasonic surface rolling process (USRP) and direct current assisted ultrasonic surface rolling process (DC-USRP). Wear behaviors were evaluated using a block-on-disc rig under lubrication conditions. Results showed that the DC-USRP treated sample exhibited the lowest wear rate of 1 x 10(-6) mm(3) N-1 m(-1), compared to that of the as-built (4 x 10(-5) mm(3) N-1 m(-1)), heat-treated (2 x 10(-5) mm(3) N-1 m(-1)) and USRP-treated samples (5 x 10(-6) mm(3) N-1 m(-1)). Consistent with changes in the wear rate, the friction coefficient was also gradually reduced. The as-built and heat-treated samples showed severe abrasive wear and delamination, while the USRP and DC-USRP treated samples displayed only mild abrasive wear. The improved wear resistance of the USRP and DC-USRP treated samples was attributed to the modified lubrication mechanism, increased hardness and compressive residual stress. Moreover, the wear resistance of the DC-USRP treated samples decreased with the increasing depth from the surface due to the effect of gradient work hardening.