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Fracture of notched round-bar NiTi-Specimens

Fracture of notched round-bar NiTi-Specimens

Category
Journal publication
Abstract
In this work fractography has been used to characterize the fracture surfaces of superelastic, notchedround-barNiTi-specimens. Several fractography studies have been performed for conventional materials, but only few studies have been conducted on NiTi-alloys. The aim of this work is to investigate the effect of semi-circular notches on the fracture behavior of NiTi. The main results indicate that the fracture process is a mixture of cleavage and micro-void coalescence, and that decreasing the notch-radius leads to a loss of ductility which manifests in a reduced fracture strain. Within the range of notches studied in this work, we can observe a transition from high scatter to low scatter in the fracture strain when reducing the notch-radius. By combining fractography studies, finite element analyses and the Rice-Tracey void-growth model, it is argued that fracture is most likely initiated close to the notch for all notch-radii studied herein, and that cleavage or quasi cleavage is the dominating fracture mechanism.
Language
English
Author(s)
Affiliation
  • Norwegian University of Science and Technology
  • Shanghai Jiao Tong University
  • SINTEF Industry / Metal Production and Processing
Year
2012
Published in
Engineering Fracture Mechanics
ISSN
0013-7944
Volume
84
Issue
April