- Joined
- Oct 11, 2005
- Messages
- 2
Hello,
I usually make my blades which up until recently have been tanto, by stock removal out of some circular saw blade steel that has consistantly performed like L6. I've been edge quenching in motor oil and sometimes vegetable oil and getting some neat natural suguha-based toran, notare and ko-midare type hamon by playing around with quenchants and quenching techniques. This has been great and I'm used to seeing a bold hamon which is visible without etching even at 100 grit, and is visible across the room when it has been etched and polished.
Last week I shaped a 22" nagasa wakizashi out of some truck springs that I had around the shop, and last weekend I did the ht: edge quenched in motor oil 3/4" deep (blade is ~7/8" at yokote, ~1 1/4" at machi) . This is where things get a little confusing so I will describe everything in detail.
The stock from which this blade was a truck spring that had been straightened in sections in my charcoal forge. This straightening also had the side-effect of annealing the steel somewhat so it was easier to work.
The blade was shaped straight like a chokuto, then about 1.5 times the sori I wanted (I wanted 1/2" over 22" when done, so I gave it 3/4") was imparted artificially by heating the blade in sections and bending it in the vise. After this, I removed all the warpage that had occurred while bending. Then I normalized by heating to critical, correcting another minor distortion and cooling completely in air.
After this the blade was heated past critical and edge quenched in warm motor oil. While being quenched, the blade went through the deformation I expected where all the positive sori came out and the blade went slightly into negative sori, then came back out of that and left me with the 1/2" sori I wanted.
After giving it several tests I noticed neither it nor the two tanto blades of the same steel, were nowhere near as hard as an L6 tanto blade I had done that same night. The tests I used were these:
With effort, the L6 blade would shave the edge of the ocs blades, but they would skate on the L6 blade.
With effort, a new wiltshire file would bite the edges of the ocs blades. Without a degree of pressure though, it would skate on the ocs blades.
However:
The L6 blade would also shave the corner of the tang of the wiltshire file
(!!)
Both the L6 and the ocs blades shaved the ocs springs that had not been touched by the fire.
When I touch the hardened edge of the L6 blade to my (small) belt grinder, I get sparks easy, but when I touch the edge of one of the ocs blades I don't get sparks unless I apply hard pressure, and then it is just the occasional spark.
I was able to hammer the 1/32" edge of the wak about 1/16" deep into the corner of my vise (probably mild steel) with no edge damage.
On that same night, I took the smallest ocs tanto blade I had heat treated, austenitized it again and edge quenched it in *cold water* for 1 second, then into the warm oil. There was no observable difference in hardness from the wak or from the other ocs tanto blade.
I fully austenitized and requenched the wak blade 3 times with the same result. The reason I did it three times was because the first time I needed to adjust the sori, the second time the (barely visible after much base polishing) hamon (if that's even what I was looking at) appeared to leave the edge about 1/2" from the tip, and the third time I can't see much of a hamon at all but it didn't matter because I had run out of charcoal and it was 4am.
So my questions to you are these:
(1)
Because the wak went through the negative-sori transformation when quenching in oil (did this all three times I quenched from critical) doesn't that mean that there *must* have been martensite formation on the edge - why else would it have curved down and then returned to a sori proportionally less than it had before than if there hadn't been martensite formation since isn't that what causes the curving?
(2)
Is it reasonable to expect *this much* of a difference in full-hardness between the L6 and the ocs? Remember that the L6 was file-cutting-hard but the edge of the ocs could be cut by that same file with some pressure. Neither has been drawn in any way.
(3)
Given that the ocs has hardened some (it will cut/shave the steel that is still in the curved bendy spring-tempered untouched form), wouldn't that too indicate martensite formation?
(4)
I haven't fully polished the wak yet but I have cleaned it up and etched to examine the hamon. I see a very light hamon in places that is barely visible but is still obscured by steel surface activities and grinding marks. If it were L6 I would say it had not hardened and that the light "hamon" I am seeing is just a line of misty nioe as I often get in my mutiple-quenched smaller blades some parts of an inch distance above the actual hardened edge. Alternatively, could I be seeing more of a hitatsura effect where most of the blade has transformed to martensite - the quenchant level was quite high? I'm not expecting a 5160 hamon to be as bold as the L6 hamon because 5160 is a deep-hardening steel, but should it be this misty, in places it is imperceptibly faint?
If it hasn't actually hardened, then the steel is not oil-hardening 5160 and I should be doing a water quench - I have read that some ocs can be a 10xx or even W1 or W2. I suppose what I'm finding confusing is that the steel is not as hard as I am used to though everything (except a clearly defined hamon) tells me it should be hardened. And if it isn't hardened, I don't want to invest the time in shaping the kissaki, yokote, establishing the niku and all the other fiddly polishing stuff if the edge or the blade will bend like licorice as soon as I put it into anything substantial. The hammer test and the fact that it is harder now than when it was in spring form are encouraging, but those of you who have worked with 5160 in the past might be able to give me a bit more solid reassurance before I sit down to work on this blade for most of my spare time in the next week or two.
Thanks for your help
I usually make my blades which up until recently have been tanto, by stock removal out of some circular saw blade steel that has consistantly performed like L6. I've been edge quenching in motor oil and sometimes vegetable oil and getting some neat natural suguha-based toran, notare and ko-midare type hamon by playing around with quenchants and quenching techniques. This has been great and I'm used to seeing a bold hamon which is visible without etching even at 100 grit, and is visible across the room when it has been etched and polished.
Last week I shaped a 22" nagasa wakizashi out of some truck springs that I had around the shop, and last weekend I did the ht: edge quenched in motor oil 3/4" deep (blade is ~7/8" at yokote, ~1 1/4" at machi) . This is where things get a little confusing so I will describe everything in detail.
The stock from which this blade was a truck spring that had been straightened in sections in my charcoal forge. This straightening also had the side-effect of annealing the steel somewhat so it was easier to work.
The blade was shaped straight like a chokuto, then about 1.5 times the sori I wanted (I wanted 1/2" over 22" when done, so I gave it 3/4") was imparted artificially by heating the blade in sections and bending it in the vise. After this, I removed all the warpage that had occurred while bending. Then I normalized by heating to critical, correcting another minor distortion and cooling completely in air.
After this the blade was heated past critical and edge quenched in warm motor oil. While being quenched, the blade went through the deformation I expected where all the positive sori came out and the blade went slightly into negative sori, then came back out of that and left me with the 1/2" sori I wanted.
After giving it several tests I noticed neither it nor the two tanto blades of the same steel, were nowhere near as hard as an L6 tanto blade I had done that same night. The tests I used were these:
With effort, the L6 blade would shave the edge of the ocs blades, but they would skate on the L6 blade.
With effort, a new wiltshire file would bite the edges of the ocs blades. Without a degree of pressure though, it would skate on the ocs blades.
However:
The L6 blade would also shave the corner of the tang of the wiltshire file
(!!)Both the L6 and the ocs blades shaved the ocs springs that had not been touched by the fire.
When I touch the hardened edge of the L6 blade to my (small) belt grinder, I get sparks easy, but when I touch the edge of one of the ocs blades I don't get sparks unless I apply hard pressure, and then it is just the occasional spark.
I was able to hammer the 1/32" edge of the wak about 1/16" deep into the corner of my vise (probably mild steel) with no edge damage.
On that same night, I took the smallest ocs tanto blade I had heat treated, austenitized it again and edge quenched it in *cold water* for 1 second, then into the warm oil. There was no observable difference in hardness from the wak or from the other ocs tanto blade.
I fully austenitized and requenched the wak blade 3 times with the same result. The reason I did it three times was because the first time I needed to adjust the sori, the second time the (barely visible after much base polishing) hamon (if that's even what I was looking at) appeared to leave the edge about 1/2" from the tip, and the third time I can't see much of a hamon at all but it didn't matter because I had run out of charcoal and it was 4am.
So my questions to you are these:
(1)
Because the wak went through the negative-sori transformation when quenching in oil (did this all three times I quenched from critical) doesn't that mean that there *must* have been martensite formation on the edge - why else would it have curved down and then returned to a sori proportionally less than it had before than if there hadn't been martensite formation since isn't that what causes the curving?
(2)
Is it reasonable to expect *this much* of a difference in full-hardness between the L6 and the ocs? Remember that the L6 was file-cutting-hard but the edge of the ocs could be cut by that same file with some pressure. Neither has been drawn in any way.
(3)
Given that the ocs has hardened some (it will cut/shave the steel that is still in the curved bendy spring-tempered untouched form), wouldn't that too indicate martensite formation?
(4)
I haven't fully polished the wak yet but I have cleaned it up and etched to examine the hamon. I see a very light hamon in places that is barely visible but is still obscured by steel surface activities and grinding marks. If it were L6 I would say it had not hardened and that the light "hamon" I am seeing is just a line of misty nioe as I often get in my mutiple-quenched smaller blades some parts of an inch distance above the actual hardened edge. Alternatively, could I be seeing more of a hitatsura effect where most of the blade has transformed to martensite - the quenchant level was quite high? I'm not expecting a 5160 hamon to be as bold as the L6 hamon because 5160 is a deep-hardening steel, but should it be this misty, in places it is imperceptibly faint?
If it hasn't actually hardened, then the steel is not oil-hardening 5160 and I should be doing a water quench - I have read that some ocs can be a 10xx or even W1 or W2. I suppose what I'm finding confusing is that the steel is not as hard as I am used to though everything (except a clearly defined hamon) tells me it should be hardened. And if it isn't hardened, I don't want to invest the time in shaping the kissaki, yokote, establishing the niku and all the other fiddly polishing stuff if the edge or the blade will bend like licorice as soon as I put it into anything substantial. The hammer test and the fact that it is harder now than when it was in spring form are encouraging, but those of you who have worked with 5160 in the past might be able to give me a bit more solid reassurance before I sit down to work on this blade for most of my spare time in the next week or two.
Thanks for your help
