Issue 78

A. A. Frantsuzov et alii, Fracture and Structural Integrity, 78 (2026) 474-488; DOI: 10.3221/IGF-ESIS.78.27

Comparative analysis of prior austenite grain size (PAGS) determination in high grade pipeline steels

Alexander A. Frantsuzov*, Artyom Dong, Konstantin S. Korobov HSM lab, Center for Engineering Systems and Sciences, Skoltech, Moscow, Russia alexander.frantuzov@skoltech.ru, http://orcid.org/0009-0000-3787-2839 artem.dong@skoltech.ru, http://orcid.org/0009-0003-5186-6605 konstantin.korobov@skoltech.ru, http://orcid.org/0009-0001-5663-2758 Eugene S. Statnik, Alexey I. Salimon, Alexander M. Korsunsky HSM lab, Center for Engineering Systems and Sciences, Skoltech, Moscow, Russia CASM&T, Moscow Aviation Institute, Moscow, Russia Laboratory of Accelerated Particles “LUCh”, NUST MISIS, Moscow, Russia

eugene.statnik@skoltech.ru, http://orcid.org/0000-0002-1105-9206 a.salimon@skoltech.ru, http://orcid.org/0000-0002-9048-8083 a.korsunsky@skoltech.ru, http://orcid.org/0000-0002-3558-5198

Citation: Frantsuzov, A. A., Dong, A., Korobov, K. S., Statnik, E. S., Salimon, A. I., Korsunsky, A. M., Comparative analysis of prior austenite grain size (PAGS) determination in high grade pipeline steels, Fracture and Structural Integrity, 78 (2026) 474-488.

A BSTRACT . In high ‑ grade casing steels operated in H 2 S-saturated environments, the sulfide stress cracking (SSC) is a serious concern. SSC is driven by hydrogen-coupled mechanisms that are sensitive to the microstructure formed from primary austenite. Even though the prior austenite grains (PAG) cannot be directly observed in the final martensitic / bainitic microstructure and its quantification in microalloyed fine grained steels is complicated, there are several ways of obtaining such information. This paper compares four approaches to the estimation of prior austenite grain size (PAGS) in high-grade pipeline steels: direct measurement of grains from metallographic images after selective grain boundary etching; the lineal intercept method with chord statistics; comparison with standard plates; and the reconstruction of the parent (austenitic) microstructure based on the martensite EBSD maps using reconstruction algorithms that implement the refinement of the orientation ratio and clustering of variants in the MTEX package. The results demonstrate that even without real PAG observed by an operator, EBSD-based parent microstructure reconstruction provides several advantages over optical PAGS evaluation methods. In particular, this approach removes the dependence on the quality of selective grain-boundary etching, reduces operator related subjectivity in grain selection, and improves the statistical representation of fine grains that may be underestimated during manual optical measurements.

Received: 05.08.2026 Accepted: 17.09.2026 Published: 20.09.2026 Issue: 10.2026

Copyright: © 2026 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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