Effect of pulse frequency on the microstructure and corrosion behavior of Ti-6Al-4V alloy fabricated by pulse arc remelting method

This study employed the gas tungsten arc welding (GTAW) pulse arc remelting method to modify the surface of Ti-6Al-4V alloy, investigating the influence of pulse frequency on its microstructural evolution and corrosion behavior in a 3.5 wt% NaCl solution. The results indicate that the prior (3 grains gradually refine as the pulse frequency increases, and the width and spacing of alpha/alpha ' martensite decrease. Compared to the sample remelted at 25 Hz, the grain size of the sample remelted at 500 Hz decreased by 80.91 %, while the lath spacing and thickness reduced by 56.7 % and 27.9 %, respectively. The maximum surface microhardness of the remelted Ti6Al-4V alloy reached 524 Hv. The alloy exhibited the best corrosion resistance at a pulse frequency of 100 Hz. However, when the pulse frequency exceeded 100 Hz, the excessively high grain boundary density intensified localized corrosion at the grain boundaries. The width of the alpha/alpha ' martensite phase is a key factor affecting the corrosion resistance of the Ti-6Al-4V alloy.