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MM: Fachverband Metall- und Materialphysik

MM 22: SYM Physics meets Industry

MM 22.13: Vortrag

Mittwoch, 28. März 2007, 19:15–19:35, H16

On the Feasibility of Nitrogen Concentration Measurements in Steels by SIMS — Nicolas Bontems¹, •Peter-Joachim Wilbrandt¹, Jürgen Gegner², and Reiner Kirchheim¹ — ¹Institut für Materialphysik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — ²SKF GmbH, Department of Material Physics, Ernst-Sachs-Str. 5, 97424 Schweinfurt, Germany

Besides the carbon distribution, which permits adjusting constant or varying hardness and microstructure across the wall thickness, nitrogen enrichment represents an effective method to improve the edge zone properties of steel components. More stable martensite is formed and higher retained austenite contents can be achieved. Since recent developments turned SIMS into a powerful technique for industrial routine carbon profile determination, the attempt was made to trace nitrogen parallel to carbon concentrations. Such a combined microanalytical measuring tool is most useful for quality control and process improvement of upcoming carbonitriding heat treatment technologies.

Five specimens with different carbon and nitrogen contents were analyzed. First tests yield good reproducibility of the counting rates and, thus, the general usability of the method. A systematic analysis of the mass spectra shows that nitrogen atoms can best be detected as negatively ionized molecule CN. As the amount of detected CN molecules is proportional to the carbon content, it was concluded that the CN/C ratio is representative of the nitrogen concentration. Comparison of such ratios with nitrogen content data proved this to be valid.