Weldability of dissimilar joint between PNC-FMS and Type 316 steel under electron beam welding

Abstract

The dissimilar butt welding joint of 11Cr-ferritic/martensitic steel (PNC-FMS) and Type 316 austenitic stainless steel (SUS316) produced by electron beam (EB) welding was studied. This study was carried out to investigate optimization of EB welding and postweld heat treatment (PWHT) for the wrapper tube materials. Optimum EB welding conditions were a focus position of 30–40 mm and a welding speed of 1750–2000 mm/min, and optimum PWHT was performed after welding at 690 °C for 60 min. As a result, no formation of δ-ferrite was observed adjacent to the fusion zone, and the mechanical properties of the welds were similar to those of the base material. In this regard, EB welding is a proper fusion welding process for dissimilar PNC-FMS and SUS316.

Keywords:

• PNC-FMS wrapper tube
• EB welding
• dissimilar welding
• δ-ferrite
• HAZ
• tensile test
• Charpy impact test
• bend test

Acknowledgements

The authors would like to thank Dr M. Ono of JFE Techno-Research Corporation for EB welding tests and valuable discussions throughout this investigation.