Abstract

It is often reported that, to successfully join NiTi shape memory alloys, fusion-based processes with reduced thermal affected regions (as in laser welding) are required. This paper describes an experimental study performed on the tungsten inert gas (TIG) welding of 1.5 mm thick plates of Ni-rich NiTi. The functional behavior of the joints was assessed. The superelasticity was analyzed by cycling tests at maximum imposed strains of 4, 8 and 12% and for a total of 600 cycles, without rupture. The superelastic plateau was observed, in the stress-strain curves, 30 MPa below that of the base material. Shape-memory effect was evidenced by bending tests with full recovery of the initial shape of the welded joints. In parallel, uniaxial tensile tests of the joints showed a tensile strength of 700 MPa and an elongation to rupture of 20%. The elongation is the highest reported for fusion-welding of NiTi, including laser welding. These results can be of great interest for the wide-spread inclusion of NiTi in complex shaped components requiring welding, since TIG is not an expensive process and is simple to operate and implement in industrial environments.

Original languageEnglish
Article number03LT01
Number of pages7
JournalSmart Materials & Structures
Volume25
Issue number3
DOIs
Publication statusPublished - Mar 2016

Keywords

  • NiTi
  • welding
  • TIG
  • superelasticity
  • mechanical cycling
  • shape-memory effect
  • SHAPE-MEMORY ALLOYS
  • WELDED SUPERELASTIC NITI
  • MARTENSITIC-TRANSFORMATION
  • PHASE-TRANSFORMATION
  • MECHANICAL-BEHAVIOR
  • WIRES
  • DEFORMATION
  • CRYSTALS
  • TENSION
  • STRAIN

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