Originally Posted by tsubame1
If harden = to make an hard cutting edge and temper = relief the stresses with a subsequent (softer) heating, well japaneses where well aware and able to make both, even in older times. It's a matter of Schools. Somes applied tempering, some not. TOGETHER with differential hardening.
Samurai too. I wonder why the heck they used the same type of technology
for almost 1000 years being such blades so prone to bending...