water tempered or oil tempered

[loiner1965]

sorry if this has been done before but how can one tell if a sword as been water or oiled tempered...reason i ask is the smith of my showa katana has been known to water temper his swords and not oil.

http://www.ryujinswords.com/kanemune2.htm

here is a link to one of his swords and mine is very similar to this...i could post pics of the hamon but cannot see hada if any,,,,,but its not in polish,

googled a few links of this smith and some of his swords are advertised as having hada....

sorry if its not nihonto but if i cannot ask here how can i find out......many thanks

[Brian]

First thing that comes to mind is how is any activity?

If you are seeing nie, nioi and other activity then a good chance it is water quenched.

Oil quenched hamon are sleepy, boring, lack nie and hataraki. Even out of polish, you should be able to see if there are nie etc.

 

Brian

[nagamaki - Franco]

While there will be some glitter reflecting off an oil quenched hamon held up to a light source, it will lack brightness and clarity, almost as if the light source was being cast through colored glass. On the other hand, a water quenched hamon forming nie and nioi when angled toward a light source will reflect light brightly, similar to the light seen coming from a bright star at night.

 

PS Brian, here's looking forward to having you back soon.

say, didn't I here something about using ultra sound to shatter kidney stones?

[GregD]

A sword by the same smith,folded and oil tempered.A photocopy(pre digital camera) of a sword by Amahide,also folded and oil tempered.

Greg

[Tavroch]

I understand nie and hataraki are found more readily on water quenched blades, while on oil quenched ones nioi is more common and their hamon looks more boring/sleepy. I guess this means the particles and cristals are finer and more evenly spread in oil quenched blades (stars/speckles versus cloudy).

The laws of physics dictate, then, that oil quenched blades must be functionally superior to water quenched ones, as smaller and more evenly distributed particles by definition mean more evenly spread internal forces.

Artistically, water quenched blades of course look better, because water quenching generates larger and more unevenly spread activities in the hamon, that are, for the same reasons, more visible.

I wonder if the (size of the) steam bubbles that form (more/less) in water/oil during the quenching could have anything to do with the size and distribution of the stuctures that are formed.

Has this been researched? What is the result of using still different quenching media?

I have no doubt that people have been experimenting with this, but are there any documented experiments?

[paulb]

Rob,

As I understand it the size of Nie crystals is controlled by:

a) the temperature the blade is heated to

b) the length of time it remains at that temperature

c) the speed with which the blade is cooled.

Of course the other thing that effects it is that the composition of the steel is able to form nie (martensite) in the first place.

 

Whether it is true I dont know, but my understanding is that blades quenched in water were superior with a harder cutting edge than those quenched in oil. On the down side the act of quenching in water introduces far more stess to the blade than oil tempering. Certainly the amount of activity in water quenched blades is far greater.

One Myth that was discussed at length at the London Shinsa was that "You dont find Nie on oil tempered blades". I beleived this for many years but apparently it is not true. Although homogeneous mill steel contains some impurities and it possible that these are capable of forming ko-nie. This is always small and unevenly dispersed. effectively it is accidental rather than created by the smith.

[Jean]

An old friend of mine (he was working for Stanley (tools)) told me that Stanley's hammers were quenched in oil because the steel was less britlle and thus was not subject to splinter. Much more elasticity.

[Tavroch]

Bear with me for a moment please; I feel a rather long rant coming up:

 

What I'd like to know is what causes the different results of oil quenching vs water quenching.

Given that the temperatures of the oil and the water are the same during quenching, one would expect a comparable rate of cooling in both media.

The temperature at the surface of the steel during quenching is influenced only by the difference in the ways in which the different media react to the heat of the steel.

I guess both water and oil will evaporate forming gaseous bubbles at the steel surface.

I guess further that the bubbles in water will be bigger, more unevenly spread and/or more violently exploding/imploding than the bubbles in oil.

I guess also that these bubbles must have a big influence on the temperature near the steel surface. Compared to the influence of convection currents in the fluid, I'd say these bubbles might be THE major influence on the local surface temperature of the steel during quenching. These bubbles might even completely determine the convection currents near the steel surface at the critical moment during quenching.

This influence on temperature alone might be a reason these bubbles are the thing that determines the activities in the resulting hamon.

In addition, would it be possible that the exploding/imploding of said bubbles DIRECTLY influences the forming of the various crystalline structures in the steel?

Kind of a shock-treatment; I know that this exploding/imploding can be quite violent at micro-scale; imploding micro-bubbles can seriously damage ship's propellers for example. And I know that the influence of shocks on the formation of crystals is a known phenomenon worthy of research in other fields.

I would be very interested in any research on the influence of these bubbles on the formation of crytalline structures in steel, especially in Nihonto.

Maybe the scale of activities such as nie and nioi is another indication that these bubbles might have something to do with their creation.

So in conclusion: only if the thickness of the layer of clay AND the temperature of the blade AND the temperature of the quenching medium AND the composition of the steel etc etc, are all just right (in other words: if the smith knows what he's doing), only then the resulting exploding/imploding bubbles cause nie, nioi and other crystalline activities to appear.

This would be a subtly different look on the quenching process of Nihonto.

[John A Stuart]

I can tell you some things I have found to be true which I noted in my apprenticeship in a forge and still see working as an engineer. When we quenched steel (of various types) our water bath had a layer of oil on top of the water to prevent shock and internal stresses. As the shaft or spindle was lowered into the bath the oil did a primary quench until it reached the water for the final quenching. When I work on steel if I quench in oil only the steel remains hot much longer and you can not handle it for quite awhile. When done in water it can be handled fairly quickly. The reason for this is the rate of thermal transference of oil is lower than water. The heat transferred to water is much, much faster and stress causing. Another thing about a water quench is that it produces insulating bubbles of steam that create all the activities depending on steel temperatures, water temperatures and even the speed of quench or if the piece is moved within the quenching medium. Oil does not produce bubbles of volatised hydrocarbons to such an extent and thus less activities produced. So the main differences are; 1) rate of heat transfer, 2) insulating effects of vaporised water. I think, not being a metallurgist. John

[Nobody]

What I'd like to know is what causes the different results of oil quenching vs water quenching.

Given that the temperatures of the oil and the water are the same during quenching, one would expect a comparable rate of cooling in both media.

I would like to say a comment.

 

The specific heat of water is extremely high among various materials. And its latent heat is also relatively high. The boiling point of water is much lower than that of oil.

Therefore we can easily imagine how water cools blade effectively.

 

1. The temperature of water does not easily rise compared to oil.

2. During evaporation of water, the temperature of liquid/vapor mixture does not exceed about 100 C, while oil temperature may become much higher.

3. Evaporation of water might prevent continuous cooling at some first phase, but it may cause stronger convection flow and accelerate heat transfer to cool blade surface.

 

BTW, cavitations are totally deferent phenomena, and the bubble attack does not apply to this evaporation by heating.

[Tavroch]

@Moriyama-san:

You are correct of course about the temperatures.

Still it is rather unclear how the steam bubbles affect the local temperature at the steel's surface at the time the phase-changes take place.

I agree cavitation probably doesn't play a role here (although you never know in violent and chaotic processes like these), but what I was getting at is the influence of (micro) shockwaves on the phase-changes and crystallisation that takes place, whether they arise from imploding or exploding bubbles.

Point being that the violent effects caused by the contact of the relatively cool water/oil with the relatively hot steel, might generate (possibly locally very energetic) shockwaves, who in turn might influence the ongoing phase-changes and crystallisation processes.

 

See for example: http://delftoutlook.tudelft.nl/info/indexb71b.html?hoofdstuk=Article&ArtID=4244

 

Knock-on effect

The phase transformations during cooling occur in two different ways. The change of austenite into ferrite takes place as part of a gradual process in which the atoms can move across relatively large distances. In comparison, the change into martensite is a more abrupt process, in which the atoms move together within a very short time span of about 1 microsecond across a relatively small distance (i.e. less than the atomic distance). As a result of this collective movement of iron atoms, the austenite lattice flips into the martensite configuration in one go. The flipping process is a bit like the knock-on effect that topples a row of dominoes. Once a single martensite disc has been formed, the rest follows, causing the lattice structure of martensite to be created in a series of abrupt reshuffles. The series of collective atom movements creates sound waves. Van Bohemen has demonstrated that the acoustic emission measured in this way can indeed be attributed to the creation of martensite.

 

So these phase-changes can cause soundwaves; they can be abrupt processes. I think it's safe then to assume it can work the other way around too: soundwaves (shockwaves) could influence or initiate these phase-changes.

[Tavroch]

By the way, I know I'm talking about stuff way over my head, but in my opinion reaching is the only way to learn things.

[Henry Stewart]

Gentlemen

 

As I pass from entry to entry I was waiting for some one to mention the viscosity difference of the two liquids,which can I believe have a marked effect on the rate of energy transfer.

 

Henry

[Guest nickn]

the sword that strarted this post looks from the hard bits a the peak of the gunome to be oil quenched water quenched blades dop not get these hard dead spots

i hope this make sense

[Guido]

water quenched blades dop not get these hard dead spots

i hope this make sense

Sorry, but even after reading your reply quite a few times it doesn't make any sense at all to me. Not being a native English speaker might be the explanation for that, though.

 

John has a lot of hands-on experience, and Koichi used to earn a living in this field. I have no background in metalurgy, but what they told us makes perfect sense to me. Why can't we just accept what they said? Anybody more qualified may step in, but for the time being I tend to stick with those who know what they're talking about.

[Guest nickn]

oil quenched blades have a hard dead spot at the top of the gunome which you do not see in water quenched gunome hamon this is not my oppinion but fact .from the photos this sword has a gunome based hamon with the tell tale hard dead bright spot that you see on oil quenched swords so in my oppinion its oil quenched

i do not have any oil quenched blades in my collection perhaps someone else can post some photos

here is a very bad picture of what i mean

[Guest nickn]

if you read the sellers description he says its not nihonto but suggests its not oil quenched he doesnt say its water quenched so from his description the stamp no hada and the photos it quite certain its oil quenched showato

[Brian]

Well..this is all way over my head, and I have always been happy to know what the results are and not exactly why. Bubbles and cavitation and stuff.... :?

I thought it was as simple as the fact that water cools the metal faster and at an ideal rate for hataraki formation, whilst oil quenches slower and not ideal for the formation of hataraki.

Therefore oil quenching was less stress on the blade, with less failed swords during this process (important during war when quantity rules over quality)

Water quenching runs the risk of more failed swords due to cracks etc.

That's how I see it...and am happy to not have to be an engineer to understand it

 

Brian

[John A Stuart]

As Brian alluded, keep it simple. I've seen articles on carbon nano-tubule formation in swords that gave such and such a characteristic as if the original smiths could have forseen that formation and its' effect. These are new technological discoveries that are coincidental to what has since been found in a particular group of swords after the fact. Interesting for specialists, but, out of the need to know for art appreciation. The same with whether non-inertial cavitation caused by low energy sound waves would effect the crystalline structure of water quenched steel. All we need to know is that doing this causes that and doing that causes this and which is more desirable. John

[Tavroch]

You are right Brian/John.

My theories about bubble-induced phase changes are bullshit anyway; the activities in the hamon exist throughout the blade, not just at the surface,

which is apparent when a blade is polished. So no such things as shockwave induced nie-specks I'm afraid.

It was a nice idea though, and I had some good fun reading up on stuff and thinking up possibilities.

 

@Henry:

I guess the viscosity of the medium only affects the speed of the convection currents and thereby the heat transfer rate.

So it at least partially explains the difference between oil and water in this regard.

[loiner1965]

just to add.....my sword which is made by fukomoto kanemune which started this thread off and i never noticed before also has the elusive winged wheel stamp on the tang....cannot take good picture of hamon as its hard to capture but easy to see if you understand....i might have it polished lol

[loiner1965]

hard to tell due to light and polish but the temper goes all the way.....not sure if its nortare or three peaks etc

[bluboxer]

Greetings,

I have seen the topic of heat treating come up several times and would like to recommend/suggest visiting this forum http://forums.dfoggknives.com/index.php ... e3&act=idx and doing a search on heat treating (the hardening and the tempering) of steels.

This is a complex subject with many nuances and a precise nomenclature.

Also,I do believe that "activity" is a result of the composition and forging of the steel and the smith tailors his heat treatment to bring out these features and for his particular requirements.

 

Respectfully,

Alan.

[Tavroch]

Does anybody have any ideas on the type of clay used when quenching in oil?

Is the same type of clay mixture used in oil as is used when tempering in water?

Is the way it is used any different?

Since when is oil tempering used?

From what period is the oldest known example of an oil tempered blade?

Are they all post-industrial age? Any medieval smiths using oil?

Any thoughts? Any documented knowledge?

Can anyone point me to some (online) documentation on the subject?

Were there ever any other media used for tempering?

[John A Stuart]

1) Department of Materials and Metallurgical Engineering at the Indian Institute of Technology, Kanpur, 208016, India

 

Published online: 25 October 2008

 

Abstract A wide variety of ferrous arrowheads were in use in ancient India. Several typical chemical analyses of arrowheads found from archaeological excavation carried out at Kaushambi are reported in this paper. The average carbon content of these arrowheads varied from as low as 0.1 wt.% to approximately 0.9 wt.%. Literary evidence for oil quench hardening of ferrous arrowheads, as reported in famous Sanskrit epics—the Rāmāyana and the Mahābhārata—have been discussed in this paper. This type of quench hardening was intentionally adopted as it helped in preventing distortion and formation of quench cracks in arrowheads. The oil quench-hardened arrowheads were rubbed on stones to sharpen them, which also brought about tempering of martensite due to frictional heat.

 

There are a few media for quenching. Water, brine, oil, air and molten salts. The oils used these days are special polymers with high flashpoints.

 

You must define for yourself tempering and hardening. Start with de-austenisation. Next eutectoid, hyper-eutectoid and hypo-eutectoid steels. Then look up pearlite, ferrite, austenite, martensite and bainite. These will define it further for you. googling these terms will be much easier than me writing it down here. John

[Tavroch]

Thanks John.

Anything more specific on the aproximate age of these arrowheads? 5000BC? 100BC?

I went through most of the stuff you mention over the years.

The eutectoid family recently in connection with Wootz steel.

Martensite I know from fencing: the 'best' (FIE approved) fencing weapons nowadays are made from

'maraging steel' (a contraction of the words martensitic and aging), which gives them the needed strength, flexibility and resitance to breakage.

At the time I was researching the claim that it would also be the type of steel

with the best guarantee to leave a flat surface after breaking instead of a sharp edge.

The advantage of which is obvious in sports fencing.

Turned out to be not the case, just a rumour.

I found that a lot of the history of iron and steel is covered in all kinds of myths and rumours.

What more do you want in a hobby eh?

(Not to mention work; I've been a metalworker, engineer and NC-programmer most of my working life.)

An inexhaustible supply of mysteries to look into.

I am wondering lately why it took me so long to discover the wonderful world of Nihonto.

I'm finding that a lot of things that interested me over the years come together here.

[John A Stuart]

Hi Rob, This is all old hat then. I thought that it was new subject matter and was pointing out some fundamentals. The Ramayana was compiled between approximately 400 BCE and 200 CE and the Mahabharata between 800 BCE and 400 CE. Somewhere in that period, for the oil quenching. John

[Tavroch]

Thanks John.

Old hat, old hat... I don't think anything is ever old hat.

I keep reading and re-reading stuff as my viewpoint changes and when learning new things.

Combining that with my less than perfect retention, I think the world of iron, steel and other metals will easily keep me busy the rest of my lifetime.