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Post by mythosequidae on Sept 19, 2009 0:10:37 GMT
Hi. They mention that during the quench, the cutting edge cools more quickly than the central blade area, resulting in a hard/resilient condition. Simply due to less material on the edge. Is this not differentially hardened? Why no temper line if this is the case?
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Post by Deleted on Sept 19, 2009 2:32:42 GMT
Differential hardening in the common usage denotes a big difference in the temperatures applied, causing different crystal structures to form. This is usually done purposefully by means of clay application or edge quenching. There will be a different hardness between the edge and the central part of the blade but it may not be enough to cause different structures to form. Keep in mind that the heat treating done on Albions is controlled well and not just a dunk in water. Are you trying to argue that the only form of hardening that would NOT be differential would be something like marquenching?
If there is differential crystal formation, the blades may not be highly polished enough to show this - reminds me of an old seax polished by a Japanese polisher and it showed a hamon.
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Post by Deleted on Sept 19, 2009 3:05:48 GMT
To the best of my knowledge:
It would technically be differential but not in the common usage of the term, like Vyapada said.
Though there is a difference in hardness it isn't that big of one
Also, in order to have a hamon you need a stark line of contrast like claying produces. This is why when a blade is edge quenched you can sometimes see a faint but still visible hamon. In this case the difference in hardness is substantial it's just not very defined.
Now think how less visible the change in hardness would be if the whole thing were quenched. Especially since there is less of a difference to begin with.
Also the level of polish has a lot to do with how visible a temper line is.
So basically it is Differentially Hardened, there is just less of a "difference" and there is no line.
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