Microstructural and Mechanical Characterization of Thin-Walled Tube Manufactured with Selective Laser Melting for Stent Application

Research output: Contribution to journalArticlepeer-review

Authors

  • E. Langi
  • L. G. Zhao
  • V. V. Silberschmidt
  • H. Willcock
  • F. Vogt

Colleges, School and Institutes

External organisations

  • Loughborough University
  • University Hospital Aachen

Abstract

This paper focuses on microstructural and mechanical characterization of metallic thin-walled tube produced with additive manufacturing (AM), as a promising alternative technique for the manufacturing of tubes as a feedstock for stents micromachining. Tubes, with a wall thickness of 500 μm, were made of 316L stainless steel using selective laser melting. Its surface roughness, constituting phases, underlying microstructures and chemical composition were analyzed. The dependence of hardness and elastic modulus on the crystallographic orientation were investigated using electron backscatter diffraction and nanoindentation. Spherical nanoindentation was performed to extract the indentation stress–strain curve from the load–displacement data. The obtained results were compared with those for a commercial 316L stainless steel stent. Both tube and commercial stent samples were fully austenitic, and the as-fabricated surface finish for the tube was much rougher than the stent. Microstructural characterization revealed that the tube had a columnar and coarse grain microstructure, compared to equiaxed grains in the commercial stent. Berkovich nanoindentation suggested an effect for the grain orientation on the hardness and Young’s modulus. The stress–strain curves and the indentation yield strength for the tube and stent were similar. The work is an important step toward AM of patient-specific stents.

Bibliographic note

Funding Information: We acknowledge the support from the EPSRC UK (Grant Number: EP/R001650/1; Title: Smart peripheral stents for the lower extremity–design, manufacturing and evaluation). The authors acknowledge the use of facilities within the Loughborough Materials Characterisation Centre of Loughborough University. Research data for this paper are available upon request to the projects’ principal investigator Professor Liguo Zhao at Loughborough University, UK (email: L.Zhao@Lboro.ac.uk). Publisher Copyright: © 2020, The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

Details

Original languageEnglish
JournalJournal of Materials Engineering and Performance
Publication statusAccepted/In press - 2021

Keywords

  • additive manufacturing, material microstructure, mechanical properties, metallic stents, nanoindentation, selective laser melting