• Selvarajan, L.
• Chandrasekaran, M.
• Choudhury, B.
• Singh, V.

Abstract

Inconel 825 is a Ni-Fe-Cr alloy which is widely used in engineering due to its exceptional corrosion resistance and high-temperature strength. Welding (joining) of Inconel 825 has attracted strong research attention over the past few years. In this work, the effects of heat input leading to precipitation and micro segregation of Inconel 825 weldments were examined in light of comparing them while using two popular welding techniques namely, Gas tungsten arc welding (GTAW) and Electron beam welding (EBW). It was discovered that excessive heat input during GTAW can lead to root cracking and solidification cracking; while EBW demonstrated better control over undercut and maintains consistent weld quality even for higher heat inputs. Both GTAW and EBW samples exhibit dendritic grain morphologies with distinctive grain boundaries. Precipitates, such as Al4C3 and TiN were observed in both processes, contributing to improved mechanical properties. While GTAW weldments show some degree of segregation for Mo, Cu, Ti, and Al, EBW weldments demonstrate negligible segregation for major alloying elements but micro-segregation of Ti and Al. In general, the mechanical properties of EBW weldments was better as the average hardness, tensile strength, and ductility was much better compared to the GTAW weldments. This can be attributed to lower heat input, faster cooling rates, and a reduced rate of elemental segregation during EBW. Finally, the fractographic analysis revealed the presence of voids and micro-voids, indicating a ductile mode of failure for both GTAW and EBW samples. These findings offer invaluable insights for selecting the appropriate environment and welding method to join Inconel 825 for critical safety applications.

Topics

• impedance spectroscopy
• grain
• corrosion
• strength
• hardness
• precipitate
• precipitation
• tensile strength
• void
• tungsten
• ductility
• tin
• joining