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- Vortrag (23)
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- Corrosion (11)
- ISO 15630-3 (10)
- Spannstahl (9)
- Spannungsrisskorrosion (9)
- Korrosion (8)
- Prestressing Steels (7)
- Stress corrosion cracking (7)
- Prestressing steels (6)
- Hydrogen (5)
- Hydrogen-induced Stress Corrosion Cracking (5)
Organisationseinheit der BAM
Tests for assessing prestressing steels' susceptibility to hydrogen‐induced stress corrosion cracking are essential for approvals, in‐house monitoring, and third‐party material testing. According to ISO 15630‐3, the time to brittle fracture by constant load under corrosive conditions in thiocyanate test solutions (A or B) at 50°C is measured. In the literature, a high scattering in stress corrosion tests is reported, which questions the integrity of the test procedure. This paper shows the results of studies about the influence of solution composition on hydrogen charging in electrochemical and permeation measurements. Electrochemical experiments show that polished steel surfaces without common drawing layers have more consistent free corrosion currents, polarization resistances, and B‐values in solution A with low scattering compared to the solution B experiments. The influence of temperature at 50°C and an ambient temperature of 22°C was also tested.
Der Beitrag zeigt die Mechanismen, Voraussetzungen und Einflussgrößen der Bimetallkorrosion wichtiger Werkstoffe im Kontakt mit nichtrostenden Stahl anhand von verschiedenen Beispielen. Darüber hinaus wird das Korrosionsverhalten von nichtrostenden Stahl im Kontakt mit Holz als saurer Baustoff und mit Beton als alkalischer Baustoff beschrieben.
For prestressing steel’s factory production control, approvals, and continuous surveillance in Germany, a susceptibility test against hydrogen-induced stress corrosion cracking is performed. The measured time to fracture results (in hours) must be reproducible and reliable in the test. ISO 15630-3 gives currently unpersuasive and diverging results using a free corrosion approach for hydrogen charging. A newly developed test method uses cathodic polarization for defined hydrogen charging instead of an uncontrolled and variable electron supply by metal dissolution during free corrosion. With this new test method, a reliable differentiation is possible between highly susceptible-known “old-type” quenched and tempered prestressing steel, i.e., Neptun, Hennigsdorfer, Sigma, and currently approved cold-drawn wires St 1470/1670 (CDS-1670) and St 1570/1770 (CDS-1770). The reproducibility of the new test method was evaluated in a round-robin test with eight attended testing institutes on a St 1470/1670 (CDS-1670) batch.
This presentation at CONSEC24 gives an overview of the new stress corrosion cracking test for prestressing steel wires using cathodic polarisation. Design of Experiments (DOE) studies on prestressing levels and cathodic current density on time to fracture will be presented, testing different prestressing steels. Finally, an experimental solution for testing strands is proposed.
The BAM developed a new test method for assessing susceptibility to hydrogen-induced stress corrosion cracking (HiSCC) of prestressed steel, especially for wires. The setup contains polished specimens pre-stressed to a constant 80% Rm stress level. The specimens are constantly charged with hydrogen during the test by an electrochemically applied cathodic current density. The time to brittle fracture is measured.
The new test method can provide a sensitive separation between different kinds of susceptible prestressed steel wires by fracture times. This enables further parameter studies with load level and cathodic current density variation. Therefore, known as high-susceptible quenched and tempered prestressing wires of “old-type” (without alloying Cr and manufactured before 1965), Hennigsdorfer and Neptun and currently approved cold-drawn wires were tested.
A design of experiments (DOE) statistical model of time to fracture was calculated for the three wires. A significant susceptibility change appears in specific load level ranges, this is the contribution of this EUROCORR lecture.
The poster contributes to the assessment of corrosivity in offshore atmospheric exposure environments according to DIN EN ISO 9224 for unalloyed steel, zinc, copper and aluminium. Studies on corrosivity from an offshore wind turbine and a distribution platform in the North Sea are presented. The results show that the corrosivity of unalloyed steel is mostly dependent on the altitude of exposure and whether it is inside or outside.
This invited talk at the Young EFC Meeting (European Federation of Corrosion) was about the new network, founded in Germany in 2023, specialising in corrosion and corrosion protection. The network is called "die junge gfkorr" and has the following aims: (i) Initiation of in-person events with excursions and a networking atmosphere. (ii) Members come from both industry and academia can find similarities in each other's work (iii) Get to know each other and learn from each other, and (iv) Members benefit long-term by using the network throughout their careers and for future collaboration on daily business and research projects.
This talk addresses the issue of hydrogen-induced stress corrosion cracking (HiSCC) in prestressing steels. The susceptibility to HiSCC is evaluated using free corrosion tests according to ISO 15630-3, which is problematic as it produces unreliable results. However, a new test method shows promising reproducible results and reveals that Cr-alloyed quenched and tempered (Q&T) steels are as sensitive to HiSCC as unalloyed Q&T steels.
Ziele der Jungen GfKORR
(2024)
Die Junge GfKORR soll ein attraktives Angebot für junge Leute sein, sich fachübergreifend zu vernetzen und einen Einstieg in Querschnittsthemen bieten. Sowohl der Korrosionsschutz zum Zwecke der Nachhaltigkeit und Sicherheit von Bauwerken als auch der Korrosionsschutz bei Energie- und Mobilitätssystemen soll in zukünftigen Veranstaltungen übergreifend betrachtet werden. Dabei wollen wir den fachlichen und informativen Input aus den Arbeitskreisen der GfKORR bei unseren Seminaren suchen. In diesem 1. Netzwerk- und Arbeitstreffen wurde die Fahrtrichtung der Jungen GfKORR genauer abgesteckt und es hat sich eine Leitungsebene gefunden. Weiter wollen wir ab 2024 interessante Präsenzveranstaltungen mit Exkursionen anbieten.
The exposé is a mandatory part of the doctoral process at TUM and should outline the topic of the thesis and the future research focus. Ideally, the exposé forms the basis for the subsequent dissertation. The candidates topic is about hydrogen-induced stress corrosion cracking (HiSCC) of prestressing steels, which is a significant concern in civil engineering, particularly for prestressed concrete roofs and bridges. The susceptibility of prestressing steels to HiSCC is mainly influenced by manufacturing processes and the chemical composition, while the ability to hydrogen charging is influenced by the environmental and surface conditions. To know about the real nature of susceptibility of the prestressing steel might be an important puzzle piece to contribute to safe prestressed concrete structures in the future. The material susceptibility of prestressing steels toward HiSCC is a topic which must be studied independently of the environmental conditions. This cumulative dissertation will focus on the most important aspects of material properties that play a role in the initiation point
of HiSCC.
