Corrosion of structural metallic materials in a seasonal thermal energy storage environment
Kaimio, Elli (2025-07-03)
Corrosion of structural metallic materials in a seasonal thermal energy storage environment
(03.07.2025)
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
suljettu
Julkaisun pysyvä osoite on:
https://urn.fi/URN:NBN:fi-fe2025073080213
https://urn.fi/URN:NBN:fi-fe2025073080213
Tiivistelmä
In the northern hemisphere, a common challenge in the utilization of renewable energy sources is their seasonality in production. One solution for the mismatch between the highest energy production during summer and the highest energy need during winter is seasonal thermal energy storages. A new energy storage is being built to Vantaa, Finland, by Vantaa Energy. In order to ensure the durability, reliability and profitability of the storage, the structural materials need to endure aggressive environment and high pressure and temperature.
In this thesis, the corrosion resistance of three structural metallic material candidates was studied in simulated conditions of the energy storage. The used materials were stainless steel 316L, stainless steel 904L and super duplex 1.4410, and they were tested in three different environments during a month-long immersion test. Each environment contained electrochemical, weight loss and welded samples of each material, to study general and localized corrosion of both, base and welded materials. General corrosion rate was determined from the electrochemical samples with two different techniques: linear polarization resistance and electrochemical impedance spectroscopy. Scanning electron microscopy and energy dispersive x-ray spectroscopy were used to study the surfaces and characterize the oxide layer of the samples after the immersion test. The samples were also visually inspected after the test to evaluate their tendency for localized corrosion.
In the experiment, the first results for the performance of the materials under the specific environmental conditions in question were obtained. Based on the results, no significant differences could be seen in the feasibility of the different materials. The used measuring techniques were capable of producing reliable and reproducible results, but also some unexpected results were obtained. Therefore, in order to draw clear conclusions for the order of the corrosion resistance of the materials, more measurements need to be performed, and the data compared and complemented to the results presented in this work.
In this thesis, the corrosion resistance of three structural metallic material candidates was studied in simulated conditions of the energy storage. The used materials were stainless steel 316L, stainless steel 904L and super duplex 1.4410, and they were tested in three different environments during a month-long immersion test. Each environment contained electrochemical, weight loss and welded samples of each material, to study general and localized corrosion of both, base and welded materials. General corrosion rate was determined from the electrochemical samples with two different techniques: linear polarization resistance and electrochemical impedance spectroscopy. Scanning electron microscopy and energy dispersive x-ray spectroscopy were used to study the surfaces and characterize the oxide layer of the samples after the immersion test. The samples were also visually inspected after the test to evaluate their tendency for localized corrosion.
In the experiment, the first results for the performance of the materials under the specific environmental conditions in question were obtained. Based on the results, no significant differences could be seen in the feasibility of the different materials. The used measuring techniques were capable of producing reliable and reproducible results, but also some unexpected results were obtained. Therefore, in order to draw clear conclusions for the order of the corrosion resistance of the materials, more measurements need to be performed, and the data compared and complemented to the results presented in this work.