Study on Microstructure and Corrosion Resistance of Ti-6Al-4V Alloy Prepared by Laser Melting Deposition Additive Manufacturing

Laser melting deposition (LMD) technology was used to prepare TC4 titanium alloy.The microstructure and mechanical properties of TC4 alloy in LMDed and rolled states were compared. The corrosion properties of the alloys in the two states were studied by electrochemical performance test and slow strain rate stress corrosion test.The results show that the microstructure of TC4 titanium alloy in LMDed state is lath-like α'martensite, the content of the β phase is minimal of only 0.3%.It is significantly different from the tensile grain structure along the rolling direction in rolled state.The nanohardness of the LMDed TC4 alloy is (6.65±0.39)GPa, which is much higher than (1.54±0.57)GPa of the rolled state. The open-circuit potential of the LMDed TC4 alloy is -0.187 V, which is lower than 0.097 V of the rolled TC4, while the corrosion current density i_corr and the passivation current density i_pass are 1.42 times, 2.7 times of those of the rolled sample, respectively.The slow strain rate stress corrosion test results show that the stress corrosion sensitivity of LMDed TC4 alloy is higher than that of the rolled alloy.