Water-Quenching vs. Oil-Quenching
Posted 31 January 2013 - 02:45 AM
There are other additives that will produce similar effects, ie. caustic soda (sodium hydroxide). John
Posted 31 January 2013 - 07:31 AM
I just wanted to bring up a couple of points regarding steel composition and hardening.
I would prefer to describe tamahagane as a "simple" steel rather than "pure" in that the two significant elements are iron and carbon with some other elements as impurities existing in insignificant amounts (hopefully).Modern steels have a higher degree of purity in a sense.
As we add alloying elements like manganese,molybdenum and chromium (just to name a few) the nose of the TTT moves further away in time so we can cool at a slower and safer rate while still obtaining sufficient martensite.
With respect to the "hard spots" observed in gunto; I feel this is an artifact of the steel composition rather than the method of quenching.
I also think that nie is not an indicator of the quenching medium but of how the steel was smelted,forged and heat treated.
The reason that smiths chose fresh water as a quenchant was because it perfectly matched the time constraints with simple steels. If they used saltwater or seawater, as I'm sure many tried, the blade did not survive the thermal shock and if they used animal fat or vegetable oils the blades did not get hard.
Now on top of all that you can through some clay on the blade to make the ridge and spine cool even slower so there is little chance of martensite forming elsewhere (differential hardening).I have heard it postulated that the thin layer of clay on the ha reduces the effect of the vapor barrier that is formed and increases the local cooling rate even further.
Posted 31 January 2013 - 02:46 PM
The yakiba is considered nioi, that is why it is often said that all swords are nioi-deki
Please open Nakayama's book page 91 or the craft of the Japanese sword (Y.Y.) page 92. Nioi deki or nie deki are related with habuchi not yakiba (which is mainly made of martensite and nie or
Posted 31 January 2013 - 04:00 PM
So, by definition, all swords are nioi based. Some have more nie in the habuchi then others. When the amount of nie becomes great (whatever that means), the sword is then said to be in nie-deki. It still has what is called a nioi-guchi. All swords have a nioi-guchi. To paraphrase Nakahara, sometimes a sword will be described as done in ko-nie-deki by one person, then another will say nioi-deki with abundant ko-nie. That is how it is....
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