Z. Shahryari, I. Keivanrad, K. Gheisari, K. Ranjbar, R. Dehmolaei, S. R. Mousavi,
Volume 6, Issue 2 (12-2020)
Abstract
In this study, Inconel 617 alloy was welded to A387-Gr.11 low-alloy steel using ER309L filler metal via gas tungsten arc welding (GTAW). First, the corrosion behavior of Inconel 617, A387-Gr, and the weld metal was evaluated by the Tafel polarization test and electrochemical impedance spectroscopy (EIS) in acidic (H2SO4), neutral (NaCl), and combined (H2SO4 + NaCl) solution at ambient temperature. The results of polarization and EIS measurements in all corrosive solutions indicate that the corrosion resistance decreases from 617 alloy to weld metal and from weld metal to low-alloy steel, respectively. The Comparison of the polarization curves of the base metals and the weld metal showed susceptibility to galvanic corrosion between Inconel 617 / weld metal in 1M NaCl solution. The behavior of galvanic corrosion of this pair was evaluated using the mixed potential theory and the electrochemical noise measurement. The results showed that in a galvanic couple of alloy 617 / weld metal, the weld metal acts as anode and corrodes in such a way that its corrosion rate increases from 0.22 μA/cm2 before joining to 1 μA /cm2 after joining.
Hossein Tahmasebi Manesh, Alireza Nasresfahani, Alireza Nasresfahani,
Volume 7, Issue 1 (8-2021)
Abstract
One of the applications of P460NH micro-alloy steel is its use in pressure vessel tanks. Electrode E8018-G can be used for welding this steel. In this study, to obtain the optimal welding parameters, the arc process based on ASME IX standard was used. Then, by sampling from the weld section, Vickers hardness test was performed and hardness profiles were drawn in different areas. Then the microstructure of each area was examined and compared with the hardness test results. The corrosion behavior of the heat affected zone, weld zone and base metal was investigated separately using the TOEFL polarization test in a 3.5% solution of NaCl. The results showed that the weld zone had the highest percentage of perlite (62%) and the base metal had the highest percentage of ferrite (73%). Also, the heat affected zone has the highest hardness number (298) and the base metal has the lowest value (210) in the Vickers scale. Evaluation of corrosion behavior of different areas also showed that the heat affected zone has the highest corrosion potential (-.651v) and the lowest corrosion current density (1.75×10-5 A/cm2). This is while the base metal has the lowest corrosion potential (-.691v) and the highest corrosion current density (1.2×10-6 A/cm2) compared to the weld metal and the heat affected zone.
