<p>An alternating magnetic field (AMF) was introduced into the narrow gap laser-arc hybrid welding process for 2205 duplex stainless steel thick plates. The corrosion performance of the welded joints was evaluated through electrochemical studies. The results revealed that joints welded with the application of AMF had a lower corrosion current density compared to those welded without an external AMF. Additionally, these joints showed higher pitting potential and polarization resistance. Microscopic electrochemical analysis indicated that joints subjected to AMF exhibited minimal cathodic current in simulated seawater, with only slight fluctuations in the anodic current peak. Overall, the corrosion levels on the joint surfaces were relatively low. After 4&#xa0;h of immersion in the corrosive medium, the average impedance of joints exposed to AMF increased by 60.7% compared to those not influenced by a magnetic field. These findings suggest that applying AMF during the narrow gap laser-arc hybrid welding process can significantly improve the corrosion resistance of duplex stainless steel welded joints, reducing their susceptibility to stress corrosion in seawater-like environments.</p>