Microstructure and corrosion resistance of welding joints of economic ferritic stainless steel

TCS345, T4003, Nirosta 4003 and JFE410RW ferritic stainless steels were welded by ER-309 welding wire in this paper.The microstructure of their base metal and joint were analyzed by metallographic approach, and the corrosion resistance of base metal and joints was evaluated by electrochemical corrosion tests.The experimental results demonstrated that, compared with that of Nirosta 4003 and JFE410RW, low content of Ti and Mn elements were found in TCS345 and T4003 ferritic stainless steels, especially the low content of Ti, which resulted in the obvious grain growth of TCS345 and T4003 ferritic stainless steels.Moreover, the welding joints of ferritic stainless steels exhibited big heat affected zone(HAZ).Compared with the microstructure of base metal, the HAZ area showed obvious large grains.As far as TCS345 is concerned, obvious grain growth is observed.In the case of Nirosta 4003 and JFE410RW, they exhibited smaller size of grain than TCS345.In 1mol/L Na₂SO₄ solution, the corrosion resistance of TCS345 and JFE410RW is better than that of T4003 and Nirosta 4003.