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 β grains gradually refine as the pulse frequency increases, and the width and spacing of α/α′ 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 Ti-6Al-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 α/α′ martensite phase is a key factor affecting the corrosion resistance of the Ti-6Al-4V alloy. • Ti-6Al-4V alloy was fabricated using the pulse arc remelting process. • The pulse remelting frequency for superior corrosion resistance was identified. • Effects of pulse frequency on grain size and phase transformation were studied. • The relationship between microstructure and corrosion resistance was analyzed.