blade quenching fact or fiction

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Rick Marchand said:
I have to humbly disagree, Fred... the results are quite different but the desired effect can appear to be similar. Though, Edge quenching and clay coating are very similar, a full quench and select temper is a very different animal and some would dare to say more "metalurgically sound"...... oops, I guess I said it.

Not that any of these methods are necessarily wrong. It would be a shame to lose those beautiful temperlines that come from differential heat treatment. However, our understanding of modern metallurgy has come a long way.... better steel, better equipment..... better results.




Rick
Click to expand...

Quoted for truth
 
AVigil said:
How about the best method to HT a camp knife and what makes it the "Best method to HT"
Click to expand...

Your idea of a camp knife could hold very different characteristics than mine. What attributes for what tasks? Cleaning fish, making fuzz sticks or busting open stumps?
 
What was the original question?

Is this that sharpening thread?

Try to stay on point:eek::D

Fred
 
Yeah.... thread drift... sorry.:o

Lets get back to the heated, touchy subjects.:thumbup:

Mr Fowler,
What are your testing methods for side-loading your edge quenched blades? What criteria do you try to nail? As Tai likes to kid about, I happen to see the value of a hard use bush blade being able to do more than just survive side-loading..... okay.... "prying"... there, I said it.
 
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Rick Marchand said:
Your idea of a camp knife could hold very different characteristics than mine. What attributes for what tasks? Cleaning fish, making fuzz sticks or busting open stumps?
Click to expand...

All of those tasks.
So what is the best HT for that camp knife and why?
 
AVigil said:
All of those tasks.
So what is the best HT for that camp knife and why?
Click to expand...

On the basis of prying open stumps alone, I would want a homogeneous martensitic blade, differentially tempered, as it would maximize strength (resistance to deformation) per any given thickness. I want the bulk of the energy I put into that blade to be directly transfered to the task of getting at those tasty mealworms. Strength comes with hardness which is why you don't see prybars being made from mild or non-hardened steel. Cleaning fish and shaving sticks with the same knife would have more to do with geometry and steel structure at the edge, so as long as one had control over heat, it wouldn't matter whether it was differentially heat treated or not.

So, in this specified scenario, one out of three tasks is better suited to a fully hardened, differentially tempered blade and the other two tasks would, for the most part, be addressed equally either way.

Fully hardened it is.

Rick
 
Rick Marchand said:
Fully hardened it is.
Click to expand...

I agree.

The days when tool-makers were forced to muck about with half-steps, old wives' tales and muttering compromises because they only had inconsistent, low-quality steel to work with, are long gone.

Today, we're blessed with an embarrassment of riches when it comes to alloys; archaic (oh boy, what a word) techniques like edge-quenching, laminating/Damascus, hamons and so forth persist entirely for aesthetic reasons.
 
I am all for learning data and research. But that also goes for real world application, experience and results. Is there any cold hard data showing a knife made to the same specs but heat treated in the manner Ed Caffery shows in his video vs. the most advanced temp controlled methods to the same knife?

All things being equal except the heat treatment, will either blade show significant difference when compared to the same tasks? Or is it just academic?
 
I'll wade in one more time .

"All things being equal except the heat treatment, will either blade show significant difference when compared to the same tasks? Or is it just academic? "

The problem with threads about "BEST" procedures is that they are all relative to the readers point of view.
Ed will see things his way. Tai a little different, Rick with a squint, and Stacy with a technical slant. Each sees "BEST" as a different thing. So the short answer is ,"Yes, it is usually academic."

As far as hard data goes, there are volumes written on metallurgy that will explain martensite vs pearlite ,etc.I am comfortable with this data.
Ed has also written a lot about the testing of his blades using his test methods. He is comfortable with his data.
Tai posts often about how his blades look,He is comfortable with his artistic outlook.
Rick likes to argue...so he defends both sides, and is never comfortable ( just kidding, Rick).
None of these people or their data sources are likely to be in total agreement about any specific knife and its use....as that is objective, not empirical.

As far as Hard facts:

Martensite is what makes a knife edge hard. No other steel structure will work as well..........hard fact.

Edges should be martensite......accepted fact.

Tempered martensite is tougher than as hardened martensite......medium hard fact.

Pearlite is softer and much less brittle than martensite....soft fact.

A blade made completely from martensite does not have transition zones to deal with.......hard and soft fact.

A blade made from differentially tempered martensite will take a beating on the spine and will resist deformation up to the breaking point.....at which it will fail.

A blade with a pearlite spine and a martensite edge will take a beating on the spine, and will deform/bend before breaking.

Mixtures of steel types and structures were done in the past to get the best blend of attributes from the materials and technology available at the time.

Mixtures of steel types and varying the structures in a blade can not make steel do more that it is engineered for in modern steel and heat treating technology.

Edge quenching works well for getting a hard edge and soft spine.

Fully hardening and differentially tempering works well for getting a hard edge and a tough spine.

Whether you do one or the other will be a matter of your personal ability and preference more that a matter of one producing a "better" knife, as both will produce a knife that will meet all the requirements of any real world use.

It is in understanding the metallurgy of heat treatment and steel types that you can make an informed decision as to how to process a specific knife. Without that understanding, one is just doing rote things that he/she read somewhere...without knowing what results are being affected, or how to change them.

Final note for those who learned all they know by reading online - Just because it is posted online somewhere doesn't mean it is good info. Even the info in some books is badly flawed. It is by getting a good understanding of the metallurgical process that you can filter the good info from the bad.

So, to sum this all up:

It is not "BETTER" to blindly follow Ed, or Stacy, or Rick, or Kevin, etc..........
It is in doing your reading and learning, and then doing you own personal testing of the results you get that will give you the "BEST" knife you can make.
 
Dan, 4 reasons you've not seen edge quenching in my shop. We go for martensite and avoid pearlite on all the steels we use in the shop. Also, I'm mainly teaching you to use 01 steel, which is a deep quench steel. We could get a hardening line, but not a beautiful wavy hamon. Plus, even to see the hardening line we'd have to rub the blades, which you know I do not do. So there are two reasons you've not seen edge quenching. The third is that on most knives, a fully hardened blade is plenty tough. Dylan has actually batonned a fully hardened 01 blade through (edge to edge) a chinese stainless shitknife blade, and the 01 blade held (with plenty edge damage). He used a steel hammer to pound the back of the 01. Lastly, I don't make prybars, and prying voids my warranty.

Last week when I finished heat treating the big knives I put their edges between the aluminum plates with a wet paper towel on the edge itself. I then drew the spine back with a mapp gas torch. You were out that day, I can show you this process anytime. This was purely for peace of mind IMO because I don't ever think the blades would fail without it. If that blade were to fail, though, I like to know I did everything I know to make it properly. Then, I can just replace it, and sleep calmly.
 
Thanks Stacy that is a great response. In the world of custom bamboo fly rods we have very similar discussions and conclusions. I appreciate you breaking it down on how you see it and not dance and dodge in giving an answer. Over the last 35+ years of buying and using knives from good makers none of them have failed to perform admirably even though having a variety of heat treating methods used on them.

Great makers, make great knives. What makes them great is the experience on what works for them and perfecting it.
 
"The problem with threads about "BEST" procedures is that they are all relative to the readers point of view."

Right on Stacy! :)
 
Fiddleback said:
Dan, 4 reasons you've not seen edge quenching in my shop. We go for martensite and avoid pearlite on all the steels we use in the shop. Also, I'm mainly teaching you to use 01 steel, which is a deep quench steel. We could get a hardening line, but not a beautiful wavy hamon. Plus, even to see the hardening line we'd have to rub the blades, which you know I do not do. So there are two reasons you've not seen edge quenching. The third is that on most knives, a fully hardened blade is plenty tough. Dylan has actually batonned a fully hardened 01 blade through (edge to edge) a chinese stainless shitknife blade, and the 01 blade held (with plenty edge damage). He used a steel hammer to pound the back of the 01. Lastly, I don't make prybars, and prying voids my warranty.

Last week when I finished heat treating the big knives I put their edges between the aluminum plates with a wet paper towel on the edge itself. I then drew the spine back with a mapp gas torch. You were out that day, I can show you this process anytime. This was purely for peace of mind IMO because I don't ever think the blades would fail without it. If that blade were to fail, though, I like to know I did everything I know to make it properly. Then, I can just replace it, and sleep calmly.
Click to expand...

Back when I made my knives by stock removal from O-1 I fully hardened them, tempered them, then drew the spine back to peacock blue. I was working at a photolab and it was mid winter, it was late at night, and my Chrysler LeBaron had all of the door locks frozen from water making it past the window weatherstripping into the mechanisms. My girlfriend had some sort of emotional crisis so she absolutely had to see me, so I used my knife to cut an access panel in the door so I could get to the mechanism and thaw it. When I hit resistance that I couldn't cut by making canopener motions (door reinforcement beam I found out once I had it open) I went back into the lab, got a ballpein hammer and batonned the knife the rest of the way through cutting the access panel, and the knife didn't break or deform (OK the edge was kind of a mess by the time I was done) and I was able to cut an access hole large enough to get my hand, a pair of pliers, and a lighter into to get the door open (looked real ugly with the duct tape bandage on the door until I made it even uglier by MIG welding it closed in the spring)

Guess that qualifies as real world abuse testing of the drawn spine method :eek::D

-Page
 
Stacy, that's gospel to me. If Ed says he'd rather a blade bend first, I can see the sense in that. If I have other ideas and wants from my knives, I'd like to think I'm free to make them that way, without being sneered at. Thanks for summoning the energy to put that moderate, intelligent response together. As far as I'm concerned, discussion over.

See Ya.
 
This kinda turned into a monster post but...

The only experience I have is real world application. When I started making knives they were only for my personal use and I wanted the strongest, toughest, most indestructible knife in the world... lol... turns out, it's not that easy to make a good knife. Immediately, passing the ABS JS performance test became a goal. A knife that could pass the test would be the ultimate survival knife. I began working with MS Wally Hayes and one of the first things he told me to check out was MS Ed Caffrey's 5160 performance test knife tutorial.(Excellent tutorial BTW.) Something that popped out while reading, was the second sentence of the paragraph on hardening.... "I recommend edge quenching ONLY on a blade that will be used for something as important as the ABS JS test." What did that mean? Why would you ONLY want to use this great technique for a test knife? Surely, it would carry over into real world hard use.:cool:

Edit to add: It has recently been brought to my attention that Ed Caffrey's intent with that "ONLY" was to mean "Especially" as he is an advocate ove the edge quench. Is that Irony or what? Sorry for the misunderstanding... however late in the game that is... lol.

About the same time, I began apprenticing with a Canadian Wilderness Survival and Primitive Living instructor in Northern Ontario. This guy had no respect for knives.. lol... digging, prying, chipping at rock.... I was disgusted..... but interested at the same time. THIS GUY would find any weakness in my knives.:thumbup: I started making knives to his specs and they failed... i made them to my specs and they failed.:grumpy: Why?.... they were bending and when I made one thick enough to resist deformation, it was too bulky. I was stumped. I sought guidance. Wally told me to fully harden the blade and draw back the spine. I told him that the last thing I wanted was my knives to break when I bent them. He quickly replied, "Well, why the hell are you make a knife that will bend, when you need it to stay strong? Make a stronger knife.... one that won't bend and you can't break.... make the tool suit the task." That's when it hit me and Ed's sentence suddenly made perfect sense. The ABS JS performance test requires the blade to be flexed 90deg. It doesn't matter if it takes 5ftlbs of torque or 500! It MUST flex and not break. They are testing your skill as a maker, not whether you make a good knife. When would you require a blade to flex that much during actual use?(okay... OTHER than a fillet knife... lol.)

I began taking bars of 5160 and running tests on pieces 1/8", 3/16" and 1/4" thick. Unground, heat treated and tempered to varying hardness. I didn't have a Rockwell tester, so simply went with tempering temperatures (my oven only went to 525F, after that, I went by colour). The 1/4" bars were rather uneventful... whichever hardness or structural state I had them in, I still couldn't bend them by hand. It started getting interesting with the thinner stock. Once more, I had to get used to the sound of metal snapping. This time around was different than my JS test quest, though. I was very careful to be aware of the amount of force I was placing upon the steel. I found that the fullhard bars took MUCH more force to flex to the same degree as the unhardened pieces and if I tempered enough, would withstand even more force. I upped the tempering temps until I felt I was losing strength and the steel would take a set more readily(this was WELL into the grey colour… my guess would be 700-900F. The soft untreated bars deformed at even the smallest degree of flex and offered very little resistance in comparison. One test, that I wish I would have done at the beginning was to take two identical, triple normalized bars, fully harden one, shine them both up, temper to peacock blue and flex each to 45degs(noting force applied/resistance and degree of set.) Then continue flexing back and forth(45deg, L&R) like a dog’s wagging tail. Realign to center and repeat the 45deg flex, once more. The result is predictable but no less shocking. The unhardened blade now flexes like lead with VERY little resistance and immediate set. The hardened and tempered blade feels no different than it did the first time. That test ALONE would have convinced me to further research a homogeneous heat treat.

At the same time, I began educating myself on the mechanical properties of each micro-structure within steel. It was very reassuring to see that the basic results from my low-tech approach coincided with the research done by the steel nerds in lab coats. (minus the metallography) I must say, that delving into modern metallurgy is a huge undertaking and I've only scratched the surface. You won't find me quoting data sheets or typing out long runs of eloquent terminology..... I'm just not there, yet. But man, I have been bitten by the bug.

My experiment taught me a very important lesson..... Unhardened prybars don’t pry, they bend and have a short lifespan. My quest for the unbreakable knife led me to a blade that was lacking performance attributes in areas that I deemed important. Sometimes, less extreme treatments can yield the most desirable results. It would be silly for me to state that the edge quenched blade is inferior to the fully hardened blade based on regular performance. Most users will never push their knives that far into the realm of abuse. I judge by what I can experience. I take into consideration the opinions and reasearch done by folks I have respect for but at the end of the day, I need to know how it affects the end user. Lateral strength affects my end users and Fully Hardened blades address the issue, in this instance.

This was the last knife I sent to my wilderness skills mentor. (almost 4yrs ago, this month.) It was only meant to test the blade so the F&F are rough. He refuses to send it back or receive a new one, for fear of losing the best knife he has ever tried to break….. That means a lot to me. It didn’t even come with a sheath but he said it fits in an old BK&T one. (that is embarrassing)

Modeled by my lovely Blue Spotted House Monkey…
Bushkeeper05.jpg
 
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Stacey that is a nice selection of "hard facts" in summary form. Thanks for posting it.
We can view "hard facts" as reality, but an accumulation of facts no matter how large, is no more a science than a pile of bricks is a house.
It is up to each individual maker to develop the total package of science into the knife he wants to make.

There is nothing new in our science, it has all been done before the art of knife making comes through how we assemble those facts and maybe a little more.
 
See,

That wasn't so hard :)

Rick I do appreciate sharing your experience in that post. It was very educational and really adds to the discussion.

Thanks


Rick Marchand said:
This kinda turned into a monster post but...

The only experience I have is real world application. When I started making knives they were only for my personal use and I wanted the strongest, toughest, most indestructible knife in the world... lol... turns out, it's not that easy to make a good knife. Immediately, passing the ABS JS performance test became a goal. A knife that could pass the test would be the ultimate survival knife. I began working with MS Wally Hayes and one of the first things he told me to check out was MS Ed Caffrey's 5160 performance test knife tutorial.(Excellent tutorial BTW.) Something that popped out while reading, was the second sentence of the paragraph on hardening.... "I recommend edge quenching ONLY on a blade that will be used for something as important as the ABS JS test." What did that mean? Why would you ONLY want to use this great technique for a test knife? Surely, it would carry over into real world hard use.:cool:

About the same time, I began apprenticing with a Canadian Wilderness Survival and Primitive Living instructor in Northern Ontario. This guy had no respect for knives.. lol... digging, prying, chipping at rock.... I was disgusted..... but interested at the same time. THIS GUY would find any weakness in my knives.:thumbup: I started making knives to his specs and they failed... i made them to my specs and they failed.:grumpy: Why?.... they were bending and when I made one thick enough to resist deformation, it was too bulky. I was stumped. I sought guidance. Wally told me to fully harden the blade and draw back the spine. I told him that the last thing I wanted was my knives to break when I bent them. He quickly replied, "Well, why the hell are you make a knife that will bend, when you need it to stay strong? Make a stronger knife.... one that won't bend and you can't break.... make the tool suit the task." That's when it hit me and Ed's sentence suddenly made perfect sense. The ABS JS performance test requires the blade to be flexed 90deg. It doesn't matter if it takes 5ftlbs of torque or 500! It MUST flex and not break. They are testing your skill as a maker, not whether you make a good knife. When would you require a blade to flex that much during actual use?(okay... OTHER than a fillet knife... lol.)

I began taking bars of 5160 and running tests on pieces 1/8", 3/16" and 1/4" thick. Unground, heat treated and tempered to varying hardness. I didn't have a Rockwell tester, so simply went with tempering temperatures (my oven only went to 525F, after that, I went by colour). The 1/4" bars were rather uneventful... whichever hardness or structural state I had them in, I still couldn't bend them by hand. It started getting interesting with the thinner stock. Once more, I had to get used to the sound of metal snapping. This time around was different than my JS test quest, though. I was very careful to be aware of the amount of force I was placing upon the steel. I found that the fullhard bars took MUCH more force to flex to the same degree as the unhardened pieces and if I tempered enough, would withstand even more force. I upped the tempering temps until I felt I was losing strength and the steel would take a set more readily(this was WELL into the grey colour… my guess would be 700-900F. The soft untreated bars deformed at even the smallest degree of flex and offered very little resistance in comparison. One test, that I wish I would have done at the beginning was to take two identical, triple normalized bars, fully harden one, shine them both up, temper to peacock blue and flex each to 45degs(noting force applied/resistance and degree of set.) Then continue flexing back and forth(45deg, L&R) like a dog’s wagging tail. Realign to center and repeat the 45deg flex, once more. The result is predictable but no less shocking. The unhardened blade now flexes like lead with VERY little resistance and immediate set. The hardened and tempered blade feels no different than it did the first time. That test ALONE would have convinced me to further research a homogeneous heat treat.

At the same time, I began educating myself on the mechanical properties of each micro-structure within steel. It was very reassuring to see that the basic results from my low-tech approach coincided with the research done by the steel nerds in lab coats. (minus the metallography) I must say, that delving into modern metallurgy is a huge undertaking and I've only scratched the surface. You won't find me quoting data sheets or typing out long runs of eloquent terminology..... I'm just not there, yet. But man, I have been bitten by the bug.

My experiment taught me a very important lesson..... Unhardened prybars don’t pry, they bend and have a short lifespan. My quest for the unbreakable knife led me to a blade that was lacking performance attributes in areas that I deemed important. Sometimes, less extreme treatments can yield the most desirable results. It would be silly for me to state that the edge quenched blade is inferior to the fully hardened blade based on regular performance. Most users will never push their knives that far into the realm of abuse. I judge by what I can experience. I take into consideration the opinions and reasearch done by folks I have respect for but at the end of the day, I need to know how it affects the end user. Lateral strength affects my end users and Fully Hardened blades address the issue, in this instance.

This was the last knife I sent to my wilderness skills mentor. (almost 4yrs ago, this month.) It was only meant to test the blade so the F&F are rough. He refuses to send it back or receive a new one, for fear of losing the best knife he has ever tried to break….. That means a lot to me. It didn’t even come with a sheath but he said it fits in an old BK&T one. (that is embarrassing)

Modeled by my lovely Blue Spotted House Monkey…
Bushkeeper05.jpg
Click to expand...
 
"We can view "hard facts" as reality, but an accumulation of facts no matter how large, is no more a science than a pile of bricks is a house." Ed Fowler

Right on Ed! :)
 
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