Effects of ultrasonic frequency pulse arc on corrosion behaviors of wire-arc directed energy-deposited Inconel 690 alloys

This study examined the impact of an ultrasonic frequency pulse (UFP) arc on the corrosion behavior of wire-arc directed energy-deposited (WADED) Inconel 690 alloys. The UFP-WADED Inconel 690 exhibited more random grain orientation, refined grains, and minor-sized carbide precipitates than the direct current (DC) sample. The introduction of the UFP arc improved electrochemical behavior, including the open circuit potential value and impedance loop, and reduced the corrosion current. The UFP component exhibited a wider passive range and higher pitting potential. Corrosion pitting occurred near the Al-enriched γ'-phase and carbide precipitates owing to the microgalvanic corrosion in the DC and UFP samples. The larger carbide precipitates in the DC sample induced defects in the passive film. The UFP arc significantly reduced element segregation and led to minor pittings, which resulted in improved corrosion resistance.