Cold metal transfer welding of duplex with ferritic and super austenitic stainless steel

Abstract

In present paper, Study of two dissimilar joint has been carried out by cold metal transfer welding. Joint 1 (J1) is grade UNS 32205; a duplex stainless steel (DSS) with grade AISI 430; a Ferritic stainless steel (FSS) and Joint 2 (J2) is grade UNS32205 with grade UNS S31254; a super austenitic stainless steel (SASS). ERNiCrMo-3 wire has been used as a filler. Scanning electron microscope (SEM) has been used to capture microstructure at higher magnification. Microstructure of both the joints‘ weld zone (WZ) showed diversified morphology such as columnar dendritic, cellular and equiaxed dendritic grains. In heat affected zone (HAZ) towards UNS 32205 Base metal (BM), different morphologies were observed such as grain boundary austenite, Widmanstatten austenite, Intergranular austenite. Unmixed zone was observed towards AISI 430 BM and UNS S31254 BM. X-ray diffraction (XRD) analysis was performed for the identification of carbide and lave phases present in the weld zone of both joint. Energy dispersive spectroscopy (EDS) was carried out to realize the variation in elemental distribution across different regions of microstructure in the weld zone of both joint. All the base metal and weld zone were subjected to Potentiodynamic polarization (PDP), Electrochemical Impedance spectroscopy (EIS) and Double loop potentio kinetic reactivation (DLEPR) test. Potentiodynamic polarization test is carried out to evaluate pitting resistance. EIS test has been performed for the evaluation of resistance offered by passive film against aggressive environment. Joint 2 shows higher pitting resistance and offers higher resistance by passive layer to corrosion than J1. DLEPR test has been conducted for measuring the degree of sensitization (DOS). Joint 1 shows 22% DOS while J2 does not show any sensitization. Evaluation of hardness, strength and impact value were done for both joints. Joint 2 possess higher hardness, strength and impact energy than J1.