황남대총 남분 출토 칼과 창의 미세조직 분석을 통한 신라의 철기제작 기술체계에 관한 연구

Abstract

The metallurgical microstructure of a sword and a spear excavated from the Hwangnam Great Tomb was examined in an effort to understand the iron technologies applied in the manufacturing of Silla iron articles. The development and peculiar distribution pattern of such diverse microstructures as martensite, pearlite and ferrite were found to have crucial information about ancient iron-smelting, steel-making and heat-treatment. It is suggested that the low temperature reduction process was in use at the time for producing bloomery iron of low C content, which was supplied as an input material for shape-forging. The strengthening of iron articles was found achieved in two steps, i.e., first by increasing the C content in a carburization treatment and then by quenching with its effect strictly confined in a specific part requiring high strength in service. The Silla iron technology as observed in the microstructure of the present artifacts may be characterized by the unique engineering procedure occurring in the order of shapeforging, steel-making and heat-treatment.