Anisotropic tensile and actuation properties of NiTi fabricated with selective laser melting

Narges Shayesteh Moghaddam, Sayed Ehsan Saghaian, Amirhesam Amerinatanzi, Hamdy Ibrahim, Peizhen Li, Guher P. Toker, Haluk E. Karaca, Mohammad Elahinia

Research output: Contribution to journalArticlepeer-review

102 Scopus citations

Abstract

This study evaluates the anisotropic tensile properties of Ni50.1Ti49.9 (in at%) components fabricated using an additive manufacturing (AM) process of selective laser melting (SLM). Dog-bone shaped tensile specimens were fabricated in three orthogonal building orientations (i.e., horizontal, edge, and vertical) with two different scanning strategies (i.e., alternating x/y and alternating in ± 45° to the x-axis). Next, the samples were subjected to tensile testing until failure, shape memory effect tests and thermal cycling under constant tensile stresses up to 500 MPa. Their failure surfaces were analyzed for possible microstructural defects. It was revealed that the build orientation and scanning strategy affect the texture/microstructure, and hence the failure stress, ductility, shape memory effect, and functional stability. Samples fabricated in the horizontal orientation with alternating x/y scanning strategy had the highest ultimate tensile strength (606 MPa) and elongation (6.8%) with the strain recovery of 3.54% after 4 shape memory effect cycles. At stress levels less than or equal to 200 MPa, these samples had the actuation strain greater than 3.8% without accumulation of noticeable residual strain. It was observed that the scanning strategy of alternating in ± 45° result in degraded mechanical and shape memory response, particularly in horizontal and edge samples.

Original languageEnglish
Pages (from-to)220-230
Number of pages11
JournalMaterials Science and Engineering A
Volume724
DOIs
StatePublished - May 2 2018

Bibliographical note

Funding Information:
This study received partial financial support from the project "Adaptive bio-inspired aerospace structures actuated by shape memory alloys" by the Ohio Federal Research Network (OFRN) through Grant WSARC-1077-400 .

Publisher Copyright:
© 2018 Elsevier B.V.

Keywords

  • Additive manufacturing
  • NiTi
  • Processing direction
  • Selective laser melting
  • Shape memory alloy
  • Tensile properties

ASJC Scopus subject areas

  • Materials Science (all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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