RRR Niobium Seamless Cavities 
                                   Roy Crooks1
                                 Waldemar Si...
RRR Niobium Seamless Cavities; Crooks, Singer                TFSRF 2010, Legnaro, October 4 – 6, 2010 


      Rationale a...
RRR Niobium Seamless Cavities; Crooks, Singer                 TFSRF 2010, Legnaro, October 4 – 6, 2010 




              ...
RRR Niobium Seamless Cavities; Crooks, Singer    TFSRF 2010, Legnaro, October 4 – 6, 2010 

  DESY: Tube Making from sheet...
RRR Niobium Seamless Cavities; Crooks, Singer    TFSRF 2010, Legnaro, October 4 – 6, 2010 

  DESY: Necking by Profile Rin...
RRR Niobium Seamless Cavities; Crooks, Singer    TFSRF 2010, Legnaro, October 4 – 6, 2010 

  DESY: Hydroforming




     ...
RRR Niobium Seamless Cavities; Crooks, Singer    TFSRF 2010, Legnaro, October 4 – 6, 2010 

  DESY: Assembled 3x3‐cell ILC...
RRR Niobium Seamless Cavities; Crooks, Singer      TFSRF 2010, Legnaro, October 4 – 6, 2010 



      BL/AWC

      Extrud...
RRR Niobium Seamless Cavities; Crooks, Singer                                                                             ...
RRR Niobium Seamless Cavities; Crooks, Singer                                           TFSRF 2010, Legnaro, October 4 – 6...
RRR Niobium Seamless Cavities; Crooks, Singer                    TFSRF 2010, Legnaro, October 4 – 6, 2010 


             ...
RRR Niobium Seamless Cavities; Crooks, Singer    TFSRF 2010, Legnaro, October 4 – 6, 2010 


                 BL/AWC Hydro...
RRR Niobium Seamless Cavities; Crooks, Singer                                                                    TFSRF 201...
RRR Niobium Seamless Cavities; Crooks, Singer      TFSRF 2010, Legnaro, October 4 – 6, 2010 




                   Assemb...
RRR Niobium Seamless Cavities; Crooks, Singer                  TFSRF 2010, Legnaro, October 4 – 6, 2010 




             ...
RRR Niobium Seamless Cavities; Crooks, Singer                                TFSRF 2010, Legnaro, October 4 – 6, 2010 


 ...
RRR Niobium Seamless Cavities; Crooks, Singer             TFSRF 2010, Legnaro, October 4 – 6, 2010 


                    ...
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Crooks - Seamless cavities

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http://www.surfacetreatments.it/thinfilms

RRR Niobium Seamless Cavities (Roy Crooks - 20')
Speaker: Roy Crooks - Black Laboratories | Duration: 20 min.
Abstract
Roy Crooks, Black Laboratories, L.L.C., Newport News, VA, USA
Waldemar Singer, DESY, Hamburg, Germany

Conventional welding of half-cells deep-drawn from niobium sheet may generate flaws near the cavity equators which limit cavity performance. Cavities have been produced from RRR niobium tube by a combination of spinning and hydroforming, using the facilities at DESY. Seamless cavities were manufactured from tubes produced by two different methods, based on pipe spun from plate and on pipe back-extruded from ingot (at ATI Wah Chang). The microstructures resulting from the two fabrication methods are described, along with SRF properties from recent tests on prototype ILC cavities.

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Crooks - Seamless cavities

  1. 1. RRR Niobium Seamless Cavities  Roy Crooks1 Waldemar Singer2 1Black Laboratories, L.L.C., Newport News, Virginia, U.S.A. 2Deutsches Elektronen‐Synchrotron (DESY), Hamburg, Germany The Fourth International Workshop on THIN FILMS AND NEW IDEAS FOR  PUSHING THE LIMITS OF RF SUPERCONDUCTIVITY October 4 – 6, 2010 Legnaro National Laboratories, Padua, Italy Support for R. Crooks under DOE SBIR Grant No. DE‐FG02‐04ER83909, and from Fermilab and Jefferson Lab
  2. 2. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  Rationale and Approach, applications for ILC 1.3 GHz SRF Cavities Advantages of seamless tube cavity production • No RRR degradation in the welding seam  • No pits associated with the HAZ • No weld contamination • Lower production costs in large production runs • Less scatter in performance compared to welded cavities Approach: Seamless tubes produced by: • Drawing or Spinning from sheet and flow forming (DESY) • Extrusions were not adequate due to large grain size • Heavily deformed and recrystallized fine‐grain billet, Back extrusion,  forward extrusion and flow‐forming (BL/AWC) 2
  3. 3. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  Tube Making Necking Hydroforming W. Singer, DESY 3
  4. 4. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  DESY: Tube Making from sheet Successful fabrication of tube and hydroformed cavities Tube is good for 3‐cells W. Singer, DESY 4
  5. 5. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  DESY: Necking by Profile Ring W. Singer, DESY 5
  6. 6. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  DESY: Hydroforming W. Singer, DESY 6
  7. 7. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  DESY: Assembled 3x3‐cell ILC Cavity W. Singer, DESY 7
  8. 8. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  BL/AWC Extruded Tube Advantages:  • The metal is exposed to steady‐state conditions for most of  the extrusion length. • Results in a uniform structure and  axisymmetric properties. Requires a billet  with a fine‐grain, randomly oriented starting  microstructure. Tubes shaped at DESY by spinning and hydroforming. 8
  9. 9. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  Billet Processing Results (3 deformation methods) 50 mm diameter sub‐scale billet, Inverse Pole Figures of radial sections,  grain boundary number fraction vs. misorientation, texture intensity a surface t/4 t/2 surface t/4 t/2 b Scaled up to 165 mm c surface t/4 t/2 Misorientation Angle Misorientation Angle 0.07 a 0.07 b 0.06 0.06 0.05 0.05 Number Fraction Number Fraction 0.04 0.04 0.03 0.03 0.02 0.02 0.01 0.01 0.00 0.00 10 20 30 40 50 60 10 20 30 40 50 60 Misorientation Angle [degrees] Misorientation Angle [degrees] Misorientation Angle from t/4 0.07 0.06 c Texture Intensity vs. Distance from Surface, inches 0.05 25 Number Fraction 0.04 20 0.03 Texture 15 Intensity 0 ODF Max 10 0.02 0.25 0.01 5 0.5 0.00 0 10 20 30 40 50 60 A B C Misorientation Angle [degrees] Process 9
  10. 10. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  BL/AWC Tube Processing & Testing Flow Forming Thickness Recrystallization 14 μm ODF max 7 Misorientation Angle 0.13 0.12 Mackenzie (random) 0.11 0.10 0.09 0.08 Number Fraction 0.07 0.06 B2B 0.05 0.04 B1C B1B 0.03 0.02 0.01 0.00 0 10 20 30 40 50 60 70 90% Rx Misorientation Angle [degrees] Rx Rx Rx Correlated Random Tensile Tests/ Roughening Formability Test Hall-Petch DESY Limiting dome height test YS, MPa vs 1/sqrt(d) from flattened tube 50-60% elongattion 100mm dome 100 B1B 40% needed 5mm/min 90 BL/AWC Y ,M a 80 S P 70 Huang and Cao Northwestern University 60 November 2009 50 0 0.1 0.2 0.3 Inve rs e s quare root of (d) 10
  11. 11. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  BL/AWC Tube (B2B) Forming at DESY December 2009 Spinning Hydroforming Final Hydroforming Stage Spinning of irises First Stage Second Stage 11
  12. 12. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  BL/AWC Hydroforming Results at DESY 12
  13. 13. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  DESY Coarse Grain SRF Test 3‐cell BL/AWC Fine Grain SRF Test 3‐cell at JLab (Peter Kneisel) at JLab (Peter Kneisel) (9‐cell testing has started at DESY) (9‐cell prepped for testing at JLab) 3-cell seamless cavity #3, Test #1 1.0E+11 1.0E+10 Q0 Q-drop. No quench 1.0E+09 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Eacc [MV/m] Superfluid Helium leak 13
  14. 14. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  Assembly of BL/AWC 9‐cell (best of lot) Welded, stiffener rings BCP, no leaks warm or cold 14
  15. 15. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  Remaining Issues • Optimum Grain Size – Small for smoothness – Larger for more elongation? (we are forming near the ductility limit  for Nb) • Optimum Crystallographic Texture – What target other than random? (guidelines from bcc sheet forming?) – Changes with higher T anneal • Intermediate Anneals (work to‐date has been at RT)? – During flow‐forming of tube – During spinning/hydroforming of cavities • Increase total elongation • Modification of hydroforming approach (Bob Rimmer, JLab) 15
  16. 16. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  Grain size optimum? Smoother surface vs. lower ductility Hall-Petch Plot YS, MPa vs 1/sqrt(d) 100 90 Y ,M a 80 S P 70 60 50 0 0.1 0.2 0.3 Inve rs e s quare root of (d) AA7075 Coarse vs fine grain Nb tube Zhao et al Act mater; 52 (2004) 4859 YS vs inverse sq rt grain size 16
  17. 17. RRR Niobium Seamless Cavities; Crooks, Singer  TFSRF 2010, Legnaro, October 4 – 6, 2010  Summary • Nine‐cell ILC geometry ILC cavities can be assembled from seamless tube  given room temperature necking and hydroforming procedures used at  DESY. • The tube from spinning or deep‐drawing requires a 3x3 cell assembly, with  iris welds between 3‐cell sections. • Heavily deformed and recrystallized billet has been shown to allow  production of a fine‐grain, weakly textured tube. • The BL/AWC fine‐grain extruded tube is capable of fabrication into a 9‐cell  cavity without welds, although the proper machine will have to be built. • The consistent microstructure of the fine‐grain extruded tube should  reduce the scatter in srf performance with production scale operations. • Tube process optimization studies are in progress. 17
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