Entwicklung von hoch stickstoffhaltigen austenitischen Cr-Mn-Mo-Ni-Stählen höchster Korrosionsbeständigkeit und Festigkeit

Translated title of the contribution: Development of high nitrogen alloyed austenitic Cr-Mn-Mo-Ni-steels with high corrosion resistance and strength

Gabriele Saller

Research output: ThesisDoctoral Thesis

Abstract

Nitrogen alloyed Cr-Mn-steels are mainly used for nonmagnetic drill collars and have to meet high requirements on strength and ductility. For reaching highest corrosion resistance the elements molybdenum and nickel had to be added to the Cr-Mn-N-steel grades used up to now, leading to alloys with a completely new composition. For this new field of alloys the complex interaction between alloy composition, producibility, microstructure and properties was investigated and evaluated by the help of systematically varied model alloys produced on industrial scale. The influence of the alloying elements nitrogen, molybdenum and nickel on microstructure, mechanical and corrosion properties was investigated in the solution treated as well as in the cold deformed condition. The degrees of cold deformation were varied up to 50 %. Additionally, empiric formulae from literature and the software ThermoCalc were tested, whether they can be applied to predict the behaviour of highly alloyed austenitic Cr-Mn-steels. The new developed group of alloys shows a significant increase concerning resistance against chloride induced pitting corrosion and meets all requirements on microstructure and mechanical properties. The knowledge gained by the current investigations allows a precise optimisation of alloy composition in the field of highly alloyed austenitic Cr-Mn-Mo-Ni-N-steels.
Translated title of the contributionDevelopment of high nitrogen alloyed austenitic Cr-Mn-Mo-Ni-steels with high corrosion resistance and strength
Original languageGerman
Supervisors/Advisors
  • Mori, Gregor Karl, Assessor B (internal)
  • Clemens, Helmut, Assessor A (internal)
Publication statusPublished - 2006

Bibliographical note

embargoed until null

Keywords

  • steels
  • austenitic steels
  • stainless Cr-Mn-steels cold deformation austenite stability precipitation behaviour microstructure
  • cold deformed properties
  • mechanical pitting corrosion
  • chloride induced

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