Alumina-forming stainless steels in liquid lead and lead-bismuth eutectic
Time: Fri 2024-12-20 10.00
Location: F3 (Flodis), Lindstedtsvägen 26 & 28, Stockholm
Video link: https://kth-se.zoom.us/j/67833310452
Language: English
Subject area: Chemistry
Doctoral student: Christopher Petersson , Yt- och korrosionsvetenskap, Kärnvetenskap och kärnteknik
Opponent: Doktor Joris Van den Bosch, Belgian Nuclear Research Centre (SCK CEN), Belgien
Supervisor: Professor Rachel Pettersson, Yt- och korrosionsvetenskap; Doktor Peter Szakalos, Kärnvetenskap och kärnteknik, Yt- och korrosionsvetenskap, Jernkontoret (The Swedish Steel 'Producers' Association); Mats Lundberg, Alleima AB
QC 2024-11-19
Abstract
This work focuses on mechanical properties, susceptibility to liquid metal embrittlement (LME), and erosion-corrosion of alumina-forming steels using a Slow Strain rate testing rig (SSRT) and an Erosion Corrosion-rig (ECO) developed at KTH. The environments investigatedare liquid lead and lead-bismuth eutectic (LBE) intended for use in high-temperature energy applications such as generation IV nuclear power or fast nuclear reactors. The lead and LBEare intended to serve as a heat-transfer medium in the reactor. These higher temperature sand harsher environments put new demands on the construction materials used. The work has been mainly focused on mechanical testing using slow strain rate testing (SSRT) to evaluate susceptibility to LME. However, since other properties, such as oxidation, are intimately intertwined with the LME phenomenon, liquid metal corrosion and erosion are also part of this work. The tested materials include a ferritic FeCrAl steel designated EF100, three alumina-forming austenitic (AFA) steels and an alumina-forming martensitic (AFM) steel. The temperature range of the tests in liquid Pb was 340-600 °C and in LBE 140-600 °C with varying oxygen activities. Microstructure analyses were performed to underst and theunderlying mechanisms responsible for LME. The ferritic EF100 showed excellent performance in liquid Pb, exhibiting no signs of being affected by LME. However, in liquid LBE, it was severely affected by LME. The effects of Bi were investigated by stepwise additions of Bi to pure Pb, and signs of LME were observed already at 3-5 wt.% Bi. The AFM alloy suffered from severe LME in both liquid Pb and LBE, starting at the melting point of the liquid metal. The AFA alloys showed no signs of LME in either liquid Pb or LBE in the temperature range of 350-550 °C and 140-550 °C, respectively. However, above 570 °C, signs of LME were observed in all three alloys. Erosion-corrosion was found to have the largest impact on steels containing Ni (e.g., 316L and AFA 3), while the steels with a higher hardness and that were able to form a protective oxide scale remained largely unaffected (Kanthal AF, APMT, EF100, Alkrothal 14, coated 316L PC/DG, and AFM).