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 Post subject: Water-Quenching vs. Oil-Quenching
PostPosted: Tue Jun 19, 2007 11:05 am 
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Jo Jo Saku
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Hi all,

maybe a silly question for some members - but what (apart from the tradition of swordmaking) makes the difference between water-quenched swords and those who were oil-quenched?
I heard, that the quenching method is even visible on a finished blade and that some Hataraki do not appear on oil quenched blades. But that´s about all I know.

- Are there any additional effects on i.e. the cutting ability or firmness of a blade?
- And what are optical indicators of an oil-quenched blade?

many thanks in advance,

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PostPosted: Tue Jun 19, 2007 3:28 pm 
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Sai Jo Saku
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Quick answer from more of a fittings collector ?:

Think of it in photography terms-

Water: high speed / short exposure shot.
click- the millisecond of existence is burned or crystallized.

Oil: slower speed/ longer exposure
click- slower cooling speed, the resolution is much more blurry and less defined.


Water: you get more. But the high stress of the rapid action can also mean a lot more goes wrong. *Tink!* blade breaks in quenching.

Oil: Makes a weapon with less or little artistic value. But chances of it surviving the process are much higher.

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PostPosted: Tue Jun 19, 2007 4:19 pm 
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Sai Jo Saku

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I like the analogy Curran, I'd like to use it sometime when trying to explain the differences.
Basically oil tempering is a more gentle process which is less likely to damage but is unable to produce the dramatic crystal structures and actvity that can be achieved through water quenching.
Interestingly I was reading an interview with the last surviving Yasukuni smith regarding the story of some years ago that Yasukuni smiths tempered in oil. He said this was definately not the case. However they did reheat blades after water quenching and cool them in oil. obviously this was at much lower temperatures so as not to destroy the crystal structure achieved with the original temper, but it releaved some of the stresses inherent in the water quenched blade.


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PostPosted: Wed Jun 20, 2007 6:04 am 
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Sai Jo Saku
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Paul,

Was that in the Yasukuni book? I seem to remember reading something similar and wondering about how that would all work out.

There is always a lot of debate about mizukage = saiha , but I've seen various things done... use of scalding water from a steam kettle, use of heated copper block (with and without meter so as to get the desired temperature for softening the machi for shortening) etc..
So the use of oil and water cooling troughs in conjuction with these other tricks can produce some odd results of all sorts.

Feel free to use the photography analogy. The wife is the classical photographer. I hoped I got the analogy right, as I didn't want to wake her to ask if I was mucking it up.

CCC

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PostPosted: Wed Jun 20, 2007 8:40 am 
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Sai Jo Saku

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Hi Curran,
The reference was in the new generation of Japanese swordsmiths by Tamio Tsuchiko which contains an interview with Osaki Yasumune who was the last living Yasukuni smith. I believe he died in 1997.


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PostPosted: Wed Jun 20, 2007 9:23 am 
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Jo Jo Saku
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Curran & Paul,

thanks for your replies so far.
Especially the photography comparison makes it very comprehensible.

cheers,

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PostPosted: Sat Jun 23, 2007 4:18 pm 
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Sai Jo Saku
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Paul,

Thanks. I have that one on my shelf. I felt I had read that before.
Good luck Martin.

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 Post subject: Re: Water-Quenching vs. Oil-Quenching
PostPosted: Mon Jan 28, 2013 3:56 pm 
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Sai Jo Saku
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Hi Paul and Martin,
I read that interview and very interesting it is too (oil in the Yasukuni forge!...that will unleash a whole raft of rumours).
I presume you are also interested in the "look" of oil quenched blades?
Over the years I have seen many and 99% of the time it is relatively easy to tell.
Firstly...the shape is 99% of the time that very distinctive gunto/seki/showato shape...
Secondly....always with the same standard of polish (usually no ACTUAL yokote (only cosmetic)...when you look at the ji surface there is 99% of the time just muji. There is no distinct nie present and the hamon is often a wider nioiguchi without distinct hataraki anywhere.
That these hamon have bright/pointy spots in the niouguchi line is often seen....I think this is strongly a pointer to oil quenching...BUT, I have seen these spots on rare occasions on gendaito by good WWII makers...eg Watanabe Kanenaga (see pic).

I raise this point as currently on another thread is a NTHK papered blade with a seki stamp...members commented that it must be showato because it had the bright spots...while I agree that the spots are a pointer, as I have also seen them on obviously gendaito blades, I think we should just rememeber that "there are always exceptions" in nihonto.
Whether this means that some gendaito ALSO are quenched in oil I can't be sure, but it might be so...or maybe the result of a post water quench "de-stressing" like in Yasukuni forge.
Regards,


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 Post subject: Water-Quenching vs. Oil-Quenching
PostPosted: Wed Jan 30, 2013 2:36 am 
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Jo Jo Saku
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I would like to add that a smith does not have a free choice of his cooling liquid. The respective steels are different, and while a pure TAMAHAGANE based carbon steel is very likely not to get hard in oil, an alloyed tool steel may crack when cooled in water.

Until recent times, there was no metallurgical knowledge in Japan, so the safest way was to follow the master's instructions. Everything in this field was - and is - practice and experience, and that is why Japanese craftsmen generally cling to their traditional methods.

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 Post subject: Re: Water-Quenching vs. Oil-Quenching
PostPosted: Wed Jan 30, 2013 3:24 am 
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While most heat transfer is done in the change of state there is some leeway achieved by the initial quenching water temperature. This is why you see seasonal reference to quenching with the water at a specific time. A hotter quench medium will reduce shock. John
Oh, BTW oil quenching is achieved by a layer of oil over water. The initial oil layer reduces the temperature somewhat to reduce shock with water being the true quench under the oil. Oil does not facilitate a rapid quench to produce martensite if used exclusively. Heat transfer to oil alone is too slow. J

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 Post subject: Re: Water-Quenching vs. Oil-Quenching
PostPosted: Wed Jan 30, 2013 3:59 am 
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Formation of martensite depends on the amount of carbon in the steel, the presence of other alloying elements, the temp of the heated blade, and the cooling rate of the quench. Oil is a slower quench than water. Slower means less stress. Less stress means less cracking of the blade.

Tamahagane is a rather pure from of steel, having small amounts of other elements. It forms lots of martensite when heated correctly and water quenched. It takes skill and experience to do so without the stress cracking the blade. Oil is easier on the blade, and while it doesn't form as much martensite because of the slower quench rate and the presence of other elements in western steel, it does permit one to harden blades with a greater margin of error and thus less cracking. It is nice for mass production. One usually won't see much, if any, nie in an oil quenched blade because nie is formed by the rapid cooling rates associated more with water quenching.

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 Post subject: Re: Water-Quenching vs. Oil-Quenching
PostPosted: Wed Jan 30, 2013 10:03 am 
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Sai Jo Saku

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Hi,

Quote:
Tamahagane is a rather pure from of steel, having small amounts of other elements. It forms lots of martensite when heated correctly and water quenched. It takes skill and experience to do so without the stress cracking the blade. Oil is easier on the blade, and while it doesn't form as much martensite because of the slower quench rate and the presence of other elements in western steel, it does permit one to harden blades with a greater margin of error and thus less cracking. It is nice for mass production. One usually won't see much, if any, nie in an oil quenched blade because nie is formed by the rapid cooling rates associated more with water quenching.


False. Japanese sowrdsmiths used water only because they didn't know another method. You can obtain martensite with all steel which are eutectoid and with oil quenching. The difference between oil and water ist that oil didn't produce vapor and the cooling is more homogeneous.

http://academic.uprm.edu/pcaceres/Cours ... MSE8-2.pdf

http://imperialoil.com/Canada-English/F ... SFenso.pdf

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 Post subject: Re: Water-Quenching vs. Oil-Quenching
PostPosted: Wed Jan 30, 2013 10:55 am 
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Sai Jo Saku
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Edit: erased first message.

Jacques, please post pics of the oil-quenched blades with nie that you are talking about.

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 Post subject: Re: Water-Quenching vs. Oil-Quenching
PostPosted: Wed Jan 30, 2013 3:23 pm 
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Sai Jo Saku

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Hi,

Quote:
Jacques, please post pics of the oil-quenched blades with nie that you are talking about.


I don't speak about nie but martensite, that's all. Saying you cannot obtain martensite with oil quenching is wrong. Yakiba is made of martensite. Nie needs a more complicated process (and water vapor).

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 Post subject: Re: Water-Quenching vs. Oil-Quenching
PostPosted: Wed Jan 30, 2013 4:24 pm 
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The point I was making, Jacques, is that oil quenching has too slow of a quenching velocity to form adequate martensite in swords, I'm thinking. A mixture of oil and water must be used to raise the rate of quenching velocity. A modern example is the use of varying % UCON heat transfer fluid 500 with water. The % varies the quench velocity for optimisation according to material. This is a polyalkylene glycol and is not an oil, but, replaces the typical diferential quenching bath. I wonder is there documentation of the quenching baths used for oil quenched gunto that can determine if it was oil over water used or was oil alone able to produce martensite enough to create an hamon on thin sword steel. When I was heat treating steels in my apprenticeship I learned that the oil created a barrier on the steel before water interface and reduced the shock. Of course I was treating webs, cranks and spindles in the tonnes of weight. John

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