Monitoring korrosionsbedingter Risse

Translated title of the contribution: Monitoring of corrosion caused cracks

Philipp Wolfgang Thomma

Research output: ThesisDiploma Thesis

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Abstract

Acoustic emission and electrochemical noise experiments are performed on steel specimens under conditions where stress corrosion cracking occurs. Tensile test specimens are produced from annealed austenitic Cr-Ni and Cr-Mn steels. All specimens are electrochemically polished before being stored for a while in a desiccator to generate a passive surface. The specimens are loaded with a constant load over yield stress in a corrosive solution. The solution is a 32 wt% chloride solution, made from calcium chloride, heated to 129°C. Some tests are performed until final fracture, others until the first small cracks are visible at the surface. The electric potential and the elongation are measured during the experiments. Images of the crack network subsurface, the surface cracks and the fracture surfaces are generated using light microscopy and scanning electron microscopy. It was possible to detect cracks and rapid crack growth shortly before and during the final fracture by the use of acoustic emission. Signals generated before the final fracture could not to be assigned unambiguously to single cracks. The size of the medium exposed sample surface was varied between experiments with electrochemical noise. It was possible to detect cracks in an early stage with the electrochemical noise method.
Translated title of the contributionMonitoring of corrosion caused cracks
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
  • Mori, Gregor Karl, Supervisor (internal)
Award date30 Mar 2012
Publication statusPublished - 2012

Bibliographical note

embargoed until 05-03-2017

Keywords

  • stress corrosion cracking
  • SCC
  • austenitic steel
  • acoustic emission
  • AE
  • electrochemical noise
  • EN

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