デジタル画像相関法による結晶粒内および粒界近傍におけるき裂先端ひずみ場の測定

抄録

Strain fields near the crack tip in single crystal and bi-crystal CT specimens of Ni-base superalloys were experimentally investigated by digital image correlation. The obtained strain fields were discussed in the coordinate system considering the crystallographic slip systems. Experimental results of single crystal CT specimens revealed that the shear strain field along slip system coordinate represented the activity of slip system and provided a reasonable estimation to the preferable direction of crack growth. It was also confirmed that the magnitude of strain field, which depended on the crystal orientation, was qualitatively correlated with crack growth rate. Additionally, influence of the grain boundary on strain field was investigated in bi-crystal CT specimen. A series of experiments, where the experimental variables were distance from the crack tip to the grain boundary, indicated that the grain boundary inhibited shear strain as the crack tip was located near to the grain boundary.