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Hydrogen damage in power industry

Sozańska M., Michalska J., Lubińska K.

Advances in Materials Science

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2007

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Vol. 7, nr 2(12)

69-75

EN

Hydrogen damage is the generic name given to a large number of metal degradation processes due to interaction with hydrogen. Especially in rower industry, several major components such as steam generator tubes, boilers, steam/water pipe lines, water box of condensers and the other auxiliary components often fail catastrophically due to hydrogen embrittlement. This article consists of a classification of hydrogen damage, brief description of the various processes and their mechanisms, and some guidelines for the control of hydrogen damage in rower plants. Furthermore, same histories of failures of steel components due to hydrogen embrittlement, which are reported in literature, are presented.

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Corrosion and hydrogen damage of steel in contact with soil bacteria and micromices. Preventive ability of organic inhibitors

Beloglazov S.M.

Advances in Materials Science

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2007

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Vol. 7, nr 2(12)

202-209

EN

The martensitic stainless steel (ca. 13%Cr, 2%Ni and 0.25%C) corrodes in anaerobic aqueous salt medium deteriorated with H2S, as metabolic product of sulfate reducing bacteria, with small rate, but absorb a high quantity of hydrogen, that formed a very thin subsurface hydrogen rich layer. It can be explained by existence of collectors in the subsurface of metal, filled withmolecular hydrogen, which prevent the deeper penetration of H while diffusing in steel. Molecularization process of H on the internal collector surface results in growth of partial H2 pressure in collectors. The further diffusion of H into the metal depth then bas to take place through the already stressed and strained metal around the collectors. The stress field prevent the hydrogen diffusion into the depth of steel. The earlier elaborated special steel anodic dissolution technique (step-strip technique) bas been successfully applied for hydrogen analyzing in austenitic steel. The hydrogen concentration profiles gained from these tests may be very useful in the explanation of the hydrogen embrittlement of high-strength Cr-Ni-steels. The H2S-content - time curves in media with SRB have the similar character and sequence as one s SRB cells number (bacterial liter) - time. The OC being studied can act as satisfactory inhibitors of SRB-induced corrosion of martensitic stainless steel in aqueous salt medium. The corrosion inhibiting of OC under study is in a good agreement between their molecular structure and inhibiting efficiency. The increase of electron density on the functional groups provide the made strong adsorption of organic molecules on the steel surface. The bactericidal action of OC on SRB corresponds essentially to their steel corrosion inhibiting effi-ciency in aqueous salt medium. Mould fungi (Aspergillus niger, Penicillium chrysogenum, Penicillium charlissii and Phialophora fastigiata) isolated from soil exhibits stimulating action on steel corrosion visible already after two days of exposure. N-containing OC having linear molecules showed significantly greater inhibiting corrosion action in media with Phialophora fastigiata and Pen. charlissii in comparison with Asp. niger and Pen. chrysogenum.

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Niszczenie wodorowe typu "rybie oczy" wybranych stali dla energetyki

Sozańska M.

Zeszyty Naukowe. Hutnictwo / Politechnika Śląska

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2006

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z. 76

1-155

PL

Wodór w stali modyfikuje przebieg wielu zjawisk fizykochemicznych i strukturalnych, prowadząc często do degradacji jej podstawowych właściwości użytkowych. Proces degradacji określany jest jako niszczenie wodorowe. "Rybie oczy" są jednym z efektów oddziaływania wodoru w stali. W części literaturowej pracy scharakteryzowano główne mechanizmy niszczenia wodorowego stali oraz opisano czynniki wpływające na powstanie efektu "rybie oczy". Zwrócono uwagę, że dotychczasowe dane dotyczące roli czynników strukturalnych w procesie pękania wodorowego mają głównie charakter jakościowy. Postęp wiedzy teoretycznej i metod badawczych poszerzył zakres możliwości zapobiegania niekorzystnym procesom zniszczenia wodorowego oraz ich kontrolę. Na podstawie analizy aktualnego stanu wiedzy i wyników wieloletnich badań własnych sformułowano tezę: powstawanie w procesie niszczenia wodorowego efektu "rybie oczy" na powierzchni przełomów nadoworownej stali jest determinowane nie tylko stężeniem wodoru, ale przede wszystkim wielkością i morfologią wtrąceń niemetalicznych, wartością obciążeń zewnętrznych oraz temperaturą procesu. Zastosowanie metod stereologicznych opartych na analizie obrazów mikrostruktury i przełomów stali umożliwi ustalenie ilościowych zależności łączących mikrostrukturę, typ przełomu i właściwości mechaniczne stali po nawodorowaniu. Badanie przeprowadzono na czterech gatunkach stali stosowanej w energetyce" A508Gr.3, A516Gr70, S500Q i 10CrMo9-10.

EN

Hydrogen can modify the course of many physical, chemical and structural phenomena in steels resulting frequently in degradation of the material fundamental features. The degradation process of this type is usually known as the hydrogen damage. The so called "fish eyes" effect is one of the potential results of hydrogen action in steels. In the literature review the main reason of the hydrogen damage were considered and factors affecting formation of the "fish eyes" have been described. It was noticed the recent data concerning the role of structural factors in the hydrogen process have rather qualitative nature. The progress in theoretical background and in experimental methods broadened the range of facilities that enable to prevent useless hydrogen damage or at least to control it. The analysis of current data and long term own studies the author to express the thesis: the fish eyes formation at the fracture surface of hydrogenated steel in the hydrogen damage process is determined not only by the hydrogen content but mainly by size and morphology of non-metallic inclusions, by external load and testing temperature. Moreover, the application of stereological methods steel fracture and microstructure image analysis permits to establish quantitative relations between the microstructure, the type of fracture and mechanical properties of hydrogenated steels. Four types of steels" A508Gr.3, A516Gr70, S500Q and 10CrMo9-10 applied in power industry were examined by the author.