L
lotfong
thank you so much! That is very helpful!
Would you mind sharing your heat treating protocol for Sheffcut?
To be honest, for monosteel stuff, I use a process that is very similar to one of Larrin's recommended HT procedures for 26c3.
So far, I use pretty much this exact same HT regimen for 26c3 and Sheffcut equally, and I haven't noticed much of a difference between the two yet, so the results are pretty much identical between the two.
Normalizing
1700f 10min and cool to magnetic
Grain refining
1450f 5min and cool to magnetic
DET anneal
1400f 30min
go to 1280f at 670f/h
from 1280f to 1100f in the oven
then cool to room temp
then I quench after 7-10min at 1460f into parks 50 and straight to temper 2x1h
300f is over 65hrc
350f yields around 64-65 hrc
400f yields a solid 63hrc
450f is around 61-62
For san mai, I used to do it as mentionned above but I wanted to try water quench japanese style, and that implies somme differences in the process.
this is a bit controversial for some smiths so I think it can be nice to simply share it and may everybody do whatever they want out of it.
I am not much of a japanophile and I can't say this is the best method and I won't bulls**t anybody here by saying so, but to be honest the process is very fun and works really well when one gets to understand it and know its limitations. I do kitchen knives as a living and have been working on japanese knives for a while already, these are interesting objects of design and the proces has a lot to play in the cleverness of it.
I've been doing it this way full time for two years now, and it gives me very good results that I am happy to stand behind as a craftsman, and I think ultimately it is what matters.
I think Harbeer Chahal (HSCIII) and Murray Carter use a pretty similar process.
I use this whole process almost identically for 1095, w1, w2, 26c3, 135Cr3, silver steel, Sheffcut, Shirogami2, Shirogami1, aogami2, vtoku2 and aogami super.
The only thing that change for some steels are the austenitization temperature and holding time
It goes without saying that the results aren't identical hardness and toughness wise, for each steel, and this was also an experiment to see what steel I liked to work with the most
For normalizing, I came to the conclusion that If you have good temp control and work carefully it works well with these steels to simply do normalizing while forging the blade at descending temps throughout the whole process, and finish the forging each time down to magnetic, making sure the last heats are around dull cherry red.
Of course I don't bash the steel like a madman when it gets that cold.
then I do the DET anneal as mentionned above.
I did some breaking tests to compare with a oven ht with precise temps for normalizing and grain refinement and there was no difference, as I think it is the DET anneal that has the most efficient grain reducing effect anyway.
then I cold forge the blade.
It sure bends like crazy, the core steel is pretty soft from the anneal, it is like below 1mm thick and is sandwiched between the wrought iron on the sides, and they take much of the beating.
I have yet to have a blade crack when I do this, and I don't claim it to redue grain or whatever, it simply work hardens a bit the sides and the blades come straighter out of quench when I do it, it also helps to hammer down the geometry a bit more and thin some setions efficiently, and makes for a very uniform, clean and good looking brut de forge texture.
After that I coat the blade with a clay+wood ash slurry with the consisteny of liquid yogurt on the blade, as evenly as possible, then dry it at the entrance of the oven with its door open.
Then I quench after 7-10min at 1430f into 90farenheit water, count to two or three (depending on the thickness of the blade, then IMMEDIATELY temper in the preheated oven, 2x1h
It is quite important to use lower aus temp than most would use with oil, for numerous reasons, and warming up the water a little helps to get a cooling rate a little more in line with the speed necessary to beat the pearlite nose while still limiting the stress on the blade. This is where I vary the temps with data I got with tests done on samples. it actually all lies between 1420f and 1480f depending of the steel, Chrome moves things a bit higher on the temp range.
Some do an interrupted quench, 2sec in water and then in oil. I've never done it as these simple steels handle the quench as satted above surprisingly well if things are done right.
The only failures I've had this way where when I didn't anneal, when I used higher temps, where the clay coat was too thin, when I used harder steel for the cladding or when the water was too cold.
The risk is quite worth it as it is surprisingly efficient to work and actually not that complicated to do and can make efficiently and quickly a good blade.
One of the most noticeable advantages I've seen form this method is that it really helps to have very, very little retained austenite and makes deburring absolutely effortless. I have seen a difference in very acute angle edges pushed to high grit, compared to the parks 50 method I used previously. I believe that if I used Cryo with parks I'd get even better results than anything else I've done so far, I should try it someday.
here are the results
300f is absudly hard (I'd say 66-67hrc), not very tough, but makes for nice leather cutting knives and delicate wood chisels and has surprisingly good edge retention for such a simple steel.
350f is still over 65hrc
400f is around 64hrc
450f is 62-63hrc
personally for kitchen knives I like the balanced edge stability and properties I get at 360f-375f after a water quench, extremely thin geometries and acute angles are well held for delicate use ( i do 0.003inch thick at 1mm from the edge, 13degrees per side), these edges are absolutely terrific and easy to get them sharp if you know your way around stones.
It passes easily hanging hair test cutting while still not being too chippy.
Very nice results, but to be honest I've tried a lot of old Globe, Simmonds and Nicholson files as a reclaimed source of carbon steel for my san mai recently and the results are pretty much on par with Sheffcut/26c3 when I use this process. One of the globe files I had checked by a friend who is an engineering teacher and has access to the proper stuff at the local university to chek out the steel comp, as they didn't spark exactly like 1095 on the spark test.
here are the specs
C- 1.22%
Mn - 0.34%
Si - 0.23%
Cr - 0.19%
and traces amount of Mo, V, W, Ni, S and P.
It sure is similar to 26c3 and Sheffcut then, a plain water quenching steel that gets very hard.
So Sheffut isn't reinventing the wheel, it's all about very simple and high carbon steels, very much in line with Shirogami 1 steel, just a bit less extreme maybe to work with.
Let me know if you have questions, it is fun to write here, I like the community and learned a ton reading here on this forum, and if I can give back I'd be more than happy to oblige.
