On the influence of stress relief annealing on the corrosion behaviors of LPBF TC4 alloys in 1%NaCl solution
The electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization curves(PDP)are utilized to investigate the effect of stress relief annealing on electrochemical behavior of TC4 titanium alloy fabricated using Laser Powder Bed Fusion(LPBF)in 1%NaCl solution.Addi-tionally,Mott-Schottky test and X-ray photoelectron spectroscopy(XPS)are employed to analyze the properties of the passive films formed on the surface of the alloys.The results indicate that the LPBF TC4 titanium alloy is primarily composed of acicular α´ martensite,whereas possesses α+β dual-phase structure after stress relief annealing.Stress relief annealing deteriorates the corrosion resistance of LPBF TC4 alloy,resulting in the lower polarization resistance and higher corrosion current density.The passive films on both alloys LPBF TC4 titanium alloy exhibit n-type semiconductors with and without stress relief annealing,but the carrier density of the alloy increases after the stress relief anneal-ing and the fraction of TiO2 in the passive film decreases,leading to a decrease in the deterioration in corrosion resistance.