I don't know how to look for the hamon

D

Don Nguyen

Joined
Oct 4, 2011
Messages
1,043
So after the quench, and maybe a tempering cycle to prevent imminent shatter, how do you look for the hamon? Some people grind a bit with 80 grit and they can find it reflecting in the light. Or a quick etch.

I have no idea what I'm doing.

Here was my process:


  1. 0.180" W2 stock (new material from Aldo)
  2. Full-flat grind to 0.080"
  3. Thermal Cycle, with 10 minute soaks, at 1600° F, 1500° F, 1400° F
  4. Thin wash of clay, let dry
  5. 1/8" Splatter of clay towards the spine, let dry
  6. Preheat oven to 1450° F
  7. Put blade in, let temperature equalize, hold for 3 minutes
  8. Quench in room temperature brine for 5 seconds
  9. Air cool
  10. Temper at 400° F for two hours, twice
  11. Grind at 80 grit to attempt to remove decarb
  12. 15 second etches in 1:4 ferric chloride
  13. ????

Here is what my clay looked like:

h9YyNRg.jpg


The blades survived the quench without any mishaps. Now, is this the decarb layer? I was grinding on it for a bit, and it seemed fairly thick to be decarb but I'm not a very experienced person on that.

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Here is after the quick etches. Looks like they didn't completely harden in a lot of places, but again, I'm new to this.

tunQYaA.jpg

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It looks like decarb mostly from thermal cycles. You can cut down on decarb by thin wash of clay per thermal or wrap in ss foil. I keep the same ss foil wrap through out the thermal cycles - worked quite well, I suspect temperatures below 1800F don't deteriorate the foil.
 
Just re-read your steps - no blade coating during thermal cycling! You've got quite a bit of decarb there, as bluntcut said. Likely more than you might suspect.

Stainless foil would definitely work. I use PBC antiscale powder. Tried ATP products and had horrible results with it, unfortunately. On thin blades like this you can have a serious layer of decarb that can render the final outcome questionable. How long were you soaking at temp for the thermal cycles?
 
For thermal cycling, I let the temp equalize and then soak for 10 minutes. Well I hope the decarb isn't too deep...

What are my recommended steps now? Grind through it and hope I hit hardened steel? In the case that I'm worried I didn't harden it properly, should I risk going through another quench?
 
Throw a fresh 120 grit belt on and go to town on one - let's see what's under there!
 
Hmmm! I'll do that. Basic question first though, when etching, does the hardened steel go black or soft?

And of the two, which would you try to grind first? :)
 
Hardened steel etches black, Decarb often etches a mottled gray on top of the black steel underneath.
 
I would check edge hardness with a file just for a quick check then grind with a finer belt.

I typically quench then immediately go over it with a new 220 and hamon is easily visible.

Tad
 
With W2, you will see the hamon at 120 grit. With something like 15n20, it comes out at about 400g. You might want to try white vinegar, or lemon juice for the etching. Lemon juice gives the nicest detail of the activity.
 
Yep....massive decarb. There is another gentlemen on a different forum who is having problems with his hamon on this very same batch of W2. IIRC, his hamon was way down towards the edge, not 1/3 up the flat as he wanted. And IIRC, every time he tried and retried....it would push the hamon down even further. Now you guys who do more hamons than I do....and know more about W2....chime in here.

I have heard that W2 does not like multiple thermal cycling , when trying to get a hamon. With W2 at fine grain, doesn't every cycle the blade goes through make it even MORE shallow hardening, which has a tendency to push the hamon way down near the edge? Not too sure if that is exactly right, but for some reason those thoughts came to me reading Don's situation, wondering if that may be the situation here.

I am seeing big time decarb with W2, just like Don is experiencing. It looks exactly like Don's pics. But I have since started applying satanite in a very thin wash, and that helps immensely. If you are doing multiple thermal cycling, you will probably have to re apply, as that thin wash tends to flake off when cooling in air. I wonder what kind of results one would get if they did NOT do any normalizing, just clay it up and harden it. I know...I like to normalize and thermal cycle everything too.
 
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My suggestion is:

Thermal cycling prior to grinding

Grind to 220

Apply satanite to blade

Bring to temp and quench...short soak

Check edge with file/hit with 220 belt.

If you dont see it then, its not there.

Tad
 
Thanks for all the help guys. Sounds like I definitely need to reduce the decarb from thermal cycling in the future.

I'll grind one of them and see what I get. From there I'll figure out what I wanna do with these...
 
My guess is that you are fine. You left the edge at .080. Decarb is not going to go nearly that deep at your times and temps. If you were grinding down to your eventual edge thickness of .010 or so would have an issue but not at that thickness. I would start to finish grind and see where the hamon pops up. If it is too low on the blade, bump the temp by 25 degrees and see what happens. You will lose a few blades figuring out the hamon thing with your equipment and techniques but in reality you dont have tons of time or money invested on a rough ground profiled blade, so I would not sweat it and just get it dialed in. Also I would bite the bullet and get parks 50, water or brine are just to severe for w2 at such thin cross sections and you will be often frustrated, as even the best smiths crack blades in water.
 
W2 varies a lot between sources and batches. When you get a batch you like...get lots more of the same batch and learn to zero in on the HT for a hamon. Some folks get a great hamon with no clay at all.
 
samuraistuart said:
Yep....massive decarb. There is another gentlemen on a different forum who is having problems with his hamon on this very same batch of W2. IIRC, his hamon was way down towards the edge, not 1/3 up the flat as he wanted. And IIRC, every time he tried and retried....it would push the hamon down even further. Now you guys who do more hamons than I do....and know more about W2....chime in here.

I have heard that W2 does not like multiple thermal cycling , when trying to get a hamon. With W2 at fine grain, doesn't every cycle the blade goes through make it even MORE shallow hardening, which has a tendency to push the hamon way down near the edge? Not too sure if that is exactly right, but for some reason those thoughts came to me reading Don's situation, wondering if that may be the situation here.

I am seeing big time decarb with W2, just like Don is experiencing. It looks exactly like Don's pics. But I have since started applying satanite in a very thin wash, and that helps immensely. If you are doing multiple thermal cycling, you will probably have to re apply, as that thin wash tends to flake off when cooling in air. I wonder what kind of results one would get if they did NOT do any normalizing, just clay it up and harden it. I know...I like to normalize and thermal cycle everything too.
Click to expand...

Each austentize makes the steel more shallow hardening, as the grains get finer.

I have been getting great clay less hamons with Aldo's latest batch of W2. I use a foil wrap for the thermal cycling.
 
How thin do you guys take your knives before heat treat? I was thinking as long as you control decarb, the thinner the knife is before heat treat, the more activity there will be in the hamon. Is that correct? I assume you could grind away some of the activity if the knife is too thick pre-heat treat.

-Adam
 
I take my edge thickness down to .030-.040" and quench in Parks 50. Maybe better to leave that thick quenched in brine? I also never get that kind of decarb, ever. But I always have to grind the crust off to get to the good stuff...
 
Don Hanson III said:
I take my edge thickness down to .030-.040" and quench in Parks 50. Maybe better to leave that thick quenched in brine? I also never get that kind of decarb, ever. But I always have to grind the crust off to get to the good stuff...
Click to expand...

Don do you do thermal cycling, and prevent scale/decarb?

I initially wasn't planning on doing much W2, hence why I didn't buy P50, but I might have gotten hooked. Maybe it's time to start thinking of the investment...
 
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