Next Article in Journal
Micro-Structure and Mechanical Properties of 2A97 Al-Li Alloy Cast by Low-Frequency Electromagnetic Casting
Previous Article in Journal
Effect of Frictional Conditions on the Generation of Fine Grain Layers in Drawing of Thin Steel Wires
Previous Article in Special Issue
Dynamic Mechanical Behavior and Microstructure Evolution of an Extruded 6013-T4 Alloy at Elevated Temperatures
Open AccessFeature PaperArticle

Comparing In Situ DIC Results from an Etched Surface with a Gold Speckled Surface

1,2,*,†, 2,3,†, 2,3,† and 1,2,†
Department of Materials Science and Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway
Centre for Advanced Structural Analysis (CASA), NTNU, NO-7491 Trondheim, Norway
Structural Impact Laboratory (SIMLab), Department of Structural Engineering, NTNU, NO-7491 Trondheim, Norway
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Metals 2019, 9(8), 820;
Received: 22 June 2019 / Revised: 16 July 2019 / Accepted: 22 July 2019 / Published: 25 July 2019
(This article belongs to the Special Issue Quasi-Static and Dynamic Testing of Metallic Materials)
PDF [33642 KB, uploaded 25 July 2019]


A ferrite-pearlite two-phase steel was investigated using in situ scanning electron microscope (SEM) tensile testing combined with digital image correlation (DIC). Two different speckled patterns were used and compared. The first pattern was achieved by etching a polished surface in order to reveal the microstructural features. Second, a gold speckled pattern was obtained. Here, a continuous layer of gold was applied to a polished surface. This continuous layer was remodeled into gold nanoparticles by keeping the specimen at 180 °C for 96 h with an Ar/Styrene mixture flowing across the specimen surface. The result is randomly distributed gold nanoparticles on the surface. These particles and the etched microstructure were then used by the DIC software to correlate an image series to obtain the local strain field of the material. The differences between the two techniques are numerous. Considering the etched surface, most microstructural features were grain boundaries and pearlite lamellas. As a consequence, large areas within grains did not provide sufficient contrast for DIC, thus restricting maximum resolution. However, the technique is fast and does not expose the material to any elevated temperatures. In contrast, the gold remodeling method provides a finely dispersed gold speckle pattern on the surface, giving excellent contrast across the recorded area. DIC with gold particles achieved a spatial resolution of 0.096 µm, compared to 2.24 µm in the DIC for the etched specimen. As a result, DIC with gold speckles can resolve slip lines. Conversely, DIC with etched microstructure resolves local strains on grain level. However, it is less cumbersome and faster to perform the test on the etched specimen. View Full-Text
Keywords: digital image correlation; in situ testing; scanning electron microscopy; strain localization digital image correlation; in situ testing; scanning electron microscopy; strain localization

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Paulsen, C.O.; Fagerholt, E.; Børvik, T.; Westermann, I. Comparing In Situ DIC Results from an Etched Surface with a Gold Speckled Surface. Metals 2019, 9, 820.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Metals EISSN 2075-4701 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top