2014 年 63 巻 7 号 p. 557-562
A chromium-molybdenum steel composed of 0.20 mass% carbon was used as a starting material. Two kinds of specimens having different case depths were made by carburizing and quenching. Using the scanning electron microscope, the crystallographic information was measured on the cross-sectional hardened layer by electron backscattering diffraction method. The kernel average misorientation, Θ, of the inverse pole figure were calculated from the carburized surface to the interior of each specimen. The area-average, Θmean, was compared to the case depth and the cross-sectional residual stress distribution measured by x-ray. As a result, the area-average of the hardened layer was larger than that of the interior of specimen after heat treatment. The estimated depth of the increment in the Θmean found to accord to the case depth and be proportional to the depth in which large compressive residual stress was distributed on the gradually polished surface. Therefore, the case depth and eigen strain distribution that induce the compressive residual stress can be indirectly estimated by electron backscattering diffraction method.