Research on the microstructure and corrosion-wear resistance mechanism of Ti–6Al–4V alloy under cryogenic burnishing

The synergistic effect of deep cryogenic treatment (DCT) coupled surface burnishing process (SBP) on the surface structure and properties of Ti–6Al–4V alloy was studied, and the surface modification layer was characterized using surface morphology, microhardness, corrosion wear and other testing methods. DCT is an extension of conventional heat treatment, and SBP is a common metal surface strengthening process. By preparing the surface nano-gradient structure, the surface strengthening of metal is enhanced. The surface hardness of the DCT-SBP sample is slightly higher than that of the SBP sample. In addition, the surface roughness of the DCT-SBP sample is lower. In the electrochemical corrosion test, the corrosion resistance of the DCT-SBP sample in Hank's solution was significantly better than that of the original sample and SBP sample. Especially compared with the original sample, the deep-cold rolling pattern increases by 0.256 V, the self-corrosion current density is the lowest, 1.317 × 10 −7 A/cm 2 , which is an order of magnitude lower than the original sample, and the polarization resistance is the largest, 2.322 × 10 5 Ω cm 2 ; the R ct value of charge transfer resistance is the highest, which is 2.989 × 10 5 Ω cm 2 . Then, in the corrosion-wear resistance test, the maximum wear scar width of the DCT-SBP sample was reduced by about 10%. It is smaller than the original sample under different load wear. And the synergistic mechanism of surface quality, microhardness, microstructure and corrosion-wear resistance of DCT-SBP specimens was analyzed.