Issue 74

A. Tumanov, Frattura ed Integrità Strutturale, 74 (2025) 20-30 DOI: 10.3221/IGF-ESIS.74.02

Modeling of the transition from transgranular to intergranular fracture at elevated temperatures in EI698 nickel alloy

Andrey Tumanov FRC Kazan Scientific Center of Russian Academy of Sciences, Russia tumanoff@rambler.ru, https://orcid.org/0000-0002-4969-3464

Citation: Tumanov, A. V., Modeling of the transition from transgranular to intergranular fracture at elevated temperatures in EI698 nickel alloy, Fracture and Structural integrity, 74 (2025) 20-30.

Received: 27.05.2025 Accepted: 29.06.2025 Published: 03.07.2025 Issue: 10.2025

Copyright: © 2025 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.

K EYWORDS . Granular structure, Phase field fracture, Transgranular fracture, Intergranular fracture.

I NTRODUCTION

ickel alloy EI698 is utilized in the fabrication of gas turbine blades, disk components, deflectors, and other engine parts that operate at temperatures reaching up to 800°C. This alloy belongs to the family of heat- and corrosion-resistant nickel-based alloys. While it lacks a direct analogue in the international market, its composition and mechanical properties are comparable to UNS07750 (USA) and NCF750 (Japan). Components manufactured from such alloys typically function under conditions of significant variable mechanical and thermal loads. Understanding the mechanisms of damage accumulation in nickel-based alloys is essential for predicting the durability of highly loaded structural elements, where damage tolerance design prevails. The failure resistance of a material and its capacity for plastic deformation are fundamentally based on dislocation transfer mechanisms. Modern theories for fracture prediction in nickel-based alloys comprise complex compilations of models that account for microstructure, temperature, loading conditions, fatigue effects, creep, and aggressive environments [1–3]. Studying the deformation behavior of nickel-based alloys, researchers found that as the temperature increases, the failure mechanisms changes from predominantly transgranular to intergranular cracking [4–6]. Researchers attribute this to changes in the mechanism of dislocation transfer across the grain boundary. The molecular dynamics methods can be considered as most detailed and N

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