Stainless versus carbon steel.

Keith Montgomery

Keith Montgomery

Joined
May 9, 2000
Messages
29,205
In a thread on the thickness of a blade it was the opinion of one maker that stainless steel blades are thick throughout their entire length because when heat treated to an RC high enough to hold an edge stainless steel would be to brittle to taper the blade to the point. Another maker got a little upset with this, posting that it was the fact that it was because stainless is usually ground and not forged that the blade is done this way.

Check out the comments of Ed Caffery and MJHKNIVES in the thread that I will link to, below. Let me know you thoughts on this matter. I am not starting this thread to promote a fight, I just thought that it was very interesting and didn't want to hijack the thread. I felt it was better to start a new one.

http://www.bladeforums.com/forums/showthread.php?s=&threadid=196573
 
Since you have obviously been here for awhile, I have to question your motives for posting such a thread. You have to know what this type of thing degenerates into.:confused:
 
Not really worth peeing up this rope yet again... :)

There are two ways to make knives, both are good. Best hasn't been discovered yet, but we're both looking for it.
 
Actually I was hoping that we could get reasonable debate on this issue from the members here and did not start this in hopes of getting people at each others throats. I figured the members here would be able to discuss this topic without starting to insult each other. Maybe I was wrong. I personally have never seen this specific issue discussed before on BladeForums. Maybe I should have done a search (in fact that is exactly what I am going to do).

If it is the consideration of the moderators here that this thread will just open up a can of worms, please feel free to lock it. I will tell you though that I am interested in level headed peoples response to this topic. Those that don't feel they can answer in a level headed manner can feel free not to take part.

Sorry if bringing this up has upset some of you. I do not think though that we should avoid what might be considered controversial topics just because it might get some people pissed off.

The fact that I have been here for a long time does not mean that I will not bring up topics that are of interest to me just to please some of the members here. As long as they are valid topics, and I personally think this one is, then I do not see what the big deal is. If it starts to degenerate into a flame war then it can quite easily be locked.

Also, I did not start this. It was started on the other thread by the comments that were made there. I just found those comments to be interesting and wondered if others did as well.
 
Well, I can see no reason for preemptive strike. Keith has always been a reasonable and valued member of the forum and I feel certain that his motives are what he attributes them to be.

I also can't see any reason why the topic can't be discussed in a civil manner, so until there's a reason to take any action, the thread stands.
 
this is WAY too broad a category.

Knife use???
Exact type of steel??
Type of grind??
Size of knife??
Enviornment of user??

we could go on.

What we need to see is a thread like:

Is D2 better than S30V in a hunting knife?
or something like that.
 
I will add:
Definition of High Carbon Tool Steel: 1% or more carbon content.
Nearly EVERY "stainless" knife steel used today falls into that definition. :p :) :p :) :p
 
Thanks Blues.

I am sure that I have seen stainless blades that have been ground so that they tapered to the point. I have never heard that these knives have a tendency to chip or break at the tip. That is the reason that I found this topic to be of interest. The fact that this could be considered a problem for some reason had never occurred to me. Is there someone that has had experience with this having happened and if so are there any thoughts as to why?
 
Sorry Tom, you are correct that the title of this thread is too broad based. I am not looking to get into whether stainless or none stainless high carbon steel (is that better?) is better for making knives. I also do not want to get into whether forging or stock removal is the best way to make a blade. Those topics have been done to death here and don't need to be gone over again.

What was brought up in the other thread that I found interesting is that one maker thought that the reason that Stainless blades were not tapered to the point was because after being heat treated to a high enough RC value to hold an edge, they would be brittle at the tip and tend to break. This is something that to tell you the truth had never occured to me. Maybe that makes me none to smart, but I was just wondering whether anyone had had experience with tapering stainless steel and what results they had had.
 
I have not tapered towards the blade but saying that stainless are by definition britle at the right Rc is just plain wrong....

I recently tested one of my blades to destruction...RWL-34 blade Rc 60 cryo treated. I bend the blade 8 times to 45 degrees with no damage other than the last 2-3 bends left the blade in about 5 degrees bend...no cracks or anything...when I finally bent it more then 50 it snapped.....but this is EXTREEME abuse....I just can´t imagine anything that would break one of my blades in regular use...even if dropped or something....
 
Good for you, Jens! Some of these stainless-bashing myths need to be debunked. Yeah, a forged blade may bend more, but is it always necessary? Of course not.
 
(Conventional) stainless steel has in its makeup elements that promote a loss of ductiliy and toughness. There are those who have figured out ways around it, since avoiding the problems is almost solely based on heat treatment and avoiding/minimizing time in certain temperature ranges. Paul Bos comes to mind, as well as Mr. Anso. Another problem is that stainless steels require higher temperatures to heat treat. This leads to a larger grain structure than most carbon steels. This in turn leads to a loss of impact toughness. Please keep the following definitions in mind when reading this post.

Carbon steel: low alloy, relatively low temperature heat treat steels such as 5160, 52100, L6, 1095, etc. Total alloying elements combined are less than about 4%.

Specialty and Tool steels: Complex alloys, typically capable of fully air hardening, such as D2, A2, M2, 3V, S7, etc. Although L6 is technically a special purpose tool steel, it is classed as a carbon steel here because of low temperature requirements and relatively low alloy content. O1 is similar, and should be ranked above in carbon steels.

Stainless steels: Enough Cr to be stainless, and for our purposes, enough carbon to be hardened. Too many to list, pick your favorite.

(edited to reflect that S30V and the other CPM steels break most of the rules of conventional metals wisdom. thanks Jerry)
 
S30V Stainless is tougher than all but 2 of the steels listed above that are actually used in knives. I've excluded S7.
 
Is this topic too broad? No! The steel doesn't matter, forged or stock removal is not the issue. The largest and most significant issue is the knife maker. Those who test, those who compare, those who seek improvement will make good blades.
Those who are mired in tradition will make knives that are substandard. I have seen many forged blades that are limited by design dictated by tradition. The same issues influence the stock remocval clan.
There are all too many substandard blades from both sides of the equation. It is up to those who wish to make something better to share,information and debate when needed, stick our necks out and seek progress.

Take a look at the knives of Bernard Sparks, Glen Marshall, both presently stock removal makers, their knives would shine in any man's hands.

Knowledge and the search for more knowledge is the key to the answer.
 
Keith, I don't see a problem with your question. It is one that will get so many answers (due to variables) that you'll never have a definitive answer...but you will have more knowledge about the subject.

Beings as I started off doing all stock removal I pretty much only paid attention to what it took to make one in such a way. I never had anything against guys that forged, I just didn't have the resources or strong enough desire to learn to forge.

Now I have been forging very aggressively for about 5 months and I have learned to appreciate the similarities and the differences in both knifemaking techniques.

Becuase of all of this I have very man friends that do stock removal and many that forge. They are ALL great guys that do really neat work. So I find it disturbing that so many makers try to stand on one side of the fence...

Like Mike said before, "aren't we all craftsmen?" That's what it's all about to me.

With that said!!! *stepping off soap-box*

I believe stock removal makers don't typically utilize a distal taper simply because they are starting with a uniform thickness steel. It is much faster and easier to hammer in that taper than it is to grind it (well, for the most part).

BUT, there are stock removal makers that grind them in. If I can taper a tang on the grinder, I can certainly taper the blade.

So many guys get in this pissy argument over impact resistance... but in all truth does it really matter with about 95% of the blades out there??? Does a 4" hunter really need to bend? Isn't it for cutting/slicing??? With that in mind, I don't see any problem with a 52100 hunter or a BG-42 hunter.

The biggest aspect of this typically comes down to guys letting their egos get ahead of their rationality. And NO, I'm not saying that has happened here. BUT, I HAVE seen it happen.

As a newcomer to foring that is absolutely astonished at what can be done with a differentially hardened forged blade...I still have absolutely no qualms saying that there are PLENTY of stock removal blades that would amaze you too. Like Ed Fowler said, it's more the maker than the steel!!!!!!!!!! :D

Nick
 
Ironically, the event that brought me back to carbon steel knives (after swearing them off years ago) was my quest for a custom stainless steel bowie!

I absorbed much information and theory on the stainless/carbon discussions just by lurking and using the search engines. Then, I began contacting makers and others who had earned my respect.

Here are the premises I used in my final decision to go 1085 instead of stainless in this specific case:

1) In every category of design that I have encountered, there is no free lunch. Without exception, compromise is inescapable in any real world design ranging from engines, amplifiers, lenses, etc.

2) Only if the criteria for the end result are known can the compromises be best chosen to maximize the design.

That's it.

Without going into the gory details of my list and the strengths/weaknesses of all the different metals I considered, I found that the only stainless steels that would give me the rust free performance I initially desired were the low carbon alloys. Unfortunately, the low carbon alloys didn't cut it in the other categories higher up on my list, so my only choice was to pick from the metals that came the closest to fitting most of my desires.

Even more unfortunately, for my next knife I'm going to have to go through that dad-gum process all over again...
 
all steels are a compramize of corrosion resistance, deductily, and edge retention. i preffer to use BG-42,S30v,ATS-34 and 440c. i make everything from 3" paring 14" bowie blades. also i distal taper almost all of my designs and dont have a problem with chipping or braking points, i flat and convex grind. in my short five years at the grind most of the chipping i have seen is on hollow ground production knives.(i take in sharpening work) and it doesn't seem to matter what the steel is. now does this mean i think all hollow grinds are infearior? no several of the top guys around here hollow grind. what seems to matter more than anything is the maker and the heat treat
 
The CPM steels still have the elements that decrease ductility and toughness, they have just found a very good way to control the elements. Chromium is the principle element that does this, and is present in every stainless. It raises the critical temperature, resulting in a larger grain size. It also forms carbides that can contribute to loss of ductility. The CPM process was specifically designed to control carbide formation and distribution, so the carbides that form are carefully controlled and dont occur in the locations or the configurations that cause trouble. CPM steels also have a finer grain structure generally. Also, elements can be added to counter the effects chromium has on temperature. CPM steels have the elements that cause the problems, but also counter the problems through manufacturing and alloy content. I suppose my above statement was overly broad. Hope this clears things up.
 
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