Advances in microscale residual stress measurement using focused ion beam milling and digital image correlation

  1. A. Dorronsoro 12
  2. J.R. Páez 12
  3. J. Navarrete 12
  4. J.M. Sánchez 12
  5. J.M. Martínez-Esnaola 12
  6. J. Alkorta 12
  1. 1 CEIT-BRTA, Donostia
  2. 2 Universidad de Navarra
    info

    Universidad de Navarra

    Pamplona, España

    ROR https://ror.org/02rxc7m23

Journal:
Revista española de mecánica de la fractura

ISSN: 2792-4246

Year of publication: 2023

Issue: 5

Pages: 237-242

Type: Article

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Abstract

The presence of residual stresses can have a paramount influence on the mechanical behaviour of materials, especially under fatigue conditions. In this paper, we present a technique for measuring residual stresses, with a spatial resolution smaller than 100 microns. The technique consists of milling a slit on a sample’s surface with a focused ion beam (FIB), and on measuring the displacements caused by stress relief around the slit. For that purpose, a digital image correlation (DIC) algorithm capable of measuring sub-pixel displacements is used, and these displacements are compared to finite element simulations. Initial measurements using this technique were carried out on a hardmetal sample, where large compressive residual stresses were present due to a grinding process. In this work, the stress state of a steel sample deformed plastically on a four point bending test was characterised. Residual stresses were an order of magnitude smaller than in the previous study. Residual stresses measured using this technique were successfully compared to values obtained using the X-ray diffraction sin2 ?? technique.

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