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Open AccessArticle

Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs

Brandenburg University of Technology Cottbus-Senftenberg, Konrad-Wachsmann-Allee 17, Cottbus 03046, Germany
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Academic Editor: Amir A. Zadpoor
Materials 2015, 8(5), 2467-2479; https://doi.org/10.3390/ma8052467
Received: 18 March 2015 / Revised: 28 April 2015 / Accepted: 30 April 2015 / Published: 8 May 2015
(This article belongs to the Special Issue Mechanics of Biomaterials)
Coronary heart disease is still one of the most common sources for death in western industrial countries. Since 1986, a metal vessel scaffold (stent) has been inserted to prevent the vessel wall from collapsing. Most of these coronary stents are made from CrNiMo­steel (316L). Due to its austenitic structure, the material shows a good combination of strength, ductility, corrosion resistance, and biocompatibility. However, this material has some disadvantages like its non-MRI compatibility and its poor fluoroscopic visibility. Other typically used materials are the Co­Base alloys L-605 and F-562 which are MRI compatible as well as radiopaque. Another interesting fact is their excellent radial strength and therefore the ability to produce extra thin struts with increased strength. However, because of a strut diameter much less than 100 μm, the cross section consists of about 5 to 10 crystal grains (oligo­crystalline). Thus, very few or even just one grain can be responsible for the success or failure of the whole stent. To investigate the relation between microstructure, mechanical factors and stent design, commercially available Cobalt-Chromium stents were investigated with focus on distinct inhomogeneous plastic deformation due to crimping and dilation. A characteristic, material related deformation behavior with predominantly primary slip was identified to be responsible for the special properties of CoCr stents. View Full-Text
Keywords: coronary stents; design; strut thickness; L-605; F-562; mechanical behavior; microstructure; orientation mapping; dislocation structure coronary stents; design; strut thickness; L-605; F-562; mechanical behavior; microstructure; orientation mapping; dislocation structure
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Weiss, S.; Mitevski, B. Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs. Materials 2015, 8, 2467-2479.

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