Effect of post-weld heat-treatment on the stress-corrosion cracking behaviour of laser-welded shape memory NiTi wires in Hanks' solution

Chi Wai Chan, Hau Chung Man

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

In this study, the stress-corrosion cracking (SCC) behaviour of laser-welded NiTi wires before and after post-weld heat-treatment (PWHT) was investigated. The samples were subjected to slow strain rate testing (SSRT) under tensile loading in Hanks' solution at 37.5 °C (or 310.5 K) at a constant anodic potential (200 mVSCE). The current density of the samples during the SSRT was captured by a potentiostat, and used as an indicator to determine the susceptibility to SCC. Fractography was analyzed using scanning-electron microscopy (SEM). The experimental results showed that the laser-welded sample after PWHT was immune to the SCC as evidenced by the stable current density throughout the SSRT. This is attributed to the precipitation of fine and coherent nano-sized Ni4Ti3 precipitates in the welded regions (weld zone, WZ and heat-affected zone, HAZ) after PWHT, resulting in (i) enrichment of TiO2 content in the passive film and (ii) higher resistance against the local plastic deformation in the welded regions.
Original languageEnglish
Pages (from-to)276-280
Number of pages5
JournalNanoscience and Nanotechnology Letters
Volume7
Issue number3
DOIs
Publication statusPublished - 1 Jan 2015

Keywords

  • Laser welding
  • Post-weld heat-treatment
  • Shape memory alloys
  • Stress corrosion cracking

ASJC Scopus subject areas

  • Materials Science(all)

Cite this