Metallurigical Analysis of Third to Fifth Century Swords with Ring Pommels Excavated in the Asan-Cheonan Region

Abstract

This study conducts a metallurgical analysis of three swords with ring pommels (Hwandu sword) manufactured during the Proto–Three Kingdoms period and the Baekje period and excavated from the Asan and Cheonan. Specifically, we carried out analyses based on a metallurgical microscope, scanning electron microscopy with energy dispersive spectroscopy. the swords were made of bloomery iron produced through direct smelting and formed by hammering hypoeutectoid steel. It was also confirmed that other heat treatment techniques than shaping were not applied to them. In addition, all of them have a high carbon content and the crystal grains are well refined, so it is believed that the hardness and strength are high. Moreover, the analytic results of nonmetallic inclusions, No.2 swords have glassy slag and the others verified the existence of fayalite and wüstite on the glassy matrix. And a high Ca content overall. The results of comparing the swords with other swords with ring pommels excavated from the corresponding region indicated that heat treatment techniques were not applied to these artifacts despite the existence of such techniques. Thus, we analyze that the study subjects were produced as ceremonial items rather than weapons. Furthermore, the calculation results of ratios, such as CaO/SiO<sub>2</sub> and (Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub>)/(CaO/SiO<sub>2</sub>), indicate that the study subjects were produced based on a similar smelting processing system. Based on the analytic results, this study also suggests a possibility of the addition of slag generation agents or the use of iron ores with a high Ca content.