Hamon vs. Quench line

Evan Miner

Evan Miner

Maker
Joined
Nov 24, 2011
Messages
152
I've read on here once before that a quench line is not the same as a hamon line and I was wondering if some one could explain to me the difference. I understand that to produce a hamon line you need to have a shallow hardening steel like 1095, and that a full hardening steel like 5160 you can get a Quench line but not a hamon line. The thing that eats at me is probably do to the basic knowledge of what each one truly is. to my understanding both are a clear separation of hardened steel and unhardened steel. To get a hamon line you use a clay or some kind of barrier to slow down the cooling process, leaving the covered part of the metal to cool slower then needed to harden the steel. A quench line is done with the same concept in mind but instead of clay you only place to area you want hardened in you cooling agent. So after all of the basic info what truly separates these two, other then process.
 
If you edge quench a blade only part way into the quenchant, the hard steel will stop at the quench line. This will cause the quench line to be straight , just as the quenchant surface was. The steel above the line is pearlite and the steel below martensite. The steel above the line may also have a lip of decarb steel and scale. You can often "feel" the line with a fingernail. A quench line can be attained on any steel that oil or water hardens. Air hardening steel do not make much of a line in most cases. A quench line may disappear with sanding. Unless the steel is low alloy and fast quenching type, the line will not show much detail or be a " fuzzy cloud". 5160 will show a line of some sort, but it won't look like the hamon you get on W2 in yaki-ire.

In a true hamon, the line is formed by the junction of the pearlite and martensite created by differential cooling. The steel under the clay cools slower and forms pearlite. The steel under the clay is protected from the air, so it has often less decarb than the hard steel. The line wanders and changes in size and shape as the steel cools. Crystals and patches of nie and nioi may appear along the line as well as in other places creating wisps and clouds. This can only happen well with a steel that has is very fast quench speed and is very low alloy. A hamon may be completely invisible until sanded out and etched ( however, over-sanding may erase or weaken it)
 
Sorry took so long to Write back been working. Thank you for the clarity on the two. The main reason I ask was iv been working with 5160 since I started making knives. Iv been working towards making a clear defined differential hardened blade with this steel, and iv tried both ways. With edge quenching I got something but like you said it sands away easy. So nothing on the finished product. I did get a nice line on one I did with my own home brew clay but for some reason it won't let me load it from my phone on to this post. I'll play around with it some more and try and get it posted
 
You won't get a "clearly defined differential hardening" with 5160, as it is a deep hardening steel. That means it will harden pretty easily, even in air to some degree. No attempt at delaying the hardening with clay will make exclusive pearlite bordered by exclusive martensite. A lower percentage of martensite mixed with some pearlite and maybe even austenite may result in a border, but most all you will see is based on decarb, not different structures.

What you got on that blade is very good for the steel type.
 
thank you for the advice it was much needed to try and reproduce what i got on the blade above. for this one what are the chances of the line still being decarb after removing .025 off both sides of the blade on my sander? so i guess the real question would be with 5160 how thick can decarb be?
 
If you sanded off that much steel, hopefully all decarb should be gone. What you see is a product of mixed structures caused by different cooling rates. From the looks, I would guess the blade was edge quenched. That is a nicely visible line, but the name for it would depend on how it was quenched. If edge quenched, it is a quench line. If fully quenched, a hamon.
Some questions:
Was the blade edge quenched?
How thick was the clay?
How fine has it been sanded to?
What has it been etched in?
Was the whole blade etched, or just the upper or lower part?
Was the pattern more visible before sanding? ( right after quench)
Was the pattern visible when sanded to the final grit, but not etched?
 
1. the blade was full quenched
2. the clay thickness was est. 3/16 a little thick but set out to achieve the line with out edge quenching
3. sanded to a rough 1200 grit before etched
4. ferric chloride
5. the whole blade was etched time deration, dilution was 10:1 for 3x5min intervals
6. the pattern was visible before sanding in the right light and angle. easier visibility the finer the grit progression.
 
the reason for the thicker clay application was based on what I felt needed to happen to compensate for the 5 to 6secs I have to bring the steel below the nose of the curve. in hopes that it would take at least 7 to 8 seconds to actually cool the spine.
 
Looks like you did everything right for the steel type. With that type of procedure and result, I would call it a hamon. Good job.
 
thank for the advise. im going to try and duplicate these results this weekend with a knife Im working on. Im also going to try to get a little more of a set design out of it if it works Ill post it and see what every one thinks
 
You must log in or register to reply here.
Back
Top