A novel combined technique of neutron diffraction and electron back scattering diffraction was applied to examine hierarchical deformation behavior of 18 mass% Ni martensitic steel. In-situ neutron diffraction experiment during tensile deformation demonstrated that intergranular stress was generated. EBSD analysis suggested that slip bands terminated not only at block boundaries, but also sub-block boundaries at a relatively small strain. In many cases, slip bands crossing sub-block boundaries were zigzagged. With increasing strain, sub-block became unclear and then block boundaries worked as a main barrier for dislocation gliding. Such kind of heterogeneous plastic flow in differently oriented hkl blocks seems to be a possible reason for the intergranular stresses.
