Neutron diffraction mapping measurement for Japanese nails in the ancient and present days

古代および現代の和釘を用いた中性子回折マッピング測定

山下 享介; Harjo, S.   ; 梅澤 修*; 川崎 卓郎   

Yamashita, Takayuki; Harjo, S.; Umezawa, Osamu*; Kawasaki, Takuro

Japanese nails have been applied to various wooden building skeletons in Japanese temples and shrines over a period of one thousand years. Since most of Japanese nails in the ancient day are designated as an important cultural property, their destructive examinations can be hardly done. In order to discuss the material and its manufacturing process of the Japanese nails, we have done some experiments on both ancient and present Japanese nails. In this study, phase, texture and residual stress of the Japanese nails were investigated using neutron diffraction. Two types of Japanese nails were provided; one was an ancient nail obtained from Houryuji-temple; the other was a present nail forged by blacksmith. BCC iron peaks are identified in both. Although the cementite and ferrous oxide peaks are detected in the present nail, no cementite is detected in the ancient nail. The residual stresses of each nail were very low. The ferrite grains of each nail were randomly oriented.