Ni基超合金のせん断型疲労き裂進展における結晶学的パラメータの影響評価

抄録

Shear dominant fatigue crack propagation in a single crystal Ni-base superalloy, NKH-304 were experimentally investigated at room temperature. A series of experiments revealed that the shear dominant cracking was influenced by both primary and secondary crystal orientation, and crack growth rates were correlated with macroscopic deformation measured by strain gauge on the back surface of the CT specimen. In order to numerically assess the effect of elastic anisotropy and the crack geometry, 3-D FEM for the CT specimen was developed. It was found from fracture mechanics analysis that geometries of 3-D inclined crack played an essential role to determine the driving force of the shear dominant crack propagation in the superalloys.