Characterization of Deformation by Cold Rolling in Ferritic Steel Containing Cu Particles Using Neutron Transmission Analysis

Neutron transmission spectra of Fe-2 mass% Cu alloy (Cu steel) were measured to characterize the changes of crystallographic texture of ferrite grains and nanostructure of dispersed Cu particles with cold rolling. Bragg edges appearing in the neutron attenuation coefficient of as-aged Cu steel show a sawteeth pattern corresponding to random texture. With increasing equivalent strain, the 110 Bragg edge changes to a peak and the 200 Bragg edge becomes sharp. These changes indicate the rotation of {110} planes toward a tilt angle of 32° to the rolling plane and the increase in the fraction of the {100} planes in the rolling plane. This can be explained by the evolution of <111>//ND, <322>//ND, and <100>//ND preferred orientations with the cold rolling, where ND denotes the normal direction. In the wavelength range longer than 0.4 nm, the neutron attenuation coefficient increases due to a small-angle neutron scattering (SANS) contribution from dispersed Cu particles in the matrix. Comparing the experimental results with simulation, the change in the SANS contribution indicates that the dispersed Cu particles are elongated with the cold rolling. These results demonstrate that the neutron transmission analysis is useful for microstructural characterization of steels and the sequential change of the microstructures.