EBSD/ECCIとデジタル画像相関法を併用した塑性ひずみ発達測定法の提案:fcc Ni切欠材の例

抄録

In the ductile crack propagation phenomenon, the plastic strain distribution differs between the surface and interior of material because of the difference in stress field. Furthermore, the interior of material is controlling factor of the crack propagation. However, digital image correlation (DIC) cannot be applied in the interior of material. Hence, it is difficult to measure the internal plastic strain distribution. We measured grain orientation spread (GOS) and dislocation density by electron backscatter diffraction (EBSD) measurement and electron channeling contrast imaging (ECCI) to obtain plastic strain maps near a notch in pure nickel as a FCC model sample. In particular, we obtained quantitative relationship among GOS value, dislocation density, and plastic strain on the surface of specimen, which were obtained by EBSD, ECCI, and DIC, respectively. After obtaining GOS value–plastic strain and dislocation density–plastic strain relations on the surface of specimen, the plastic strain distribution in the interior of specimen was also determined by measuring the GOS value and dislocation density. Both of the GOS value and dislocation density showed a linear correlation with plastic strain on the surface of specimen. Furthermore, the dislocation density–plastic strain relation showed a relatively smaller deviation than the GOS value–plastic strain relation. In the interior of specimen, as the distance from the notch tip became longer, the plastic strain determined by the GOS value and dislocation density monotonously decreased.