Posted On August 28, 2013 by Print This Post

Baselard, Bayonet and Poniard: The Hidden Lives of Blades with Adam Firestone

A knife through the heart…a knife to the gut…common phrases you’ve read (or written) before. Today, RU contributor and weapons expert Adam Firestone eschews metaphors and gives us an in-depth analysis of the real thing. 

While guns are often the go-to weapon for both heroes and villains, there’s something fascinating about a knife.  From the samurai’s katana to the assassin’s stiletto, there’s something that draws us to the blade.  Perhaps it’s the singular and personal nature of combat when knives are involved, the deadly simplicity of a fixed blade or the legends that blades have inspired for millennia. (Excalibur, Stormbringer, Kusanagi or Dyrnwyn, anyone?)  Whatever the reason, blades are an inescapable part of legend, myth, fiction as well as mundane reality.  (You’d be hard pressed to find a soldier, police officer or detective who doesn’t carry a knife as a backup or utility tool.)  Additionally, blades have provided substance and focus for fictional characters for centuries, from Dumas’ D’artagnan to Brecht’s Mack the Knife to Follett’s Henry Faber (Eye of the Needle).

Regardless of their mystical properties, knives represent an interesting study in science and technology.  In this month’s column, we’ll explore the metals and metallurgy that give blades their unique characteristics.

Blade steel is only one component in how a knife performs.  One must also consider the blade’s intended use and match the characteristics to that use.  Hence, factors such as blade profile are important. For example, a tanto isn’t the best choice to skin a deer. But perhaps most important characteristic is the heat treatment. A good solid heat treatment on a lesser steel will often result in a blade that outperforms a better steel with inferior heat treatment.  Bad heat treatment can cause a stainless steel to lose some of its stainless properties, or cause a tough steel to become brittle. Unfortunately, of the three most important properties (blade profile, steel type, heat treatment), heat treatment is the one that is impossible to assess by eye, and as a result excessive attention is sometimes paid to the other two.

Again, the blade’s intended use is of paramount importance.  Many knowledgeable people deride 440A stainless steel, but there are few better materials for a marine or wet weather blade.  Properly heat treated 5160 is wonderfully tough, but if the application is skinning deer, the edge holding qualities of 52100 are probably more important.

STEEL ALLOYS
At its most basic, steel is iron with carbon in it.  Other alloying metals are added to bring out different characteristics in the steel. Here are the important steel alloy materials in alphabetical order, and some sample steels that contain those alloys:

Carbon: Present in all steels, it is the most important hardening element. Also increases the strength of the steel. Knife grade steel should usually have greater than 0.5% carbon, which makes it “high carbon” steel.

Chromium: Added for wear resistance, hardenability, and (most importantly) for corrosion resistance. A steel with at least 13% chromium is classified as a “stainless” steel.  Despite the name, all steel can rust if not maintained properly.

Manganese: An important element, manganese aids the grain structure, and contributes to hardenability. Also strength & wear resistance. Improves the steel (e.g., deoxidizes) during the steel’s manufacturing (hot working and rolling). Present in most cutlery steel except for A-2, L-6, and CPM 420V.

Molybdenum: Molybdenum prevents brittleness and maintains the steel’s strength at high temperatures.  It is present in many steels, and air hardening steels (e.g., A-2, ATS-34) always have 1% or more molybdenum — molybdenum is what gives those steels the ability to harden in air.

Nickel: Used for strength, corrosion resistance, and toughness. Present in L-6 and AUS-6 and AUS-8.

Silicon: Contributes to strength. Like manganese, it makes the steel more sound while it’s being manufactured.

Tungsten: Increases wear resistance. When combined properly with chromium or molybdenum, tungsten will make the steel into a high speed steel. The high speed steel M-2 has a high amount of tungsten.

Vanadium: Contributes to wear resistance and hardenability.  Vanadium helps produce fine-grained steel. A number of steels have vanadium, but M-2, Vascowear, and CPM T440V and 420V (in order of increasing amounts) have high amounts of vanadium. BG-42’s biggest difference with ATS-34 is the addition of vanadium.
CARBON AND ALLOY (NON-STAINLESS)
These steels are the most commonly  forged. Stainless steels can be forged but it is very difficult. In addition, carbon steels can be Adam Firestonedifferentially tempered, to give a hard edge holding cutting edge and a tough springy back.  Stainless steels are not differentially tempered. Of course, carbon steels will rust faster than stainless steels, to varying degrees. Carbon steels are also often more consistent than stainless steels — all of the steels named below are fine performers when heat treated properly.

In the American Iron and Steel Institute (AISI) steel designation system, 10xx is carbon steel, any other steels are alloy steels. For example, the 50xx series are chromium steels.

In the Society of Automotive Engineers (SAE) designation system, steels with letter designations (e.g., W-2, A-2) are tool steels.

There is an American Society for Metals (ASM) classification system as well, but it isn’t seen often in the discussion of cutlery steels.

Often, the last numbers in the name of a steel are fairly close to the steel’s carbon content. So 1095 is ~.95% carbon. 52100 is ~1.0% carbon. 5160 is ~.60% carbon.

O-1
(Note:  the accompanying tables show standard alloy compositions by percentages of alloyed elements – the primary (and  assumed) component in all steels is iron)

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.90

1.60

0.00

0.50

0.00

0.00

0.00

0.50

0.00

This is an oil hardening (i.e., quenched in oil when removed from the forge) steel very popular with forgers, as it has the reputation for being “forgiving”. It is an excellent steel, that takes and holds an edge superbly, and is very tough. It rusts easily, however. Randall Knives uses O-1, so does Mad Dog.

W-2

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.00

0.35

0.30

0.00

0.00

0.00

0.20

0.00

0.00

A water hardening steel, W-2 is reasonably tough and holds an edge well, due to its 0.2% vanadium content. Most files are made from W-1, which is the same as W-2 except for the vanadium content (W-1 has no vanadium).

W-1

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.00

0.35

0.30

0.00

0.00

0.00

0.00

0.00

0.00

See W-2

The 10-series — 1095 (and 1084, 1070, 1060, 1050, etc.) 1095 as an example

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.95

0.40

0.00

0.00

0.00

0.00

0.00

0.00

0.00

Many of the 10-series steels are used for cutlery, though 1095 is the most popular for knives. When taken in order from 1095-1050, the steel goes from more carbon to less, from better edge holding to less edge holding, and tough to tougher to toughest. As such, 1060 and 1050 are often used for swords. For knives, 1095 is the “standard” carbon steel. It is reasonably tough and holds an edge very well, though without care it oxidizes (rusts) easily. This is a simple steel, which contains only two alloying elements: 0.95% carbon and 0.4% manganese. The various Ka-Bars are usually 1095 with a protective black coating.

0170-6 – 50100-B

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.95

0.45

0.00

0.45

0.00

0.00

0.20

0.00

0.00

These are different designations for the same steel: 0170-6 is the steel makers classification, 50100-B is the AISI designation. A good chrome- vanadium steel that is somewhat similar to O-1, but much less expensive. The now defunct Blackjack made several knives from O170-6,and Carbon V may be 0170-6. 50100 is basically 52100 with about 1/3  the chromium of 52100, and the B in 50100-B indicates that the steel has been modified with vanadium, making this a chrome-vanadium steel.

A-2

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.00

0.45

0.00

5.00

0.00

0.00

0.25

0.00

0.00

An excellent air hardening tool steel, it is known for its great toughness and good edge holding.  It is an air hardening steel, and as such cannot be differentially tempered. Its outstanding toughness makes it a frequent choice for combat knives. Chris Reeve and Phil Hartsfield both use A-2, and Blackjack made a few models from A-2.

L-6

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.70

0.45

0.00

0.75

1.50

0.00

0.00

0.00

0.00

A band saw steel that is very tough and holds an edge well, but rusts easily. It is, like O-1, a forgiving steel for the forger. If you’re willing to put up with the maintenance, this may be one of the very best steels available for cutlery, especially where toughness is desired.

M-2

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.95

0.45

0.00

0.45

0.00

0.00

0.20

0.00

0.00

A “high speed steel”, it can hold its temper even at very high temperatures, and as such is used in industry for high heat cutting jobs. It is an excellent edge holder. It is tough but not as tough as some of the toughest steels in this section; however, it will still be tougher than the stainless steels and hold an edge better. It rusts easily.  Benchmade uses M-2.

5160

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.60

0.80

0.00

0.80

0.00

0.00

0.00

0.00

0.00

A steel popular with forgers, it is extremely popular now and a very high end steel. It is essentially a simple spring steel with chromium added for hardenability. It has good edge holding, but is known especially for its outstanding toughness (like L-6). Often used for swords (hardened in the low 50s Rc) because of its toughness, and is also used for hard use knives (hardened up near the 60s Rc).

52100

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.10

0.35

0.30

1.45

0.00

0.00

0.00

0.00

0.00

A ball bearing steel, and as such is only used by forgers. It is similar to 5160 (though it has around 1% carbon vs. 5160 ~.60%) and more chromium, but holds an edge better. It is less tough than 5160 however. It is used often for hunting knives and other knives where the user is willing to trade off a little of 5160’s toughness for better edge holding.

D-2

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.50

0.40

0.00

12.00

0.00

0.80

0.90

0.00

0.00

D-2 is sometimes called a “semi stainless”. It has a fairly high chromium content (12%), but not high enough to classify it as stainless. It is more stain resistant than the carbon steels mentioned above, however.  It has excellent edge holding, but may be a little less tough than some of the steels mentioned above and it does not take a beautiful finish.  Bob Dozier uses D-2.

STAINLESS STEELS

Remember that all steels can rust. But the following steels, by virtue of their greater than 13% chromium, have much more rust resistance than the above steels. It should be pointed out that there doesn’t appear to be consensus on what percent of chromium is needed for a steel to be considered stainless. In the cutlery industry, the de-facto standard is 13%, but the ASM Metals Handbooks says “greater than 10%”, and other books cite other numbers. In addition, the alloying elements have a strong influence on the amount of chromium needed; lower chromium with the right alloying elements can still have “stainless” performance.

420

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.15 – 0.40

0.23

0.21

12.2

0.00

0.00

0.00

0.00

0.00

Lower carbon content (less than 0.5%) than the 440 series makes this steel extremely soft, and it doesn’t hold an edge well. It is used often for diving knives, as it is extremely stain resistant. Also used often for very inexpensive knives. Outside salt water use, it is too soft to be a good choice for a utility knife.

440 A – 440 B – 440C (data for 440C listed)

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.20

1.00

1.00

18.00

0.00

0.75

0.00

0.00

0.00

The carbon content (and hardenability) of this stainless steel goes up in order from A (.75%) to B (.9%) to C (1.2%). 440C is an excellent, high end stainless steel, usually hardened to around 56-58 Rc. All three resist rust well, with 440A being the most rust resistant, and 440C the least. The SOG Seal 2000 is 440A, and Randall uses 440B for their stainless knives. 440C is fairly ubiquitous, and is generally considered the penultimate general- use stainless (with ATS-34 being the ultimate). If a knife is marked with just “440”, it is probably the less expensive 440A; if a manufacturer had used the more expensive 440C, she’d want to advertise that. The general feeling is that 440A (and similar steels, see below) is just good enough for everyday use, especially with a good heat treatment. 440-B is a very solid performer and 440-C is excellent.

425M – 12C27

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.54

0.35

0.00

13.5

0.00

1.00

0.00

0.00

0.00

Both are very similar to 440A. 425M (0.5% carbon) is used by Buck knives. 12C27 (.6% carbon) is a Scandinavian steel used often in Finish puukkos and Norwegian knives.

AUS-6 – AUS-8 – AUS-10 (aka 6A 8A 10A) (data for AUS-8 listed)

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

0.80

1.00

1.00

18.00

0.00

0.75

0.00

0.00

0.00

These are Japanese stainless steels, roughly comparable to 440A (AUS-6, .65% carbon), 440B (AUS-8, .80% carbon) and 440C (AUS-10, 1.1% carbon). AUS-6 is used by Al Mar. Cold Steel’s use of AUS-8 has made it pretty popular.  AUS-10 has roughly the same carbon content as 440C but with slightly less chromium, so it should be a bit less rust resistant but perhaps a bit tougher than 440C. All three of the AUS steels have some vanadium added (which the 440 series lacks), which will improve wear resistance.

ATS-34 – 154-CM

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.03

0.25

0.25

14.00

0.00

4.00

0.00

0.00

0.00

One of the most popular high end stainless steels. 154-CM is the original American version.  ATS-34 is a Hitachi product that is very, very similar to 154-CM, and is the premier high quality stainless. Normally hardened to around 60 Rc, it holds an edge very well and is tough enough even at that high hardness. Not quite as rust resistant as the 400 series above.  Many custom makers use ATS-34, and Spyderco (in their high end knives) and Benchmade are among the production companies that use it.

ATS-55

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.00

0.50

0.40

14.00

0.00

0.60

0.00

0.00

0.00

Similar to ATS-34, but with the most of the moly removed and some other elements added. The intent was to get ATS-34 edge holding with increased toughness. Since moly is an expensive element useful for high speed steels, and knife blades do not need to be high speed, removing the moly decreases the price of the steel while at least retaining ATS-34’s performance. Spyderco is using this steel.

CPM T440V – CPM T420V (data for CPM440V listed)

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

2.20

0.50

0.50

17.50

0.00

0.50

5.75

0.00

0.00

Two steels that hold an edge superbly (better than ATS-34), but it’s difficult to get the edge there in the first place. These steels are both high in vanadium. Spyderco offers at least one model in CPM T440V. Custom maker Sean McWilliams is a big fan of 440V, which he forges. Depending on heat treatment, expect to have to work a bit harder to sharpen these steels — also, don’t expect ATS-34 type toughness. 420V is CPM’s follow-on to 440V, and with less chromium and almost double the vanadium, is more wear resistant and may be tougher than 440V.

NON-STEELS USED BY KNIFEMAKERS

Cobalt – Stellite 6K

Carbon

Manganese

Silicon

Chromium

Nickel

Molybdenum

Vanadium

Tungsten

Cobalt

1.20

0.80

0.00

28.00

0.00

0.00

0.00

5.00

60.00

A flexible material with very good wear resistance, it is practically corrosion resistant. Stellite 6K, sometimes seen in knives, is a cobalt alloy. David Boye uses cobalt for his dive knives.

Titanium
Newer titanium alloys can be hardened near 50 Rc, and at that hardness seem to take something approaching a useful edge. It is extremely rust resistant, and is non-magnetic. Popular as expensive dive knives, because the SEALs use it as their knife when working around magnetically detonated mines.

Ceramics
Numerous knives have been offered with ceramic blades. Usually, those blades are very very brittle, and cannot be sharpened by the user;  however, they hold an edge well. Boker and Kyocera make knives from ceramic. Kevin McClung came out with a ceramic composite knife blade that much tougher than the previous ceramics, tough enough to actually be useful as a knife blade for most jobs. It is also user-sharpenable, and holds an edge well.

Bringing it Back to the Book

Readers love technical details, especially when it fleshes out characters with whom they’ve become involved. The trick is to give them just enough to satisfy the craving while not being carried away by the arcana. (By now you’ve realized that I have a bit of a problem with that…) Think of the way James Bond rattles off knowledge about missiles or wines or gold bullion; the technical nuance provides a richness of detail that will both inform and entertain.

***

Are you in the market for a new kitchen knife or arming your character with a sword or Ka-bar? Adam is open to your questions, so ask away!

***

Author Anna Sugden joins us on Friday, August 30th.

***

Bio: Adam Firestone brings more than 25 years of experience with weapon systems including small arms, artillery, armor, area denial systems and precision guided munitions to Romance University. Additionally, Adam is an accomplished small arms instructor, editor, literary consultant and co-author of a recently published work on the production of rifles in the United States for Allied forces during the First World War.

Adam has been providing general and technical editing services to authors and publishing houses specializing in firearms books since the early 2000s. Additionally, Adam provides literary consulting services to fiction authors including action scene choreography, technical vetting and technical editing. In this line of experience, Adam has had the fortune to work with well known authors including Shannon McKenna and Elizabeth Jennings.

Check out Adam’s blog here: http://adamfirestoneconsultant.blogspot.com/

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7 Responses to “Baselard, Bayonet and Poniard: The Hidden Lives of Blades with Adam Firestone”

  1. Okay, I never would have thought there’d be violence in one of my books, but now I’m absolutely determined to use this new knife blade knowledge, whatever it takes. Thank you for the amazingly detailed discussion – it’s inspiring!

    Posted by Lori Schafer | August 28, 2013, 8:50 am
  2. Morning Adam…

    I agree with Lori, every time you have a new post, I feel empowered to use a bayonet/tank/knife in some scene. =)

    Unfortunately I write romantic comedy, but I’m pretty sure I could make the tank work….

    I have to say, I grinned a bit at the over-fired steel – it’s something I have to pay particular attention to when working with heat and metal when making jewelry!

    Brilliant stuff as always, I’m sure when it comes time to kill someone off, I’ll be looking at this post again!

    carrie

    Posted by Carrie Spencer | August 28, 2013, 9:01 am
    • Hi Carrie,

      It might be useful to remember that knives are tools as well – and the difference in steels might make for some interesting events in terms of blade snapping, bending, etc…

      All the best,

      Adam

      PS – Tanks have many uses….

      Posted by Adam Firestone | August 28, 2013, 9:54 am
  3. Adam – From tanks to blades – the extent of your knowledge never ceases to amaze me! Thanks so much for another fascinating blog! (And thanks to Jennifer Tanner for posting it!) I wish I wrote historical romance so I could have my characters swash some buckles with whatever blades gentlemen (or pirates!) were likely to use in that period. Thanks for educating us – I like the idea of having a character who is able to rattle off James Bond-like knowledge of metallurgy. Very cool!

    Posted by Becke Martin Davis | August 28, 2013, 10:42 am
  4. Hi Adam,

    Speaking of James Bond, he went old school at the end of Skyfall. Swords are so cool!

    Mary Jo

    Posted by Mary Jo Burke | August 28, 2013, 12:51 pm

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