CERN Accelerating science

Article
Report number	CERN-ACC-2019-0050
Title	Assessment of the Mechanical Properties of Ultra-High Purity Niobium after Cold Work and Heat Treatment with the HL-LHC Crab Cavities as Benchmark
Author(s)	Gallifa Terricabras, Adria (CERN) ; Amorim Carvalho, Alexandre (CERN) ; Aviles Santillana, Ignacio (CERN) ; Barriere, Simon (CERN) ; Calaga, Rama (CERN) ; Cano Pleite, Eduardo (CERN) ; Capatina, Ofelia (CERN) ; Crouvizier, Mickael Denis (CERN) ; Dassa, Luca (CERN) ; Meyer, Mickael Sebastien (CERN) ; Valverde Alonso, Nuria (CERN) ; Benke, M (Miskolc U.) ; Hlavacs, A (Miskolc U.) ; Krallics, G J (Miskolc U.) ; Mertinger, V (Miskolc U.) ; Palotas, A B (Miskolc U.) ; Sepsi, M (Miskolc U.) ; Szabo, G (Miskolc U.) ; Szucs, M (Miskolc U.)
Publication	2019
Imprint	24 Jun 2019
Number of pages	7
Note	Presented at SRF, Dresden, Germany, 2019
Accelerator/Facility, Experiment	CERN LHC
Project	CERN HL-LHC
Free keywords	crab cavities ; SRF ; mechanical properties ; tensile test ; cross rolling ; deep drawing ; niobium ; Nb RRR300 ; cold work ; 4 mm sheet ; effective plastic strain ; heat treatment ; recrystallization ; annealing ; thickness reduction ; pressure vessel ; hardness ; microstructure ; 650 °C
Abstract	The High Luminosity Large Hadron Collider (HL-LHC) is the upgrade of the world’s largest particle collider; it will allow the full exploitation of the LHC potential and its operation beyond 2025. An essential part of the HL-LHC project are the Crab Cavities, that are particle de-flecting SRF cavities of non-axisymmetric shape made of bulk ultra-high purity Nb. Since the cavities are produced by complex metal sheet forming processes, followed by a heat treatment (HT) for H outgassing (650 °C, 24 h), there is uncertainty on their mechanical properties after manu-facturing and in service conditions (2 K). Mechanical tests at room temperature have been conducted on RRR300 pure Nb samples. The samples were previously submitted, by cold cross-rolling, to different levels of plastic deformation representative of the effective plastic strain seen by the Nb sheets during forming operations. Moreover, a comparison of the mechanical properties of cold cross-rolled samples before and after HT has been established. Results of evolution of the microstructure and hardness are also presented. This study can be of interest for Nb cavities to be submitted to HT at 650 °C, and may help to push the design of novel SRF cavities.
Copyright/License	publication: © 2019-2024 The Authors (License: CC-BY-3.0)

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