Ironmaking and steelmaking process research on Chinese long ring pommel Dao in Han dynasty

The long ring pommel Dao (a kind of single-edged blade), a significant indigenous Chinese weaponry innovation of the Western Han Dynasty, is researched this study. Employing a comparative research methodology, we conduct a scientific analysis of samples excavated from the tombs of marquisates across various regions of China, spanning from the northern to the southern extremities. This analysis encompasses metallographic examination, inclusion composition analysis, and scanning electron microscopy (SEM), complemented by the application of a metallurgical kinetic model to reconstruct key smelting operations. The semifinished materials of the long ring pommel Dao are sourced from two primary origins: bloomery carburized steel and cast iron-puddling joint decarburization steel (cast iron-Chaogang steel). Both pathways exhibit a predominance of FeO_x·SiO_2y oxide inclusions. Our investigation particularly emphasizes the Fe₂SiO₄ inclusions, which have a melting point of 1178℃. By leveraging the length/width ratio of Fe₂SiO₄ inclusions, we can ascertain whether the smelting process involved an all-liquid phase. Notably, the length/width ratio of Fe₂SiO₄ inclusions in the cast iron-puddling joint process exceeded 5. Additionally, our findings reveal that during the cast iron-puddling joint decarburization process, when the forging temperature falls below 880℃, the mesh-like Fe₂SiO₄ inclusions undergo fragmentation. This phenomenon provides crucial insights into the forging system of the Han Dynasty, facilitating a more detailed reconstruction of its metallurgical practices.