Small-Scale System for Evaluation of Stretch-Flangeability with Excellent Reliability
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We propose a system for evaluating the stretch-flangeability of small-scale specimens based on the hole-expansion ratio (HER). The system has no size effect and shows excellent reproducibility, reliability, and economic efficiency. To verify the reliability and reproducibility of the proposed hole-expansion testing (HET) method, the deformation behavior of the conventional standard stretch-flangeability evaluation method was compared with the proposed method using finite-element method simulations. The distribution of shearing defects in the hole-edge region of the specimen, which has a significant influence on the HER, was investigated using scanning electron microscopy. The stretch-flangeability of several kinds of advanced high-strength steel determined using the conventional standard method was compared with that using the proposed small-scale HET method. It was verified that the deformation behavior, morphology and distribution of shearing defects, and stretch-flangeability results for the specimens were the same for the conventional standard method and the proposed small-scale stretch-flangeability evaluation system.
This work was supported by a National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 2014R1A2A1A10051322). This study was supported by the Brain Korea 21 PLUS Project for the Center for Creative Industrial Materials (F16SN25D1706).
Conflict of interest
The authors declare that they have no conflict of interest.
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