Steel FAQ draft: Comments/critiques please!

J

Joe Talmadge

Joined
Oct 3, 1998
Messages
4,842
Hi folks,

I'm going to attempt to attach my current draft of the Steel FAQ to this post. I'm looking for comments and critiques on the content. Note that the formatting and editing is not done yet, so I'm not looking for critiques on that yet.

I believe that the FAQ should primarily be aimed at people newer to knives. While I'd be very pleased if the FAQ also served as a reference to more knowledgeable readers, my first objective is to give the relative newbie a knowledge base that will help him understand and enjoy knives more. So, while I'm looking for any comments, from the newer guys I'm looking for answers to the questions: did the FAQ address the right questions, and did it do so in a clear manner -- keeping in mind of course that steel is a complicated subject, and the FAQ may end up raising as many new questions as it answers old ones. For the more knowledgeable folks, are the facts presented correct?

Also note that I've been planning to add in more direct comparisons. That is, I'd like someone to be able to read the FAQ and figure out that 5160 is tougher than A-2 is tougher than D-2. I know, this kind of thing depends on heat treat and final hardness, but I'd like to give a general idea of what to expect, when the blades are heat treated competently to typical knife blade hardness. I have not made much progress on doing this yet -- anyone wants to take a shot at the Non-stainless blade section, for toughness and wear resistance, please be my guest :)

Steel FAQ attached, I hope!

Joe
 

Attachments

Joe,
Excellent work, as I would expect from you. When I first started out in this hobby you FAQ's were very educationial, and continue to be.

The most essential, and often misunderstood, aspects of selecting a steel is matching it with the primary and edge geometery.
You have placed emphasis on that in section B, which I really like. If there is one thing that is carried away from the FAQ, I feel this is the most important.

In section C you have distinguished between strength and toughness, and have done an excellent job explaining it in easily understood terms. This is something that I have seen even experienced knife makers confuse.

One point on edge holding that I would go into more depth on is that steel strength (resistance to deformation) in the vast number of cases, will be the true determining factor for edge holding. Wear resistance inly overcomes strength as a factor when slicing through abbrasive materials (which by definition casue wear) such as cardboard, sheet rock, roofing shingles, insulation, etc, usually associated with building trades. When push cutting (whitttling, cutting through vinyl and aluminum siding, coping wood, etc steel strength again becomes far more important, as most of the edge dulling will be from rolling, which is what a high strength steel avoids.
This is related to the general rule you list on matching steel selection with function, I just thought a little more detail would be helpful.

For chromium: You may want to distinguish between free chromium molecules (which influence corrosion resistance) and "bound" chromium molecules that have been used in carbide formation.

I really like the links sections, I would reccomend they be hyperlinked in the FAQ if possible. The crucible site is awesome, and I refer back to it often.

In general, I think you did a simply excellent job. A fact filled reading, and one that should be mandatory for every knife knut.

Thanks for putting the time and effort into this Joe.

Take care,
Chad
 
Wait a minute! I thought this sort of thing was "private label" -- if you publish a FAQ on it, all the newbies will know as much as the rest of us!

Hmmm ... that's how I learned so much around here, reading FAQs. OK, go for it.

I had a little trouble, reading through all those masses of words piled up on each other. So I copied it to my word processor, and I've gotten about halfway through formatting and proofing it.

I'll have it all ready later today, but my eyes are aching again. Break time!

(Thank, Joe! There's a lot of good material in there!)
 
Yeah, I know, the formatting is ugly. I do my formatting with emacs, where I'm using lisp libraries to re-format things the way I want. However, HP is closed this week, so I only have access to my home Windows machine, and when it comes to Windows, I'm not so good. I'm editing this thing with notepad, and don't know how to do even simple things like re-adjust the paragraphs. Pathetic! I think I know how to do this in Word, but I don't want the file to be converted to Word, I want a text file so it can be easily read on rec.knives..

The trials and tribulationss of a unix bigot.

You think it looks bad here, you should see what it looks like on knifeforums. I wasn't able to make it an attachment there, so I had to put it in inline, and the auto-wrapping has made it unreadable.

Joe
 
Hey Joe,
For a comparison of carbon steels, I think Crucible has some sweet charts, maybe they would let you use them, or the least hyperlink to them.
Benchmade had a fairly good chart for a2, d2, m2 IIRC.
Just a thought.

Chad
 
GREAT JOB! I am very impressed. That is a very comprehensive steel FAQ. It is a "one stop shop" for just about everything to do with cutlery steel (unless you want to go into some extremely high level stuff). I agree with Esav....this article is dangerous....far too much great information and explanation in one place. It just makes it too easy :mad: :D

I am no steel expert, but did find two things I wasn't sure about in the FAQ:

"The knifemaker will be making a tradeoff of strength versus toughness. Within the hardness range that the steel performs well at, as hardness increases, strength also increases, but toughness decreases.."

I've seen some of Crucible's steel charts where a steel is actually tougher at say, 58 RC than 55 RC. I think A2 is the example I'm thinking of (not exact numbers). Am I right on this? If so, could you explain why this occurs?

"Stainless steels are not differentially tempered."

Correct me if I'm wrong, but I think I heard that Jerry Hossom had some of his largest blades (machetes or swords, can't remember) that were made of ATS-34 differentially tempered (I can't remember if he did it or Paul Bos).

I apologise if I'm way off base on these....I thought I'd mention them
just in case.

Again, congrats, that is a wonderful resource :D
 
Joe, one small suggestion::: put the introduction in CAPITAL LETTERS. the most over looked is how every thing fits together. I love the intro!!! its gonna take me a week to soak in the rest. :D
take care
guy
 
Sorry Joe, I haven't yet read the file. I'm just chiming in now to comment on what Andrew Lynch said about stainless steel and differential heat treatments. Jerry Hossom has had some blades of his, in ATS-34, differentially heat treated. I know this, because Jerry told me over e-mail, and I called Paul Bos about how to do it. The instructions on how to put a soft back on a stainless blade are in a post in Shop Talk, made by me. If I have time later tonight, I'll dig up the thread for you, or you can just do a search there.
 
Joe: I love all the FAQ I've read in here before, and this is just another great one to add to the list.
Some proofing and spell checking is necessary, but sitll, very nice. Very informative and definately a good read.
I didn't know there are other *nix people in here ;)
 
This is excellent resource for the knife community. For those of us who are not into the steels, it gives us a concise analysis of what is what.

Thanks - nicely done.
 
I liked the note about "sharpening for performance." I reduced the angle on my BM ares and it cuts better than ever. It is also easy to sharpen using my SP 204. I have a question about manganese. I have read before that it increases wear resistance, but I have never read the mechanism which leads to this increase. Also, I have read that it ties up sulfer and aids in hardenability. I didnt see anything explaining the difference between hardness and hardenability. It is a subtle but important difference. One would think it would be fairly obvious, but it took me a while to catch on.
 
Elwin,
One function of maganese is to promote small grain size, by helping to minimize grain growth in heat treat. A finer grained steel is less likey to see tear outs, and is stronger than a course grained steel (all else being equal). Or I could be dead wrong, wouldn't be the first time.

Chad
 
Joe, looks great so far but I'm not sure how much it helps answer the newbies' question "which steel should I get?" I know the answer is "it depends," but the FAQ doesn't compare the steels in a manner that would help someone easily pick one. Other than 420, I think you called each one "a very good steel," and while there are many very good steels, some are much better than others and I'd like to see them differentiated more clearly.

I'd also like to see a chart added with the elemental composition and percentages for all steels mentioned. There are a few elsewhere online that you might be able to borrow or compile.
 
Jason, That's a good point, I definitely set out originally to answer the "which steel should I go with" question, which is why I want to try to have some way to compare the steels directly to each other -- that's what I was trying to get at above with my request at the top of this thread. I don't think I can provide something as simple as a canonical list, from best to worst. I'm not even sure I can give a straight list even if I divide up the traits, like a wear resistance list, toughness list, etc. Some of the steels, particularly the non-stainless ones, are heat treated to such a wide range of hardnesses that I don't think we can always guarantee 1095 is tougher than D-2, or vice versa -- not with people putting 1095 in both big fixed blades (relatively softer) and smaller blades (relatively very hard). For the same reason, it can be difficult to compare two steels at the hardnesses most common found in knives, the range can be too big for some steels. We can compare the toughness of two steels as if they were heat treated to the same hardness, but when do we ever see, say, D-2 and 5160 heat treated to the same hardness?

Anyway, the way I was going to try to approach this is to directly compare steels that we see used for relatively similar uses -- D-2 and M-2, say, and then kind of branch out, comparing those to "next-closest neighbors" such as A-2, then A-2 to L-6 and O-1, etc. So I'd provide a way that the reader could compare two steels directly, but he might have to follow a chain of other steels, and as he goes, he'd hopefully become aware that he's got to keep the particular heat treats and final hardnesses in mind. In fact, I will look through again to add notes on what kinds of blades a particular steel is often used for. I'm definitely working on tightening this up so it's easier to compare steels more directly.

I think the same exercise is much easier with stainless steels, which generally seem to be heat treated to much smaller ranges of hardness. In addition, I have lots of hands-on head-to-head experience with most stainless steels, so I feel confident that I can do a reasonable job here. I was going to do this once I got the non-stainlesses squared away.

I may be making this much more complicated than it needs to be, but I also don't want to oversimplify things into ordered lists that can lead to wildly wrong assumptions. Anyway, I'm open to suggestions on how to present steel comparisons in such a way that they are both understandable to someone new, but don't lead to wildly wrong conclusions at times.

Element lists are something I"ve thought about, too. I originally left them off because for newbies, I think knowing the composition of a particular steel doesn't tell much. I actually don't believe that anymore, I think steel composition can be useful to anyone. But I've still left the composition out for another reason. My favorite format for looking at steel compositions is a big chart with the steels listed vertically and the elements listed horizontally. Since the FAQ is plain text, there's no way to do this as a well-formatted table, and I think a big jumble of compositions would clutter the FAQ and do more harm than good. As a result, I've included links to steel composition charts in the links section, but didn't include a plain text table.

Joe
 
Andrew and Crayola, thanks for pointing out the differential tempering on stainless steels. I've heard of this, but never actually talked to anyone firsthand who claimed to know how to do it. If someone out there actually knows how, and is selling knives this way, I'll change the FAQ there.

I also think Andrew is probably right about my generalization that harder always means less tough. When I want to introduce a statement that I think is accurate for most practical purposes, but is not strictly factually correct, I usually hedge by introducing it with the phrase "In general", which hopefully I did in the passage you mention (I'll go back and look). In addition to what you pointed out, there are often different heat treats that could get you to the same final hardness, but with different properties. Maybe I should flesh this out some more in the FAQ.
 
Okay, jumble of replies:

chad: Thanks for all the comments! I won't respond to each separately, but I'm digesting them all and will add them in the FAQ where I can.

Thanks for the comments, guy, calyth, and Practical Use.

Elwin: I re-did manganese too

Hey, who's that Ron guy :)

Joe
 
Andrew, impact toughness is dependent on the strength of the steel to a degree. Thus even though a steel will generally be less prone to brittle fracture at a lower RC, it can have a lower score on an impact toughness test. This effect of strength is reduced by using v-notch charpy testing. There are three types often used, not notched, v-notched, c-notched. They are often not labeled specifically, but they should be.

-Cliff
 
Joe, great work, and a great service for the forumites.

I pulled the file into Word, turned on "Track Changes", and am sending you my comments/editorials in that document via Email.

Great work.

On the subject of "which steel should I buy"... an easy topic to deal with for the newbies, but in doing so, you'll get heated debate from the more "seasoned" (jaded?) oldtimers. But I'd go for it anyway... the newbies will benefit more than what hassle the knowitalls can muster. It would be a basic guideline document for newbies, not a definitive statement of fact.

One potential approach: a matrix that showed each steel, and commented on these traits on a 1 to 5 scale, could be useful to newbies:

relative cost
relative suitability for blades designed for:
* slicing
* push cutting
* slicing in abrasive media
* chopping and other high impact use (toughness)

ease of sharpening in steels optimal hardness range
corrosion resistance
available from production makers (yes, limited, no)
available from custom makers (yes, limited, generally no)
(the Japanese steels are rarely used by custom makers, at least in the USA)
Availability in forged blades

Again, great work... thanks for taking your personal time out to develop something that benefits the forumits.
 
Thanks! I look forward to your comments. If you sent the file to my HP account, I won't see it until Monday. Have a good July 4th!

Joe
 
You must log in or register to reply here.
Back
Top