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Lecture

Precipitation behavior and corrosion resistance of nickel-free, high-nitrogen austenitic stainless steels

Thursday (27.09.2018)
15:15 - 15:30 S1/01 - A4
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Nickel-free, nitrogen alloyed austenitic stainless-steels, with about 19 wt.-% Mn and 0,8 wt. % N, are an interesting alternative to classic CrNi austenitic stainless steels due to their superior mechanical properties (Rm > 900 MPa, A5 > 50 %, Av > 350 J) in the solution annealed condition. The formation of chromium-rich nitrides during suboptimal heat treatment, processing or application leads to an inhomogeneous distribution of alloying elements in the microstructure, which reduces the corrosion resistance. Consequently, an accurate knowledge of the sensitization behavior is indispensable for the use of nickel-free, high-nitrogen austenitic stainless steels. The relationship between artificial aging, phase formation and corrosion resistance was investigated on the alloys X8CrMnN18-19 (1.3815) and X8CrMnMoN18-19-2 (1.4456), both alloyed with 0,8 wt.-% Nitrogen, in the present work. The microstructural evolution was studied by LM and SEM while the corrosion resistance was characterized with the electrochemical potentiodynamic reactivation (EPR) and the KorroPad indicator-test. Both alloys showed increased corrosion susceptibility within critical aging parameters. Finally, a sensitization diagram was described successfully for both alloys showing the positive effect of molybdenum.

Speaker:
Dr.-Ing. Paul Rosemann
Bundesanstalt für Materialforschung und -prüfung (BAM)
Additional Authors:
  • Patricia Pensel
    Otto von Guericke University Magdeburg
  • Saskia Roßberg
    Otto von Guericke University Magdeburg
  • Christopher Müller
    Otto von Guericke University Magdeburg
  • Dr. Andreas Burkert
    Bundesanstalt für Materialforschung und -prüfung (BAM)