Details

Autor(en) / Beteiligte

• Singh, Jeetendra Kumar
• Roy, Gour Gopal
• Prakash, P. N.
• Rai, Abhishek
• Manna, I.
• Kanjilal, D.
• Dutta Majumdar, Jyotsna

Titel

Effect of beam oscillation on microstructure, defect density, and resistivity of electron beam welded niobium

Ist Teil von

• Welding in the world, 2022-12, Vol.66 (12), p.2483-2495

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The degradation of residual resistivity ratio (RRR) in the weld zone of the electron beam welded component is the main problem associated with the application of a niobium-based cavity. The present study concerns understanding the effect of beam oscillation on the characteristics of electron beam welded niobium processed under optimum current, voltage, and scan speed. In the electron beam welded niobium, there is coarsening of microstructure in the weld zone. Grain size in the range of 1 mm has been in the fusion zone as compared to 20 µm in the as-received material. It is observed that there is an increased area fraction (82 to 94%) of low-angle grain boundary (< 15°) in the weld zone as compared to the base metal (75.2%). Beam oscillation does not seem to have any significant impact on the microhardness and it remains almost constant across the fusion zone (FZ), heat-affected zone (HAZ), and base metal. No new phase has formed after electron beam welding but a strong texturing effect along (110) plane has been observed in the fusion zone. Beam oscillation was also found to increase the residual stress in the fusion zone (223.3 to 358.1 MPa) as compared to the static beam. In addition, beam oscillation causes increased resistivity in the weld zone due to the introduction of a larger volume fraction of micro porosities (0.4 vol%) as compared to the static beam (0.2 vol. %).