Printed in the Republic of Korea Studies in Iron Manufacture Technology through Analysis of Iron Artifact in Han River Basin during the Proto-Three Kingdoms

Abstract: The most widely excavated iron artifacts used as weapons or farm tools from central southern regions of Korea were subjects of non-metallic inclusion analysis through metallographic examination, microhardness measurement, and scanning electron microscopy with energy dispersive X-ray spectroscopy. Through metallographic inter-pretation and study of the analyzed results, the steel manufacturing and iron smelting using heat processing in the iron artifacts excavated from the central southern region of the ancient Korean peninsula was studied, and the analysis of the non-metallic inclusions mixed within the metal-lic structures was interpreted as the ternary phase diagram of the oxide to infer the type of iron ores for the iron products and the temperature of the furnace used to smelt them. Most of the ancient forged iron arti-facts showed Al2O3/SiO2 with high SiO2 contents and relatively low Al2O3 contents for iron ore, indicating t hat for Al2O3 below 5%, it is presumed that magnetic iron ores were reduced to bloom iron (sponge iron) with direct-reduction process for production. The temperature for extraction of wustite for Al2O3 below 1 % was found to be 1,020∼1,05 0℃. Considering the oxide ternary constitutional diagram of glassy in-clusions, the steel-manufacturing temperature was presumed to have been near 1,150∼1,280 ℃ in most cases, and minimum melting tem-perature of casting iron part excavated in Daeseong-ri. Gyeonggi was near 1,400℃, and it is thought that hypoeutectic cast iron of about 2.3% carbon was casted and fragility of cast iron was improved by de-carburizing in solid state