Two types of steel alloys (St.17Mn1Si and st.22MnAl) and their fusion welded parts applying different thermal treatment techniques were tested electrochemically. Their electrochemical characteristic including: the electrochemical potential values and current density of the base metals, heat affected zones and welding pools are estimated. Correlations are developed to express the effect of the electrochemical potential of the heat affected zone as an additional independent variable of the models. Also the evaluation of corrosion resistance behavior of welded alloys used as corrosion medium 3% NaCI solution in presence of air, oxygen and carbon dioxide for 3300 hrs were investigated visually and experimentally using different techiniques. The developed models estimated are candidated to be used to determine the electrochemical characteristics of other related classes of welded steel alloys