Effect of Post-Weld Heat-Treatment on the Stress-Corrosion Cracking Behaviour of Laser-Welded Shape Memory NiTi Wires in Hanks' Solution
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.
Keywords: LASER WELDING; POST-WELD HEAT-TREATMENT; SHAPE MEMORY ALLOYS; STRESS CORROSION CRACKING
Document Type: Short Communication
Publication date: 01 March 2015
- Nanoscience and Nanotechnology Letters (NNL) is a multidisciplinary peer-reviewed journal consolidating nanoscale research activities in all disciplines of science, engineering and medicine into a single and unique reference source. NNL provides the means for scientists, engineers, medical experts and technocrats to publish original short research articles as communications/letters of important new scientific and technological findings, encompassing the fundamental and applied research in all disciplines of the physical sciences, engineering and medicine.
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