Ferritic stainless steels are used in the “cold end” of automotive exhaust systems, in the form of welded tubes. The use of this class of steel in the mentioned application is due to its competitive price, acceptable mechanical strength at high temperatures and excellent corrosion resistance. In addition to the oxidation problems at high temperatures caused by the flow of gases from the engine in the exhaust system tubes, the external surface of stainless steels is subject to atmospheric corrosion, which is aggravated by the presence of chloride ions, which can be observed in regions located near the coast. In the present work, AISI 409 ferritic stainless steel sheets were subjected to autogenous welding by the GTAW process, with different welding parameters, with the objective of evaluating the influence of the morphology of the weld region on the corrosion resistance of the joints formed. The welds obtained were characterized according to their microstructure and mechanical properties (Vickers microhardness), and electrochemical corrosion tests were performed in an aqueous solution containing 3.5% NaCl (weight). To evaluate corrosion resistance, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used. After performing the tests, it was possible to observe hardening in the weld region, in addition to the formation of large grains in the fusion zone and in the heat affected zone. It was also possible to observe that GTAW welding affected the resistance and corrosion pattern compared to the base metal, with the direction of the weld bead in relation to the sheet rolling direction, the welding speed, and consequently the weld grain profile were decisive factors in this behavior.