• Development of reliable Nb-316L SS transition joints is an important step towards use of austenitic SS helium vessel for superconducting RF (SRF) cavities of particle accelerators.
• Use of SS helium vessel (in place of titanium) makes its fabrication process simple & cost effective.

Highlights:

• A new indigenous process has been developed to produce Nb pipe/316L stainless steel flange joints suitable for application in low-b SRF cavities (Fig. 1).
• Important features of the new process are:
  • freedom from brittle intermetallics (ductile joint)
  • uniform and controlled braze gap
  • efficient utilization of braze filler metal
  • simplified pre-braze fitting procedure
  • environment friendly cleaning procedure and
  • simple storage conditions for pre-braze assembly
• The new process is easily adaptable on the shop floor and it marks significant improvement over existing global vacuum brazing practice.

Publications:

1. Abhay Kumar et al., J. Mater. Eng. Perf., 24(2), 2015, 952-963.
2. Abhay Kumar et al., Welding Journal, 94, 2015, 241s-249s.
3. Abhay Kumar et al., ASME J. Manuf. Sci. Eng., 139(1), 2017, 015001-8.