Not sure where to put this, so here it goes.

[Spongebobby]

Dear steel junkies and kin, I was wondering what the rockwell hardness of an authentic samurai sword made by a mastersmith would be, i'm not expert on these things. I just heard a good samurai sword could stay paper push-cutting sharp for decades. Is this true? What do you think a rockwell on one of those would be?

 

[Bigfattyt]

Probably get a better response in the sword forum. Maybe a mod will move it.

 

[Shorttime]

Educated guess.

50-56 Rockwell for the cutting edge.

47 Rockwell roughly for the blade spine.

Bladesmithing and tempering was an art, and a well understood process. But Feudal Japan was a metal-poor island, and, of course, they had little understanding of metals chemistry. My guess, again, educated but still a guess, is that hardness will vary with the chemistry of the steel and the smith's understanding of the process.

I can tell you this for sure: I would not want to be the one to put Rockwell tester marks in an authentic Katana!!!!

 

[BP Green]

Interesting question though.