The old blade smith tradition can talk to us, should we listen?

[pig]

The old blade smith tradition can talk to us, should we listen?

First:
-I am an other old hobby smith
-I am not a metallurgist
-English is not my language (Shame on me, I do not even use the spelling check!)
-There are many facts and many blieves about techniques, difficult to position for sure as fact or believe

I introduce (can be too long intrduction?) a discussion topic, I hope to find interested smiths to share opinions.

I know that BG-42 or CMP-440V are more interesting to many as a discussion topic. To my mind the name of "The general knife discussion group" could be as well "The fancy commercial steel brand group", just a peronal opinion not a fact. I did find the same thing with computers, young people are interested about most new, commercial brands, things nothing to do with basic principles of computer internals. Some sense with this too. Old forging techiques are discussed 2000-3000 years before us and will we discussed probably next 3000 years. On the other hand BG-42 is discussed couple of years and will live perhaps many years ahead. Very parallel with computers- aging 3 years! After 2000 years not even the best books of history will know BG-42 ever exsisted. So, we have unique possibility to discuss about it? Also we can talk about BG-42, but the old tradition is something we must to listen too. Listening is more difficult than talking.

I would prefer to focus on bare carbon steels and low alloy steels as 5160, 52100..... Generally speaking the steels easily to handle and HT without new fancy tools as electrical, vacume,.... ovens. (Still also very fancy new steels can be handled with old methods at some extent for exampe so called "austenite forging".)

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Some words (at very vague popular level) about the terminology and concepts, written "newbies" in mind:
-The problem that the same part of a steel can't be very hard and very though at the same time is unsolvable. There is a "trade off".
Smith's solution to this problem is that the edge part is hard and the spine though. No solution offered by super alloys (well, they are brittle whole time mostly).
-Austenite is a form of a hot steel to be hammered (all alloyed elements are a kind of unorganized, free, if you wish)
-With quenching (very rapid change from hot to cool) we change this form to very organized structure (tied in a way, matrix) which is very hard and brittle called martensite
-With tempering (warming some amount) we give up a little bit about this organization and get more though steel, also more soft unfortunately.
-Let's imagine you travel with a time machine to the middle ages with a sword made from BG-42. These unlearned people out there will laugh at your brittle sword made from a new high tech alloy of our modern times! (I just try to make my point clear at easy popular way, I know nobody is suggesting to make a sword from BG-42 to day). I mean new alloy is not a solution to all problems.
-Most common misunderstanding is that the overall hardness equals the cutting ability. The cutting ability depends many things as the fine crystalline stcructure and cutting hard sharp carbides
-The steel hrdness is measured by Rockwell test (HRc)- examples: HRC 50, though spine, HRC 61-58 hard edge, wear resistant too, a high carbon steel directly after queching HRC about 67-64, very brittle

Examples: HRC 50- file bites easily
HRc 58- new fine file scratchs the steel
HRC 61- new fine file slides
HRC>65 the steel scratchs a little bit glass (from quenching, not tempered, high carbon steel)
-If you still decide to use something as ATS-34, BG-42 CPM-440V you should buy enough equipments, because temperatures are very high, steel are not forgiving, you can't measure for example the quenching temperature with a magnet.
-You should have factory specs about max HRC, quenching temp and tempering curves
-A commercial fine new brand of the steel do not make a good blade, smith's work do

Infomation is available even in Internet, books are better. For example you can seek from internet terms: quenching, tempering, annealing, normalizing, austenite, martensite, perlite, bainite, crystalline structure, grain size, carbides, .....
To my mind a blade smithing book with a chapter of elementary metallurgy is the best.
Second best is a book with a name as "elementary basic metallurgy"
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I do not know, is my terminology course useful or stupid.
Please, comment to this thread.

Random opinions about blade forging:
-A metallurgist of my steel supplying company said that if we cut the steel stripes from a sheet in the roll pressing moving direction (I do not know the right word), forging do not help (Indicating it helps sometime! We do not know it or it never even existed)
-Ed Fowler suggest lot of forging from big pieces downwards to get better more fine structure
-Jim Hrisoulas suggest perhaps odd things to many, aus-forging and edge packing (explained later)
-I did similar blades one just grinded from a bar and other edge packed and aus- forged from the same bar, HT and dimensions the same. I tested sawing against a copper bar and tested sharpness with cutting arm chair and sawingn leather stripes (Big difference, I do not tell which kind, nobody believes me anyhow)


Aus- forging:
Aus- forging is a very old German blade forgin techique (the term from a Jim Hrisoulas' book). Simply meaning, forge near the lowest allowed temperature. (Too low, blade is destroyed easily! ) The forging takes lot of time, the steel is warm enough only during few hits. On the other hand the grain size is not enlargening because the temperature is so low.

Edge packing:
Forge the blade shape roughly. Bend it edge down on the anvil horn as some semi circle taking into accout the lenght and thickness (difficult, no, challenging, yes). Start hitting with hammer peen inside circle. The blade will be eventually straighten, because inside becomes longer. This is supposed to creare a great fine grain structure.

I do not hit ever vertically on the edge, spine on anvil or on the spine, edge on the anvil to correct bending finally.

I had to build a tool for edge packing. I am clumsy, not able to hit at a precision of 1/32 inch!


Any opinions or experience about aus-forging or edge packing or other techiques?
Any questions about forging?
Your own forging techniques?

Please, start the discussion!



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(pig)

 

[rdangerer]

Originally posted by pig
The problem that the same part of a steel can't be very hard and very though at the same time is unsolvable. There is a "trade off".
Smith's solution to this problem is that the edge part is hard and the spine though. No solution offered by super alloys (well, they are brittle whole time mostly).

I certainly don't want to hijack this thread off into the wrong direction.

But I do want to mention that there are a couple of "super alloys" that can be left fairly hard and yet still retain good toughness, specifically CPM3V and CPM1V, especially 3V. S7, S5, and L6 shown as benchmark for "tough", shock resistant. Per Crucible:
http://www.crucibleservice.com/datash.cfm
http://www.crucibleservice.com/eselector/prodbyapp/tooldie/champloy.html
http://www.crucibleservice.com/eselector/prodbyapp/tooldie/labelle.html
http://www.crucibleservice.com/eselector/prodbyapp/tooldie/crus7t.html

Steel, toughness ft-lb, @ Rc
============================
S7, 120 ft-lb, Rc57
S7, 85 ft-lb, Rc59
S5, 138 ft-lb, Rc59-60
S5, 146 ft-lb, Rc58-59
L6, 15 ft-lb, Rc63-65
L6, 43 ft-lb, Rc60-62
L6, 38 ft-lb, Rc58-60
L6, 68 ft-lb, Rc56-58
CPM3V, 85 ft-lb, Rc58
CPM3V, 70 ft-lb, Rc60
CPM1V, ~ 110ft-lb, Rc56

Note L6 has a "double toughness hump" to consider in final edge hardness.

3V has the additional advantage of abrasion resistance well past the simple carbon steels or low alloy steels, in the range of D2's abrasion resistance.

What you'd want to compare to the above is a carbon steel's actual toughness AT THE EDGE, at the hardness you choose for that carbon steel edge.

And then you can debate whether you prefer a spring temper on the spine, or a full hardness/strength spine.

Ok, hijack over... now back to your original host's questions:

Any opinions or experience about aus-forging or edge packing or other techiques?
Any questions about forging?
Your own forging techniques?
Please, start the discussion!

 

[RHINOKNIVES]

i have a feeling that a sword of BG-42 ground and diff,HEAT TREAT to say 57rc would amaze!the smiths of the middle ages. we tend to glamoize past with excaliber! and magical jap swords.

 

[Burt Foster]

Well Pig, I think you're doing it again. You're asking such a large question. Large to ask, and even larger to answer! That's ok, better to ask unanswerable questions than to have nothing to ask.

Forgive me if I go off in a direction that you did not intend, but your questions were so numerous, that my response has to be justified in there somewhere.

In thinking about my reaction to your original post title, and the effect we bladesmiths will have on the future of bladesmithing, I always come back to the "artistry" of the smithing process. I really do believe that most discussions about the perfect steel, the perfect heat treatment, and edge geometry, etc. are largely academic. It is actually fairly common for me to talk to someone who has a knife that I know is total junk, but he thinks it's great. He talks about all the things it will do, how sharp it is, etc. Maybe he never had a good knife, or maybe he wouldn't like one even if he had one.

My point is, these types of discussions are very interresting, but ofter leave no one's mind changed, and that's ok. When I am asked these types of questions personally, I usually deal with them from the angle that when it comes to a handmade knife, the more raw the materials were when the maker started and the more his hands were used in the process, the "better" the knife. Not always from the standpoint of rope cuts or blade bending or all that. But, let's be honest here. As makers, we are selling appreciation. We are appealing to a person's need to own something "special." There's no way you can tall me that one of my knives is really 20-30 times "better" in a qualitative sense than a knife 20-30 times cheaper. But people pay it, all the time, because they "appreciate" the work, the sweat and the creativity that went into each knife.

Now I do think a forged blade is better qualitatively. But I know I could make a stock removal knife and sell it and a customer who owned a forged blade of mine could not tell the difference except in a "laboratory" type setting.

The reason that bladesmithing is "superior" and it's popularity is growing greatly, is that it tends to appeal to a person's sense of and "old-world" craft more than a stock-removal knife.

As opposed to the smiths of the past, we actually have the luxury of knowing what's in our steel. A smith proficient in his craft could make a good knife out of any piece of steel. So I think the real tradidion is not in comparing steels and heat treatments, but keeping our minds right about our work, and striving to give our customers what they really need. What they need is an object of function and beauty that brags about it's heritage, not it's chemistry.

 

[jhiggins]

Hey Pig, it's great to have an inquisitive mind in this forum, so please do not be afraid to ask those questions! Your questions are very thought-provoking. Also, if I may add: I think you should stop apologizing for your English. It's much better than many people I know who are born and raised right here in the USA. I applaud your humilty, however. Now on to my reply...

I have used an ausforging technique on my blades before. Fact is, I used it not even knowing what it was called, I just thought it was a "good idea" to work-harden the edge of the blade a little. Seemed to work well, and the knives I have all made like that have stood the test of time quite well.

 

[Alarion]

I do not like high-alloy steels. It's not that I do not have the precise electronic ovens necessary to properly heat treat them. It's just I don't like that kind of smithing. Not that I find it "inferior" or "not real smithing". Just a matter of tastes. I will probably do in the end inox knives. They are so convenient.
But I like much more good ole carbon steel, far simpler to handle, and that can be easily forged and HTd without a lot of complex equipment.
BTW, I never dug in the technique of bending the blade beforehand and then hammering the edges. I first hammer the edge, and the blade bends backwards, then, when the thicker spine is stil quite hot, while the edge is at a dull red (thus much harder) i hammer vertically and re-straighten it. The edge doesn't get much rebated, and the blade straightens perfectly.
I think it pays to do a LOT of normalizing cycles after such forging, checking constantly for blade warpage (such treatment levaes LOTS of residue tension in the blade). I normalize, heat, check for warp, correct it with a few taps, check again, normalize and on this wa until the blade is perfectly straight.