Water Quenching Wootz?

[Jacob Christian]

Hello All, 

 

I am working on a wootz Wakizashi and am about ready to heat treat. I normally make Japanese swords out of W2 and do an interrupted quench in warm water but I'm wondering if I might be better off going with oil. 

 

I started going over the chemical composition of my feed material and came up with a manganese content that seems slightly high. 

 

I guess with all of the work that it took to get here it shouldn't even be a question of whether I should use water or not but I have heard that water is the better way to go with wootz.

 

If I did water, then 760C for 15?

 

 

 

[Francis Gastellu]

I don't have good insight to your question (though you might want to consider brine, to which I was recently introduced, but I don't know enough so i'll let those who know better than I do chime in), I just wanted to say good luck for your heat treat, the wakizashi looks good so far!

[Tim Mitchell]

DO NOT WATER QUENCH!!! Wootz is not Japanese steel and you can only do a water quench if you use a slicing action in and out of the water.  You have a significant level of Manganese in that steel (thanks for providing that, it makes giving advice easier) and so the steel will be very hardenable and could get too stressed from the water quench. 

 

Now you may wonder why I say not to water quench even if the steel has similar chemistry to other water quenching steels.  The reason is that not only do you have a much higher carbon content than most water quenching steels, you also have a crystalline structure in the steel which creates possible crack locations. Japanese swords do not have this weakness. Most beginning wootz smiths and even many experienced smiths do not forge their ingots high enough to be able to get full conversion from a dendritic structure to a laminar structure.

 

Hopefully you will have enough V in there to make the pattern visible enough.  Manganese darkens the matrix in the background of the steel and chokes out the pattern from Carbide Forming Elements like Vanadium.  As a result you have to increase the Vanadium level to counteract the Manganese content in the blade or you will get no real pattern.

 

So back to how to quench... using a heated thin oil is best for hardness, however the old blades were often only partially edge quenched which left the main part of the blade Pearlite and the blade edge only quenched Martensite.  No tempering was required as the heat from the unquenched spine would temper the blade edge.  Other methods were used such as a warm air blast which makes a very fine Pearlite structure in the blade.  But for your purposes you probably will want to do a full quench in light oil which has been well heated. Of course it goes without saying that you need to do several Normalization cycles on the blade before you do the hardening quench to relieve the stresses in the blade.  Good Luck! I look forward to seeing the final pattern in your blade.  Well done for having a crack at Wootz!

Edited February 10, 2022 by Tim Mitchell

[Jacob Christian]

Thanks for the reply Tim, I have read many of your posts about wootz and they have all been informative! I was worried about the manganese... So much so that I have developed a cleaner recipe where I can half the Mn content and clean up the extra Si by removing the cast. 

 

Pretty much the only reason I wanted to do a water quench was for the natural sori and more active hamon. I saw some other posts talking about using hot oil (180F) and that would still induce positive curvature. I have test etched and I believe that I got the cementite spherodized, test etches didnt reveal any dendritic structures. The puck went for a 6 hour roast at 1100C and beginning forging was also done at a orange-yellow heat but alas, I am still pretty new at making wootz. Been at it for about 8 months (Weekends and such) and this is the second real ingot I have forged. Talk about a steep learning curve!!

 

Here is the link for the post about positive sori with hot oil if anyone who sees this is interested. 

 

 

2 hours ago, Tim Mitchell said:

Hopefully you will have enough V in there to make the pattern visible enough.  Manganese darkens the matrix in the background of the steel and chokes out the pattern from Carbide Forming Elements like Vanadium.  As a result you have to increase the Vanadium level to counteract the Manganese content in the blade or you will get no real pattern.

 This part is very interesting, I did not know that. I will definitely keep it in mind for future melts!

 

I will be having a go at quenching the blade this weekend so I will be back with pictures regardless of what happens. Using oil it should be quite safe. Oil ill be using is parks 50.

 

Edited February 10, 2022 by Jacob Christian

[Jacob Christian]

On 2/7/2022 at 10:48 AM, Francis Gastellu said:

I just wanted to say good luck for your heat treat, the wakizashi looks good so far!

Thanks! I need the luck, I would be extremely depressed to lose a wootz blade in a quench. Well Actually I have lost a small one in quench.... But it was a test and many things were wrong with that whole setup.

[Tim Mitchell]

No worries Jacob, I am glad that you have been getting some benefit from my wootz posts on here.  I am really passionate about providing good information to make things easier for people like you, starting out in the craft.

 

Having a little bit of Mn in there is good for hardenability of the blade especially if you have been making a super clean steel. The old blades used to have Phosphorus in them which aids in hardenability and under tempering can actually make the blade brittle.  It wasn't a problem for them back then but with modern heat treat it can be an issue.  The old blades also had copper which aids in hardenability as well as a little Mn which wasn't uncommon.  So you have to have some elements in there which aid in getting the hardness in the blade on quenching, whether that is air quench, oil or very careful momentary water slicing quench. 

 

As far as hamon formation, you may likely get a hamon but the type of hamon is different due to the acid etching and heat treat of the blade being slightly different.  Wootz normally speaking (with lower Mn) will have a thickness hardening nature.  Over about 1/8" thickness it usually won't harden and on your blade that would mean a nice differential hardening line... However the Mn level in your blade aids in hardenability and so it will go beyond that thickness in hardening. You can counteract that by not doing a full plunge of the blade but by doing more of a edge in a long bath kind of quench, cutting edge first. Interrupting the quench.

 

I often recommend that you don't use your final sword to do heat treat tests.  Take a wedge of the same ingot which has been through the same processing as your blade and do a quench test to see if it gets the hardness you desire and if you get the differential hardness you are looking for.  If the wedge test is a success you can have more confidence that your blade quench will go well. 

 

Essentially you are dealing with a unique and new steel each time you change your formulation of your ingots and that means that your processing changes and your optimal heat treat changes.  So if you want the best result for your blade.... TEST A WEDGE...

 

Now one other comment about your V levels.  When you increase carbide former levels significantly you will have them resisting the conversion of the pattern in the ingot to laminar structure.  So the higher the CFEs get the more dendritic the ingot will stay.  This is the sort of effect you see in the higher carbon percent ingots.  There are ways to get around this issue but it can be risky.

 

Forging at 1100°C in the first stage should give you a nice laminar pattern, I look forward to seeing your results!

Cheers,
Tim.

[Jacob Christian]

Alright I did the quench last night and it seems that everything went well! I couldn't bring myself to heat my parks 50 to 180F because of oil degradation so I did a 3 sec interrupted quench into 130F plain tap water and then into room temp parks 50 to finish cooling off. The blade was kiln heated to 760C and left to soak for 15 minutes. 

 

It is interesting that you mentioned doing a test wedge because that is exactly what I did. I forged bevels on the wedge and treated the same way that I did the waki and it came out well. You can clearly see the hardening line as well as some wootz pattern.

 

So much great information! I will be adding more notes in my documentation, thanks again Tim! Also I have been posting regular updates to my IG story if you are interested. The name is BesslenBladeworks.

 

Now time for some pictures.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited February 12, 2022 by Jacob Christian

[Jacob Christian]

Sorry for the giant videos... I didnt see a way to make them smaller. 

[Tim Mitchell]

Thanks for the videos Jacob.  There were all kinds of different quenches from ancient times and some of those only worked on specific ingot chemistries at the time.  It was common though to not dunk the blade in like you did here, but to only put the edge in and rock it back and forward.  They even did this with a heated light oil.  One very important thing that I would underline if I could is that every new formulation is a NEW STEEL.. and so what has worked in the past or in historical recipes with one steel formulation won't work the same with the new one.  Wootz is just like all other steel in that there are different formulations and the only thing that they all have in common is that they have a dendritic structure to begin with.  That will make some of the ways we treat ingots similar but there are still many differences and so there will be failures and lots of learning until you find something that you know well and can get a really good quality product with. 

 

One other piece of advice I would give is that you do your heat treating in the dark or in very low light so you can get a better gauge of the temperature at different stages of your quench.

[Doug Lester]

I hold with the advice to only water or brine quench if a fast oil won't get the job done.  I had to do that once when I ran into a bad batch of 1095.

 

Doug