How "not" to get a hamon?

Self Made Knives

Self Made Knives

Well-Known Member
Hey guys, new day, new problem. I recently got some 1095 for NJSB to try instead of the O1 I've been using. My process is to drill, mill, and rough grind the bevels down to about a dime's thickness. I pretty much finish everything but the bevels before heat treat. I use anti-scale compound from Brownells, ATS34 maybe, can't remember the name exactly. I go into oil quench edge first.

After HT I do my finish grind on the bevels, then hand sand to correct and flatten anything I missed on the grinder. I only go up to about 220 grit finish and then abrasive blast for an even matte look. Then I patina the blade. I've used ferric chloride, hot vinegar, Parkerizing, and recently Birchwood Casey Super Blue. The bluing has became my favorite just due to how fast and easy it is.

So, problem, in the pics below you can see the blade on the bottom has a noticeable hamon or temper line. Two on top are O1 and what I'm used to getting. This line affects the final finish a lot! I don't want a temper line! Is there something I can do to make this come out like the O1?
1095 temper line 1.jpg1095 temper line 2.jpg
 
Not to be flippant but you either need to let your grain grow larger or find a different steel. 1095 is a shallow hardening steel, especially if it is a bit low on manganese, as the 1095 from Aldo is. What you are running into is a problem with shallow hardening steels in sections under about 1/4" with fine grain. The difference between the rate of cooling between the surface and the core of the blade is minimal and will be controlled by the thickness steel. That translated into the steel out to about 1/8" or so, depending on the grain size, forming martensite and pearlite in sections thicker than that. The reason that you are not seeing it in the O1 is that it is a more complex steel that delays the conversion to products of austinite.

Doug
 
Everything Doug said for sure. You might improve your chances of a full harden with either faster oil or (if want to risk some breakage) brine. There are other steels that would be a better choice - maybe 1084? Why did you move away from O1 if it was working (just curious).

I suspect your antiscale was ATP641. I don't know this, but I suspect that coating may slow the quench just a touch - and that is a touch that you just can't afford with shallow hardening steels.

Rob!
 
Ok, first, I really like O1 but this particular design is in 5/32" and I was having a hard time finding it in sheets big enough for water jet/laser cutting. So, 1095 seems to be popular, thought I'd give it a try. I like the anti-scale clay, sure would hate to do without it. So, what have I got here? Cutting edge is fully hardened, what do guys think about the rest of it? Should it still be a good knife overall? It seemed ok, but I don't have a hardness tester.
 
I would say that the knife should have a good edge that is fully hardened. The darker area above the hamon and the handle should be pearletic steel. It won't be as hard or as strong as the martensetic edge but it will be tougher. The handle material will be reinforcing the tang to add some strength there so it's not that much of a concern. I see no reason that the knife shouldn't be a fine cutter, just don't use it as a pry bar.

Doug
 
Doug, thanks for your comments. I have about 35 blanks cut out of this 1095. About 20 of them are spoken for by customers. Do you think this knife is ok to be sold as is? Should I change my process for the future blades? Guess what I'm trying to ask, in general, would HTing the I did this be satisfactory in a performance aspect? If so, I can figure out something about the finish. If not, I'm going to have to figure out what to change.
 
Some people go out of their way to make blades like that to satisfy buyers who think that superior knifes should have a hamon. What you are seeing is not a defect, just a different way of making a knife blade.

I don't know what qenchant you use but if you have the time to get some in a quick quenching oil like Parks #50 it will help you get past the nose of the cooling curve on the edge section. Of the grocery store oils I understand that Canola oil is pretty fast but it won't be as fast as the commercially prepared oils. Then again there is always brine which has a way of finding stress risers in the design and breaking the blade. I haven't used brine in a while and not for many blades but I do have to admit that I never cracked anything in it. I can't say the same for Peanut oil.

If you go to hypefreeblades forum and do a search there's quite a bit on heat treating 1095.

Doiug
 
I used canola oil on these. I have used auto transmission fluid in the past, but everybody seems down on that idea. It seemed faster to me than the canola, but who really knows. There's no local supplier for me to get Parks and I've been to cheap to pay the outrageous shipping. Maybe I need to rethink that.
 
This is beyond my knowledge level but will offer the grunts logic of take the ugly one and abuse it like pvt. Joe Snuffy would and see how it performs? I know you care about how your knives are and want to have your name on good quality not junk. Brother you may have to step up the quenchant to the big boy level.
 
I like the look! Especially the one on the right. I know a lot of makers that work hard to differentially harden their knives. 1084 from Aldo is close enough to 1095 in producing a knife and is very difficult to get a hamon from unless you use a torch to harden it.
 
Knifemaker.ca, my temper cycle was 450 deg for 2 hours. And, George, don't get me wrong, I love a good hamon! Just don't want that effect on this model. This is my take on a survival knife and I like it to be a nice matte, uniform patina or black oxide finish. I went on and finished these three with bluing yesterday, and the 1095 temper line is showing through a little. I think the abrasive blast finish is exaggerating the effect. Making sheaths tonight, I'll try to get a pic of the finished "finish" tonight.
 
Anthony:

My question would be, "Do you think you could replicate the Hamon at will or was it just an accident?" I would love to get a Hamon on demand as easily as you seemed to get that one.

Wallace
 
Wallace, ain't that the way it goes! People with curly hair want it straight, people with straight spend a bunch of money to get it curly! I'd say its repeatable, I didn't do anything out of the ordinary. I'm going to make a couple of hunting knives next with the same steel. One was ordered with a black finish and orange g10 scales. The other is just for experimenting with this hamon effect. So, we'll see if it happens again. Like the guys said before, maybe it was the anti-scale compound. Stinks not knowing what you're doing!

EDIT: Just FYI, that line wasn't visible during hand sanding, appeared during the mechanical "etch". I think you get a similar result with chemical etch as we'll.
 
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Thanks Self Made for being the guinea pig for us again. I have been wanting to experiment with some different steels. I've been using O1 and files thus far. 1095 & 1084 was what I wanted to experiment with. I actually want to start playing with hamon lines.
So to date I've only used vegetable oil heated to 120 for both my O1 and file steel. Is the Parks suitable for quenching O1, 1095, 1084 and most similar steels or is it steel specific? For example Veg oil for O1 and Parks for 1095 meaning I have to keep multiple oil containers on hand. And as Parks is designed as a quenchant does it need to be heated? My shop averages 40 degrees in the winter, does parks need heating to a nice 70 degrees under those circumstances?
 
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