Time-resolved X-ray imaging for observing solidification of steels

X-ray imaging techniques for observing solidification of steels and the experimental results of pure Fe, carbon steels, and Fe-5.3 mass% Si steel using SPring-8 are reported. Some X-ray imaging techniques such as absorption contrast, topography and phase contrast and the in-situ observation method of solidification at SPring-8 are explained. When there is a difference of density between the solid and liquid pure Fe, the solidification process can be observed by detection of the solid/liquid interface of pure Fe. The increasing process of dendrites arms of carbon steel, and transformation from the δ phase to the γ phase were observed. The concentration of Si in the liquid phase of Fe-5.3 mass% Si was measured by imaging of absorption coefficient change. Illustrated are X-ray imaging techniques, X-ray absorption coefficient of some elements, Brilliance of synchrotron radiation at SPring-8, setup for the in-situ observation of solidification, the static image of solid/liquid interface for pure Fe, the intensity of the transmission image in the vicinity of solid/liquid interface, growing interface of pure Fe, dendrites of carbon steels, coarsening of the secondary dendrite arms in 0.3 mass% C steel, dendrite arm spacing during coarsening for 0.3 mass% C steel, transformation from the δ phase to the γ phase, and imaging of absorption coefficient change in Fe-5.3 mass% Si steel. (S.Y.)