Issue 50

Ch. Apostolopoulos et alii, Frattura ed Integrità Strutturale, 50 (2019) 548-559; DOI: 10.3221/IGF-ESIS.50.46 548 Focused on the research activities of the Greek Society of Experimental Mechanics of Materials Comparison of the mechanical response of B400c and B450c dual phase steel bar categories, in long terms Charis Apostolopoulos, Argyro Drakakaki University of Patras, Greece charrisa@upatras.gr , https://orcid.org/0000-0001-7414-8444 drakakaki@upatras.gr, https://orcid.org/0000-0002-0448-2719 Alkiviadis Apostolopoulos University of Ioannina, Greece prothesis.apostolopoulos@gmail.com Konstantinos Koulouris University of Patras, Greece kkoulouris@upnet.gr , https://orcid.org/0000-0003-2449-2751 A BSTRACT . In this work, the effects of chloride-induced corrosion on temp- core B400c and B450c steel grades are evaluated, in terms of corrosion resis- tance and mechanical characteristics, after the performance of Tensile and Low Cycle Fatigue Tests. Both steel categories, characterized by high strength and high ductility, have been used in existing structures, indicating that they demonstrate different performance against the ascribed corrosion environ- ments. B450c steel grade seems to preserve higher energy reserves, ensuring higher expectancy to the corresponding reinforced concrete structures. Ad- ditionally, due to buckling and buckling reversal, both steel grades dem- onstrate limited ductility at 4%. Finally, when cyclically stresses occur, crack nucleation is taking place, at the areas where sulphides, FeS and MnS can be found, leading to sub-surface crack propagation, interacting with external pits. K EYWORDS . Corrosion; Dual phase steel bars; B400c; B450c; Mechanical behaviour; Degradation of mechanical performance. Citation: Apostolopoulos, Ch., Drakakaki, Arg., Apostolopoulos, Alk., Koulouris, K., Com- parison of the mechanical response of B400c and B450c dual phase steel bar categories, in long terms, Frattura ed Integrità Strutturale, 50 (2019) 548-559. Received: 28.01.2019 Accepted: 29.05.2019 Published: 01.10.2019 Copyright: © 2019 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. I NTRODUCTION einforced concrete has been the most popular material for more than a century. During these years, in an effort to upgrade the reliability of the structures, various steel grades, characterized by high strength and ductility, have been used as reinforcement. However, there is a plethora of degradation factors that may affect the performance R