I want to like 52100... but..

Ed Fowler said:
Another misconception that exists and is often repeated is that 5160 is more forgiving than 52100 steel.
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gday Ed

I dont understand what "more forgiving" means in this context. Could you either explain it please in laymans terms or using engineering nomenclature.

Also, my current process is starting with annealed stock, my blanks are formed. I then triple normalise for grain refinement, then do a single quench in a vacuum furnance using an inert high pressure gas quenchent, down to -300F cyro then triple tempering. So far this is the best method Ive tried but Im always pondering new things to try.

So whats your thoughts on 3 normalises, 1 quench, 3 tempers? Did your colleague do mettalographic examination on this sequence? Did the exam show you have higher retained austenite over 3 quenches? How did it perform?

My hesitation for doing three quenches is in the stresses and potential buckling hassles with quenching.
 
Nullack: The old maxim intends to state that only those who possess greater knowledge can forge 52100. I may even have stated it myself, I learned on 5160. 52100 preformed much better and I switched to using it exclusively and started working with Rex and together we started learning fast. Then one day Wayne Goddard challenged me to work up some 5160 blades using all the knowledge we had learned using 52100. I forged out a blade from a JD Load Control Shaft using our new methods and then tested the blade to destruction comparing it to a 52100 blade. It preformed very close to the 52100 blade, could not beat it, but was within what I would estimate as 10 to 20 % of the 52100 blade.

Our present methods result in no measurable retained austenite in our forged blades using three post forging quenches, two flash normalizing cycles and one full normalize cycle, three anneals at 988 f., three hardening quenches and three tempers. Since we started using the three post forging quenches we have experienced no warped blades. To answer the question before it happens, there was no measurable carbon loss from a 5 1/2 inch round bar to a finished blade.

One rule: you never know the potential of a blade until you have tested it to destruction doing what you intend your blades to do and more.

I believe you ordered my DVD's, am I correct?
 
Try this to see if it will post the photo I want, if not this is the thread on knifetalkonline

Re: Next HEPK Seminar July 20
« Reply #28 on: July 29, 2009, 11:47:07 AM » Quote Modify Remove Split Topic

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This is the final destructive test of the seminar test blade. As usual with every destructive test we gained more knowledge.
 
This is a photo of our last 5160 test blade. You can see the transition zones in the side of the blade. Looking into the fracture or "tear" as Rex calls it you can see that the transition zones are not limited to the surface, but mirror the internal micro structure of the blade. This Blade gave up on the 4th 180 flex, it tore in three stages, first along the edge, then to the transition zone, then up to the soft back, then tore parallel to the spine. The blade could have been straightened and used as a knife. If you were at Blade Show West the blade was there for inspection.
374538554.jpg

This is a photo of our flex testing setup, the vice, smooth jaws and torque wrench jig. The smooth plates are to reduce the sharp jaws of the vice from creating stress raisers in the blade during multiple flexes.
374538557.jpg
 
Ed Fowler said:
Some hold tenaciously to the science of steels like a drunk hangs onto a lampost for support, rather than using the illumination provided to explore where none have gone before.
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Wow (content aside) that's damn near poetry.

Thanks for posting the 5160 destruct test photos. I see where you clamp the torque wrench jig behind the ricasso, but how do you decide where to clamp along the blade in the vise?

Whose thumbs with the ever ready duct-tape-aids?!

All the best, Phil
 
The blade was about 5 inches long, using what I call the modified Price grind we need to set the blade deep enough that it won't fly out due to the geometry of the blade during testing. 90 foot pounds of torque is a lot and safety is a main consideration. Before this part of the testing the tip was driven into old hard bone, engraved mild steel and did not deform.

The taped up thumbs belong to Harold Locke a student from California who attended our last seminar. He got a little close to the 2 x 72 inch grinding belts sometimes, in spite of sore thumbs he practiced grinding blades for 7 days and left with some nice blades.

Harold is very strong and each time he heard a snap, he stopped increasing the torque and we examined the blade. We have destroyed many blades this way, but this is the first time we noted the blade tearing in separate stages. We had previously failed to observe the obvious.

The blade returned to withing 20 degrees of straight each flex, after the hardened portions tore, it remained bent at 90 degrees as the soft back had little spring to it.

It is important to note the tear turning parallel to the blade spine, it can still be straightened and used as a knife.

The modified Price grind allows the blade smith to dictate where in the blade the flex will occur. On this blade I ground the thinnest area just in front of the ricasso. I could have just as easily set the flex point further ahead.

Each blade has its own little variables to be considered thus allowing the opportunity for learning a little more with each blade destroyed.
 
Bill Burke said:
I am not sure what you are reffering to. If it is the zones on the blade in the picture I posted then on what information are you basing this statement?
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Mr. Fowler's video on "52100 Wootz". If the knife in that photograph was not made in the same fashion as was demonstrated in that video my previous statement may have been incorrect - however, if it was - my assessment is likely correct. It's just as likely a conclusion as the 'varying levels of hardness' determination - in point of fact, more so. Of course, after reading the positively ridiculous quote here my guess is my viewpoint is moot.

Originally Posted by Ed Fowler-
"Some hold tenaciously to the science of steels like a drunk hangs onto a lampost for support, rather than using the illumination provided to explore where none have gone before."

Another quote, as viewed on Mr. Fowler's own page-
"All of the information you are about to view is proven by Rex and I through many hands on experiments and laboratory testing of each and every event that follows. Forging a high endurance performance knife is an art based on science that is subject to empirical evaluation."

I'm sure I'm taking one of these out of context...
 
It also occurs to me that my presence in this thread may have the same effect of other posters pointless tirades against reason. I'll keep my footprint limited to what it is here, as I don't wish to be a further incendiary.

Mr. Burke, maybe we'll get to discuss this further some other time.
 
Ed Caffrey said:
Here's my perspective.... The reason I do all of this testing and experimenting in my shop, using the mentioned "established standards" as a starting point is simply because NONE of the established data is based on using this steel, or any of the others for that matter, to create the items/uses we are. It has always been my thought pattern to take the next logical step(s), as it relates to what I am trying to achieve with the given steel.

Concerned "established standards".... if you've ever looked at/used a heat treating manual, look closely at the first couple of pages or the inside cover page. You will find a "key" which usually states something like "all of the data in this book was achieved utilizing as 1" cubic section of the indicated material", or something of that nature. What thats telling you is that they used a 1"x1"x1" piece of the steel type to acquire the data. Now I don't know about you folks, but I have NEVER made a knife blade that is 1" thick, and there is a difference! I gotta run to an appt. but will continue this a bit later!

OK, back from my appt. To continue with where I was going. The "industry standards" are based on the broadest spectrum of uses for the indicated steel(s). In other words, if you treat the steel according to those specifications, it SHOULD be OK for MOST applications. Thats just not good enough for me. I'm using the steel for a very specific function, but within that function there are several distinct characteristics that I desire. I want not only excellent cutting ability, but also the toughness and durability, but just as important is the ability of the end user to be able to easily resharpen the blade. Its going to be up to the individual maker to determine the characteristics that they desire, and strive for those. What I desire may not be the same as you, but the methods that may seem the long way around to you, are whats required to achieve what I desire. Its always a give an take situation with blades...you give up a little of one thing to acquire a little of another. The trick is finding the balance point where all the aspects/attributes are where YOU want them.

Since I came back to complete this post, I read the two after it. Thanks for the support Mitch, I think you understand where I'm going with this. Sam: Try what you mentioned in your post! Seriously, thats how we learn. If it works out where you achieve the overall package you desire in a finished blade, then you've solved the riddle of 52100 for yourself.

OK, I gotta finish this up and get to work. I'll describe how I came about the 3x thing with 52100. I already talked about the thermal cycling in a previous post, so I won't repeat that here. The 3x quench can be either an edge or full quench, what the spectrographs showed is that no hardness change takes place, but the the 2nd and 3rd quenches show successively reducing amounts of retained austinite, as well as refinement of the grain. (NOTE: My method is to quench the blade, and allow it to cool IN the oil, to approx. room temp before doing a 2nd or 3rd quench) What I found odd about it at first was that after the 2nd and 3rd quench a file would cut the steel more easily, which made me believe the steel was getting softer. But there was no Rc hardness changes...the testing proved that. Now that could simply be that the surface was decarbed and cut more easily, but even after a clean-up grinding, it still held true. It stood to reason with me that if I was setting things up in that manner, then the 3x tempering would be of benefit too. It was only a guess at first, but in the end the testing proved that guess to be the correct one. The gentleman who does the testing for me has a way more technical vocabulary than I, and his input was, in my translation, that due to the specific amounts of Cr in both 52100 and 5160, these method did indeed improve this particular steel for knife blades over a basic "heat, quench, temper" method.
Some may call it "Voodoo", or whatever they want, but its proven that it creates a MUCH better blade from 52100, than one that has been treated to industry standards. OK, gotta get to work, will check back this evening!
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Ed,

I quoted your whole post but this is about from the bold on down. I'd like to thank you for posting that and I'd have missed it if I hadn't gone back to the beginning of this thread to reread it. It is the first time I've ever seen specific cause/effect detail from any 52100-blade makers (I'd love to be pointed to others I've not seen... by anyone).

An aspect that is really interesting to me is Scott mentioning bearings are heat treated to have 8% to 20% retained austenite and your finding retained austenite lessens in blades as quenches increase.

I was wondering if you had other data driven observations on 52100 you find interesting and if you could break out the time to post them here?

Mike
 
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Matt: we are from two camps, but I do not feel we are at war!
The two statements are not dichotomous - Some regurgitate the dictates of science and apply what is proven with no diversion from what is known as "fact".

History knows many examples of this phenomenon. From thousands of years before Columbus to the Wright Brothers and into the present - innovation has had to fight 'science' or known fact and tradition.

Science is at its best when it describes what happened rather than dictates what will happen or condem what is 'impossible'.

I do not mind debate for we all learn from discussion. If we have failed to communicate some aspect, ask again and I will try to explain.
 
You have convinced yourself of a peculiar view of what science is all about, Ed Fowler. What I would call a layman's definition, which lacks a real understanding. While it may sound good to you and many around you, to those better informed it comes off as pure self-serving bullsh!t that no longer even merits rebuttal.

And that's all I'll say on this thread.
 
Albert Einstein:
I think that only daring speculation can lead us further and not accumulation of facts.


Albert Einstein:
There is no logical way to the discovery of these elemental laws. There is only the way of intuition, which is helped by a feeling for the order lying behind the appearance.


Henri Poincare:
Science is facts; just as houses are made of stones, so is science made of facts; but a pile of stones is not a house and a collection of facts is not necessarily science.
 
Me, I'd rather a specifics driven discussion about modified HT of 52100 maximizing it's knife characteristics than talking about talking about it.

Mike
 
Matthew Gregory said:
Mr. Fowler's video on "52100 Wootz". If the knife in that photograph was not made in the same fashion as was demonstrated in that video my previous statement may have been incorrect - however, if it was - my assessment is likely correct. It's just as likely a conclusion as the 'varying levels of hardness' determination - in point of fact, more so. Of course, after reading the positively ridiculous quote here my guess is my viewpoint is moot.
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Matt, If you are talking about the damask pattern of the blade as being alloy banding then you could in all probability be correct. but if you are refering to the three visible bands that follow the conrtor of the blade, as seen in the picture below, then your assumsions are incorrect as these are indeed zones of differing hardness.

87374_1_b.jpg
 
Probably 3 years ago, maybe more, I came across an article about 52100. I thought I linked it into my bookmarks but over the past days I've not found it. If I'm remembering, it was from a state knifemakers organization in the southest... like, maybe Arkansas, but maybe not. It seemed to me to be a modification of the sort-of-standard " triple, triple, triple". Does that ring a bell with any one... can you direct me to the article?

Mike
 
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