Bill,
Let me recap the last 2 hours of reading; the Boss is at work, and I walked away from work long enough to really digest the the amazing information in this thread.

1. there are a whole spate of excellent knife steels out there
2. use is a primary consideration in the steel selection
3. 'stainless' does not mean it won't 'rust'
4. The matrix size directly affects the sharpness and possibly the durability of of the edge
5. the addition of various other metals, salts, and nonmetals can directly affect matrix size of the finished product (chemically and physically)
6. The metal continues to change throughout the working process, and that process is tailored to the metal itself so that the physical and chemical changes are going in the correct direction.
7. heat is good, heat is bad
8. cold is good, cold is bad
9. there are changes in the metal during the working process that cause a 'grain' i.e. austentising, martensiting, etc. in the blade itself and this grain is dependent on the annealing, heating, cooling and original chemical (what's in there)/physical (matrix size)/temporal (how long heated and cooled, and change in temperature over time of change)
10. the most exposed area of the metal (actually the sharpened edge) is also the area that is most dependent on the 'stainless' capabilities of the blade - as the atmospheric conditions may cause salts to form that will dull the edge by chemical breakdown.
11. hardness is good, hardness is bad
12. matrix size affects the edge holding and ultimate sharpness of the edge

13. I need to reread this thread to find out how much I missed and still don't know.

and finally - you really are a lot smarter than you look, your depth of knowledge amazes me - even about music - but you really need to change that one light bulb in the shop stereo.

All of the ABOVE but, #13 Kind'a says it ALL!! The answer to #13 is INFINITESIMAL!!!!

Take care Brother!!!:D
Martin

x SF med,
I really like your take on things, you speak many truths in ways I would not have thought of.
Will look forward to discussing details after the trip to Atlanta.

Thank you for the kind words.

Bill, Martin-
Thanks!
I went back through my list after a little sleep, and realized the list above, almost gets one to the point where you can design the blade once you figure out how the knife is going to be used.
The design of the knife; edge versus spine thickness; shape of the edge(s); length, depth, breadth of tang; known treating/annealing properties of the metal; re-matrixing; and the grain of the martensiting/austensiting ... may cause reconsideration of the steel used after the prototype is underway, based on the production capabilities if the blade is going into mass, or even in some cases limited production, just from the QC process on each blank prior to final edge shaping and sharpening.

Bill... in the words of my concrete busting and pouring buddy, you really just might be a rocket surgeon - I gain more and more respect for you, your craft, the art and the science of your designs the longer I know you.

Mr Harsey
 

I am looking at a leatherman Supertool 300 to replace a leatherman I lost over the weekend. I noticed the blade is 420 HC steel as opposed to 154 CM or S30V that you see on some other tools. This tool will see some pretty hard use (farming hunting camping)

Can you tell me about 420 HC? how does it compare? major differences?

Thanks

I went to my old Tac-30 (SWAT) teams annual banquet dinner the other night and a member of the team had made knives with a Kydex scabbard, with engraving on them for people leaving the team. I liked the knife and asked him to make one for me. He does 'Black Dog Knives.' He is/was also a team member and KCSO Deputy.

He said "It will be made from ATS-34, with micarta scales and will include a custom Kydex sheath. " $100 Plus Tax & engraving ($25) depending on the number of letters.

He'll engrave the following on the knife as well as the SWAT Logo.

LT. My Name
TAC-30 Founding Member
1968-1984

The knives that I looked at did look good and had nice thick blade. Is that ATS-34 a good choice? The blade shape looked like a larger version of my PS knife.

420HC is a medium carbon good working blade steel that is fairly stainless. The quality of any given blade steel is only as good as it's optimum heat treat and I have no knowledge of how these are done.

When all heat treated correctly for knife use 420HC does not have quite the edge holding of 154CM and the next rung up the edge holding ladder is CPM S-30V.

ATS-34 is a very good knife steel. Here is how it came into existence:

First, it was Bob Loveless who revolutionized modern knife making with both his designs and dedication to testing alloys of tool steels for knife use.

Loveless found a very high grade of tool steel produced by Crucible Specialty Tool Steels in Syracuse New York called 154CM. This was a big jump forward in knifemaking as it was both a high performance steel and has good stain resistance.

Crucible at that time was owned by Colt Industries. Loveless was having some problems sourcing the steel from them, forget if it was pricing or something else but the result was Loveless going to Japan, founding the Japanese Knifemakers Guild on the way, meeting the president of Hitachi Steel and asking him to make a steel with "about the same" ;) chemical composition as 154CM and the result is ATS34 which I have used a lot of in the past.
It's good steel.

Thanks, Bill.

IIRC, Al Mar used quite a bit of ATS34 as well.

TR

Thanks Bill! :)

Thank you for this thread Mr. Harsey, it's a great read. Being a knife lover the chemical make up of blade steel has fascinated me. GO CPM S30 V! :D I especially like your explanations on what goes on at the molecular level during the heating and cooling processes with respects to freezing it in the ideal configuration. I hope this is even relevant but it made me think of a time I was fortunate enough to have a plane ride next to a guy that worked with NASA in the carbon fiber area and he was explaining to me (among other fascinating things) the differences in the molecular structure of a diamond carbon molecule as opposed to the I guess you could say "spun fiber" carbon molecule (carbon fiber) they use (not your average carbon fiber) as well as the individual strengths. What are your thoughts on or what have you heard/read about the possible applications of such molecular manipulation of carbon molecules for the making of blades? Not sure if I'm out in left field with this... I was also wondering if you have any knowledge of the OU-31 steel that Kikuo Matsuda employs and what your take is? I love the look of his work but haven't foot the bill for one yet. Thanks again for the great thread.

Knifemakers opinion
 

Well, after hours of reading this post I still don't know how you choose the material if you like a shape of a knife for ex. in a web shop. Many knife brands choose the material for the knife instead of you for the use of the knife they make. Many steel producers make almost the same steel material in different names. Uddeholm, Böhler, etc. are famous steel factories and most of knife makers are choosing from they steels according the meaning of the knife. I am a knife maker too and also I am choosing different material for an assault knife than the survival one. Assault knife I make harder for ex. around 62 HRC, survival knives I make around 58 HRC just for easy sharpening in field. Harder material harder to sharpen but the edge takes longer, and via. So, I mean if you order knife from knifemakers they will offer from they available materials the best for your needs, but if you fall in love with a knife on the internet you have no chance to choose, just if you order a copy from a maker. I say that if the blade is for fight choose material around 62-63 HRC (never go over, may break in field) or if the blade is for common knife use search for 58-59 HRC hard material. No meaning for the name of steel. My best blades I made from recycled materials. (ball bearings, car springs, chainsaw chain) Good heat treating is the most necessary, the best material could be bad without a good heat treating.

The points of choosing knife (and material): hardness, stainless -or not, shape (full tang I prefer) and thickness, sharpening and cleaning attributes, handle material, love it or not. That simple. Would it be the hardest and greatest material if you cannot sharpen by yourself. (There is another knowledge for sharpening...)

There is no best steel material for knives, just difference for uses.

There is no bad knife, just bad hand for it...

Bill, this is not for You, I know You know all about that.
Sorry for the poor english...

Gentlemen,

I want to personally thank everybody who contributed to this topic! As a senior materials engineering student, this information has been invaluable to some real world scenarios and examples of materials science at work. Progressing through the pages of pure gold here, "I now know what I don't know"..

V/R
LD

Odikter,
Sorry for the delay in responding, very bad manners on my part.

Welcome to the knife area and if you would like, please post pictures of some of your knives here. I would like to see them.
Your english is much better than my Finnish or Sami.

We will talk more about steel hardness soon.

Your very, humbly, welcome.
Good news we haven't screwed up your work yet too.

We have access to a few metallurgists if you might need more help.