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Graded ultrafine grained materials by incremental bulk metal forming

: Neugebauer, Reimund; Bergmann, M.

Postprint urn:nbn:de:0011-n-1416150 (1023 KByte PDF)
MD5 Fingerprint: 1c8c76392a9068ffe059c9580c90627d
Created on: 21.4.2011

Mori, K.-I.:
Metal forming 2010, 13th International Conference on Metal Forming. Proceedings : Sept. 19 - 22, 2010, Hotel Nikko Toyohashi, Toyohashi, Japan
Weinheim: Wiley-VCH, 2010 (Steel research international 81.2010, Nr.9, Special Edition)
ISBN: 978-3-514-00774-1
International Conference on Metal Forming <13, 2010, Toyohashi>
Conference Paper, Journal Article, Electronic Publication
Fraunhofer IWU ()
gradation rolling; severe plastic deformation; graded material; ultrafine-grained

Ultrafine grained materials provide special properties like high strength at sufficient ductility. These materials can be obtained by various manufacturing approaches. The most common manufacturing processes using solid coarse grained billets are methods based on extreme strain generation and are called Severe Plastic Deformation processes. In these processes, the complete material volume is plasticised and formed. The present article focuses on a new approach for partial Severe Plastic Deformation to create ultrafine-grained materials capable of bridging the gap between refining the complete volume and the surface only as well as overcoming some technical limitations of Severe Plastic Deformation methods. Based on the application of incremental bulk forming the theoretical fundamentals of manufacturing of a graded workpiece and a new type of rolling process for rod shaped billets are presented. The major feature of the process is high strain generation by kneading. Kneading is characterized and the interaction with forming parameters described. Different aluminium alloys have been processed and investigated. The change of the materials microstructure and properties in different regions are analyzed. The material is characterized by a coarse grained core and an ultrafine-grained, several mm thick surface area. The technology provides an approach for products with a graded grain size and property distributions adapted to the load requirements.