A preliminary study on the role and implication of plate-type iron artifacts in the ancient iron technology of Korea

Special iron objects in the form of a narrow plate with a fan-shaped blade on one or both ends, but with a substantial variation in shape and size, have continually been excavated from ancient historical sites located in the southern part of the Korean peninsula. The frequency and abundance of their excavation imply that they must have played a crucial role in the initial shaping of the Korean iron industry. Little is known, however, of their intended purposes or the exact engineering processes applied in their production. Speculation suggests that they might have been used as currencies or intermediate materials for the making of finished products. This study examined the microstructures of three such iron objects from the Korean Three Kingdoms Period (ca. 300–600 AD). It was determined that they were made of low carbon iron generally containing a number of non-metallic inclusions, with hints of surface carburization particularly at the ends of the plates. These results reveal the likely presence of an iron technology based primarily on the bloomery technique as opposed to the Chinese style of iron-making based on cast iron technology, which was also in use in ancient Korea.