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- Sep 16, 2002
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Draw filing, or?
-
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I hate to beat a dead horse, but I have a few questions
- Thread starter IH8U
- Start date
Draw filing, or?
- Joined
- Mar 6, 2007
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- 779
I guess I would call it draw filling, but it was more of angle filing. the files I used have the edges on an angle (30 degrees, maybe?) and that is the direction I went. After I got most of the material removed I moved to a very, very small diamond file and tried to go as straight as possible in a perpendicular fashion to make the grind lines look straight and to clean up the deeper cuts from the bigger file.
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- Sep 9, 2003
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1550F is a bit high for 1084 and VERY high for 1095. I have taken 1095 to 1500F with very short soaks with success but 1550F is higher than I would ever dare go. 1500F for the 1084 and 1475F for the 1095.
My reference for longer soaks for 5160 comes from Verhoevens book, in reference to evenly distributing the Cr for 52100. I know they are not the same steel, but we're moving the same element. I'm assuming the Cr is not evenly distributed in the cementite and ferrite, which may be incorrect. I was thinking of soaks as long as 1 hour, probably more like 1/2 hour. I've read of some issues with 5160 having hardenability trouble when soaked for too short a time, or at too low a temperature. Since the other half of chromium's job in 5160 is to increase hardenablility, I am guessing that this was caused by spotty Cr concentrations leading to low hardenablility in the low Cr areas. An hour long soak may not be needed, but IMS the carbon is redistributed and fairly even in a matter of seconds, while the Cr takes tens of minutes. Of course there is some overlap there and specifics will depend on initial structure.
On another, but similar, note, has anyone tried under heating 1095 to get more carbide with tougher martensite? Something along the lines of a sub 1400 degree soak for maybe an hour? For all you guys looking for information on your 1095, dont to this, unless you want to experiment (read ruin good blades) and have some 1095 to burn, so to speak.
On another, but similar, note, has anyone tried under heating 1095 to get more carbide with tougher martensite? Something along the lines of a sub 1400 degree soak for maybe an hour? For all you guys looking for information on your 1095, dont to this, unless you want to experiment (read ruin good blades) and have some 1095 to burn, so to speak.
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- Sep 9, 2003
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The chromium may not be evenly distributed throughout the ferrite but the cementite is transient, occurring wherever the carbon manages to gather in concentrations of 6.7% and this will indeed happen more readily around chromium and other carbide forming alloys. However substitutional alloy atoms themselves will still take much longer times to diffuse than would the carbon atoms moving in the matrix around them. And here is the situation at hand, freer carbon such as the Cementite lamellae of pearlite will move very rapidly at normal austenitizing temperatures, but bound up in the form of speroidal carbides surround chromium will take much longer to liberate and distribute, with the chromium atoms taking even longer beyond that. At the average soak temperature and times used by most bladesmiths complete alloy homogenization would not be a common expectation. As I mentioned in another thread for consideration, iron carbide gives up and releases carbon atoms for diffusion to adjacent lower carbon layers when welding Damascus in just a few heats, however if the chromium or other substitutional atoms could move any significant amount even above 2200F all Damascus would get really boring quite fast. I am sure that a whole redistributing of chromium carbide would be going on in welding. That is not to say that I haven’t seen some fuzzy Damascus layers from some sharing of alloys before
Oh well, back to the drawing board, or library in this case.
The micrograph is pretty interesting. I suppose that answers my question. I though of it when I read Wayne Goddards answer to a question about 9260 and S7, proposing that the chromium in 5160 formed carbides that allowed it to hold an edge better than either of these 2 steels, presumably at approximately the same hardness. I didnt think it would unless the Cr pushed the eutectoid low enough to allow it, and Cr also raises the critical temperature, so it was an even guess on my part. That micrograph also seems one plausible explanation of carbide banding in 5160 that Ed Fowler and some of his students have reported, especially given the tendency to forge at lower temperatures than most. Speaking of proper austenizing and holding temperatures, that 9260 is one that I bet has given people fits. IIRC, the austenizing temperature is nearly 1600 deg F, well above the non-magnetic point.
BTW that blade profile above looks great. I'm a big fan of the scalper patter, and that comes pretty close. Simple, straight forward design with nothing to get in the way.
The micrograph is pretty interesting. I suppose that answers my question. I though of it when I read Wayne Goddards answer to a question about 9260 and S7, proposing that the chromium in 5160 formed carbides that allowed it to hold an edge better than either of these 2 steels, presumably at approximately the same hardness. I didnt think it would unless the Cr pushed the eutectoid low enough to allow it, and Cr also raises the critical temperature, so it was an even guess on my part. That micrograph also seems one plausible explanation of carbide banding in 5160 that Ed Fowler and some of his students have reported, especially given the tendency to forge at lower temperatures than most. Speaking of proper austenizing and holding temperatures, that 9260 is one that I bet has given people fits. IIRC, the austenizing temperature is nearly 1600 deg F, well above the non-magnetic point.
BTW that blade profile above looks great. I'm a big fan of the scalper patter, and that comes pretty close. Simple, straight forward design with nothing to get in the way.
- Joined
- Jul 21, 2001
- Messages
- 2,869
We can debate theory endlessly, If you want to know how your heat treat worked, simply test your knives doing what you want them to do. It is that simple, try various methods, test your knives, compare to a reference blade, keep records and keep experimenting until you find the performance qualities you want. Then you know.
If you want to know what kind of knives a maker offers, simply ask him how he tests his blades and ask if he guarantees performance.
If you want to know what kind of knives a maker offers, simply ask him how he tests his blades and ask if he guarantees performance.
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- Mar 18, 1999
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- 2,114
What Ed Fowler said has some merit but I must admit that this is a VERY interesting discussion.
Going back to my old days of working instrumentation, I always keep one thing in mind. The temps listed are guidelines. Guidelines for the sake of accuracy. I once made a service call to a grocery chain's bakery. They had just gotten some wiz-bang new engineer right out of Texas A&M and he was out to change the world (which he did but that is at the end of this little story). I had scheduled a routine service call to check their instruments that control and record each batch. He told me that he wanted everything as accurate as it could be. I questioned him and he was adament. I once again asked him if he was "sure". He was. "Even the controllers?"
"Yes, even the controllers."
Well, made a note of how far off they were and then reluctantly calibrated them. I made sure that the guy that ran the ovens knew what I had done. They were 20 degrees off. The young wiz-bang engineer was proud of himself. I took my time and waited around. The first batch that came out was gummy, or like dough.
"WHAT DID YOU DO?!?!?!"
"Only what you asked." I replied.
The strip chart recorders indicated that this batch was 20 degrees off.
To make a long story short, I "re-calibrated" the controllers to what they were before.
Thermocouples accuracy, particularly type K which we all use, is 4-8% accurate at best. The controllers we use are 1-2% at best. What your controlller says may be off by as much as 25 degrees from the next guys. I am able to check mine on occasion with test equipment I have available to me but everyone else doesn't have theat luxury.
Just be mindful of this. If your heat treat doesn't quite work out like "everyone else's", well...it may not be the same "as everyone else's."
I recommend the following:
Remove as many flies in the ointment at possible and keep the constants constant. Quenching medium, temperature of the quench, steel and or supplier, etc. It never hurts to experiment but know the constants.
One other thing...take notes!
Craig
Going back to my old days of working instrumentation, I always keep one thing in mind. The temps listed are guidelines. Guidelines for the sake of accuracy. I once made a service call to a grocery chain's bakery. They had just gotten some wiz-bang new engineer right out of Texas A&M and he was out to change the world (which he did but that is at the end of this little story). I had scheduled a routine service call to check their instruments that control and record each batch. He told me that he wanted everything as accurate as it could be. I questioned him and he was adament. I once again asked him if he was "sure". He was. "Even the controllers?"
"Yes, even the controllers."
Well, made a note of how far off they were and then reluctantly calibrated them. I made sure that the guy that ran the ovens knew what I had done. They were 20 degrees off. The young wiz-bang engineer was proud of himself. I took my time and waited around. The first batch that came out was gummy, or like dough.
"WHAT DID YOU DO?!?!?!"
"Only what you asked." I replied.
The strip chart recorders indicated that this batch was 20 degrees off.
To make a long story short, I "re-calibrated" the controllers to what they were before.
Thermocouples accuracy, particularly type K which we all use, is 4-8% accurate at best. The controllers we use are 1-2% at best. What your controlller says may be off by as much as 25 degrees from the next guys. I am able to check mine on occasion with test equipment I have available to me but everyone else doesn't have theat luxury.
Just be mindful of this. If your heat treat doesn't quite work out like "everyone else's", well...it may not be the same "as everyone else's."
I recommend the following:
Remove as many flies in the ointment at possible and keep the constants constant. Quenching medium, temperature of the quench, steel and or supplier, etc. It never hurts to experiment but know the constants.
One other thing...take notes!
Craig