Thanks for the responses folks, just the information I was looking to hear.
I certainly won't argue your knowledge of the properties of steel. That's definitely a losing battle on my part.
But, I wasn't claiming that I notice a difference between harder and softer steel, if that's what you inferred from my statement. I was just saying that in my (limited) experience, the san mai blades I've used have seemed to have less flex than the monosteel knives I've used. Obviously, that's quite a small sample, and I guess probably says more about those particular knives than it does about the inherent differences in blade construction.
I'd certainly like to hear the scoop on this though. Are there any metallurgical factors at play concerning the stiffness between mono/clad blades, or is it just down to the properties of individual knives?
the san-mai knives i've used have tended to be quite stiff, which i like, but i'd say that they are stiff because they tend to have thicker spines than monosteel knives. i love san-mai knives like Heiji, Shig (and the good) Takedas. i hope to try a DT san-mai,some day.
The examples of san mai I have made, have no "softer" layer. I construct mine using all hardenable steels. O1, 1084, 15N20. If the bend, and if they take that bend, I screwed up big time!
Hoss made a post quite a while back saying that san mai blades are stiffer due to the tension created between the different steels when forge welded. Hoss - correct me if I'm wrong.