2005 Volume 91 Issue 1 Pages 39-46
"Ohkajiba", which is the Tatara steelmaking process in Edo and Meiji eras, early modern times, corresponds to the recent steelmaking shop process including blooming mill process of the integrated iron and steel works. Those processes include the decarbonizing process of pig iron, Zuku and Bugera, the removal process of inclusions, mainly oxides, the homogenizing process and manufacturing process of products such as "Hocho-tetsu and Waritetsu", mild steel.
Considering the thermal technology in early modern times, it was supposed not to be able to melt low carbon steel such as the Hocho-tetsu though pig iron was probably able to melt due to its low melting point. It means decarbonizing process at the "Ohkajiba" should basically be half-melt reaction or solid reaction. In spite that the rate of decarbonizing process under this half-melt reaction or solid reaction supposed to be extremely slow based on the general modern metallurgical reaction kinetics, decarbonizing rate at the "Ohkajiba" was very fast based on the some descriptions about the operation at the"Ohkajiba". That rate is equal to that in large size open-hearth furnaces, though it is slower than that of large size basic oxygen furnaces. Those facts are amazing for modern metallurgists.
In this report, supposed operations with decarbonizing process in the "Ohkajiba", information from a modern blacksmith of Japanese swords and the simulation results were proposed and some considerations from the point of view of modern metallurgy were discussed through those results.
