Influence of grain size on high temperature fracture in a Mg AZ31 alloy

Panicker, MRR and Chokshi, AH (2011) Influence of grain size on high temperature fracture in a Mg AZ31 alloy. In: Materials Science and Engineering A, 528 (7-8). pp. 3031-3036.

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Abstract

Tensile experiments at 673 K and grain sizes from similar to 8 to 17 mu m revealed large ductility at a low strain rate and a reduced ductility at a high strain rate, corresponding to a change from a high to a low value for the strain rate sensitivity. High strain rate deformation led to fracture by flow localization, whereas low strain rate deformation involved fracture by cavity nucleation and growth. Analysis revealed that grain boundary migration can assist significantly in reducing the stress concentrations caused by grain boundary sliding, thereby retarding cavity nucleation. Calculations demonstrate that the interlinkage of voids parallel and perpendicular to the tensile axis occurs significantly, so that it is not always possible to use the cavity shapes to distinguish between diffusion and plasticity controlled growth. Cavitation damage evolves slowly in materials with a coarser grain size because of reduced nucleation related to a reduction in the strain rate sensitivity and associated grain boundary sliding. (C) 2011 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	Materials Science and Engineering A
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Magnesium; Superplastic; Fracture; Cavity nucleation; Cavity growth
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	30 Mar 2011 08:30
Last Modified:	30 Mar 2011 08:30
URI:	http://eprints.iisc.ac.in/id/eprint/36343

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