TY - THES

T1 - Tubing qualities for extremely high corrosive environments

AU - Stechauner, Georg

N1 - embargoed until 18-05-2016

PY - 2011

Y1 - 2011

N2 - The importance of chemical composition and microstructure on carbon dioxide corrosion of carbon and low alloy steels is generally recognized, however certain aspects are still uncertain as to what degree the parameters influence the corrosion. Moreover contradictory results can be found in literature. As chemical composition and microstructure are not independent variables, the same microstructure can be seen for different chemical compositions and vice versa. Many authors use different parameters such as temperature, immersion time, testing method and so on, and it is therefore almost impossible to compare them directly. As a consequence of this actual situation, OMV wanted to investigate the behavior of selected steel grades at certain parameters, which were of the companies’ interest. The aim of this work is to find the best steel fitting for the chosen parameters and to compare them to the literature in order to clarify this topic. The results shall be used for further tests, in order to see in which fields work still has to be done, and to be a basis for the engineers in choosing the right material. This work starts with a literature review, which will present the reader the state-of-the-art on the topics of CO2 corrosion basics and environmental influences, as well as the influence of chemical composition and microstructure. In the next chapter the sample treatment, used testing methods, mass loss and electrochemical measurement, as well as the statistical evaluation will be described. The next section presents the results of all the conducted tests which will be discussed in the following section. On the last pages, a conclusion will be drawn of the experiments and an outlook on the topic will be given. It was shown that the carbon steels performed better for the used environments than low alloyed steels with chromium. A great influence on the variance of the results was found to be within the amount of used medium. Generally a higher corrosion rate was found for short testing times. Only a small influence of the microstructure on the corrosion rate was found.

AB - The importance of chemical composition and microstructure on carbon dioxide corrosion of carbon and low alloy steels is generally recognized, however certain aspects are still uncertain as to what degree the parameters influence the corrosion. Moreover contradictory results can be found in literature. As chemical composition and microstructure are not independent variables, the same microstructure can be seen for different chemical compositions and vice versa. Many authors use different parameters such as temperature, immersion time, testing method and so on, and it is therefore almost impossible to compare them directly. As a consequence of this actual situation, OMV wanted to investigate the behavior of selected steel grades at certain parameters, which were of the companies’ interest. The aim of this work is to find the best steel fitting for the chosen parameters and to compare them to the literature in order to clarify this topic. The results shall be used for further tests, in order to see in which fields work still has to be done, and to be a basis for the engineers in choosing the right material. This work starts with a literature review, which will present the reader the state-of-the-art on the topics of CO2 corrosion basics and environmental influences, as well as the influence of chemical composition and microstructure. In the next chapter the sample treatment, used testing methods, mass loss and electrochemical measurement, as well as the statistical evaluation will be described. The next section presents the results of all the conducted tests which will be discussed in the following section. On the last pages, a conclusion will be drawn of the experiments and an outlook on the topic will be given. It was shown that the carbon steels performed better for the used environments than low alloyed steels with chromium. A great influence on the variance of the results was found to be within the amount of used medium. Generally a higher corrosion rate was found for short testing times. Only a small influence of the microstructure on the corrosion rate was found.

KW - Steel

KW - chromium

KW - carbon

KW - carbondioxide

KW - corrosion

KW - microstructure

KW - grain size

KW - ferrite

KW - pearlite

KW - martensite

KW - chemical composition

KW - autoclaves

KW - electrochemistry

KW - Stahl

KW - Chrom

KW - Kohlenstoff

KW - Kohlendioxid

KW - Korrosion

KW - Mikrostruktur

KW - Korngröße

KW - Ferrit

KW - Perlit

KW - Martensit

KW - chemische Zusammensetzung

KW - Autoklaven

KW - Elektrochemie

M3 - Diploma Thesis

ER -