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MM: Metall- und Materialphysik

MM 41: Nanostructured Materials IV

MM 41.3: Talk

Friday, March 31, 2006, 13:00–13:15, IFW D

CORRAX - A TI-FREE STAINLESS MARAGING STEEL INVESTIGATED BY 3 DIMENSIONAL ATOM PROBE — •Stefan Höring¹, Nelia Wanderka¹, Wolfgang Neumann², John Banhart¹, Harald Leitner³, and Helmut Clemens³ — ¹Hahn-Meitner-Institut Berlin, Glienicker Str. 100, 14109 Berlin — ²Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr. 15, 12489 Berlin — ³Institut für Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, Franz-Josef-Strasse 18, A - 8700 Leoben

Maraging steels are widely used for aerospace parts as well for tools and dies because of their good mechanical properties. Stainless maraging steels can be used as dies in the glass industry because of its good surface properties. The high strength of these steels is achieved by a precipitation hardening process. Typically these precipitates are in nanometer scale. An alloy with the technical name Corrax with the chemical composition 73.46 Fe-12.76 Cr-8.52 Ni-3.39 Al-0.79 Mo-0.58 Si-0.39 Mn-0.11 C (in at. %) was solution heat treated at 850 ^∘C for 1/2 h and subsequently aged at 525 ^∘C for 3 h, 10 h and 100 h. The microstructural evolution after annealing was studied by high resolution methods such as three dimensional atom probe (3DAP) and high resolution transmission electron microscopy (HRTEM). After 3 h annealing time small precipitates of nearly spherical morphology and of about 3-4 nm in diameter were formed. They are enriched in Ni and Al with an atomic ratio close to 1. While further heat treatment these precipitates grow to plates along one fixed direction.