# W2 Heat Treat Questions



## nelsonchenknives (Aug 9, 2019)

Hi all, I did my first heat treat ever today, and some very basic questions came to mind, maybe someone here can enlighten me.

1. For the hardening process, can I place the blades in the kiln as it's heating up to the austenitizing temp? My kiln takes about 10-15 minutes to actually get up to 1450F, will there be adverse effects?

2. I read on the data sheet that the quenched W2 steel need to go into tempering oven before the temp drops below 150F, is there any truth to this? the kiln takes a long time to cool down from the hardening temp, and I would rather not use a toaster oven since I don't trust the thermostat on it...

3. I often see tempering cycles listed as, say 450F for one hour for two cycles, isn't this the same as 450F for two hours (one cycle), or something else happens between the two tempering cycles?

Sorry for the long post, thanks in advance : )


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## RDalman (Aug 11, 2019)

1, yes likely adverse effects
2 yes
3 yes something else happens


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## nelsonchenknives (Aug 11, 2019)

RDalman said:


> 1, yes likely adverse effects
> 2 yes
> 3 yes something else happens


 Thanks for the reply Robin, 

1. So do I place the steel in the kiln after it reaches temp? 
3. So I take it that I need to let the steel come down to room temp between the tempering cycles? 

I also shot you a DM on IG, if it's easier for you answer there, thanks!!!


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## RDalman (Aug 12, 2019)

nelsonchenknives said:


> Thanks for the reply Robin,
> 
> 1. So do I place the steel in the kiln after it reaches temp?
> 3. So I take it that I need to let the steel come down to room temp between the tempering cycles?
> ...



Really it depends on your kiln. If you can control its ramp well enough not to overshoot badly the blades can be in, but typically I would say it better to let the kiln be up at temp a good while before setting in the blades. 
3 yes it's about tempering new martensite from the first cycle


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## RDalman (Aug 12, 2019)

And I will write here also; Do not take data sheets or self proclaimed internet experts numbers as gospel. Testing out different temps and times with your own gear with every steel is the way to good results, the results YOU want. Example for w2, I would test austenitizing-temps in the 790-850 range with oil quench. Then file and breaktests, and those will show you which got you the hardest and finest grain, that is likely your best temp. Rockwell-tests will give you a better sure hardness result, but with file and breaktest comparison it's pretty easy imo to tell better samples, I send out for hrc after that. And then again after tempering and knife-tests.


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## BT11 (Aug 12, 2019)

I always find that when I open my kiln door I lose 80-100c pretty quickly. So I'll overshoot the temp for 50c or so, open the door, blade in, close the door. My kiln (paragon) will then usually be 50c under my now desired critical temp. It usually take 5-6 minutes for it to homogenise and reach critical temp again. Do the desired soak time then quench.


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## nelsonchenknives (Aug 12, 2019)

I think I'm going to stick to putting the knives in early, since the kiln doesn't seem to overshoot temp at all (ramp slows down drastically as it approaches set temp). It sounds like there's not a whole lot of penalty to let the knife soak longer in the heat? I'm talking about reasonable amount of time like 5-10 minutes extra? 

Also, what is the reason for not letting the quenched steel drop below a certain temp before going into the tempering oven?


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## BT11 (Aug 12, 2019)

Steel will continue to change after the quench, even if it's cool enough to touch with your hand. So with W2, or any steel that requires a fast quench medium, this risk of cracks is still there as it continues to cool/change. Starting tempering while its still around 150f/70c will help reduce those stresses ripping apart your blade.


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## BT11 (Aug 12, 2019)

nelsonchenknives said:


> I think I'm going to stick to putting the knives in early, since the kiln doesn't seem to overshoot temp at all (ramp slows down drastically as it approaches set temp). It sounds like there's not a whole lot of penalty to let the knife soak longer in the heat? I'm talking about reasonable amount of time like 5-10 minutes extra?



If you are going to do that then it may not be necessary to do a soak time, depending on how quickly your kiln can ramp up through the temp range. Low end for W2 is around 780c/1440f. So technically your steel has reached critical at that point, and your soak time is the time it takes 787c/1450f.


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## BT11 (Aug 12, 2019)

The reason for my last point is I've played with W2 from NJSB. It was a fickle steel for me. Tried a number of different temps and soak times in my kiln. Could never get good hamon control. I had much better success in my gas forge with hamon control, although it was more difficult to have a steady temp. Best hamon appeared with essentially no soak time. Just bring the blade to critical, then quench. I know a number of other makers who had issues with W2 from NJSB. 
I swapped my steel (with full disclosure) to another maker for some timber. Cant be bothered with that steel


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## nelsonchenknives (Aug 13, 2019)

i've only quenched test coupons so far, so i haven't run into cracking. i'll probably stick a quenched blade in a 150f oven to keep it warm while waiting for the kiln to cool past tempering temperature... 

i grabbed my w2 from usaknifemaker this time, but i had full intentions to get it from NJSB... 

have you tried talking to aldo? maybe he can point you in the right direction.


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## BT11 (Aug 13, 2019)

nelsonchenknives said:


> have you tried talking to aldo? maybe he can point you in the right direction.



I'm based in Sydney, Australia mate. But that job was done for me by another maker in the USA who had issues. He made a few phone calls and spoke with Aldo. He also tried a number of different things, and no resolve. At the end of it Aldo wasn't overly helpful, and refused to accept that maybe it was the steel being problematic. The maker even had some old stock W2 (not from NJSB) and tested it alongside the new natch NJSB. Old stock worked as it should, NJSB with quite severe underhardening in places and hamons doing what ever they wanted.
I've seen a number of makers here in Oz use NJSB W2 steel, with hamons going all over the place. Certainly not planned hamons. 

So not an isolated experience. And as such, I wont touch NJSB W2.


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## nelsonchenknives (Aug 13, 2019)

that sucks, w2 is no good to knife makers if it doesn't produce hamons : /

i'm probably going to look into other hamon-able steels, since w2 can vary so much in carbon and other elements. not a very good material to work with if you want a stable process.


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## BT11 (Aug 13, 2019)

nelsonchenknives said:


> that sucks, w2 is no good to knife makers if it doesn't produce hamons : /
> 
> i'm probably going to look into other hamon-able steels, since w2 can vary so much in carbon and other elements. not a very good material to work with if you want a stable process.



Sorry Nelson, didn't mean to rain on your parade mate haha

1095 fron Alpha Knife Supply produces repeatable hamons nicely. Havent used 26c3 yet, but some makers (Trey - Comet) are getting some nice results with it too


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## nelsonchenknives (Aug 14, 2019)

don't worry, you've probably just saved me a bunch of time and frustration. 

i'm gonna still carry out the experiments with w2, and get some samples of 26c3 as well. 

i do like the fact that w2 has some vanadium, which seems to be absent from other hamon steels.


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## Tim Rowland (Sep 9, 2019)

My typical W2 heat treat is clay up my spine, heat soak at 1450f for 4 minutes, quench in parks 50 for the best hamon activity. You can use clean calola oil but it is not as fast quenching as an engineered quenching oil like parks.
Right into temper at 400f for 2 hours. Usually gets me in the ballpark of 62rc.
If you are worried about the thermostat on a toaster over just stick a oven dial style thermometer in it and record where your dial is to actually hold 400f 425f and 450f. write it on the top of the toaster oven in sharpie and your good to go.

here is a little kwaiken style blade quench in pre-heated canola oil, as you can see not as much activity in the hamon but its there.


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## MattM82 (Sep 20, 2019)

Having read through the thread I thought I’d just add a couple of quick points/thoughts.

The others here have given some great advice.

When doing hamons I was always taught less clay, less heat. So a very thin clay coat and then I ht at 800c into Haughtons K quench.

To answer your question about longer soaks in the kiln, the result will be more scale/de carb as kilns create an environment of high heat completely exposed to air. You can negate this with anti-scale compounds, foil or clay will help if doing hamons.

As far as tempering, if you don’t trust your toaster oven, but your kiln cools too slowly, start your temper in your toaster oven, but at a much lower temp. Perhaps 50c lower... don’t rely on it as a cycle but it will get the process started in a timely fashion while you set up your kiln.


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## VICTOR J CREAZZI (Mar 3, 2020)

Tim Rowland said:


> If you are worried about the thermostat on a toaster over just stick a oven dial style thermometer in it and record where your dial is to actually hold 400f 425f and 450f. write it on the top of the toaster oven in sharpie and your good to go.


I have a friend who, once he got his toaster oven set to where he wanted it, glued the knob in place and uses the plug to turn the oven on and off.


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