University of Oulu

Afkhami, S., Lipiäinen, K., Javaheri, V., Amraei, M., Salminen, A., & Björk, T. (2023). Effects of notch-load-defect interactions on the local stress-strain fields and strain hardening of additively manufactured 18Ni300 steel. In Materials Science and Engineering: A (Vol. 876, p. 145165). Elsevier BV.

Effects of notch-load-defect interactions on the local stress-strain fields and strain hardening of additively manufactured 18Ni300 steel

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Author: Afkhami, Shahriar1,2; Lipiäinen, Kalle1; Javaheri, Vahid3;
Organizations: 1Laboratory of Steel Structures, LUT University, Lappeenranta, Finland
2Laboratory of Laser Processing & Additive Manufacturing, LUT University, Lappeenranta, Finland
3Materials and Mechanical Engineering, University of Oulu, Oulu, Finland
4Department of Mechanical and Materials Engineering, University of Turku, Turku, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 10.4 MB)
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Language: English
Published: Elsevier, 2023
Publish Date: 2023-08-25


This study investigates the influence of geometrical notches on the local (true) stress-strain curves, deformations, and strain hardening behavior of maraging tool steel 18Ni300 processed via the laser powder-bed fusion method as an additive manufacturing approach. For this purpose, five types of specimens with different notch designs were manufactured; these samples were considered to study the effects of the notch stress concentration factor and the notch position on the material's mechanical response against the applied external load. Accordingly, using the digital image correlation technique, true stress-logarithmic strain curves were plotted and compared for various points in the vicinities of the notches while the specimens were subjected to quasi-static tensile loads. Further, the strain (work) hardening behavior of the material at each point was then evaluated and compared with other points by plotting their strain hardening diagrams from the first derivative of the stress-strain curves. The results showed that the strain hardening of the samples increased with the stress concentration factor (notch sharpness) while its ductility decreased accordingly. Furthermore, notch location and shape also showed determining roles in defining the material behavior. Ultimately, higher stress concentrations, internal positioning, and less gradual changes in geometric features (C-shaped notches compared to V-shaped ones) can result in higher defect sensitivity, more decrease in ductility, and more likely catastrophic failures in metals processed by additive manufacturing.

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Series: Materials science & engineering. A, Structural materials: properties, microstructure and processing
ISSN: 0921-5093
ISSN-E: 1873-4936
ISSN-L: 0921-5093
Volume: 876
Article number: 145165
DOI: 10.1016/j.msea.2023.145165
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
214 Mechanical engineering
Funding: This study was carried out at LUT University as a part of the project DREAMS, funded by Business Finland.
Dataset Reference: Data will be made available on request.
Copyright information: © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (