Specification of niobium sheets O. Capatina G. Arnau Izquierdo W. Weingarten S. Atieh
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∙10-5torr or better. ASTM B393 – 09e1 Standard specification for Niobium and Niobium Alloy Strip, Sheet, and Plate. EN 10204:2004 Metallic products: Types of inspection documents ASTM E112-96(2004)e1 Standard method for determining average grain size prEN 4050-4:1994 Aerospace series - Test method for metallic materials; ultrasonic inspection of bars, plates, forging stock and forgings - Part 4: Acceptance criteria ISO 4287:1997 Geometrical Product Specifications (GPS) -- Surface texture: Profile method -- Terms, definitions and surface texture parameters ISO 4288:1996 Geometrical Product Specifications (GPS) -- Surface texture: Profile method -- Rules and procedures for the assessment of surface texture GENERAL CHARACTERISTICS Chemical composition: • PURE NIOBIUM “based on ASTM B393, Type 5, UNS R04220 withfurtherrequirements“ • RRR 300 grade (Type 5, UNS R04220) • Limits for the main impurities:
Structure: Grain size number 6 or finer According to ASTM E112-96(2004)e1 Mechanical: • 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. GENERAL CHARACTERISTICS
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 QUALITY CONTROL
Sheet dimension (half cell shape) are determined by the manufacturing process • For small series spinning is more adapted than deep drawing or hydro forming • Establishsheetmaindimensions,spinning test has been carried out with following outcomes: • Required sheet Ø ≈ 520 mm → dimension 520 mm x 520 mm • Thickness: Starting thickness 3 mm & 4 mm Loss in thickness ≈ 0.6 mm Tacking into account Dimensions spinning t loss - 0.6 mm thickness tolerances - 0.1 mm chemical etching and EP - 0.2 mm optimised start thickness is 3.5 mm
Final sheet dimension: 520 mm x520 mm x t 3.5 mm t 3.5 mm Ø 520 mm Dimensions Sampling, witness pieces, tests, etc.
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 Open points