Cross-sectional imaging of quenched region in a steel rod using energy-resolved neutron tomography

We demonstrate the collection and analysis of energy-resolved neutron tomography for the nondestructive inspection of a martensite phase in a quenched iron rod. The energy-resolved (4D) tomography technique can extract the internal information of crystalline phase and microstructural features, such as the distribution of martensite. However, care must be taken when performing energy-resolved neutron tomography on a strongly textured sample in which the crystal grains are preferentially oriented and the neutron attenuation spectrum depends on the direction. As the standard tomography algorithm is based on the assumption that the attenuation is isotropic, anisotropy in the neutron attenuation distorts the reconstructed information. In other words, energy-resolved neutron tomography can be a powerful tool for nondestructive martensite observation in iron materials, which are usually not strongly textured.