San mai wa gyoto

Hi Bill, just curious really - how does the RHC differ across different parts of the blade? I kinda get that differentially treated (ie. Hamon) blades have a relatively soft spine and harder cutting edge. But is it a similar case with San Mai and if so how does the relative hardness differ from that in a typical clay method W2 blade?

Sorry if this question doesn't belong in this forum, but I'm very interested in the properties of this particular style of knife.

Cheers...Pete
 
Hi Bill, just curious really - how does the RHC differ across different parts of the blade? I kinda get that differentially treated (ie. Hamon) blades have a relatively soft spine and harder cutting edge. But is it a similar case with San Mai and if so how does the relative hardness differ from that in a typical clay method W2 blade?

Sorry if this question doesn't belong in this forum, but I'm very interested in the properties of this particular style of knife.

Cheers...Pete

Pete, with a difrentially hardened blade the blade steel is all the same and either clay has been applied to the spine to retard heating/cooling or some form of heat manipulation is used (heating only the edge to austinizing temp or heating the already hardened spine/soft back draw to soften it more than the edge). to get the edge hard and the spine softer.

With san mai construction the sides/outer cladding of the blade are nonhardenable steel (whether damascus or mono steel) and the core is a hardenable steel. the whole blade is then austenitised and quenched leaving the core from spine to edge hard and the sides of the blade soft. this give a little more support to the hardened core than a soft spine hard edge. the disadvantage is that the blade has little resistance to bending. However a bent san mai blade is easily straightened.
 
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