Analysis of New Nitinol Ingot Qualities

New ingot qualities, processed by optimized vacuum arc remelting (VAR), optimized vacuum induction melting followed by VAR and VAR followed by electron beam remelting, were compared with standard quality. Finished components as well as diamond-shaped samples representing a typical dimension of self-...

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Bibliographic Details
Published inJournal of materials engineering and performance Vol. 23; no. 7; pp. 2450 - 2456
Main Authors Steegmüller, Rainer, Ulmer, Jochen, Quellmalz, Michael, Wohlschlögel, Markus, Schüßler, Andreas
Format Journal Article
LanguageEnglish
Published Boston Springer US 01.07.2014
Subjects
Characterization and Evaluation of Materials
Chemistry and Materials Science
Corrosion and Coatings
Engineering Design
Materials Science
Quality Control
Reliability
Safety and Risk
Tribology
corrosion behavior
fatigue
extra low inclusions
mechanical testing
radial force
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Summary:New ingot qualities, processed by optimized vacuum arc remelting (VAR), optimized vacuum induction melting followed by VAR and VAR followed by electron beam remelting, were compared with standard quality. Finished components as well as diamond-shaped samples representing a typical dimension of self-expanding stents were produced using Nitinol tubing drawn from the new ingot qualities. Metallographic longitudinal sections were prepared and analyzed to determine inclusion size and distributions of the various ingot qualities. Radial force and uniaxial tensile tests were used to determine the mechanical properties of fully processed material and tubing, respectively. Transformation temperatures of tubing as delivered from supplier and processed stents were measured by differential scanning calorimetry and deformation-and-free-recovery testing. Finally, fatigue tests were performed on diamond-shaped samples to evaluate the strain-life characteristics of the new ingot qualities. Results of this study are compared to ADMEDES historical data from standard Nitinol materials to gain an assessment of the new improved ingot qualities with regard to the production of Nitinol vascular implants. The latest developments in Nitinol ingot quality are highlighted and the results of the comparison from technical point of view are shown.
ISSN:1059-9495
1544-1024
DOI:10.1007/s11665-014-1054-0