Berlin 2005 – wissenschaftliches Programm
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M: Metallphysik
M 37: Symposium Tomographic Methods in Materials Research
M 37.1: Vortrag
Dienstag, 8. März 2005, 11:00–11:20, TU H1058
3D-Atom Probe investigation of carbide dissolution in a pearlitic steel subjected to severe plastic deformation. — •Yu. Ivanisenko1, X. Sauvage2, H. Rösner1, and H.-J. Fec ht1,3 — 1Institut für Nanotechnologie, Forschungszentrum Karlsruhe, 76021 Karlsruhe, Germany — 2Institut des Matériaux de Rouen, Université de Rouen, BP 12, 76801 Saint-Etienne-du-Rouvray, France — 3Abt. Werkstoffe der Elektrotechnik, Universität Ulm, 89081 Ulm, Germany
Pearlitic steels find a wide application in industry mainly as a material for rails and tyre cords. Phenomenon of decomposition of carbides occurring either during the exploitation of rails, or during the cold drawing of wires is very important because it decreases the ductility, and consequently leads to the loss of mechanical properties.
The application of 3D Atom Probe to study the process of strain induced cementite dissolution in pearlitic steels is very promising because it allows to detect the concentration of the elements in alloys with atomic resolution. Here we report our results on 3D AP investigation of pearlitic steel (Fe - 0.76 wt. % C - 1.2 wt. % Mn) following the room temperature severe plastic deformation by high pressure torsion. We show that decomposition of carbides starts already in the beginning of straining with a gradual decrease of the carbon concentration and formation of transitional non-stoichiometric phases with carbon contents of 8-16 at. %. A parallel HRTEM investigation has demonstrated that these phases, still keeping the lamellar shape, are partially amorphous. Increasing the strain further leads to a considerable decrease of size and amount of such carbon-rich areas and formation of carbon segregations on grain boundaries of nanocrystalline ferrite and along the dislocations.