2013 Volume 77 Issue 8 Pages 318-327
The manufacturing technique of steel sheets in the Edo period has been investigated from a Kusazuri armature that is a protector of the waist. The size of the steel sheets is 300 mm by 235-265 mm and 0.6-1.0 mm in thickness. Most of the steel sheets are composed of multiple steels with different carbon contents. The nonmetallic inclusions in the steel sheets are FeO and a few 2FeO•SiO2. Most of the nonmetallic inclusions are finely distributed in the sheets while some lie in lines in parallel to the sheet surface. The nonmetallic inclusions which are arranged in lines were produced during forge welding. From the number of lines, forge welding was performed one to three times. The nonmetallic inclusions are elongated in the side direction of the sheet than the longitudinal direction. This means that a large plate was extended while maintaining the width of 300 mm and was cut to the length of 235-265 mm. The Vickers hardness of the sheets was larger than that of annealed steel sheet in the literature, suggesting that annealing was not performed to the steel sheets after forging. Finally, the steel sheets were shaped and curved slightly.
