Issue 51

D. Fernandino et alii, Frattura ed Integrità Strutturale, 51 (2020) 477-485; DOI: 10.3221/IGF-ESIS.51.36 477 Microstructural damage evaluation of ferritic-ausferritic spheroidal graphite cast iron D. O. Fernandino, N. Tenaglia, R. E. Boeri INTEMA, Universidad Nacional de Mar del Plata-CONICET, Av. Colón 10850, Mar del Plata, B7606BVZ, Argentina dfernandino@fi.mdp.edu.ar , https://orcid.org/0000-0003-4647-2663 ntenaglia@fi.mdp.edu.ar , http://orcid.org/0000-0001-6372-88816372-8881 boeri@fi.mdp.edu.ar , http://orcid.org/0000-0001-7083-579X579X V. Di Cocco, C. Bellini, F. Iacoviello Università di Cassino e del Lazio Meridionale, DiCeM, via G. Di Biasio 43, 03043 Cassino (FR), Italy. vittorio.dicocco@unicas.it , http://orcid.org/0000-0002-1668-3729 costanzo.bellini@unicas.it, http://orcid.org/0000-0003-4804-6588 francesco.iacoviello@unicas.it, http://orcid.org/0000-0002-9382-6092 A BSTRACT . The goal of this work is to improve the understanding of the relation between the microstructural characteristics of Intercritical Austempered Ductile Cast Iron (IADI) and the damage micromechanisms observed during its tensile loading. The experimental methodology involves heat treatments to obtain IADI and the assessment of the damage mechanisms (sequence and occurrence) during step by step tensile testing. The damage evaluation was carried out by observing the surface of the tensile test specimen with optical and scanning electron microscopy. The results show that small cracks start forming soon after the yield stress is surpassed. The crack initiation is preferentially located at matrix-nodule interface. As loading increases, cracks also develop at the ferritic grain boundaries and the ausferritic/ferritic interfaces. Consequently, at higher strain values, a competition between the plastic deformation on internodular zones and crack propagation along ausferritic phase is observed. Finally, the final fracture is produced by the propagation of cracks across the internodular ligaments and through the ausferritic/ferritic interface that later coalesce into a single dominant crack leading to the material failure. K EYWORDS . Spheroidal Graphite Cast Iron; Fracture mechanisms; Intercritical ADI; Tensile test. Citation: Fernandino, D. O., Di Cocco, V., Tenaglia, N., Bellini, C., Iacoviello, F., Boeri, R. E. Microstructural damage evaluation of ferritic-ausferritic spheroidal graphite cast iron, Frattura ed Integrità Strutturale, 51 (2020) 477-485. Received: 10.11.2019 Accepted: 12.12.2019 Published: 01.01.2020 Copyright: © 2020 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.