X-ray transmission imaging with X-ray diffractometry and time-resolved tomography with three-dimensional X-ray diffraction microscopy have been used to observe solidification and transformation in carbon steel and other Fe-based alloys. The imaging techniques showed a massive-like transformation, in which multiple austenite grains were produced in a single δ grain through a solid–solid transformation. The critical velocity from the diffusion-controlled growth of the γ phase to the massive-like transformation was as low as 5 µm/s. X-ray imaging indicated that the δ phase transforms massively to the γ phase in the conventional solidification processes, such as continuous casting. The massive-like transformation and multiple γ grains that were produced in the transformation were related to the subsequent microstructure evolution and casting defect formation. Solidification model including the massive-like transformation is expected to improve our understanding the solidification and the related phenomena in the peritectic steel systems.

通过X射线衍射法进行X射线透射成像以及通过三维X射线衍射显微镜进行时间分辨断层扫描已被用于观察碳钢和其他铁基合金的凝固和相变。成像技术显示出大块样的转变，其中通过固-固转变在单个δ晶粒中产生了多个奥氏体晶粒。从的扩散控制生长的临界速度γ相对大量样变换为低至5 μ米/秒。X射线成像表明δ相大量转变为γ常规凝固工艺（如连续铸造）中的相。块状转变和转变中产生的多个γ晶粒与随后的组织演变和铸件缺陷形成有关。包括块状相变在内的凝固模型有望增进我们对包晶钢体系中的凝固及其相关现象的理解。