Hamon?

Gene Kimmi

Gene Kimmi

KNIFE MAKER
This is a knife I made a few months ago. I just noticed what looks to be a hamon in it. Is it possible to get a hamon doing a regular quench, or is it something else? If so, is it the steel that makes it possible? This is a blade out of an old buzz saw blade that was quenched in peanut oil.
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Yep, sure looks like a hamon to me. A lot of people call it auto-hamon, but there is nothing auto about it. You got it because your blade geometry and heat treat process made the condition right to create a hamon.
 
only way to really get a hamon like that I have seen some will quench the edge only and let the back air dry, I dunno if you did this? (outside of differential treating and or clay hardening)
 
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When i look at the antlers behind you and the nice hamon you get without trying all I can think is...some guys have ALL the luck! Lol.
 
No edge quench on this knife. It was heated to a little above non magnetic and quenched in 130 deg peanut oil. The hamon is faint and only visible in the right light, I just didn't realize this was possible without trying to do it.

Thanks Ted. That was my buck of a lifetime. My luck on the hamon would probably be the opposite way if I tried to do it.
 
You didn't say what steel you were using. If you are using a shallow hardening alloy and you produce good grain structure in your blade it will only harden to a maximum thickness, probably somewhere about 1/8". Thicker than that you will end up with a band of mixed martensite and pearlite fading to all pearlite as it gets thicker. As far as testing it with a Rockwell hardness tester the fly in the ointment there is that you have to have parallel sides to do the testing. The bevels on the blade will through the HRc measurement off.

Doug
 
I'm not sure what the steel is. It was cut from an old circular saw blade, what I call a buzz saw blade. I've read that a lot of them were from L6 steel.
 
Looking at the pic, there are a few things that contributed to the "hamon"...... It's a pretty safe bet that the blade was a bit on the cool side when quenched, and the thinner cross section near the edge is all that was through hardened. Combine that with the fact that it was "mystery" steel, and just about anything could happen. :)

Something I've come to understand in attempting to help others is the fact that most don't realize that there is a difference between heating steel to a given temp, and having the steel at the temp when it hits the quench. I worked with one individual for a couple of months, before it occurred to me to ask him where his quench tank was in relationship to his heat source.... "About 20 feet away" was the answer he gave me. He was heating a blade, then walking 20 feet (give or take) to his quench tank.... no doubt the steel was well below temp by the time he got there and quenched a blade. Little things that might seem insignificant do make a difference. :)

As Doug mentioned, Rc testing it will be near impossible to do accurately unless the surfaces are parallel.

The biggest bane we face these days with using "recycled" materials is the fact that nearly everything has gone to "spec manufacturing"..... In short, that means that specifications no longer call for a particular type of steel for an item.... now a days the function is stated, with the caveat of "use the cheapest material available". That means that the exact same item, from the exact same company, could be any number of different steels from production run to production run. If folks choose to use "recycled" steel, then it's just a constant guessing game.
 
GeneK said:
... I've read that a lot of them were from L6 steel.
Click to expand...

This is a long standing myth in our field, the reliability of which is witnessed in this particular blade, L6 would not have given you hamon. Is the blade mounted up yet? I ask because you may be able to re-heat treat it. About two thirds of the way out the habuchi line comes dangerously close to the edge, there will be pearlite colonies there, reducing edge holding, and you won't get too many sharpenings before most of the edge will follow.

As Doug pointed out, this is most likely a shallow hardening steel, probably 10xx series. Peanut oil is one of the slowest vegetable oils I have tested. If you were to redo it in 130°F canola you could get even more vibrant natural hamon with more hardened edge. While clay adds control and the ability to structure the hamon, the most eye catching ones I have done were simply bare blades that matched the blade thickness to the maximum cooling ability of the quenchant. 1095 in an 11 second oil or bloomery material in Parks #50 produces vibrant thunderhead cloud like designs that intentional hamon wouldn't duplicate.
 
Sorry it's taken a while to get back to this thread. Thank you all for the good info.

Ed, I place my quench tank at the base of my forge stand, so I'm pretty confident in the steel being hot enough for the quench. Could it be caused by the peanut oil being too hot? I made 3 of these knives from the saw blade and quenched them all the same evening. I remember checking the temperature of the oil after quenching the second blade and it was in the 160 - 170 degree range. After seeing this, I set my tank outside (this was last Dec or Jan) to cool before doing the 3rd one. I'm guessing this is the 2nd blade that was quenched in the hotter oil.

Kevin, this is a finished knife that it sounds like I need to tear down and re-quench. After reading of all the problems with mystery steel, I had given up on the saw blades and have been purchasing knife steel. I have also switched to an 11 second quench oil from Tru-Grit. I'll have to try quenching this blade in that to see if I get a hamon with it.
 
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