Quantification of large deformation with punching in dual phase steel and change of its microstructure - Part II: Local strain mapping of dual phase steel by a combination technique of electron backscatter diffraction and digital image correlation methods

Nobuo Nakada, Ken Ichi Ikeda, Hiroshi Shuto, Tatsuo Yokoi, Toshihiro Tsuchiyama, Satoshi Hata, Hideharu Nakashima, Setsuo Takaki

研究成果: ジャーナルへの寄稿学術誌査読

19 被引用数 (Scopus)

抄録

To evaluate heterogeneous strain distribution developed by pre-deformations in dual phase (DP) steel accurately, a combinational technique of Electron Backscatter Diffraction (EBSD) and Digital Image Correlation (DIC) methods was newly introduced in this study. A good correlation is established between kernel average misorientation calculated by EBSD and local equivalent strain measured by DIC in ferrite matrix of DP steels regardless of the difference in deformation process, which means that an EBSD orientation map can be easily converted into an applicative strain map by employing the individual correlation formula. This new technique reveals that very large strain region is locally formed within dozens of micrometer from the punched edge in a punched DP steel. On the other hand, hard martensite grains dispersed in DP steel remarkably promote the heterogeneity of strain distribution in ferrite matrix. As a result, the large strain region is also developed in the form of bands in a cold-rolled DP steel by only 60% thickness reduction at least, as if it is affected by the distribution and morphology of martensite grains. In addition, the local strain mapping demonstrates that the equivalent strain of the large strain band in cold-rolled material is comparable to that of the heavily deformed edge in punched one. The very large strain band in ferrite matrix is characterized by ultrafine grained structure, which leads to the possibility for the losing ductility in ferrite matrix and the martensite cracking.

本文言語英語
ページ(範囲)2077-2083
ページ数7
ジャーナルisij international
56
11
DOI
出版ステータス出版済み - 2016

!!!All Science Journal Classification (ASJC) codes

  • 材料力学
  • 機械工学
  • 金属および合金
  • 材料化学

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