Heat treating damascus steel

B

Bush Monkey

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Is heat treating damascus steel problematic because different steels require different heat treating formulas in order to maximize their performance?
 
Is heat treating damascus steel problematic because different steels require different heat treating formulas in order to maximize their performance?


It doesn't have to be, but often is when damascus makers choose steel combinations that are poorly matched for heat treatment.
 
Thank you. If a damascus maker chooses different steel, each with its own independent heat treating formula, "matches" them perfectly and then heat treats the multi-steel blade using a single heat treat formula, what is sacrificed? If heat treating is steel specific, as it is professed to be, then heat treating different steels the same way is sub-optimal.

It doesn't have to be, but often is when damascus makers choose steel combinations that are poorly matched for heat treatment.
 
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I'm going to take a shot at a layman's answer. Yes. :3:

Damascus presents a whole pile of heat treat considerations. You are right, that different steels will respond differently to any given heat treat profile - and I think the "matching" Kevin was talking about is the matching steels that will not only provide aesthetic contrast, but also yield usable hardness for both steels. I also understand that if the layers are sufficiently fine, there is a likelihood that some some carbon migration may occur, leaving no layer exactly as you expected it to be. Of course, many of the layers common in Damascus will not harden at all - nickel for example, or 309SS, though an argument can be made that those elements will contribute to a 'toothy' edge that will cut some things very well.

Hardness testing on Damascus blades is also something between suspect and impossible. Think of it as a toasted cheese and mayo sandwich. You really don't know if you are pushing the diamond penetrator into toast or cheese - or cheese that is squishing into a glob of mayo.

Quenching is also suspect. One popular ebay seller of Damascus uses (among other things) 5160 and 1095 - both of which demand very different quench media.

I think it's important that a knife blade should be capable of being used, and there is bound to be some sacrifice (trade off is a better word) in any Damascus blade. Lastly, how many Damascus blades ever get used - nevermind used hard.

Rob!
 
There are many misconceptions that have arisen over the years that are a result of thinking in absolutes about “damascus.” We can avoid them if we always try to keep this basic premise in mind- damascus, or pattern welding, is not a product but a process. We get in to all kinds of trouble in setting ourselves to be proven wrong whenever we refer to, or even think of, “damascus” as if it were one singular material. The process of pattern welding can include any number of infinite combinations of steels, and any number of procedures to combine them, all ranging from rather terrible to exceptionally good.

I have heard people, who really should have enough time in the field to know better, say something as ridiculously absolute as “damascus steel requires a special quenchant.” What?:31: Perhaps their steel combination required a special quench but other combinations simply use the same quench as the parent alloys. And I know some tool steel mixes that will get impressively hard just cooling in air.

One of the most common misconceptions is the Rockwell thing. For years old timers have said that you can’t Rockwell damascus, but this was because they were still working off from the outdated, and incorrect notion, of hard and soft layers based upon carbon content. I personally work off from a toughness vs. abrasion resistance model, not hard and soft, and my damascus invariably Rockwells even more consistently than either of its two parent steels alone. However, two pattern welded materials that will render a Rockwell tester useless are welded cable (without extended folding) and anything with pure nickel in it. Even 1095 and 1018 will Rockwell if it has been folded to any extend, but the numbers will all be in the low 40’s, unless the 1095 is a mass majority. Once again- a infinite number of possible materials we can call “damascus” some Rockwell beautifully, others not at all.

One area that I have done some serious research the testing on is the cutting ability of hard/soft, versus varying levels of abrasion resistance. Things like pure nickel mixes do cut very aggressively on soft fibrous materials, so if you want to tear up rope and paper in an impressive way they will do it. But if you want to cut on harder things like solid cardboard or wood, it will not hold up so well. I have many micrographs that reveal why this is. The soft nickel layers tend to not just wear at a faster rate, they actually tend to tear and blow out leaving a very toothy edge as it cuts these soft fibrous materials, but something of substance will then apply pressure to the exposed and unsupported rakers of hard steel which will collapse to a dull edge overall. But most puzzling is that so far my tests reveal a surprising lack of gains in impact strength from the nickel, so I have yet to find the anticipated benefits in toughness from pure nickel.

The one misconception that is longest in dying is the idea of layers of differing carbon content. Carbon diffusion is surprising fast at welding temperatures and mixing low carbon material with good blade steel only lowers the overall carbon content. I also have plenty of micrographs showing how well carbon can move between these layers even on the first weld and by the time you are approach 100 layers carbon will be pretty much even throughout. I have also tested some of the popular old mixes that included 1018 and sure enough they are tougher, but that is because they struggle to reach 45 HRC even with a brine quench.

On the subject of this thread, the alloying moves much, much slower via diffusion, so much that the layers can easily keep their alloying autonomy. So if you mix a water hardening steel with a very deep hardening oil quenching steel, you may move their carbon around but the respective hardenability will remain the same and you will have to choose which steel is going to get the proper heat treatment and which one will be sacrificed. This will not merely be problem of edge holding and other blade properties, but what do you suppose that nice straight blade is going to do when one steel hardens with the massive BCT expansion and the other one doesn’t?

There is a reason why the most popular mix going these days is 10XX/15n20, it really works. It works in performance, it works in stunning color contrasts, it welds and forges very well and it heat treats with virtually no comprises.

It has been my experience that if a well made damascus is not seeing every bit as heavy use as any mono-steel blade it is a sad loss. Carbon steels by themselves stain and rust under almost any use, regardless of how careful one is, well made damascus has a very durable finish that does not show this staining nearly as much and is much more fixable if it does. And if the steels are well chosen the stuff can handle any hard use a single steel would, I say this from the perspective of the first smith to win an ABS cutting competition with a damascus blade, and every competition I ever cut in I made it a point to use a damascus blade. This is not to brag myself up, I am a nerd that chops like a girl, this is to emphasis that a well made damascus is the equal of any single steel in hard use. But there is a lot of damascus out there that is not so well made, and it starts with the steel choices.
 
I think what Kevin might have been referring to with the match in steel has more to do with the expansion rates of the paired steels than the contrast, though that is important. From what I've read several times on these boards is that steels mismatched on their expansion rates can shear apart during the quench when one alloy shrinks much more quickly than the other in the mix. Weldability can also be an issue. Some steels just don't want to weld without a special atmosphere. Some might weld fine to a simple steel but not one of the other more complex tool steels. You can't get just any combination of steels to easily stick together and stay that way. I was told that several times when I was just a new newbie, as opposed to just being a newbie, and I wanted to do everything at once.

Doug
 
Thank you for weighing in.

If there are absolutes for heat treating specific types of steel and damascus is made from specific steels then it stands to reason that damascus is not immune to the professed absolutes of heat treating.

The optimal formula for heat treating is either steel specific and using a single heat treating formula for a multi-steel blade is sub-optimal OR the optimal formula for heat treating is not steel specific and heat treating a multi-steel blade using a single heat treating formula is/can be optimal. Unfortunately, we can't have it both ways.

If, heat treating is not steel specific and absolute, then we can discard most of what has been written about heat treating.

I don't know how objective cutting competitions are. Are all or most blades that win these competitions mono-steel blades or multi-steel blades? Tool steels are used in many applications where performance is superior to aesthetics. If well made damascus is "the equal of any single steel in hard use" then it would stand to reason that we would see well made damascus being used hard in applications outside of knifemaking and cutting competitions.


Jeff

There are many misconceptions that have arisen over the years that are a result of thinking in absolutes about “damascus.” We can avoid them if we always try to keep this basic premise in mind- damascus, or pattern welding, is not a product but a process. We get in to all kinds of trouble in setting ourselves to be proven wrong whenever we refer to, or even think of, “damascus” as if it were one singular material. The process of pattern welding can include any number of infinite combinations of steels, and any number of procedures to combine them, all ranging from rather terrible to exceptionally good.

I have heard people, who really should have enough time in the field to know better, say something as ridiculously absolute as “damascus steel requires a special quenchant.” What?:31: Perhaps their steel combination required a special quench but other combinations simply use the same quench as the parent alloys. And I know some tool steel mixes that will get impressively hard just cooling in air.

One of the most common misconceptions is the Rockwell thing. For years old timers have said that you can’t Rockwell damascus, but this was because they were still working off from the outdated, and incorrect notion, of hard and soft layers based upon carbon content. I personally work off from a toughness vs. abrasion resistance model, not hard and soft, and my damascus invariably Rockwells even more consistently than either of its two parent steels alone. However, two pattern welded materials that will render a Rockwell tester useless are welded cable (without extended folding) and anything with pure nickel in it. Even 1095 and 1018 will Rockwell if it has been folded to any extend, but the numbers will all be in the low 40’s, unless the 1095 is a mass majority. Once again- a infinite number of possible materials we can call “damascus” some Rockwell beautifully, others not at all.

One area that I have done some serious research the testing on is the cutting ability of hard/soft, versus varying levels of abrasion resistance. Things like pure nickel mixes do cut very aggressively on soft fibrous materials, so if you want to tear up rope and paper in an impressive way they will do it. But if you want to cut on harder things like solid cardboard or wood, it will not hold up so well. I have many micrographs that reveal why this is. The soft nickel layers tend to not just wear at a faster rate, they actually tend to tear and blow out leaving a very toothy edge as it cuts these soft fibrous materials, but something of substance will then apply pressure to the exposed and unsupported rakers of hard steel which will collapse to a dull edge overall. But most puzzling is that so far my tests reveal a surprising lack of gains in impact strength from the nickel, so I have yet to find the anticipated benefits in toughness from pure nickel.

The one misconception that is longest in dying is the idea of layers of differing carbon content. Carbon diffusion is surprising fast at welding temperatures and mixing low carbon material with good blade steel only lowers the overall carbon content. I also have plenty of micrographs showing how well carbon can move between these layers even on the first weld and by the time you are approach 100 layers carbon will be pretty much even throughout. I have also tested some of the popular old mixes that included 1018 and sure enough they are tougher, but that is because they struggle to reach 45 HRC even with a brine quench.

On the subject of this thread, the alloying moves much, much slower via diffusion, so much that the layers can easily keep their alloying autonomy. So if you mix a water hardening steel with a very deep hardening oil quenching steel, you may move their carbon around but the respective hardenability will remain the same and you will have to choose which steel is going to get the proper heat treatment and which one will be sacrificed. This will not merely be problem of edge holding and other blade properties, but what do you suppose that nice straight blade is going to do when one steel hardens with the massive BCT expansion and the other one doesn’t?

There is a reason why the most popular mix going these days is 10XX/15n20, it really works. It works in performance, it works in stunning color contrasts, it welds and forges very well and it heat treats with virtually no comprises.

It has been my experience that if a well made damascus is not seeing every bit as heavy use as any mono-steel blade it is a sad loss. Carbon steels by themselves stain and rust under almost any use, regardless of how careful one is, well made damascus has a very durable finish that does not show this staining nearly as much and is much more fixable if it does. And if the steels are well chosen the stuff can handle any hard use a single steel would, I say this from the perspective of the first smith to win an ABS cutting competition with a damascus blade, and every competition I ever cut in I made it a point to use a damascus blade. This is not to brag myself up, I am a nerd that chops like a girl, this is to emphasis that a well made damascus is the equal of any single steel in hard use. But there is a lot of damascus out there that is not so well made, and it starts with the steel choices.
 
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I love it when Sir Cashen posts.


Thank you for weighing in.

If there are absolutes for heat treating specific types of steel and damascus is made from specific steels then it stands to reason that damascus is not immune to the professed absolutes of heat treating.

The optimal formula for heat treating is either steel specific and using a single heat treating formula for a multi-steel blade is sub-optimal OR the optimal formula for heat treating is not steel specific and heat treating a multi-steel blade using a single heat treating formula is/can be optimal. Unfortunately, we can't have it both ways.

If, heat treating is not steel specific and absolute, then we can discard most of what has been written about heat treating.

I don't know how objective cutting competitions are. Are all or most blades that win these competitions mono-steel blades or multi-steel blades? Tool steels are used in many applications where performance is superior to aesthetics. If well made damascus is "the equal of any single steel in hard use" then it would stand to reason that we would see well made damascus being used hard in applications outside of knifemaking and cutting competitions.

Jeff

Im not sure as to what you are refering to , like planer blades or mower blades , but it would not be cost effective.

AND we can have it both ways if we use steel that has the same heat treat methods , like the 10XX steels and 15N20 as Kevin said.

Dwane
 
from Alpha knife supply:

15n20 Heat Treating Information:
Austenitize: Heat to 1480°. Quench in oil.
Temper: Temper at least once for 30 minutes. Tempering twice for two hours each time is preferred. Use the table below to achieve desired hardness.

15N20-TC.gif


1080 Heat Treating Information:
Austenitize: Heat to 1545°-1615° and hold for 5 minutes. Quench in oil.
Temper: Temper twice for two hours each time. Use the table below to achieve desired hardness.

1080+-TC.gif


Insofar as a neophyte like me can determine, the two different steels above call for different heat treat formulas.

Note: I don't think Alpha, despite its name, is part of the knifemaking aristocracy.
 
Wow, does that ever open up a pile of questions. :)

Better start off by saying the last sentence of my reply above wasn't meant to be an attack - sorry if it came across that way. A large measure of my experience has been with stainless Damascus, cable Damascus, thunderforge Damascus and such - hence my experience with varying rockwell reading on a blade. I've also seen it on 1084/15n20 blades, but to a lesser extent. I guess I'm one of those old timers... :) but I'm not saying you can't rockwell Damascus - just that it's one more thing that can screw up a rockwell test (along with something unnoticed on the anvil, a burr on a pinhole, a tiny bow in the workpiece, less that parallel surfaces....).

I do understand the notion of carbon migration but had presumed it to be material, but incomplete. I stand corrected. How is it then, that with something like 1095/1018, we are still able to etch layers - and if 1095/1018 just makes (for example) 1060, why not just start out with the mono 1060?

My musing about quenchant wasn't suggesting a special quenchant. The question arises that if someone uses steels that have different quench requirements (ex O1 and 1095) do you choose the fast or the slow quenchant - and does the performance of the other steel suffer because of that choice? (You covered this above in part. Is this just an example of the folly of mismatched steel in Damascus?)

Lastly, would I be very much wrong to suggest your ABS competition knife beat out the other blades because of superlative edge geometry and heat treat. If not, I'm interested in how performance characteristics are improved by Damascus in a way that can't be realized with a mono?

My thoughts on (some) Damascus have improved through this thread. Keep talking. I have an open mind?
 
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O.K. I tried.

I felt I owed the benefit of the doubt regarding this thread, it is disappointing that I was wrong. I believe I have fully answered the original topic questions, and as a moderator should not make myself available for any more baiting. Would anybody else care to try to keep this thread constructively informative? If so, let me set some ground rules, the title and topic of this thread was posted as “heat treating damascus steel”, not a debate on the legitimacy of industrial heat treating methods, keep it on topic.

I really do not think I am mistaken that the vast majority of visitors here just want some helpful guidance in navigating the challenges of heat treating knives, with no need for the drama. While threads attempting to save heat treating from the evil clutches of science, or art, do entertain enough to make three pages, they are simply “Jerry Springer” moments, contributing nothing to that helpful exchange of information. Let that be the ground rule for all future threads.

P.S. Many people are not aware that the term “trolling” actually does not refer to nasty little creatures that live under bridges frequented by families of goats, but instead comes from the method of fishing where one dangles the bait from a moving boat to see if they can get any bites in the drive by. Good anglers know the exact bait to use, and hooked fish are the ones who can’t resist biting. Let’s not have either since that sport is illegal in these waters.
 
O.K. there were three more posts in the time I was typing my last one. I will have some answers for you Knifemaker.ca, in the meantime do not assume you have drawn my ire in any way.
 
You ask some very good questions. I wish I had the answers. I considered using damascus but insofar as I can determine, there are no gains in performance to match the significant cost increase.

I respectfully excuse myself from this thread.

ps Dissent = trolling.



Wow, does that ever open up a pile of questions. :)

Better start off by saying the last sentence of my reply above wasn't meant to be an attack - sorry if it came across that way. A large measure of my experience has been with stainless Damascus, cable Damascus, thunderforge Damascus and such - hence my experience with varying rockwell reading on a blade. I've also seen it on 1084/15n20 blades, but to a lesser extent. I guess I'm one of those old timers... :) but I'm not saying you can't rockwell Damascus - just that it's one more thing that can screw up a rockwell test (along with something unnoticed on the anvil, a burr on a pinhole, a tiny bow in the workpiece, less that parallel surfaces....).

I do understand the notion of carbon migration but had presumed it to be material, but incomplete. I stand corrected. How is it then, that with something like 1095/1018, we are still able to etch layers - and if 1095/1018 just makes (for example) 1060, why not just start out with the mono 1060?

My musing about quenchant wasn't suggesting a special quenchant. The question arises that if someone uses steels that have different quench requirements (ex O1 and 1095) do you choose the fast or the slow quenchant - and does the performance of the other steel suffer because of that choice? (You covered this above in part. Is this just an example of the folly of mismatched steel in Damascus?)

Lastly, would I be very much wrong to suggest your ABS competition knife beat out the other blades because of superlative edge geometry and heat treat. If not, I'm interested in how performance characteristics are improved by Damascus in a way that can't be realized with a mono?

My thoughts on (some) Damascus have improved through this thread. Keep talking. I have an open mind?
 
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Actually I am very Ire-ish, there is actually a Cashen river in County Kerry:3:
One source of misunderstandings in forum discussions is the similarity, yet distinct differences with e-mail and other one-on-one talks. I think it is no secret that I take great exception to a lot of bad information that has been prevalent in the knife business for too long, to this I plead guilty, and it is my motivation for wanting to continue helping where I can. Because of this, every time I post on a forum, I post as if I am speaking to every person out there that will ever read the words. This is something that I want folks to be aware of whenever I may address a point that they have raised. So Knifemaker.ca you are good as gold in my book, your point about Rockwell could not possibly get me down on you when it has been repeated by so many other good people, but I would be remiss if I failed to offer the counter data I have because of our good relationship.

So that nobody gets any wrong ideas about who I am correcting on the spirit of this thread, it is the original post that now appears to have less to do with finding answers than finding an argument. And just to show that I have no interest in “gotcha!” I will let Bushmonkey research and find the error on his posted charts, and have the chance to correct it on his own.

Knifemaker.ca, Your questions:

I can’t explain your experience with 1084/15n20 blades, just that I have never encountered it. I have even Rockwelled plenty of that mix made by other makers with the same consistent results, although all were heat treated by me.

1095 and 1018 will show a patterning for the same reason a Japanese sword has hada. Even though it is the exact same steel folded on itself, the welding process will alter the chemistry in the weld zone. But there will also be some chemistry variations with the 1095/1018 (e.g. Mn effects the contrast much more than carbon).

Why would one use 1095 and 1018 instead of just starting with good 1060? Good question, I have always wondered that myself. Let me know if you find a satisfactory answer.:3:

My point on the cutting competition is once again on finding the facts in the middle instead of the hyperbole at the extremes. When damascus first made its heavy comeback in modern knives, it was touted as superior to mono-steel, this was not only an arrogant path to go down it was foolish and did the material no favors. When people caught on to the marketing the reaction swung the pendulum the other way for many (reinforced by some poor mixes and manufacturing), and some folks got the idea that it was all inferior to mono-steel. There are a million people using 0-1 for knives, some are nailing it some are not, should the fact that there are some bad O-1 knives out there permit us to proclaim “O-1” as inferior steel? Or does it allow us to say some folks have figured out how to use it and some have not. The damascus in my competition blades would not, and could not, have been superior to monosteel, but I needed to demonstrate that they were easily equal, after I had heard there were rumors that nobody used damascus on competition because it was not as good.

Folks a forum that is meant for friendly advice on a craft is not meeting it goals when anybody feels they need to defend instead of explain. As I stated before, that is happening in this thread, and it needs to change. If Knifmaker.ca felt uncomfortable, it was due to my poor communication skills, for which he has my apologies. If one starts a thread looking for an argument, I must call that for what it is, with no apologies for doing my job here.
 
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One caution on the various charts, diagrams, and other data found at different sources. These are the results of experiments done on a vary specific alloy, under specific conditions, some of which may not be specified, with a specific set of instruments and equipment. Each alloy has a target range of constituent elements plus if it's made from all recycled steel there can be a little more than a trace of some other elements not mentioned in the normal mix. Also if you give two experimenters the same lot of steel to test with the same equipment and instruments and method they could come up with results, though close, having a significant difference. Then let us say that just a little boron, and I mean just a tad, got into the mix; all sorts of data would be knocked into a cocked hat. So the results that I get with my forge, turkey fryer quench tank filled with peanut oil, and kitchen oven with one lot of an alloy could easily be different from what someone would get using a regulated molten salt tank, a regulated quench take with a circulation pump filled with a commercial quenchant, and a regulated heat treating kiln with a different lot of the same alloy.

P.S. Kevin, don't feel bad about having Irish in your background. There's some in mine too and with all the Dutch it's one heck of a mix:9:
 
I hesitate to say anything, but…
I don’t see any real difference between “discussion” and arguing or debate.

Discussion 1 : "consideration of a question in open and usually informal debate."

Good discussion should be "open" to all perspectives and logic, in my opinion.

I think Bush Monkey’s logic is sound, don’t take any offense to it and don't see it as "baiting", (which is a word that is generally used as a pejorative in this context). There is no evidence in this thread to base that kind of assumption on.
 
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We appreciate your input but that problem has been addressed, your post is now off topic as we have moved beyond the issue, if we can’t avoid revisiting it the thread will have to end.
 
O.K. Kevin, I just got back from being out of town a few days, so I'm a bit late.

I do think that pattern welded damascus is generally more problematic than mono steels. These apples vs oranges debates tend to go in circles anyway,... but then again steel is steel and it all has a few things in common.

Hammer on! :)
 
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