Specification of niobium sheets

131/05/2010

O. Capatina G. Arnau Izquierdo W. Weingarten S. Atieh

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Chemical composition: • PURE NIOBIUM “based on ASTM B393, Type 5, UNS R04220 with further requirements“ • RRR 300 grade (Type 5, UNS R04220) • Limits for the main impurities:

Element Max. Content wt%

Ta 0.050W 0.007Ti 0.005Mo 0.005

All other metallic impurities, each

0.003

H2 0.0002N2 0.0010O2 0.0010C 0.0010

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Technical Specification• Sheets shall be made from ingots produced by electron beam vacuum melting.

Forging and rolling shall be made in clean conditions to avoid any contamination with foreign particles. Final annealing shall be made in a proper vacuum of 2 10∙ -5 torr or better.

ASTM B393 – 09e1 Standard specification for Niobium and Niobium Alloy Strip, Sheet, and Plate. EN 10204:2004 Metallic products: Types of inspection documentsASTM E112-96(2004)e1 Standard method for determining average grain sizeprEN 4050-4:1994 Aerospace series - Test method for metallic materials; ultrasonic inspection of bars, plates, forging

stock and forgings - Part 4: Acceptance criteriaISO 4287:1997 Geometrical Product Specifications (GPS) -- Surface texture: Profile method -- Terms, definitions

and surface texture parametersISO 4288:1996 Geometrical Product Specifications (GPS) -- Surface texture: Profile method -- Rules and

procedures for the assessment of surface texture

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Homogeneity and surface quality:Parallel surfaces (RF side & back side) and bulk material have to be free of defects

• Surface defects:RF side, surface roughness Rt ≤ 15 µm.back side, surface roughness Rt ≤ 60 µm.visual inspection and optionally by Eddy current(according to a written procedure approved by CERN)

• Bulk defects:shall be ultrasonically inspected for the presence of continuity faults and for variations of attenuation which are indicative of microstructural heterogeneities.

Structure:Grain size number 6 or finer According to ASTM E112-96(2004)e1

Mechanical:Tensile strength Rm

min.

140 N/mm2

Yield stress Rp 0.2%

min.

max.

50 N/mm2100 N/mm2

Elongation at break A5 min. 30%Vickers hardness HV10

max.

60

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Test FrequencyChemical analysis other than H2, N2, O2 and C

Every melt

H2, N2, O2 and C Every batch on final productStructural analysis Every batch on final productTensile mechanical properties Every batch on final productHardness Every item (location to be agreed)RRR Every batch on final productVisual inspection Every item, 100 % on both sidesEddy current inspection (option) Every item, 100 % on both sidesUltrasonic for continuity faults Every item and/or intermediate

product, 100 % Ultrasonic for variations of attenuation Every item, 100 %Roughness Every batch on final productDimensions Every item

Tests carried out by the manufacturer for each item delivered. Items are considered in the same batch if they have in common: melt, rolling and have been annealed in the same charge

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• Sheet dimension (half cell shape) are determined by the manufacturing process• For small series spinning is more adapted than deep drawing or hydro forming

• Establish sheet main dimensions, spinning test has been carried out with following outcomes:

Required sheet Ø ≈ 520 mm → dimension 520 mm x 520 mmThickness:

optimised start thickness is 3.5 mm

spinning t loss - 0.6 mmthickness tolerances - 0.1 mmchemical etching and EP - 0.2 mm

Starting thickness 3 mm & 4 mmLoss in thickness ≈ 0.6 mmTacking into account

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t 3.5 mm

Ø 520 mm

Sampling, witness pieces, tests, etc.

Final sheet dimension: 520 mm x520 mm x t 3.5 mm

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• Stiffening rings in Nb RRR40→ specification is done

• Interface Nb to NbTi and Ti tank to done• Extremities to done in tubes or spinning?• Quantities to checked