Bushcraft Knife – Blade Steel

 

 

steel on grinder

 

What to consider?

Every steel shares the same properties, but each is better or worse in its own accord.

Hardness

  • Measured in the Rockwell Scale (HRC), knife steels usually range from the mid 50’s to the mid 60’s. The higher the number, the harder the steel.
  • How easily dose the steel bend or dent?
  • Will the steel be hard enough to support as thin of an edge as you want?
  • Is it so hard, that a fine cutting edge will chip under regular use?

Toughness

  • How easily does the steel break?
  • How far will it bend before it snaps?
  • If the tip of your knife gets stuck in a knot in a log, will it snap off if you try to wiggle it free or will it “roll with the punches?”
  • Is the steel so soft, that your knife’s edge rolls and bends under typical use?

Wear Resistance

  • How well does the steel resist abrasion?
  • Can you cut through miles of cardboard or rope without sharpening or will you have to stop every moment or so to touch up your blade?

Corrosion Resistance

  • Will the steel stain, pit or rust easily?

Edge Retention

  • The combination of Hardness, Toughness and Wear Resistance.
  • How well will the cutting edge of your knife holding up to general use?

 

What’s in it?

Elements in Bushcraft Knife steel

Chemistry Time

Carbon

  • The first and foremost hardening element in steel. Every steel needs it and every steel has it. The more of it in the mix, the harder but often more brittle the steel becomes.  Any steel containing carbon levels of .8% or more is considered high carbon steel.

Chromium

A corrosion resisting element, chromium is a defining element of stainless steel, usually at levels of 12% or more. Small amounts of chromium can make steel softer but tougher. Large quantities, however, can decrease toughness.

Cobalt

  • Increases heat and wear resistance.

Copper

  • Adds corrosion resistance, and sometimes strength if concentration is more than .75%.

Manganese

  • Adds hardenability, strength and toughness. It also helps steel’s hot working properties.

Molybdenum

  • Adds corrosion resistance and weldability.

Nickel

  • Helps with corrosion resistance and strength.

Nitrogen

  • Often found as an impurity, but is intentionally added for strength.

Phosphorous

  • Increases tensile strength, hardenability, corrosion resistance and machinability. However, it can also make steel brittle.

Silicon

  • A deoxidizer, it helps make steel strong and hard. It also makes steel less electrically conductive.

Sulfur

  • Most often thought of as an impurity. However, a minimum amount is necessary for machinability.

Tungsten

  • Adds hardness and strength.

Vanadium:

  • Increases strength and toughness. It also refines the carbon molecule, allowing a finer cutting edge.

 

Name some Steels, already.

Bushcraft Knife steel

Lets talk steel.

In the Bushcraft Knife Guide, I spoke about blade steels. I also clarified that I was generalizing. Here’s what I meant by that. I spoke about Carbon Steel and Stainless Steel. I used these terms because I felt it would be more familiar. It is common to hear steel broken into only two categories, steel that is stain resistant or stainless steel and steel that is prone to corrosion or carbon steel. In Reality there are many categories of knife blade steels. It is also common to hear about high carbon steel vs stainless steel. This is another common mistake. Stainless steel can be high carbon steel. The Designation “high carbon,” simply means that the steel contains carbon in saturations more than .8%.

Stainless Steel

154 CM

  • A tough steel with good corrosion resistance and wear resistance. It’s Very similar to 440C with the addition of molybdenum. This steel is American made and was very popular in the 90’s.

ATS 34

  • Very Very similar to 154 CM, but made in Japan. This steel became popular as an alternative to 154 CM when 154 CM was difficult to find in sizes knife makers needed.

420 & 420 HC

  • Another tough stainless with good corrosion resistance. 420 steels have less carbon than 440, is softer, but is also tougher.
  • HC stands for High Carbon. 420 HC has increased levels of carbon compared to 420 but still less than 440. It can be brought to a higher hardness than 420.

440 A, B & C

  • Similar to 420 steels but with a higher carbon content. Carbon content increases among the three in alphabetical order. 440A is the softest and cheapest of the 3.
  • 440B is slightly higher in carbon and harder than 440A.
  • 440C is a relatively common and high end stainless. It’s tough with good corrosion resistance and can be brought to a decent hardness, usually around 56-58 HRC.

AUS 6, 8 & 10

  • Both made by AISI, AUS series is comparable to 440 series, but with the addition of vanadium. The added vanadium refines the carbide making this steel is generally tougher and allows for a keener edge. AUS’s carbon content increases with its number.
  • AUS 6 is the cheapest and softest.
  • AUS 10 has the most carbon and is the hardest, comparable to 440HC.
  • AUS 8 is the most commonly used and offers a good ratio of hardness vs toughness.

VG 1 & VG 10

  • VG 1 is a tough steel with decent wear resistance. This steel is used as the core for knife manufacturer Cold Steel’s laminated, “San Mai” steel
  • VG 10 is similar to VG 1 but with added vanadium and cobalt. The vanadium refines the steels grain while the cobalt makes it tougher. Because of its excellent edge quality and retention and high corrosion resistance, it is commonly used for high end Japanese kitchen cutlery.

CPM – Crucible Particle Metallurgy

A steel manufacturer that uses a proprietary process to create excellent steel. The steel’s ingredients are melted together and turned into powder, which is then hot pressed to shape. CPM claims this process evenly distributes the steel’s elements creating a tougher, stronger steel. These steels are different enough to warrant Their own category.

CPM 154cm

  • Identical to 154 CM, but with the increased strength and edge retention that comes with the CPM production process.

CPM S30V

  • Specifically made for the knife industry and with hope of being an all-around super steel, this steel has fallen short of expectation. It is often described as lacking toughness. This steel has the lowest carbon content of the series.

CPM S35VN

  • Created as an improvement over S30V, offering better toughness.

CPM S60V

  • This steel has increased levels of carbon and vanadium over S30V and S35V. S60V is very hard, wear resistant and can achieve a very fine edge.

CPM S90V

  • S90V has less chrome but more carbon and much more vanadium than S60V. It is harder more brittle and less corrosion resistant. It is known for its amazing wear resistance.

CPM S110V

  • Even more wear resistant and much more corrosion resistant than S90V. This steel is often used in high end kitchen cutlery.

CPM 1V

  • As wear resistant as A2 but several times tougher.

CPM 3V

  • Better wear resistance than CPM 1V but not as tough.

CPM 9V

  • Very hard and wear resistant steel. Lower levels of carbon and vanadium make this steel tougher than CPM 10V.

CPM 10V

  • Thanks to added vanadium and carbon, CPM 10V is harder, more wear resistant and has a finer grain than CPM 90V. The added hardness makes it more brittle. Its toughness is on par with D2.

Alloy Steel

5160

  • A common spring stee, it’s known for its toughness and decent wear resistance. Relatively easy to heat treat, so expect to see a lot of back yard customs made from this. Makes a great chopper.   Tool Steel

A2

  • A very tough steel, but not known for its great edge retention or fine grain. Often described as having a toothy edge.

D2

  • A semistainless steel thanks to its 12% chromium content. It is very tough stuff, compared to stainless steels, but not as tough as carbon steel. It is often too brittle at high hardness leading to chipped cutting edges or tempering to a lesser hardness. This steel also has relatively large carbides, which can leed to a toothy edge.

O1

  • A common choice for the bushcraft knife and one of my favorites. It is considerably tough, but less than 5160 and A2. It is, however, more wear resistant and takes a keener edge, thanks to finer carbon molecules.

M2

  • This is a high speed tool steel and is capable of retaining its temper at high heat. It is tougher than D 2. It is often used to make hacksaw blades and other high speed cutting tools. Many from the woodcarvers convert these hacksaw blades into woodcarving knives.

W2

  • Has good wear resistance but isn’t very tough. This steel lends itself well to being differentially hardened. It naturally doesn’t fully harden within the core of thick knives. Chrome Steel

AISI 52100

  • This is, in many cases, my all around Favorite steel. It acts a lot like O1 but is more wear resistant and tougher. It also has very fine carbides, which equal a finer cutting edge that can be scary sharp.

SR101

  • Chemically identical to 52100, but is heat treated differently. The results are a generally considered to be an improvement over 52100, being tougher at a higher hardness.

Carbon Steel

1095

  • One of the most common and widely used carbon steels on the market and for good reason. Although prone to rust, this steel does it all well. This is a chemically simple steel with a carbon content of .95% and is relatively easy to work with. As a result, it can be tempered according to the desired hardness and toughness. It also holds a great edge. It does sometimes chip under impact. Choppers are better of using one of the 10XX series steels with less carbon.

1084

  • I believe this steel is no longer in production and has been replaced by 1080. It is almost identical to 1095 except its carbon content is around 85%

1080

  • Has replaced and is almost identical to 1084 in every way, except slightly less carbon. This is tough stuff, but less wear resistant and hard than 1095, due to its decreased carbon content. Great for big knives that expect a lot of abuse.

1070

  • Very similar to 1080, but with even less carbon, with average concentrations around 70%. This steel is tougher than 1080, but less wear resistant and hard.

1055

  • This is the really tough stuff, more so than any of the above 10XX series. However, it is also the least wear resistant and hard. It is often heat treated to spring steel temper to further increase its toughness. This steel is used for blades that take a lot of punishment and don’t need the wear resistance, like swords.