On the Applicability of the Master Curve Concept for Ductile Cast Iron based on experimental and microstructural results

  • Based on the state-of-the-art research and regulations, the application of the fracture mechanics master curve (MC) concept to ferritic ductile cast iron (DCI) is being investigated in a joint research project (MCGUSS) between BAM Berlin and MPA Stuttgart. The experimental program included a basic mechanical-technological material characterization consisting of tensile, Charpy and Pellini tests. To determine the relevant loading rate for brittle fracture, instrumented C(T)25 fracture tests were performed at different loading rates at a temperature of -40°C. The relevant loading rates are 5x10^3 MPa√ms-1 and 5x10^4 MPa√ms-1. A series of dynamic fracture tests consisting of DC(T)9, C(T)25 and C(T)50 specimens were performed at MPA. BAM performed corresponding test series with SE(B)10 (pre-cracked Charpy), SE(B)25 and SE(B)140 specimens to cover the influence of specimen geometry. In total about 400 tests were performed during this project. The experimental program is complemented byBased on the state-of-the-art research and regulations, the application of the fracture mechanics master curve (MC) concept to ferritic ductile cast iron (DCI) is being investigated in a joint research project (MCGUSS) between BAM Berlin and MPA Stuttgart. The experimental program included a basic mechanical-technological material characterization consisting of tensile, Charpy and Pellini tests. To determine the relevant loading rate for brittle fracture, instrumented C(T)25 fracture tests were performed at different loading rates at a temperature of -40°C. The relevant loading rates are 5x10^3 MPa√ms-1 and 5x10^4 MPa√ms-1. A series of dynamic fracture tests consisting of DC(T)9, C(T)25 and C(T)50 specimens were performed at MPA. BAM performed corresponding test series with SE(B)10 (pre-cracked Charpy), SE(B)25 and SE(B)140 specimens to cover the influence of specimen geometry. In total about 400 tests were performed during this project. The experimental program is complemented by extensive fractographic and metallographic studies using scanning electron microscopy and cross sectioning, as well as characterizations of the chemical composition of the material and of the morphology and distribution of the graphite particles. KJcd values were evaluated for all C(T)25 specimens and some C(T)50 and DC(T)9 specimens. First Master Curve analyses suggest that modifications on the Master Curve setup will be neccessary for instance changing the coefficient from 0.019 to 0.045. This modification requires further validation and is only one of many possible modifications. The SE(B) specimen results clearly show an inverse size effect. This does not correlate with the weakest link effect attributed to steels which dictates lower fracture toughness values for larger specimens. Due to the presence of graphite particles in the DCI material, it is currently assumed that these particles play a significant role in the failure behavior of DCI materials and the following fracture mechanism is proposed: “Specimen size-dependent arrest of local brittle fracures before global brittle failure by weakest link”.zeige mehrzeige weniger

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Autor*innen:Marcel Holzwarth, Wolfram BaerORCiD, Uwe Mayer, Stefan Weihe
Dokumenttyp:Beitrag zu einem Tagungsband
Veröffentlichungsform:Graue Literatur
Sprache:Englisch
Titel des übergeordneten Werkes (Englisch):Proceedings of 9th SEDS Workshop: Safety of Extended Dry Storage
Jahr der Erstveröffentlichung:2025
Organisationseinheit der BAM:9 Komponentensicherheit
9 Komponentensicherheit / 9.6 Additive Fertigung metallischer Komponenten
Herausgeber (Institution):Gesellschaft für Reaktorsicherheit (GRS)
Erste Seite:1
Letzte Seite:3
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Angewandte Physik
Freie Schlagwörter:Ductile cast iron; Dynamic fracture toughness; Master curve; Safety assessment; Statistics
Themenfelder/Aktivitätsfelder der BAM:Energie
Energie / Kerntechnische Entsorgung
Veranstaltung:9th SEDS Workshop: Safety of Extended Dry Storage, 20.-22. Mai 2025
Veranstaltungsort:Garching, Germany
Beginndatum der Veranstaltung:20.05.2025
Enddatum der Veranstaltung:22.05.2025
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:02.07.2025
Referierte Publikation:Nein
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