Duplex stainless steels (DSS) grade 2205 has an austenitic-ferritic microstructure with an average volume fraction of approximately 50:50. Such this duplex microstructure improves simultaneously the mechanical properties and corrosion resistance. Hence, it has numerous applications in marine environments and petroleum industrials. However, welding operation is often a vital process since it changes the microstructure, austenite-ferrite (γ/) ratio and also causes precipitation of various phases such as σ, α´, χ, etc. in weld and HAZ regions. This certainly have remarkable influence on weld properties such as toughness and corrosion resistance. This paper is devoted to genuinely characterize the microstructure of a multi-pass hybrid GTAW-SMAW weldment of 2205 DSS. Single root-pass GTAW and consequently multi-pass SMAW operations were performed on a V-shape weld groove. The weldment was prepared by the welding parameters according to the AWS standard D1.6. Ni-rich filler electrodes of grade ER2209 and E2209 was used, respectively, for GTAW and SMAW operations. The microstructure was quantitatively characterized to obtain γ/ ratio in weld, HAZ and base regions. A full spectrum of microstructure among GTAW, SMAW, inter-passes, cover-pass and corresponding HAZ regions of GTAW and SMAW regions were carefully examined. The results indicated that γ/ ratio was decreased to 30:70 and 40:60 in HAZ and weld regions, respectively. This is due to the fact that austenite formation was restricted during rapid quenching by welding operation. However, employing Ni-rich filler noticeably rewarded the austenite formation. The microstructure morphology also changed significantly. Vertical micro-hardness profile was measured on weldment from the cap pass to the root pass. It was indicated that hardness value increases significantly in weld and HAZ due to formation of precipitates such as nitrides. Combining the microstructural examination and micro-hardness results confirmed the presence of precipitate and formation of a narrow HAZ band with variable width about 100-200 µm.

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