I want to like 52100... but..

Quirky Example #1: 52100 is very sensitive to overheating. It will give you no outward signs that overheating has occurred, until you have a finished blade and it simply cuts poorly and will not hold an edge.

Quirky Example #2: Refer to post #39

Mitch is proceeding in what I would call the correct manner. 52100 IS NOT a steel for beginners. If you think you want to work with 52100, then start with 5160 first, as its MUCH more forgiving. Learn 5160 and then apply what you've learned to 52100. 52100 does not give you second chances. If you don't nail things the first time, whether it be in the forging, or any other step there after, you come out with way less blade than what is possible with this steel.
People might look at it as me being prejudiced, but the fact is that I can make two identical blades from 52100, one via stock removal, using the "industry standards" and another forged, using what I have learned, and there is absolutely no comparison, the forged blade will out perform the stock removal blade in every single area.
Sam: I'm not trying to be condescending, so please don't take it that way..... If you stick with this, in about 10 years, you will understand what we're getting at....you just need a little more experience under your belt.
 
Ed Caffrey said:
Quirky Example #1: 52100 is very sensitive to overheating. It will give you no outward signs that overheating has occurred, until you have a finished blade and it simply cuts poorly and will not hold an edge.

Quirky Example #2: Refer to post #39

Mitch is proceeding in what I would call the correct manner. 52100 IS NOT a steel for beginners. If you think you want to work with 52100, then start with 5160 first, as its MUCH more forgiving. Learn 5160 and then apply what you've learned to 52100. 52100 does not give you second chances. If you don't nail things the first time, whether it be in the forging, or any other step there after, you come out with way less blade than what is possible with this steel.
People might look at it as me being prejudiced, but the fact is that I can make two identical blades from 52100, one via stock removal, using the "industry standards" and another forged, using what I have learned, and there is absolutely no comparison, the forged blade will out perform the stock removal blade in every single area.
Sam: I'm not trying to be condescending, so please don't take it that way..... If you stick with this, in about 10 years, you will understand what we're getting at....you just need a little more experience under your belt.
Click to expand...

I'll go you one further Ed, I have taken two knives as close to identucle as I can make them. Both stock removel blades from flat sheet obtained from chuck Bybee. One treated to the industry standard as found in the crucible book. The other treated in my "normal" 3x subcriticle aneal, 3x quench and 3x temper. the 3x knife made more cuts on hemp rope and bent 90 degrees without breaking, the "induatry standard blade broke on a 90 degree bend and as mentioned would not hold it's edge as long cutting rope. both blades rockweld at ~60 hrc after tempering.

I know that the triple quench has been discussed to death and passed off as smoke and mirrors and voodoo and everything else. But let me ask how many of the nay sayers have tried this method and given it a fair chance before saying that it is bullspit? I do not think that using industry standard heat treating proceedures is wrong, Just like Ed I believe there is room for improvement.
 
Ed Caffrey said:
Quirky Example #1: 52100 is very sensitive to overheating. It will give you no outward signs that overheating has occurred, until you have a finished blade and it simply cuts poorly and will not hold an edge.

Quirky Example #2: Refer to post #39

Mitch is proceeding in what I would call the correct manner. 52100 IS NOT a steel for beginners. If you think you want to work with 52100, then start with 5160 first, as its MUCH more forgiving. Learn 5160 and then apply what you've learned to 52100. 52100 does not give you second chances. If you don't nail things the first time, whether it be in the forging, or any other step there after, you come out with way less blade than what is possible with this steel.
People might look at it as me being prejudiced, but the fact is that I can make two identical blades from 52100, one via stock removal, using the "industry standards" and another forged, using what I have learned, and there is absolutely no comparison, the forged blade will out perform the stock removal blade in every single area.
Sam: I'm not trying to be condescending, so please don't take it that way..... If you stick with this, in about 10 years, you will understand what we're getting at....you just need a little more experience under your belt.
Click to expand...

Thanks for the info Ed, i understand where you are coming from just trying to get a bit more understanding of things.

Condescending no not at all, I am still a new guy at this that is why I am happy with my 1084 :D
 
Grain growth from overheating is a known problem and its not unique to 52100. Same with other things like distortion in quenching. What tool makers know about tool steel is that each alloy exhibits these qualities to a lesser / higher degree than some others. i.e. 52100 is sensitive to over heating for unwanted increases in grain size.

This is why people who heat treat to colour are not doing a good heat treat job. In some alloys in particular like S5 they are more sensitive so you have to carefully control all temps otherwise it will be junk.

None of this stuff is new ground though. Tool makers have been making blanking / shearing / shredding / chopping knives for ages and theres been tremendous amounts spent on making better knife tools. Its a mistake to think the research is not relevant to cutlery knives.
 
I started talking about multiple quench over 20 years ago, the concept was heresy!
Same with the thought of three cycles. Try what we suggest and judge for your self.

Is 52100 harder to forge? No let it soak at about 1700 f. and it forges as easlily as most other steels.

52100 can be a beginners steel just the same as anyother steel, all you need to know is how. We have taught many students to forge it well in a one week seminar, they leave with true hgh endurance performance blades. All they need is a chance and practice.

Rex and I and others have been working on the same batch of steel since before 1992, we still learn and the next year should be very productive. Just remember Science has a job, that is to explain art. My filing cabinate contains many reports, theories and questions, but performance is the only judge we follow.
 
What I greatly admire about your approach Ed is that you experiment and try things out. When you observe a difference you then go about a good scientific process of inquiry to identify what exactly is going on.

Youve helped me achieve above industry standards by refining the grain size through multiple heat cycles and achieving mechanical properties that are higher than what the mill specifies as being typical for that material. Thanks for that :)

Some things are difficult to measure in knives but where it is clear cut (haha the pun) is mechanical properties because objective and repeatable standardised tests exist to measure them.
 
I will admit I am new at knife making, but not new to using a process whatever that process would be. Yes there are "industry standards" that have been developed by billion dollar idustries for the specific use of 52100 to suit the purposes at hand, be it bearings or anything else.

It is also true that among others Mr Caffrey and Mr Fowler have developed a process that suits the specific use they have (i.e. making knives). Thier process works because they have put the due diligence in research and testing. Who is to say the work they have done is not just as valid as any other industry. I have seen videos from both men and neither of them strike me as the type who would "poke and hope" after all they have thier careers at stake. In the case of Mr. Fowler, he has been working with a metallurgist for a number of years just to develop his methods. Mr Caffrey has also put his steel through traditional research.

Im not trying to choose sides, but I am a results oriented person. Its hard to argue with success no matter how it is achieved. Ill paraphrase
Bob Loveless ...make the best knife you can and let the market sort it out.

As for Ed and Ed, Im wondering how many of your 52100 knives have you gotten back from a customer because they failed to perform the job they were intended to perform?

Just my $.02

Sean
 
I have never received a knife back that failed to perform the job.
One collector purchased camp knives from a number of mastersmiths and worked them very hard! Some destructed, some quit. Some stood behind their guarantee, others claimed he had 'abused' the knife and refused any repairs, replacement or refund.
He was very complimentary about my camp knife and plans to write up his results in the future.

An unconditional life time guarantee is a good thing for the maker because he gets to see what went wrong and compensate for it in future knives. BUT your best knowledge will come from your personal testing in your shop using your knives for the intended purpose and much more.

An area maker came to my shop with photos of his knives wanting me to write about him, they were pretty! I asked to see and test one of his knives, he declined to let me see one. I asked how he tested his knives and he said he knew they were good enough and that was all that mattered!

You will only know through your personal knowledge - you cannot depend on others using your knives and relating their experience. This information can be of use, but you as a maker should know more about the limitations of your knives before one of your clients has to depend on one in the field.

Then you will learn much more my sharing your personal lessons with others. You will face much criticism, but a few will do their own experimenting, some will contact you and knowledge grows.

Some hold tenaciously to the science of steels like a drunk hangs onto a lampost for support, rather than using the illumination provded to explore where none have gone before.
 
This is one of the 52100 blades I made to test and while grinding I noticed what I thought was a hardening line, so I thought "Cool!" and etched it overnight in vinegar.

I cleaned it up under running water with 4x0 steel wool and it revealed something that I think is weird. Three distinct bands, the upper, softer band and the middle band which I thought would be the hardened martensite but there is a third band at the edge that is dark but has light splotches in it.

In thinking about it, I would have to assume that this band at the edge is probably a result of overheating. This blade has only been snap tempered; I put a bit of oil on the blade and a few drops of water and hold in front of the forge, tang first, until the water starts boiling and after another second or two I quench it.

Any comments?

Gedc0145c.jpg


Gedc0147c.jpg
 
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Without watching your work from the first, it is difficult to say what we see.
I would sharpen the edge and test for edge flex. If it chips I would temper a little higher. If it does not chip I would test it for cut on hemp rope or what ever testing medium you have, cut until the edge is dull. Compare cutting your results with a comparison knife and write down the results.

That does appear to be a transition zone in the center of the blade, but like I said would have to know more to be sure. You can put the blade in a vice, flex it until it breaks and if there is a cone of fine grained steel inside of the blade in the area of what appears to be a transition zone you may have done well.

Use a jig and a torque wrench on the blade while flexing the blade just to have an index of strength of the blade for future reference.

Take complete notes and just maybe they will be of value in the future.
 
First let me say Bravo to Ed for challenging us to find out how this all works for OURSELVES. If there was a perfect steel for everyone there would only be one out there to use. We need to do our own testing starting from the established industry standards and achieve all that can be from the steel we choose to use. This is the Journey we set out upon and it is up to us to complete it to the best of our ability.

69,

In your test blade, has it been quenched. I am assuming it was since you felt it was a transition line you had seen when grinding. What I see in your blade is an uneven grain pattern probably from over heating (as you mentioned) and uneven or incomplete thermocylcles. Then your edge does not seem to be even either so I would think your forging temps were way too high for this steel. It is easy to do with 52100 and as Ed pointed out you have no second chances with this steel. It needs to be forged at the lower end of the range in order to get better results. Now this is what I see and I will bow to those who have worked this steel much more if they have a better prospective.

Good luck
 
Thanks for the info Ed.

I will put the blade through at least another proper temper cycle before I do anything else with it.

When I hardened the blade, I used a magnet and checked often for non-magnetic and once there, I continued to heat until the non-magnetic area grew about another 1/2" or so up the width of the blade for 3 times.
 
69_knives said:
This is one of the 52100 blades I made to test and while grinding I noticed what I thought was a hardening line, so I thought "Cool!" and etched it overnight in vinegar.

I cleaned it up under running water with 4x0 steel wool and it revealed something that I think is weird. Three distinct bands, the upper, softer band and the middle band which I thought would be the hardened martensite but there is a third band at the edge that is dark but has light splotches in it.

In thinking about it, I would have to assume that this band at the edge is probably a result of overheating. This blade has only been snap tempered; I put a bit of oil on the blade and a few drops of water and hold in front of the forge, tang first, until the water starts boiling and after another second or two I quench it.

Any comments?

This looks to me like you are close. I would go ahead and temper three times at 350 for two hours per cycle and let cool to room temperature in the oven. then do as Ed F. suggests and do some edge flexes and cutting with it. It is common to see two or more zones of hardness when edge/diffrentially hardening 52100. here is a picture of one of Ed's knives to show what I mean.
3346_1_b.jpg
Click to expand...
 
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 provded to explore where none have gone before.
Click to expand...

Ed. in time, those who resist the advancement of materials and heat treating will have to eventually accept that the science of it has grown. This comes to the core of what science is about - it is self correcting. Once science realises that there is more to it and enough time passes the people who dispute progress are eventually dragged along kicking and screaming by the shear evidence and data of the facts.

I think that part of the problem is that some knife makers like to think they exist in a bubble outside of the science of engineering. This is simply not the case. The fact is that the tool and die industry have been making cutting tools for over a century. Billions of dollars has been spent on research and development - far more than what any R&D a knife maker could ever spend.

When I studied your techniques for grain refinement, I found that science had indeed braced your notions for using heat treating cycles to refine grain sizes. It is not simply your personal tests and your colleagues metallographic analysis of your blades, it is indeed accepted as fact this works. Here's another fact for the doubters of Ed's technique for thermal cycling fine grains, back in 1978 a scientific paper "
The grain size dependence of fracture toughness in an Al-6.0% Zn-2.5% Mg alloy" was published which looked at the mechanical properties versus grain size.

The reality is that knife making does not exist in a bubble and there is a whole world of data, facts and known truths out there.
 
An oft-quoted journal from R.A. Grange demonstrates grain refinement using multiple quenches back in 1966.
 
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Another misconception that exists and is often repeated is that 5160 is more forgiving than 52100 steel.

If we start with a quality 5160 steel and develop the blades to their maximum potential, 5160 can almost equal the potential performance of 52100 steel.

By quality 5160 steel I refer to John Deer Load Control shafts, these are subject to quality control that approaches the quality control in top 52100 steel, there may be other sources of quality 5160, but the John Deer 5160 from load control shafts have never demonstrated any quality issues in my test blades. On my form I have a photo of a 5160 test blade that was tested to destruction. You can see 4 transition zones in the partially broken 5 inch blade that gave up on the last of 8 - 80 degree flexes, each requiring over 90 foot pounds of torque. I would post a link or photo here but do not know how. It is in the thread about our last seminar. You can purchase a new load control shaft over 1 inch in diameter and 18 inches long for around $100.00. A cost of less than $10.00 a blade for average hunting knives.

We can make mediocre blades from any steel, I have many blades that failed in destructive tests due to imperfections in the steel before I ever touched it. abs members testing in my shop have brought failed blades and the imperfections in the steel were obvious.

I used to love to work with unknown scrap steel, learned a lot, but soon decided I was wasting my time. I do not condemn others using scrap or unknown steel but made my choice years ago to work with the best steel I could obtain. Just remember that when a blade breaks or fails the real learning occurs when you figure out why!

A client gave me a metallurgical microscope, I was excited! I asked Rex how quick I could learn to understand what it could tell me. He said a few books and several 100 hours in a lab with a man coaching me. I quickly decided my place was not trying to read a microscope - Rex does his work and I do mine, it took a while to learn to communicate, but I feel we do well.

Multiple quench was known before WWI, but little talked about for various reasons. I discovered it honestly on my own hook and was very bashful about talking about it until Daryl Meier gave me the courage to write it up. While it can never be proved, I believe some of the original men working with Wootz knew it well.
 
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