Title: Numerical investigation of size effect on material behaviour in micro upsetting process

Authors: Wei Zheng; Bingtao Tang; Guangchun Wang

Addresses: School of Materials Science and Engineering, Shandong Jianzhu University, Jinan, China ' School of Materials Science and Engineering, Shandong Jianzhu University, Jinan, China ' Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan, China

Abstract: In recent years, the micro-forming technology has been becoming the hotspot of micro-manufacturing researches. However, the theory of metal forming in macro-scale cannot be used to guide the micro-forming process directly due to the size effect. In this study, a region model considering the grain shape, orientation and boundary was proposed based on Hall-Petch equation. The constitutive relationships of materials in grain region and grain-boundary region were deduced by introducing the scale parameters. To verify the proposed model, relative experiments have been designed and performed. Moreover, the finite element model of the most common micro-forming like micro upsetting was established integrating the region model. The effects of grain distribution, specimen size and grain size on material behaviour were well studied based on the simulation results. The researches in this paper will be developed to provide guidance for more complex micro-forming processes in future.

Keywords: microforming; micromanufacturing; size effect; grain distribution; simulation; region modelling; material behaviour; micro upsetting process; metal forming; grain shape; grain orientation; grain boundary; Hall-Petch equation; specimen size; grain size.

DOI: 10.1504/IJMPT.2016.076377

International Journal of Materials and Product Technology, 2016 Vol.53 No.1, pp.71 - 85

Received: 14 Oct 2014
Accepted: 27 Sep 2015
Published online: 05 May 2016 *

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