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Production of high strength hollow shafts using hardening and Q-P process

Herstellung von hochfesten Hohlwellen mittels Härten im Werkzeug und Q-P Prozess
 
: Masek, Bohuslav; Vorel, Ivan; Opatová, Katerina; Kurka, Petr; Hahn, Frank; Mahn, Uwe

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Qin, Y.:
4th International Conference on New Forming Technology, ICNFT 2015 : Glasgow, UK, August 6–9, 2015
Les Ulis: EDP Sciences, 2015 (MATEC Web of Conferences 21.2015)
ISBN: 978-2-7598-1823-5
Art. 06009, 6 S.
International Conference on New Forming Technology (ICNFT) <4, 2015, Glasgow>
Englisch
Konferenzbeitrag
Fraunhofer IWU ()
high pressure forming; hollow shaft; hot stamping; Q+P process; structural parts; 42SiCr

Abstract
Innovation opens new opportunities in the field of processing hollow semi-products, as it offers the potential for manufacturing complex-shaped structural parts with enhanced properties. This introduces a manufacturing route comprising the following steps: internal high pressure forming, hot stamping and thermomechanical Q&P processing. In this manufacturing route, the demonstration product, a tube–shaped stock, is first austenitized. It is then expanded in a closed die by internal pressure of nitrogen until the material touches the die wall. As a result, it cools down quickly and martensite begins to form. At a temperature above the Mf, the cooling is interrupted and the workpiece is transferred to a furnace and tempered. The furnace temperature is below the Ms temperature. Within several minutes, a mixed microstructure forms, consisting of martensite and stabilized retained austenite. Thanks to this microstructure, the material exhibits a favourable combination of high strength and adequate ductility. Martensite imparts sufficient strength to the material whereas the retained austenite provides ductility. At a carbon level of approximately 0.4 % and with a simple Si-Mn-Cr-based chemistry, strengths of 2000 Mpa and A5 mm elongations of 15 % can be achieved.

: http://publica.fraunhofer.de/dokumente/N-360398.html