Corrosion Property Group

Aged deterioration due to corrosion of many social and industrial infrastructures constructed during the period of high economic growth are becoming serious problems year by year. In addition, with a diversification of metallic materials and usage environments, a variety of corrosion problems occurs. In corrosion property group, various corrosion deterioration behaviors of metallic materials exposed to different environments have been investigated in order to solve many corrosion problems. Furthermore, we aim to contribute to the improvement of the reliability and durability of metal materials under a wide range of environments through elucidation of their corrosion mechanisms.

Specialized Research Field

1. Stress Corrosion Cracking for Welded Stainless Steel under Simulated Radiation Environment

Although the formation of passive oxide film on the surface of austenitic stainless steels ensures excellent resistance to general corrosion, the welding process can increase the susceptibility to localized corrosive attack on the passive film through the introduction of metallurgical changes and residual stresses in the materials. Therefore, SCC (Stress Corrosion Cracking) enhanced by localized corrosive attack is one of major concerns for the use of welded stainless steel as structural materials. In the present study, SCC tests are conducted at 473K for welded SUS308 stainless steel in high-pressure water (1) doped with hydrogen peroxide, (2) under ultraviolet irradiation.
The objective is to understand the processes of SCC initiation and propagation in dendrite structure at weld in simulated radiation environment.


2. Development of protective coatings for magnesium alloys

Magnesium alloys attract attention as a lightweight material for transportation equipment and as a biodegradable material for stent and bone fixation devices. The practical use of Mg alloys does not show a significant progress due to the very low corrosion resistance regardless of the application field. We are therefore developing various corrosion protection coatings which show a suitable corrosion resistance depending on the application: from high corrosion resistant to biodegradable coatings.
Calcium phosphate coatings are mainly examined because calcium phosphate shows various solubility depending on the crystal structure, crystallinity and composition.


3. Hydrogen permeation behavior of steel materials under atmospheric corrosion environment

Usage of higher strength steels has been required in the field of transportation equipment and infrastructure from the viewpoint of saving energy and safety in recent years. However, the higher strength steels show remarkable susceptibility to hydrogen embrittlement, and it is reported that the hydrogen embrittlement occurs even by a little amount of hydrogen penetrated due to atmospheric corrosion. It is very important to understand the behavior of the hydrogen penetration and permeation caused by corrosion reaction, in order to further expand the use of high strength steels in the future hydrogen energy society. We especially focus on the visualization technology of permeated hydrogen, and investigate the usefulness of surface potential measurement for detection of permeated hydrogen of steel materials under atmospheric corrosion environment. 


4. Establishment of evaluation method for atmospheric corrosion property of steel materials and elucidation of corrosion mechanism

Appropriate repair and reinforcement are required for long-term reliability of steel infrastructures, and the understanding of corrosion property of steel materials in atmospheric environment leads to a selection of appropriate materials. In this study, monitoring technique of corrosion rate by the electrochemical impedance method is considered in order to establish the evaluation method for atmospheric corrosion property of steel materials. In addition, we aim to clarify the relationship between environmental factors and corrosion behavior by corrosion tests of steel materials in the chamber controlled temperature and relative humidity. 


Group Leader

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Corrosion Property Group
1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047 JAPAN
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