The response of entrainment defect distribution to varied fluid flow parameters in the high pressure die casting of Al alloys

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Authors

  • R. Watson
  • T. Zeguer
  • M. Buckley
  • N. R. Green
  • S. Ruffle

External organisations

  • University of Cambridge
  • Jaguar Land Rover, UK
  • Doncasters Precision Castings
  • JVM Castings Ltd

Abstract

High Pressure Die Casting is an economical means of manufacturing complex thin walled parts in high volumes. However, the process is prone to high levels of surface turbulence and fluid break-up, which results in the entrainment of bifilm defects. A study was carried out on a commercial casting to identify how changes in melt velocity and mould geometry affected the distribution of damaging bifilm defects, and the distribution of fracture stress. The statistical analysis of tensile test data indicated that two distinct defect populations existed; one of which caused relatively few failures, but often accounted for a large reduction in fracture stress when present. Where this defect population was not significant, Weibull moduli of 20 to 30 were achieved, comparable to sand castings with well-designed running systems. SEM fractography was also performed on a selection of samples to determine the probable cause of failure. A comparison of the SEM analysis to the statistical results indicated that bi-film defects initiated the fracture of those samples that failed at significantly lower stresses. Additionally, it was demonstrated that the geometric distribution of these cases was strongly correlated to changes in fluid flow conditions, suggesting that targeted modifications to mould geometry could increase the in-service reliability of High Pressure Die Castings.

Details

Original languageEnglish
Title of host publicationMaterials Science Forum
Publication statusPublished - 2013
Event6th International Light Metals Technology Conference, LMT 2013 - Old Windsor, United Kingdom
Duration: 24 Jul 201326 Jul 2013

Publication series

NameMaterials Science Forum
Volume765
ISSN (Print)02555476

Conference

Conference6th International Light Metals Technology Conference, LMT 2013
CountryUnited Kingdom
CityOld Windsor
Period24/07/1326/07/13

Keywords

  • Fractography, High pressure die casting, Weibull analysis