Metallurgical and Materials Transactions A

, Volume 38, Issue 8, pp 1833–1844

Defect Band Characteristics in Mg-Al and Al-Si High-Pressure Die Castings

Article

DOI: 10.1007/s11661-007-9243-1

Cite this article as:
Gourlay, C., Laukli, H. & Dahle, A. Metall and Mat Trans A (2007) 38: 1833. doi:10.1007/s11661-007-9243-1

Abstract

Bands of positive macrosegregation and porosity commonly follow the surface contour of components produced by high-pressure die casting (HPDC). In this article, Al alloy AlSi7Mg and Mg alloys AZ91 and AM60 were cast into tensile test bars using cold-chamber (cc) HPDC. Microstructural characterization revealed that externally solidified crystals (ESCs) are not necessary for defect band formation, and that defect bands can form both near to and relatively far from any surface layer of different microstructure. The defect bands were 140 to 240 μm thick. In addition to defect-band-related macrosegregation, the castings also contained inverse segregation and surface segregation. Defect bands are shown to have the characteristics of the dilatant shear bands reported in past rheology studies, indicating that defect bands form due to strain localization in partially solid material during the HPDC process.

Copyright information

© THE MINERALS, METALS & MATERIALS SOCIETY and ASM INTERNATIONAL 2007

Authors and Affiliations

  1. 1.CAST CRC and the ARC CoE for Design in Light Metals, Materials EngineeringThe University of QueenslandBrisbaneAustralia
  2. 2.Hydro Aluminium Metal, Research & Technology DevelopmentSunndalsøraNorway

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