MATEC Web of Conferences
Volume 21, 20154th International Conference on New Forming Technology (ICNFT 2015)
|Number of page(s)||6|
|Section||Hydroforming and Tube Forming|
|Published online||10 August 2015|
Production of high strength hollow shafts using tool hardening and Q-P process
1 Research Centre of Forming Technology – FORTECH, University of West Bohemia, Pilsen, Czech Republic
2 Fraunhofer Institute for Machine Tools and Forming Technology IWU, Chemnitz, Germany
3 Faculty of Mechanical Engineering, University of Applied Sciences, Mittweida, Germany
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.
© Owned by the authors, published by EDP Sciences, 2015
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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