Four-dimensional annihilation behaviors of micro pores during surface cold working

Hiroyuki Toda, Tomoyasu Yamaguchi, Mitsuru Nakazawa, Yoshimitsu Aoki, Kentaro Uesugi, Yoshio Suzuki, Masakazu Kobayashi

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


The aimihilation behavior of micro pores in an aluminum alloy casting during surface cold working was continuously observed using the synchrotron radiation microtomography. To analyze micro pore annihilation behavior, the displacement of artificially dispersed particles was measured and thereby local strain distributions were mapped in high-density. A peening treatment annihilated most of the micro pores with a diameter of over 10 μm in the upper part of the specimen that could initiate fatigue cracks. The annihilation behavior of the micro pores could be understood as a function of effective strain locally accumulated around them, and not as a function of local hydrostatic strain. The effective strain varied significantly, with some large pores remaining where local effective plastic strain was relatively low. The complete annihilation of large pores in the surface layer suggests that the application of sufficiently long surface cold working is effective in improving the high-cycle fatigue properties.

Original languageEnglish
Pages (from-to)1288-1295
Number of pages8
JournalMaterials Transactions
Issue number7
Publication statusPublished - 2010 Jul


  • Healing
  • Pore
  • Strain mapping
  • Surface hardening
  • X-ray microtomography

ASJC Scopus subject areas

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


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