Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 49: Phase Transitions VI

MM 49.2: Talk

Friday, February 29, 2008, 12:00–12:15, H 0107

Investigation of the reverted austenite phase in carbon free stainless maraging steel after long term heat treatment — •Stefan Höring, Daniel Abou-Ras, Nelia Wanderka, and John Banhart — Hahn-Meitner-Institut Berlin, Berlin

The main aim of this work was to investigate the microstructure evolution of the carbon free stainless maraging steel Corax after long term heat treatment at 798 K. The mechanical properties of maraging steels are influenced by the amount of reverted austenite. Therefore, the volume fraction, the grain size and the location of the reverted austenite was determined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Results of all investigations confirmed that even after long aging time (3000 h) the volume fraction of the austenite is still nearly unchanged. The correlation between crystal orientation of martensite- and the austenite phases is studied by means of EBSD measurements. The austenite grains reached sizes up to 0.05 mm. Long term annealing leads to the formation of new phases located mainly at the grain boundaries. The results of micro-hardness measurements of Corax steel are correlated with the evolution of the microstructure.