Clustered shrinkage pores in ill-conditioned aluminum alloy die castings

Yoshihiko Hangai, Osamu Kuwazuru, Takayuki Yano, Takao Utsunomiya, Yozo Murata, Soichiro Kitahara, Sujit Bidhar, Nobuhiro Yoshikawa

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


The geometric features of clustered shrinkage pores (CSP) in ill-conditioned aluminum alloy die castings were revealed and their effect on the fatigue strength was discussed. To obtain the geometric features of CSP, an observation using a commercial microfocus X-ray computed tomography (X-ray CT) system was carried out and the position and size of CSP were confirmed. However, the detailed geometry of the CSP could not be clearly observed by X-ray CT, because each pore in the CSP was too small to observe owing to the insufficient resolution of the CT image. We developed a serial sectioning system with a polishing machine and an optical microscope. Observation using the serial sectioning system clearly showed that a CSP consists of many interconnected small pores, which formed an extremely complicated shape. The CSP was thought to grow from relatively large gas pores, which connect to small pores and consequently generate a cavity with a huge volume and a complicated geometry. The complex geometry of CSP resulted in the concentration of stress around CSP, and significantly undermines mechanical properties such as tensile strength and fatigue strength.

Original languageEnglish
Pages (from-to)1574-1580
Number of pages7
JournalMaterials Transactions
Issue number9
Publication statusPublished - 2010 Sept


  • Aluminum alloy
  • Casting defect
  • Die casting
  • Fatigue
  • Serial sectioning
  • Shrinkage porosity
  • X-ray computed tomography

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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