High-selectivity imaging of closed cracks in a coarse-grained stainless steel by nonlinear ultrasonic phased array

Yoshikazu Ohara, Koji Takahashi, Yoshihiro Ino, Kazushi Yamanaka, Toshihiro Tsuji, Tsuyoshi Mihara

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

In measuring crack depths by ultrasonic testing, there are two difficulties; crack closure and coarse grains. Crack closure can cause the underestimation or miss-detection. Coarse grains can hide crack tip responses due to strong linear scatterings at coarse grains. To solve these problems, a combination of a crack opening method, global preheating and local cooling (GPLC) and a high-selectivity imaging method, load difference phased array (LDPA) was proposed. However, it has yet to be verified. Here we formed a tightly closed fatigue crack in a coarse-grained stainless-steel specimen using a stepwise-decremental method. In the specimen, we demonstrated that our method is useful in selectively imaging closed cracks in coarse-grained materials.

Original languageEnglish
Pages (from-to)139-147
Number of pages9
JournalNDT and E International
Volume91
DOIs
Publication statusPublished - 2017 Oct

Keywords

  • Closed cracks
  • Coarse-grained stainless steel
  • Nonlinear ultrasonic phased array
  • Thermal stress

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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