Wasserstoffeinfluss auf die chloridinduzierte Spannungsrisskorrosion austenitischer Stähle

Translated title of the contribution: Hydrogen influence on the chloride induced stress corrosion cracking of austenitic steels

Thomas Rauscher

Research output: ThesisDiploma Thesis

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Abstract

Material damage caused by stress cracking corrosion (SCC) represents a serious technical problem in many ways. On the one hand this failure mechanism is barely recognized due to its fracture property which only shows little deformations and on the other hand very high crack propagation rates might cause sudden thus catastrophic material failure. Furthermore ductile metals can even fail during uncritical mechanical load due to apparently brittle cracks caused by corrosion. Despite all efforts spent on this subject, research programs have not yet succeeded in establishing a comprehensive theory, which explains all different corrosion forms and their natures of appearance in detail. Even more contribution factors are controversially discussed in the literature. This thesis analyses the impact of hydrogen on the SCC of austenitic steel within aqueous chloride solutions. Additionally the pH value, the potential and corrosion promoters (As2O3) were examined as contributors to the above mentioned failure mode. The investigated material is an austenitic CrMnN steel which was stressed by 4 point bending tests under constant load in hot 50% Wt. CaCl2 - solutions. To measure the impact of the pH value, NaOH or H2SO4 was sporadically added to the electrolyte. The potential dependency was examined by using additional cathodic as well as anodic load. During these tests the potential-time curves were accommodated and the lifetime of the samples was determined. Subsequently, light-microscope investigations as well as hot extraction analyses were executed in order to check for hydrogen contents. Representative samples were even examined using the scanning electron microscope.
Translated title of the contributionHydrogen influence on the chloride induced stress corrosion cracking of austenitic steels
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
  • Mori, Gregor Karl, Supervisor (internal)
Award date8 Apr 2011
Publication statusPublished - 2011

Bibliographical note

embargoed until 01-03-2016

Keywords

  • hydrogen
  • stress corrosion cracking
  • corrosion resistant austenitic steel
  • 4-point bending test
  • hot extraction analyses

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