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Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel

Mirshekari, G. R ; Sharif University of Technology | 2013

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  1. Type of Document: Article
  2. DOI: 10.1016/j.optlastec.2013.05.014
  3. Publisher: 2013
  4. Abstract:
  5. The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the laser joints were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), Vickers microhardness (HV0.2) and tensile testing techniques. The results showed that the NiTi-NiTi laser joint reached about 63% of the ultimate tensile strength of the as-received NiTi wire (i.e. 835 MPa) with rupture strain of about 16%. This joint also enabled the possibility to benefit from the pseudo-elastic properties of the NiTi component. However, tensile strength and ductility decreased significantly after dissimilar laser welding of NiTi to stainless steel due to the formation of brittle intermetallic compounds in the weld zone during laser welding. Therefore, a suitable modification process is required for improvement of the joint properties of the dissimilar welded wires
  6. Keywords:
  7. Laser welding ; AISI-304 stainless steel ; Energy dispersive spectroscopies (EDS) ; NiTi ; NiTi shape memory alloys ; Strength and ductilities ; Ultimate tensile strength ; Vickers microhardness ; X-ray diffraction analyses (XRD) ; Austenitic stainless steel ; Biocompatibility ; Biomedical equipment ; Elasticity ; Energy dispersive spectroscopy ; Joining ; Optical microscopy ; Scanning electron microscopy ; Shape memory effect ; Tensile strength ; Tensile testing ; Testing ; Wire ; X ray diffraction analysis ; Laser beam welding
  8. Source: Optics and Laser Technology ; Volume 54 , 2013 , Pages 151-158 ; 00303992 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0030399213001898