Chloridinduzierte Korrosion an austenitischen Stählen unter schwingender Beanspruchung

Anna Visser

Research output: ThesisDoctoral Thesis

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Abstract

For special applications in the oil and gas exploration austenitic stainless steels are required, which withstand the cyclic mechanical loading under corrosive environmental conditions. Two established alloying concepts are CrNiMo and CrMnN steels. The present doctoral thesis focuses on the corrosion fatigue behaviour of a cold worked austenitic stainless steel which merges both concepts in a CrMnNiMoN alloy. Therefore tests under cyclic loading were conducted in corrosive electrolytes ranging from mild to aggressive conditions and the fracture surfaces were analyzed. The results show the effect of different types of localized corrosion on the material performance under cyclic loading. Depending on the testing conditions pitting and stress corrosion cracking interfere with corrosion fatigue, leading to reduced fatigue strength. Furthermore the electrochemical properties of the new alloy and of two steels of the established alloying concepts were investigated and compared under the influence of varied testing parameters such as chloride content, temperature and pH-value. In addition immersion and repassivation tests were conducted and the passive layers was analysed by atom probe tomography. This work contributes to an improved understanding of the relation between material properties and corrosion fatigue behaviour under different environmental conditions. The results show the effect of different types of localized corrosion on the material performance under cyclic loading.
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Mori, Gregor Karl, Assessor A (internal)
  • Pippan, Reinhard, Assessor B (internal)
Publication statusPublished - 2016

Bibliographical note

no embargo

Keywords

  • corrosion fatigue
  • stress corrosion cracking
  • pitting

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