Stainless or Carbon? Toughness or strength?

[Diamond Dave]

Now that sounds interesting......................

[joelbolden]

Does the corrosion resistance come from the blade coating?

[Nokton]

Stainless or carbon blades,
Excuse me, no one yet spoken of the angle the blade is sharpened
to. I have many high quality knives, fixed blade and folding.
One of my favourites, a 10 inch Reg Cooper Bowie. High carbon steel,
sharpen this
to a 15 degree angle, it holds its edge. Find my knives with stainless
steel blades hold their edge better with a 20 degree angle of sharpening.
Any comments ?
Nokton

[TAHAWK]

Nokton, are you referring to the total included angles?

[Nokton]

Tahawk,
Refer to the angle the blade is sharpened to. Reference to a lateral line.
Nokton

[bushcraft]

Im a Carbon man most of the time.

Kris

[Nokton]

This is not intended to be an essay or a comprehensive discussion on the topics here, but rather an overview of said topics!

Strength: This really can mean several things, so let me break it down a little. We have tensile strength and toughness/ductility.

Tensile strength is an important factor in area's where the steel is unlikely to be put under lateral stress or be asked to flex. In essence you want a steel that resists movement. An example would be the steel armour in a tank. A high carbon steel with 1% carbon, treated properly can be as much a 10 times as strong as mild steel.

Generally a steel that is a plain Jane carbon steel hardened properly will have a good elastic range, in that it will bend a fair way and return to true afterwards. It is able to do this many times without fatal stress fractures forming. When you add alloys to increase wear or rust resistance for example then the steel tends to be more in the plastic range. Thus the steel will more likely be unable to flex much before stress causes a fracture and failure. Remember that the hardness of the steel in tempering is a vitally important factor. Any steel over hardened will chip out at the edge, where the same steel at a lower hardness would simply 'give' at suffer a dink in the edge rather than a stress failure. This is of course a simplification!

Ductility is where the steel is able to flex a fair bit but not required to be amazingly strong. An example of this would be in a bridge where the steel must be able to bend and flex without breaking.

It is generally agreed that plain carbon steel is more elastic than stainless steels at the same hardness. All steels have an ideal range for hardness depending on usage. Lets leave it at that for now!

What does this mean to a knife user? A tough blade will most likely have poor edge holding (wear resistance), a hard blade will have much better edge holding... Simple? No! If cutting is the task, you want a strong blade, if chopping is your thing you want a tough blade. This is often why larger blades have a less hard blade and certainly why a sword needs a tough edge! Why do you think stainless steel swords are so naff?

Now we break the rule above! Crucible Particle Metallurgy steels (CPM 440V or S30V for example) break the rule. This is how! The steel does not need to be amazingly hard as it is simply the carrier for carbides. In a normal carbon steel knife, iron carbides are the cutters. In a top end stainless steel, you get the formation of things like chromium carbides and vanadium carbides. Well in a steel like CPM 440V it was discovered that the large quantity of alloy made this steel very brittle at or above Rc of 60 (Rc, this is a way to measure hardness, in essence a diamond is pressed into the material under a set weight. The penetration gives the hardness). As the carbides in the matrix were doing all the real cutting it was decided to reduce the steels hardness to make it more tough!

Many notice that stainless steels are somewhat harder to sharpen. The reason is simple, the extra alloy that gives you things like stainless or other features, in turn increase the numbers of very very hard carbides. Which in turn are harder to cut with a sharpening stone! The answer? Use a diamond hone! Or simply accept that both stain-LESS and carbon steels have strengths and weaknesses. Understand what you want from a steel and chose the right one for the job.

.
Hi Mon General,
You ever checked out Fallkniven laminated knives?
Stainless outer and vg 10 inner, and the sharpest knives I ever owned.
Got two of them General, an 8 inch and 5 inch, the Odin, and Frey.
Am very picky, but cannot fault them in any way. the quality of
craftsmanship is second to none, and am sure the knives endure
far more abuse than I would ever subject them to.
Does my above resolve any of your questions?
Nokton.
With an aside, and a smile, Fallkniven make a cap. Anyone know
where I can obtain one?

[Chris the Cat]

Question for the General please from a newcomer
(all be it one with the sense to commision a Guyceps knife!)
Where does manganese fit in to this discusion? I have a hand forged
manganese bladed knife but know little about this steel or its properties,
can you shed any light on the mater please?
Rgards.
Chris the Cat

[Chris the Cat]

(or anyone else for that mater!)

[narsil]

One of the principal uses of manganese as an alloying element is to increase the strength and toughness of steels, especially in an un-hardened state. Most steels have a bit of manganese.

Manganese steels are often medium carbon structural steels although, as with other alloying elements its difficult to make very general statements without knowing the make up of the alloy in question

Sometimes it's used, together with nickel steel to produce high contrast damascus patterns.

[deovolens]

Stainless 90HRC flexible blade, only one side sharpened.No joke, german manufacturers never do

[Shinken]

90 Hrc?

[deovolens]

Yes clearly printed:oberflächenharte von ca 90° rockwell durch titanbeschichtung

[fluffy]

perhaps it was tested at right angles?

How would we go about buying one?

[Shinken]

I dont know alot about hardness so trying to learn here. Could it be 90 hrb? I thought 68 hrc was the highest?