Regensburg 2004 – scientific programme
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M: Metallphysik
M 17: Hauptvortrag Jürgen Gegner
M 17.1: Invited Talk
Tuesday, March 9, 2004, 14:00–14:30, H16
Metal Physics in Heat Treatment Technology - Carburization and Decarburization of Steels — •Jürgen Gegner1, Peter-J. Wilbrandt2, Reiner Kirchheim2, and Wolfgang Nierlich1 — 1SKF GmbH, Material Physics, Ernst-Sachs-Str. 5, D-97424 Schweinfurt — 2University of Göttingen, Institute of Material Physics, Tammanstr. 1, D-37077 Göttingen
Thermochemical processes in rim zones of steels represent a close point of contact of metal physics to classical engineering industry. Carburization is a well-established hardening technique, whereas case decarburization is primarily relevant to heat treatment and hot-working operations as undesired side effect. The technological background is sketched. Experimental results illustrate the influence on the edge zone. By metallography, microhardness and X-ray diffraction measurements, the microstructure and mechanical properties are characterized. Their relation to the carbon distribution is of special interest. A novel microchemical measuring technique, based on secondary ion mass spectrometry, is used to determine carbon depth profiles with high concentration accuracy and spatial resolution. A numerical simulation tool is adopted for data analysis. The model takes into account phase transformations as well as blocking surface layers. Reliable predictions of carbon profiles require knowledge of the concentration-dependent carbon diffusivities in steels. These data are determined by a new isothermal powder pack decarburization technique.