There are two general categories of steel that knife
blades are made of- Carbon Steel and Stainless steel.
Both of these categories of steel are widely used today
due to their unique characteristics. Generally, carbon
steel can hold a better edge than stainless steel, but
stainless steel has better corrosion resistant
properties. There is a tradeoff between corrosion
resistance and edge retention.
Carbon Steel is made of iron and a very
small amount of carbon. Carbon steel is categorized into
four classifications- low carbon (or mild) steel, medium
carbon steel, high carbon steel and very high carbon
steel. Low carbon steel contains .05% to .3% carbon.
Medium Steel contains .3% to .5% carbon, high carbon
steel contains .5% to .95% carbon, and very high carbon
steel contains .96% to 2.1% carbon. High carbon steels
are the most widely used carbon steel for making blades,
because once heat treated, they can maintain a good
balance between high toughness and the ability to
Stainless Steel is made of iron, a very small
amount of carbon and a very small amount of other
elements such as chromium, vanadium, molybdenum,
tungsten and nickel. When these other elements are added
to iron and carbon, the metals’ resistance to corrosion
is increased. Varying amounts of carbon and these other
elements are added to iron to form different types of
stainless steel, called alloys. High carbon stainless
steels are widely used for making blades because high
carbon content is needed to increase the blades’ edge
Powder Metallurgy Steel was developed to allow
high wear resistant steel to also have a high toughness.
The steel is rapidly solidified into a powder rather
than slowly cooled in a large ingot. It is then formed
to shape under high pressure and heat. This process
decreases the average carbide and grain size, and raises
the toughness, edge retention, and grindability compared
to steels produced by conventional processes.
Properties of Blade Steel
Edge Retention: the degree in which a blade
can hold a sharp edge.
Corrosion Resistance: the degree in which a
steel can resist rusting (oxidation).
Hardness: the degree in which a steel will
resist permanent deformation. Blade steels are measured
on a Rockwell Scale (example: Rc 56-58).
Hardenability: the degree in which a steel can
be hardened by a heat-treating process.
Strength: the degree in which a steel can
resist applied forces.
Toughness: the degree in which a steel can absorb
energy prior to fracturing.
Ductility: the degree in which a steel can
flex or bend without fracturing.
Wear Resistance: the degree in which a steel can
resist wear and abrasion.
Manufacturability: the degree in which a steel
can be machined, ground, and heat-treated.
There is a tradeoff (inverse proportion) between
hardness and toughness. The harder a blade is, the more
brittle (less tough) it will be. A hard blade will hold
an edge longer, but will be more susceptible to
breaking. The hardness of a blade steel is measured on
the Rockwell (Rc) scale. Blade steels are hardened
through the heat treating process. The most common
hardness for high carbon steel blades is Rc 52-58. The
most common hardness for stainless steel blades is Rc
56-60. A blade with an Rc hardness less than 52 is
considered soft. A blade with an Rc hardness greater
than 60 is considered very hard (brittle).
Carbon: not an alloying element, because it is
present in all steels, but it is the most important
hardening element. Increasing carbon increases hardness.
It also increases the strength of steel but, added in
isolation, decreases toughness. Blade steels are
generally made of high carbon steel with at least .5%
improves corrosion resistance, wear resistance and
hardenability. Steel with at least 13% chromium is
generally deemed "stainless" steel. Adding chromium in
high amounts decreases toughness.
improves strength and hardness, and permits quenching in
It also intensifies the individual effects of other
elements in more complex steels.
Copper: improves corrosion
Manganese: improves hardenability, strength
and wear resistance. It also improves the steel during
the manufacturing process.
Molybdenum: improves hardenability, tensile
strength and corrosion resistance (particularly
pitting). It also helps to maintain the steels strength
at high temperatures.
Nickel: improves toughness,
hardenability and possibly corrosion resistance.
Nitrogen: improves corrosion
resistance when used in place of carbon. Nitrogen can
function in a similar manner to carbon but offers
unusual advantages in corrosion resistance.
Phosphorus: improves strength, machinability, and
hardness, but creates brittleness in high
strength. Like manganese, it makes the steel more sound
during the manufacturing process.
Sulfur: improves machinability when added in
Tungsten: improves wear resistance. It is a
carbide former. When combined properly with chromium or
molybdenum, tungsten will make the steel become a
Vanadium: improves wear resistance and
hardenability by promoting a fine grain structure, which
improves toughness and allows the blade to take a very
sharp edge. It is a carbide former. Vandium carbides are
the hardest carbides.
0170-6 : 0170-6 is the steel makers
classification for 50100-B steel.
1045, 1050, 1055, 1060, 1084, 1095 : From 1045
up to 1095 there is an increase in carbon content. The
higher the number, the more wear resistant, but the less
tough (more brittle) the steel is. 1050 and 1060 are
often used for swords. 1095 is the most popular of the
10 series steels for making knives. When properly heat
treated, it is a reasonably tough steel, holds an edge
well and it is easy to sharpen. It does, however, rust
easily. It is a simple steel, which contains only carbon
12C27 : Similar to 440A. 12C27 is a
Scandanavian Sandvik stainless steel often used in
Finish and Norwegian knives. It is a high purity steel
that performs very well when properly heat treated. It
has good hardenability and wear resistance. It has a
higher toughness and corrosion resistance than 13C26 and
AEB-L. It has less wear resistance, but higher edge
retention than 440C.
13C26 : Similar to AEB-L. It is a
Scandinavian Sandvik stainless steel. It has
better hardenability and wear resistance, but
lower toughness and corrosion resistance than
154CM : An American made Crucible steel that
has similar machining and grinding qualities of 440C,
but has a definite advantage in both hardness and
toughness over 440C. Can be somewhat hard to sharpen.
Normally hardened to around Rc 60, it holds an edge very
well, often better than S60V, and is tough even at high
hardness. Not as stain resistant as the 400 series.
Because of its excellent edge retention, it is suitable
for blades that will endure extreme use.
17-7 PH : - A high corrosion resistant
precipitation-hardening, stainless steel. It has a high
chromium, nickel and aluminum content. It is used for
applications requiring high strength and resistance to
corrosion, including salt water corrosion. It offers a
good compromise between martensitic stainless steels
(heat-treatable) and austenitic stainless steels (non
4116 Krupp : A fine grained, stainless steel
made by ThyssenKrupp in Germany. Due to its high
chromium content, it is often used for hygienic and food
processing applications, including kitchen cutlery. Its
high carbon content gives it a high strength and an edge
retention ability that outperforms the 420 and 440
series stainless steels. Other alloying elements
contribute to grain refinement. This increases blade
strength and edge toughness in order to allow for a
finer, sharper edge.
420, 420HC, 420J, 420J2 : The 420 series
performs at the low end of the stainless steels. They
are tough, due to being soft, and they are very stain
resistant, but they are not very wear resistant. They do
not have very good edge retention. They are a low cost
stainless steel and they machine easily. The 420 series
steels are often used on inexpensive and fantasy knives.
420J2 is often used as knife liners and due to its
corrosion resistance, is also used for dive knives and
fillet knives. 420HC, also referred to as modified
stainless, due to its increased carbon, is roughly
comparable to 440A. It has a relatively high edge
retention compared to the other 420 stainless steels,
but it still has a low wear resistance.
425M : Very similar characteristic to 440A.
440A, 440B : The 440A and 440B stainless
steels can be hardened more than the 420 series, for
better strength. They are also more wear resistant, with
proper heat treating, although wear resistance is just
getting to the point of acceptability for knife blades.
440B has a higher carbon content and hardenability than
440A. They both have a higher corrosion resistance than
440C : A very good, high-end stainless steel,
usually hardened to around Rc 56-58. It is very tough
and has good edge retention, compared to the other 440
series stainless steels, due to its higher carbon
content. But it is not as stain resistant as the other
440 stainless steels. It is tougher and more stain
resistant than ATS-34 but has less edge retention. Its
toughness can be increased with a sub-zero quench
process. It was the first widely accepted stainless
steel by knife makers. Until the ‘high-tech’ stainless
steels came along, it was the most popular stainless
steel in the knife industry. It cuts easier than carbon
steels, and it grinds much easier than O-1. It also
anneals at very low temperature.
440V : Similar to 440C, but does not get quite
as hard. It does, however, have better edge retention
and is much more difficult to grind.
50100-B : Also known by the AISI designation
as 0170-6 steel. It is a good chrome-vanadium steel that
has many similarities to O-1, but is much less
expensive. It has approximately one third the chromium
of 52100 steel. The ‘B’ indicates that the steel has
been modified with vanadium, making this a
5160 : A spring steel that is similar to 1060,
but with one percent chromium to increase hardenability.
It is often used for swords and large knives. It has
excellent edge retention, wear resistance and toughness,
but it is difficult to grind. It performs well over a
wide range of hardness. It is a popular forging steel.
52100 : A ball bearing steel with similar
characteristics to 0170-6 but with three times the
amount of chromium. It has similar characteristics as
5160, but it holds a better edge. With the proper heat
treating, it can be as tough as 5160.
6A, 8A, 10A : See AUS Series.
A-2 : An exceptional air-hardening, cold
worked tool steel. It has an excellent resistance to
annealing and warping, but is difficult to
differentially temper. It is tougher than D-2 and M-2,
but is less wear resistant. It is just slightly harder
to grind than 0-1. It has excellent flexibility and
AEB-L : Similar to 13C26. Most popular for
kitchen knives. It has similar characteristic as 440B.
It heat treats like 440C and has good edge retention
when cryogenically heat treated. It grinds easy, but can
have unusual grinding characteristics. It is very easy
to polish and buff.
ATS-34 : Very similar to 154CM, but it has
slightly less manganese and slightly more phosphorus,
silicon and sulfur. It is made in Japan by the Hitachi
Corporation. It is a very tough steel. It has very good
edge retention, even when hardened to Rc 60. Although,
it is not as rust resistant as the 400 series stainless
steels. It is a very clean steel, but it comes with a
hard, black outer coating that must be removed before
grinding. One method of removing the coating is to soak
it in vinegar.
ATS-55 : Similar to ATS-34, but with reduced
molybdenum, phosphorus and sulfur removed, and cobalt
and copper added. It is a good steel, but does not hold
an edge as well as ATS-34. It is also less rust
resistant. It is comparable in performance to AUS-8.
AUS-6, AUS-8, AUS-10 : Sometimes referred to
as 6A, 8A and 10A stainless steel. AUS-6 is roughly
comparable to 440A, and competes with 420J. AUS-8 is
roughly comparable to 440B and competes with ATS-55 and
Gin-1. AUS-10 is roughly comparable to 440C, but
slightly tougher and slightly less corrosion resistant.
It competes with ATS-34 and 154CM. The AUS series
stainless steel contains vanadium, unlike the 440
series, which increases its wear resistance and edge
retention. The vanadium allows a sharper edge to be put
on the blade.
AUS-8A : A high carbon, low chromium stainless
steel that is tougher, but less corrosion resistant than
AUS-8. It has better edge retention than AUS-8, but less
edge retention than 440C.
BG-42 : A high performance, bearing-grade,
martensitic, proprietary stainless steel made by Timken
Latrobe Steel. It is often used in the aerospace
industry. It is similar, but tougher and more stain
resistant than ATS-34. It has more manganese than ATS-34
and it contains vanadium, unlike ATS-34. This gives it
better edge retention than ATS-34. It has a high wear
resistance, which can make it difficult to sharpen. It
can also be difficult to manufacture. Because of its
high strength and hardenability, it is well suited for
Boye Dendritic Cobalt (BDC) : A stainless
steel containing cobalt that has excellent wear
resistance and corrosion resistance. It has good
toughness, but a low strength. It is produced by David
Boye using a casting process.
Carbon V : A proprietary carbon steel that is
trademarked by Cold Steel. It is unclear exactly what
type of steel it is, but it has characteristics similar
Cowry X : Similar to ZDP-189.
CPM 10V : A very high vanadium tool steel
made by Crucible. It was designed to provide superior
wear resistance while maintaining toughness and
fabrication characteristics comparable to D2 and M2. It
has excellent wear resistance, but low corrosion
CPM 3V : A vanadium tool steel made by
Crucible. It was designed to provide maximum resistance
to breakage and chipping in a highly wear-resistant
steel. It has excellent wear resistance and toughness.
It also has good corrosion resistance. However, when
this steel does corrode, it tends to pit rather than
CPM S30V : A high carbon, high vanadium
martensitic stainless steel made by Crucible. This
stainless steel was created by Dick Barber of Crucible
Materials Corporation specifically for the cutlery
industry. It was designed to offer the best combination
of toughness, wear resistance and corrosion resistance.
It is tougher than D-2 and 440C and compares in
toughness to A-2. It has excellent wear resistance and
hardenability. It has a corrosion resistance comparable
to 440C. It is comparable to D-2 for grinding and
machining and much easier to grind than S60V or S90V. It
has superior edge retention and wear resistance to
BG-42, due to higher carbon and much higher vanadium.
This is an all around excellent cutlery steel.
CPM S60V : A high carbon, high vanadium
stainless steel. It is made from Crucible’s
particle metallurgy process. It has outstanding wear
resistance and edge retention. But it can be difficult
to grind and sharpen. It can also be difficult to heat
treat. The hardness can be reduced, in order to keep
CPM S90V : Similar to S60V, but packed
with more carbon and vanadium. This results in extremely
high wear resistance and edge retention- possibly better
than any other stainless steel used in the cutlery
industry. It is tougher and more wear resistant than
S60V. It is has some comparable characteristics to
BG-42. It is very difficult to grind, sharpen and heat
D-2 : An excellent air hardened, cold worked
tool steel. It has increased carbon and chromium over
A-2, which results in very high wear resistance. For a
tool steel, it has very good corrosion resistance. D-2
is often referred to as a semi-stainless, due to its
high chromium content and very good corrosion
resistance. D-2 is much tougher than the premium
stainless steel, including ATS-34 and 154CM. But, it can
be difficult to grind, due to its tendency to work
harden easily. It also will not take a mirror polish,
due to its ‘orange peel’ appearance.
GIN-1 : A very good stainless steel, sometimes
referred to as G-2. It has slightly less wear resistance
and strength than ATS-34. It is more wear resistant than
ATS-55. It is often used as a low cost alternative to
ATS-34 or 154CM.
INFI : A proprietary tool steel used only by
Busse Combat. Some of the carbon is replaced with
nitrogen. It is comparable to D-2 in corrosion
resistance. It has very high toughness for a high-alloy
ingot steel. It has extremely good wear resistance. It
is a good overall tool steel with an excellent balance
of corrosion resistance, toughness and edge retention.
It is good for large blades and blades that need to
endure extreme use.
L-6 : A carbon steel that is used for band saw
and circular saw blades. It is a medium carbon steel
that can be oil hardened. It has slightly better wear
resistance than plain carbon steels. It is similar to
the Swedish band saw blade steel 15n20. It has very good
toughness, but extremely low hardenability and corrosion
M-2 : A high speed tool steel (HSS), which
means it will not loose its temper during high heat
cutting jobs. This quality is mostly irrelevant for the
cutlery industry. M-2 is most commonly used for lathe
cutting tools. It has very high wear resistance and a
fine grain structure for toughness. It has a high
hardenability and slightly better corrosion resistance
than most tool steels.
O-1 : An good oil hardening, cold worked tool
steel. It has excellent edge retention and toughness.
But it is hard to grind and has very low corrosion
resistance. It is popular among forgers because it is
very forgiving and can be heat treated repeatedly if a
mistake is made.
O-6 : Slightly outperforms O-1. It is tougher
and holds a better edge than O-1. It has very good wear
resistance. It is very easy to heat treat, but very
difficult to grind.
San Mai III : A proprietary premium layered
steel used by Cold Steel. It is made with three layers-
a high carbon center, surrounded by lower carbon outer
layers. This allows for good edge retention in the high
carbon center layer, while maintaining toughness with
the outer layers. The exact steels used are a trade
SK-5 : A high carbon steel made in Japan. It
is the Japanese equivalent of 1080. It has a high
hardenability. It has a mixture of carbon-rich
martensite and small un-dissolved carbides. The carbides
increase wear resistance. This helps to create a good
balance between toughness and edge retention. This steel
is often used for making hand tools.
Stellite 6-K : Contains no iron, so it does
not need heat treating. It has exceptionally hard
particles contained in a softer alloy. It has a low
strength, but very good wear resistance. It is difficult
Talonite : A cobalt super-alloy. It is very
soft, Rc 42-47, and has a very low strength, but it is
very easy to work.
Vasco Wear : This steel is no longer produced.
It contains a high amount of vanadium. The vanadium
gives it very good edge retention and wear resistance.
But it is very hard to grind.
VG-1 : A proprietary stainless steel used by
Cold Steel. Its contents are a trade secret. It is a
lower cost alternative to their San Mai III steel.
VG-10: A high carbon, vanadium stainless steel.
It has very good edge retention, similar to BG-42 and
AUS-8. It has better corrosion resistance than ATS-34
and 154CM. It has very good wear resistance, almost as
good as 154CM. It is a very good overall high end blade
W-1, W-2 : Similar to 1095. It is a moderately
tough steel with very good edge retention, but low wear
resistance. W-2 contains vanadium, which allows it to
hold a better edge than W-1. They both have a high
hardenability. W-1 is often used to make files.
ZDP-189 : A powdered metal stainless steel with
high carbon and very high chromium. It has extremely
high wear resistance, comparable to CPM S90V. It has
excellent hardenability. But it has low toughness and
edge retention. It also has fairly low corrosion
resistance. It is difficult to grind and sharpen.