|
Hokkaido University Collection of Scholarly and Academic Papers >
Graduate School of Engineering / Faculty of Engineering >
Peer-reviewed Journal Articles, etc >
Quantification of Large Deformation with Punching in Dual Phase Steel and Change of its Microstructure : Part I: Proposal of the Quantification Technique of the Punching Damage of the Dual Phase Steel
| Title: | Quantification of Large Deformation with Punching in Dual Phase Steel and Change of its Microstructure : Part I: Proposal of the Quantification Technique of the Punching Damage of the Dual Phase Steel |
| Authors: | Yokoi, Tatsuo Browse this author | | Shuto, Hiroshi Browse this author | | Ikeda, Ken-ichi Browse this author →KAKEN DB | | Nakada, Nobuo Browse this author | | Tsuchiyama, Toshihiro Browse this author | | Ohmura, Takahito Browse this author | | Mine, Yoji Browse this author | | Takashima, Kazuki Browse this author |
| Keywords: | dual-phase steel | | hole expansion test | | electron backscatter diffraction | | nano indentation | | local strain mapping | | strain distribution | | micromechanical characterization | | strain localization | | grain refinement | | shear fracture |
| Issue Date: | 15-Nov-2016 |
| Publisher: | Iron and Steel Institute of Japan |
| Journal Title: | ISIJ International |
| Volume: | 56 |
| Issue: | 11 |
| Start Page: | 2068 |
| End Page: | 2076 |
| Publisher DOI: | 10.2355/isijinternational.ISIJINT-2016-312 |
| Abstract: | Dual Phase (DP) steel is used in automotive body parts for weight saving and crashworthiness, however there is an issue of DP steel in low stretch flange ability evaluated by hole expanding tests. In order to improve stretch flange ability of DP steel, it is important to estimate the damage of punching quantitatively and to clarify the change of microstructure before and after punching because the hole expansion ratio is decided in the ductility remained after pre-strain equivalent to punching. Therefore we tried to measure the damage of punching by unique techniques of Electron Backscatter Diffraction (EBSD), nano-indentation and micro-tensile testing and to observe fracture surface by Scanning Transmission Electron Microscope (STEM). Average EBSD-Kernel Average Misorientation (KAM) value and pre-strain damage have strong correlation, thus average KAM value can become the index of the damage. The nanohardness and tensile strength using micrometer-sized specimens increased with increasing average KAM value in the ferritic phase as approaching the punching edge. A shear type fracture occurred without necking in the specimen cut out in the area of the edge. The ultrafine-grained ferritic microstructure was observed in the sample cut out in the same area with STEM. It seems that the ductility loss of the punched DP steel was probably attributed to localized strain into the ultrafine-grained ferritic microstructure. |
| Rights: | 著作権は日本鉄鋼協会にある |
| Type: | article |
| URI: | http://hdl.handle.net/2115/75455 |
| Appears in Collections: | 工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
|
Submitter: 池田 賢一
|
