Advances in Engineering Advances in Engineering features breaking research judged by Advances in Engineering advisory team to be of key importance in the Engineering field. Papers are selected from over 10,000 published each week from most peer reviewed journals.
Acta Materialia, Volume 60, Issues 13–14, August 2012, Pages 5079-5088
Bilal Mansoor, A.K. Ghosh
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2136, USA
Materials Science and Engineering, Masdar Institute of Technology, Abu Dhabi, United Arab Emirates
Abstract
In this work the effect of multi-pass friction stir processing (FSP) followed by warm pressing on an as-extruded ZK60 Mg plate was investigated. The microstructure, texture and resulting mechanical properties are reported here. Multi-pass FSP to partial depths on the top and bottom plate surfaces produced a novel, layered structure with three distinct microstructural zones associated with stirred, transition and core regions. In the stirred zone, FSP, followed by pressing at 200 °C, created a 0.8 um ultrafine grain size which accounts for ∼55 vol.% of the material. The transition region (∼10 vol.%), showed extensively sheared coarse grains distributed in a matrix of finer grains. However, the core region (∼35 vol.%) showed extensive twinning inside coarse grains in an overall bimodal microstructure reminiscent of extrusion. The processed Mg with a strong basal texture exhibited high yield strength (>300 MPa) and retention of adequate tensile ductility (>10%). The enhancement in mechanical properties of processed Mg is found to be highly influenced by the layered microstructure: UFG grained stirred zone, finer precipitates and strong basal texture.
