Mcrostructure and Technology of Ancient Iron Axes Excavated from Suchon-ri, Gongju, Korea

摘要

A cast iron axe from the second century BC and a forged iron axe from the fourth century AD were excavated from the Gongju Suchon-ri site. Metallurgical examination shows that the cast iron axe was made of white cast iron alloys of hyper-eutectic and pearlite of near eutectoid composition with temper carbon. This axe was decarburized to produce steel in an oxidizing atmosphere for a long time. However, cementite and malleable cast iron coexisted inside the axe because of an insufficient heat treatment time for decomposing cementite into ferrite and temper carbon. By contrast, the microstructure of the blade of the forged iron axe consisted of martensite formed by quenching. The cast iron axe is evidence that the Gongju area imported ironware from China in the second century BC. The forged iron axe supports the idea that the forging technique was used throughout Southern Korea in the fourth century AD.