Abstract
Following research into methods for making practical use of Japanese swords, the following points were noted;
(1) Upon examination of the forging face, it was found that the microstructure, hardness, and residual stress differed.
(2) In order to discover more about clad forging, a pre-heat treatment of the full annealing process was necessary.
(3) Especially in the core steel, non-metallic inclusion was noted in the area of the sharp side of sword.
(4) Upon examination of sample A, B, and C, all were found to contain pure material; the sample C however had high amount of Ti, Ca and V.
(5) Ordinary a core hardness of Hv 200 is obtained by addig 0.1% C while quenching, however, an edge hardness of Hv 700800 can be easily obtained by the addition of 0.50.6% carbon.
(6) Compared to other research materials, sample C had a low residual stress after compressive stress; however, sample C showed signs of past tempering and grinding that may account for the low residual stress. It is assumed not to be an error in measurement.
(7) Upon examination of the microstructure, the central portion of the sword showed overheating in low carbon steel ferrite. Follow-up research on old and new sword should include the traditional Japanese sword virtues of strength, cutting ability, and flexibility.
