1957년 원주 법천사지 지광국사탑 수리에 사용된 철물(鐵物)의 재료학적 특성 연구

Abstract

National Treasure no. 101, the stupa of State Preceptor Jigwang from the Beopcheonsa Temple Site in Wonjuhas been transferred from place to place and reassembled several times since it was built. In particular, overalldismantling and repair was carried out in 1957 to restore parts damaged by bombing during the Korean War. Documented information on the repair process and materials used at that time does not exist. However, varioustypes of metal materials used for this stupa have been identified during conservation work. Besides clamps anchorbolts, 9mm-thick circular rebars were mainly used for joining the parts of this stupa, while circular rebars and wiresof various thicknesses were used for joining the parts with mortar restoration materials. Although deformed bars aretypically used for stone pagodas classified as architectural structures, smooth circular rebars were used in this case. In terms of restoration using mortar, material shapes were transformed, bound alternately, and twisted irregularly toimprove bonding strength and coherence in order to insert restoration materials and to bolster structural weaknesses. In addition, metallographic analysis showed the material to be hypo-eutectoid steel with low carbon content. Manynon-metallic inclusions in the shape of drops of different sizes were included, which do not affect the wholeelemental composition due to the very small quantities involved. Qualitative and EPMA analysis of Mn and S, whichwere not identified by SEM-EDS area analysis, established an even distribution of MnS in crystal grains of themicrostructure, regardless of the shape of the samples. It is presumed that secondary homogenization and softeningmight have been conducted after manufacturing to facilitate the working process. Furthermore, in consideration ofproperties indicating that the thinner the steel is, the less carbon content contained and the greater the elasticity andelongation, it is judged that restoration work was ordered.