Hybrid Welding Process in Lieu of Conventional Practices for Fabrication of Austenitic Stainless Steel AISI 304L Components in Nuclear Facility

Gas Tungsten Arc Welding (GTAW) is widely used in nuclear industry owing to its better root quality and greater control of weld pool in real time. However, the process is quite slow (75-100 mm/min) compared to other slag-based processes. This is a disadvantage especially when thicker sections need to be welded. In this work, authors have proposed combination of GTAW (Root & Hot Pass) & Flux-Cored Arc welding (FCAW) [Hereafter referred as Hybrid] to weld AISI 304L components in nuclear fuel reprocessing facility aiming at improved productivity without offsetting quality requirements. For qualification, weld pads were prepared using 12 mm thickness AISI 304L plate. They have to meet ASME Section IX requirements and other supplementary requirements such as IGC Pr C testing as per ASTM A 262.For comparison of the results, full GTAW weld pad of 12 mm thickness was also made and subjected to same tests. Macro & Micro-structural investigations of combination of welding process welds were also carried out. Since accelerated corrosion under heavily oxidizing atmosphere (4-8) M Nitric Acid) in nuclear facility applications is the life limiting factor during service, Stress corrosion cracking (SCC) testing as per ASTM G36 of weld pads has also been studied on GTAW + FCAW & FCAW all weld metal. Details of the experimental work and the results are presented here. A detailed analysis of the experimental results reveals that the proposed welding procedure has potential for field applications in nuclear industry with increased productivity with substantial advantages.