This is that accidental hamon I mentioned.

AddictChris

AddictChris

Joined
May 18, 2019
Messages
43
for the curious. I posted in a separate thread that I had differentially hardened a W1 blade by accident by leaving some scale on it when I hardened it.

I had no intention of differentially hardening this. I didn’t know that scale would have that much effect. I’m a n00b :-)

Anyway, it’s all learning.

Anyway, long story short, the whole edge is hard and I thought it mostly looked cool, so I etched and polished it. For an accident it’s pretty cool. It’s just a kitchen knife for myself so no harm no foul

Cut-hamon2.jpg
 
Stacy E. Apelt - Bladesmith said:
That looks like decarb that has not been fully ground away.
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Originally yes. It was decarb from normalizing in my evenheat oven left on the blade that caused the differential hardening.

Is there a difference between decarb and scale? Apologies if I misspoke.

This pic is after grinding and sanding up to 1000 grit, and then a few cycles of lemon juice etch and polishing with mother’s
 
That looks pretty great! I’d be happy with that.
How much of a “noob” are you? That’s a good looking integral. Did you forge that yourself?
 
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Josh Rider said:
That looks pretty great! I’d be happy with that.
How much of a “noob” are you? That’s a good looking integral. Did you forge that yourself?
Click to expand...

Thanks. I started forging about 6 or 7 months ago. I’ve made a few non-blade things as well, but this is my 4th knife. I forged it from a piece of 1” round W1 drill rod. Hardest part of forging this was getting the width I needed at the base of the blade and keeping it as close to the bolster as I could.
 
Scale is iron oxide that forms on the surface as a layer. As it gets thicker, it starts to flake off, especially during forging. Scale is a very hard form of iron oxide.

Decarb is steel on the surface that has lost its carbon content due to oxidation. This layer is not flaky, and can look like the rest of the metal when ground/sanded. When etched or allowed to patina a bit, it shows as a much darker color. This layer has little or no carbon left and will not harden, thus it is very soft.

Every blade that has been heat treated has a ;ayer of decarb on it. The layer may vary form a few thousandth to a few hundreds of an inch. Coating the blade with something, using an inert gas HT oven, wrapping the blade in HT foil, or using salt pots will keep the decarb to a much lesser amoumt.

As the surface temperature of a blade exposed to the air increases, so does the decarb and scale. When heating to 2000°F during forging, the scale falls off every heat. In HT at 1500°F the scale is less, but the decarb still happens. IF a stainless steel or high alloy blade was HTed at 1950°F and not placed in a sealed foil packet, it would be so severely decarbed it would be ruined.
 
John mc c said:
Knife looks great
Has blade been etched?
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Yep. This was 6 cycles of etching with lemon juice and polishing with mothers mag.

The round shape near the base by the spine used to be the logo I stamped into it, but I didnt stamp deep enough and most of it got ground off finishing the blade. Another lesson learned. Stamp it good and deep.

I was interested in the way it hardened right where the stamp was, and in the same shape as the stamp. Work hardening?

FTR, it originally looked like this. Its a logo I designed for my guitar building business thats based on a tattoo that I share with my son. He died 2 years ago and I dedicate my work to him.

Phoenix-line.png
 
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Accidental hamons are a thing, for sure! I used to make chef's knives out of 1/8" thick W2 and Blue2, and usually would get an "accidental hamon" on them. These days I use thinner stock, 1/16"-3/32", and deeper hardening steel.
 
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