Fast quench, Deep hardening, and Hamon?

[Cushing H.]

Lots of things here ... but let’s try... a couple recent threads triggered me to look more into steel hardening (deep versus shallow), quenchant rate (fast versus slow), .... and it all started with a mention of Hamon.... if Virus limitations lift enough that I can build a HT oven, I will likely face these issues ... so here goes:

I get the metallurgy of deep versus shallow hardening. So, IF one is limited to one quenchant, are you always better off getting a fast quenchant (like Parks?). And then if wanting to play with differential hardening, go to shallow versus deep hardening steels? Or is this a “it depends” thing, and there is a need to match the quenchant speed to the type of steel?

on Hamon ... they are nice ... but seem so much more subtle than an etched damascus pattern. Can you create them using a deep hardening steel and a slow quenchant ... or are you limited to a shallow hardening steel, regardless of quenchant? Also ...I would imagine that for a “user” blade, or a kitchen knife that is frequently used, cleaned, and wiped, that a Hamon would easily become less visible fairly quickly ... so is Hamon really more restricted to collectibles and display pieces?

 

[Skiller1nc]

to get a good looking hamon you need a shallow hardening steel with as little manganese as possible. Quenchant is important but not as much as steel. deep hardening steels will be very hard to get a hamon out of. You might be able to pull a straight, plane line hamon out of something like 1084 but it wouldn't be optimal regardless of the quench oil used.

Your best bet, especially if you will soon have a heat treat oven is some of aldos w2. As far as quenchant, the faster it is the more activity and imho better-looking hamon you will get. For w2 lots of makers use parks 50 with great results, you need a fast oil for w2. I have been using heated brine and having great luck with activity and no cracking. There are 4 things I wish I had done sooner when getting into hamons. 1. Get some satanite, it works better than anything else ive tried to use for claying the blade. 2. use less clay than u think you need 3. get some 1500 grit silicon carbide powder off eBay to polish, I tried so many different polishes and ways to polish because I didn't want to spend the money on it. Hindsight I should have done it long ago, sand to 1200 grit, etch, polish, and boom. 4. A proper heat treat will do more for a hamon than any amount of polishing or applying clay.

as for a patina and use covering them up. It depends, some of my kitchen knives are patinaed in a way that the hamon is still visible but of course not as bright and clear as day one. Other knifes the hamon is all but gone.

 

[DustinY]

to get a good looking hamon you need a shallow hardening steel with as little manganese as possible. Quenchant is important but not as much as steel. deep hardening steels will be very hard to get a hamon out of. You might be able to pull a straight, plane line hamon out of something like 1084 but it wouldn't be optimal regardless of the quench oil used.

Your best bet, especially if you will soon have a heat treat oven is some of aldos w2. As far as quenchant, the faster it is the more activity and imho better-looking hamon you will get. For w2 lots of makers use parks 50 with great results, you need a fast oil for w2. I have been using heated brine and having great luck with activity and no cracking. There are 4 things I wish I had done sooner when getting into hamons. 1. Get some satanite, it works better than anything else ive tried to use for claying the blade. 2. use less clay than u think you need 3. get some 1500 grit silicon carbide powder off eBay to polish, I tried so many different polishes and ways to polish because I didn't want to spend the money on it. Hindsight I should have done it long ago, sand to 1200 grit, etch, polish, and boom. 4. A proper heat treat will do more for a hamon than any amount of polishing or applying clay.

as for a patina and use covering them up. It depends, some of my kitchen knives are patinaed in a way that the hamon is still visible but of course not as bright and clear as day one. Other knifes the hamon is all but gone.

I went for the fine pumice FFFF, i'll report here with some results. I just updated my thread on this - got an insane natural hamon accidentally.

 

[Willie71]

The more shallow hardening the steel, the better the hamon potential. If manganese is higher than 0.4%, hamon potential drops off. Any element that aids in deeper hardening such as chromium, nickel, or manganese will decrease hamon potential.

The faster the quench, the greater the hamon potential. Also, higher potential for cracks.

Geometry plays a big part. Steel hardens in the peak of a wedge fastest, making clayless hamon’s possible. Geometry, steel condition (shallow hardening, fine grain, a bit of vanadium to keep grain boundaries pinned etc, like W2) is the greatest potential. Hitachi White is basically iron, carbon, and almost no manganese. You have to have some manganese, or the sulphur and other impurities become more problematic. Hitachi white is quite clean.

Decreasing carbon content increases hamon potential. Or, lowering aust temp to get less carbon in solution increases hamon potential. This comes back to geometry. The point of the wedge austentized first, and if there is not enough carbon in solution, you get better hamon potential. Lower temps decrease carbon in solution, or steels like 1050 with lower carbon have great hamon potential.