SRF2011 - List of Authors (Janda, D.)

Paper	Title	Page
THPO059	Correlation of Microstructure, Chemical Composition and RRR-Value in High Purity Niobium (Nb-RRR))	863
	R. Grill, W. Simader Plansee Metall GmbH, Reutte, Austria M. Heilmaier, D. Janda TU Darmstadt, Darmstadt, Germany W. Singer, X. Singer DESY, Hamburg, Germany
	For manufacturing of Nb-RRR sheet material a thorough understanding of material properties and niobium metallurgy is necessary to meet the required regarding material properties as specified for the XFEL project. Especially for the RRR value it is known, that residual stresses, and increased levels of vacancy and impurity concentrations, and dislocation densities after the final heat treatment can cause a severe degradation of the RRR value. Also, a comprehensive understanding of the influence of further microstructural properties (e.g. different textures due to rolling operations and annealing, dislocation substructures, etc.) on the RRR-value is lacking. For specimens having RRR-values in the range of 360 to 430, the crystallographic texture has been investigated and correlated with the measured RRR values. Furthermore, the possible influence of different impurity levels on the RRR value was calculated, compared with the measured values and discussed with regard to the current material specification for the XFEL project.

Paper

Title

Page

Correlation of Microstructure, Chemical Composition and RRR-Value in High Purity Niobium (Nb-RRR))

863

R. Grill, W. Simader
Plansee Metall GmbH, Reutte, Austria
M. Heilmaier, D. Janda
TU Darmstadt, Darmstadt, Germany
W. Singer, X. Singer
DESY, Hamburg, Germany

For manufacturing of Nb-RRR sheet material a thorough understanding of material properties and niobium metallurgy is necessary to meet the required regarding material properties as specified for the XFEL project. Especially for the RRR value it is known, that residual stresses, and increased levels of vacancy and impurity concentrations, and dislocation densities after the final heat treatment can cause a severe degradation of the RRR value. Also, a comprehensive understanding of the influence of further microstructural properties (e.g. different textures due to rolling operations and annealing, dislocation substructures, etc.) on the RRR-value is lacking. For specimens having RRR-values in the range of 360 to 430, the crystallographic texture has been investigated and correlated with the measured RRR values. Furthermore, the possible influence of different impurity levels on the RRR value was calculated, compared with the measured values and discussed with regard to the current material specification for the XFEL project.