In this work AA5083 plates were welded using two different methods including Constant Current Gas Tungsten Arc Welding (CCGTAW) and Pulsed Current Gas Tungsten Arc Welding (PCGTAW). In both methods, sampeles welded with AC and square wave current. In order to calculate heat input of welding with AC, some relations in both methods were obtained. Cyclic potentio dynamic polarization, susceptibility to intrgranular corrosion (NAMLT test) and Mott-Scotky tests were performed on weldments. In order to design potentiodynamic experiments, evaluate the effect of each pulse welding parameters on corrosion resistance of weldments and extract the optimum conditions for welding parameters to achive higher pitting potential, Taguchi approach (Qualitek software) and a L8 array were used. Microstructural analysis and micro analysis of base metal, heat affected zone (HAZ) and weld metal were charactersied with scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Results showed that the anodic and cathodic pericipitations in pulsed welded sampeles were less and smaller than other observed in constant current welded sampeles. Although anodic and cathodic precipitations in HAZ grain boundries which were continues in constant current welded joints became discreet. Results of cyclic polarization showed better corrosion resistance in pulse welded joints. The susceptibility to intergranular corrosion tests showed that three pulse welded sampeles with relative heat input 0.64, 0.73 an 0.74 were not susceptible to intergranular corrosion but the constant current welded joints were susceptible. Mott- Scotky analysis showed that passive filmes on AA5083 aluminum alloy in %3.5 NaCl solutions is a n-type semiconductor and HAZ of the weldments have more oxygen vacancies in their passive films. HAZ of the pulsed welded joints have less oxygen vacancies than HAZ of the constant current welded joints.
