The Evaluation of Corrosion Behavior of AISI 347 Stainless Steel to ASTM A335 Low Alloy Steel Dissimilar Welds

In the present study, the corrosion behavior of AISI 347 austenitic stainless steel to ASTM A335 low alloy steel dissimilar joint was investigated. For this purpose, two filler metals, ER309L and ERNiCr-3, were selected to be used during the gas tungsten arc welding process. To investigate the corrosion behavior of the joints after welding, the specimens were tested in 3.5% sodium chloride solution using Tafel and cyclic polarization tests. Also, the microstructures of base and weld metals were evaluated using optical microscopy. The microstructural evaluations showed that a two-phase structure consisting of dendritic and inter-dendritic regions with primary austenite solidification was observed in ERNiCr-3 filler metal and a primary skeleton-shaped ferrite in austenitic matrix was observed in 309L filler metal. The results of electrochemical tests also showed that 347 austenitic stainless steel base metal had more resistance to corrosion in comparison to A335 low alloy steel base metal, due to more amounts of chromium and nickel in its structure. Also, ERNiCr-3 filler metal displayed better resistanceto pitting corrosion.