NEW Steel FAQ
Joe Talmadge
comments. One new thing I tried: most people didn't just want descriptions
of steels, they wanted direct comparisons. Obviously there are limits to
how much you can generalize, but I gave it a shot in the stainless section
... just an experiment.
Author: Joe Talmadge j...@cup.hp.com
Last Updated: June 2003
Table of Contents:
I. What makes a steel perform?
A. Introduction
B. Sharpen for performance
C. Design for performance
D. Properties of performance steels
E. What's the "best steel"?
II. Elements of Steel
III. Steels
A. Non-stainless Steels
B. Stainless Steels
C. Damascus Steel
C. Non-steel used for cutler
IV. Selected URLs for steel information
V. Bibliography
I.WHAT MAKES A STEEL PERFORM?
A. Introduction
Steel is the heart of the blade. The search for higher-performance
steels has to a number of wonderful materials in recent years. Steel
by itself isn't the sole determiner of knife performance, of course.
Heat treatment, blade geometry, handle geometry and materials all
effect how a knife performs for a particular job. However, those
other qualities can be difficult to measure. You can't tell by
looking at it how well a blade has been heat-treated, and you can only
make educated guesses on how well the blade and handle geometry will
work. With steel, however, you can get a full listing of its alloying
elements, something measureable and somehow satisfying.
As a result, it's easy to fall into the trap of putting too much
emphasis on the steel itself. A knife is more than steel, and it's
important not to forget that. In addition, many modern steels perform
so well, that knife decisions can often be made based on other factors
than marginal increases in steel performance.
The question of "what's the best steel" or "rank the following steels
in order from best to worst" often comes up. The resulting replies
can never be totally accurate, because depending on the jobs the knife
will be used for, the blade geometry, and the quality of the heat
treat, what is "best" and what is "worst" can be very fluid. If you
want to make an educated decision about steels, try to learn the
basics of steel properties, and go from there.
B. Sharpening for performance
That doesn't mean that significant performance advantages can't be had
by choosing the right steel for the job. In fact, choosing a steel
can significantly impact the performance of a knife. But, to really
bring out the performance of a particular steel, you need to take
advantage of the better steel in your sharpening plan. If a weak,
brittle steel can perform the job when sharpened at
25-degrees-per-side, a strong, tough steel might give you some
marginal performance improvements if it, too, is sharpened at
25-degrees-per-side. However, to really bring out the performance of
the better steel, trying bringing it down to 20-degrees per side, or
less. The advantage of the better steel is that it is strong and
tough enough to hold up with a small edge angle -- and smaller edge
angles radically out-perform bigger edge angles. It's easy to get a
10-to-1 perform advantage for certain cutting jobs by cutting 5
degrees off your sharpening angle.
This leads to the general rule:
To really see the advantages of a better steel, exploit that
steel in your sharpening program. If you're going to sharpen
all your knives at the same angle regardless of steel, you
might de-emphasize steel choice somewhat.
On the internet, I'll often see someone posting about wanting to
upgrade from their ATS-34 folder to one that has S30V, and then in a
different post, declare that they sharpen all their knives at
20-degrees-per-side. Why spend all that extra money for S30V, just to
get some marginal wear resistance advantages but no other performance
advantages? If that same user would take advantage of S30V's superior
toughness and drop the edge angle to 15-degrees-per-side, they would
see a large leap in cutting performance, along with the extra wear
resistance. Because of choosing the right sharpening angle, the more
expensive S30V knife now gives an impressive return on investment.
*Now* you can see what all the fuss is about!
C. Design for performance
In the section above, we highlighted what the user can do to bring out
the best performance in a high-performance steel. But the user is
only half the equation; now we will look at what the knifemaker might
do with a higher- performance steel. As the knifemaker moves from one
steel to another, it is often possible to modify the design of a
particular knife to take advantage of the newer steel, and raise
performance.
For example, it is possible to make a hard-use "tactical/utility"
knife from ATS-34. To make sure the ATS-34 will take the kind of
stresses it might see in this environment, the edge might be left a
bit thick (sacrificing cutting performance), or the hardness brought
down a touch (sacrificing strength and wear resistance), or both. If
the same maker moves to much-tougher S30V, he might be able to thin
out the edge, thin out the entire knife, and raise the hardness,
bringing up performance as a whole. Moving to differentially-tempered
5160 might allow the maker to re-profile even more for performance.
If we're talking about a fighter, moving from 1095 to 3V might allow
the maker to make the knife much thinner, lighter, and faster, while
significantly increasing cutting performance and maintaining edge
integrity.
So to really take advantage of the higher-performance steel, we want
the knifemaker to adjust the knife design to the steel, wherever he
thinks it's appropriate. If a knifemaker offers the same knife in
multiple steels, ask about what the characteristics are in each steel,
and the how's and why's of where the design has changed to accomodate
each steel offered.
Note that there can be good reasons that a knifemaker might not change
the blade profile even though the steel has changed. Maybe he's
particularly good at heat-treating one steel or another, so that the
differences between disparate steels are minimized. Maybe the
higher-performance steel is not available in the next stock thickness
down. Maybe instead of higher cutting performance, the maker would
rather offer the same cutting performance but in a knife that can take
more abuse. Maybe his customers tend to only buy thicker knives
regardless of performance.
So work with the maker to understand the choices being made with the
different steels being offered. If you understand the kind of
performance you need, you'll be able to make a wise choice.
D. Properties of performance steels
What is it we're looking for in a steel, anyway? Well, what we are
looking for is strength, toughness, wear resistance, and edge
holding. Sometimes, we're also looking for stain resistance.
Wear resistance: Just like it sounds, wear resistance is the ability
to withstand abrasion. Generally speaking, the amount, type, and
distribution of carbides within the steel is what determines wear
resistance.
Strength: The ability to take a load without permanently
deforming. For many types of jobs, strength is extremely important.
Any time something hard is being cut, or there's lateral stress put on
the edge, strength becomes a critical factor. In steels, strength is
directly correlated with hardness -- the harder the steel, the
stronger it is. Note that with the Rockwell test used to measure
hardness in a steel, it is the hardness of the steel matrix being
measured, not the carbides. This, it's possible for a softer, weaker
steel (measuring low on the Rockwell scale) to have more wear
resistance than a harder steel. S60V, even at 56 Rc, still has more
and harder carbides than ATS-34 at 60 Rc, and thus the S60V is more
wear resistant, while the ATS-34 would be stronger.
Toughness: The ability to take an impact without damage, by which we
mean, chipping, cracking, etc. Toughness is obviously important in
jobs such as chopping, but it's also important any time the blade hits
harder impurities in a material being cut (e.g., cardboard, which
often has embedded impurities).
The knifemaker will be making a tradeoff of strength versus toughness.
Generally speaking, within the hardness range that the steel performs
well at, as hardness increases, strength also increases, but toughness
decreases. This is not always strictly true, but as a rule of thumb
is generally accurate. In addition, it is possible for different heat
treat formulas to leave the steel at the same hardness, but with
properties such as toughness, wear resistance, and stain resistance
significantly differing.
Stain resistance (rust resistance): The ability to withstand rust
(oxidation). Obviously, this property can be helpful in corrosive
environments, such as salt water. In addition, some types of
materials are acidic (e.g., some types of foods), and micro-oxidation
can lead to edge loss at the very tip of the edge, over a small amount
of time. In "stainless" cutlery steels, stain resistance is most
affected by free chromium -- that is, chromium that is not tied up in
carbides. So, the more chromium tied up in carbides, the less free
chromium there is, which means more wear resistance but less stain
resistance.
Edge holding: The ability of a blade to hold an edge. Many people
make the mistake of thinking wear resistance and edge holding are the
same thing. Most assuredly, it is not; or rather, it usually is not.
Edge holding is job-specific. That is, edge holding is a function of
wear resistance, strength, and toughness. But different jobs require
different properties for edge holding. For example, cutting through
cardboard (which often has hard embedded impurities), toughness
becomes extremely important, because micro-chipping is often the
reason for edge degradation. Whittling very hard wood, strength
becomes very important for edge-holding, because the primary reason
for edge degradation is edge rolling and impaction. Wear resistance
becomes more important for edge holding when very abrasive materials,
such as carpet, are being cut.
There are other properties that significantly effect how a steel
performs:
Ability to take an edge: Some steels just seem to take a much sharper
edge than other steels, even if sharpened the exact same way.
Finer-grained steels just seem to get scary sharp much more easily
than coarse-grained steels, and this can definitely effect
performance. Adding a bit of vanadium is an easy way to get a
fine-grained steels. In addition, an objective of the forging process
is to end up with a finer-grained steel. So both steel choice, and
the way that steel is handled, can effect cutting performance.
Manufacturing process: Cleaner, purer steels perform better than
dirtier, impure steels. The cleaner steel will often be stronger and
tougher, having less inclusions. High quality processes used to
manufacture performance steel include the Argon/Oxygen/Decarburization
(AOD) process, and for even purer steel, the Vacuum Induction
Melting/Vacuum Arc Remelting (VIM/VAR) process, often referred to as
"double vacuum melting" or "vacuum re-melting".
Edge toothiness: Some steels seem to cut aggressively even when razor
polished. For these steels, even when they're polished for
push-cutting, their carbides form a kind of "micro serrations" and
slice aggressively.
E. What's the "best steel".
Understanding these properties will get you started to fundamentally
understanding steels and how choice of steel can effect performance.
I often see people asking, "what's the best steel"? Well, the answer
depends so much on what the steel is being used for, and how it's
heat-treated, that the questioner can never possibly get an accurate
answer. For a knife lover, it's worth spending a little time
understanding steel properties -- only by doing so well he really
understand what the "best steel" might be for his application.
Putting it all together, you can see how these properties might
determine your steel choice. To pick on S60V and ATS-34 again, there
seems to be a feeling that S60V is "better" in some absolute sense
than ATS-34. But S60V is often left very soft, around 55-56 Rc, to
make up for a lack of toughness. Even left that soft, an abundance of
well-distributed vanadium carbides gives S60V superior wear resistance
to ATS-34, at acceptable toughness levels. However, does that mean
S60V is "better" than ATS-34? Well, many users will find edge rolling
and impaction the primary causes of edge degradation for everyday use.
For those users, even though S60V is more wear-resistant, S60V is also
so soft and weak that they will actually see better edge retention
with ATS-34! The S60V user can leave the edge more obtuse (raise the
sharpening angle) to put more metal behind the edge to make it more
robust, but now the S60V will suffer serious cutting performance
disadvantages versus the thinner ATS-34 edge.
So, the next general rule:
Knowing the uses you'll put your knife to, and exactly how
those uses cause edge degradation, will allow you to make a
much better choice of steel, if you generally understand steel
properties.
The properties of different steels will be laid out below. But in
your search for the knife with the "best steel" for your uses, I
always suggest you ask the makers of the knives you're considering
which steels they would use. The knifemaker will usually know which
steels he can make perform the best. And as pointed out above, heat
treat is absolutely critical to bringing out the best in a steel. A
maker who has really mastered one particular steel (e.g., Dozier and
D-2) might be able to make that steel work well for many different
uses. So never go just by charts and properties; make sure you also
consider what the knifemaker can do with the steel.
III. ELEMENTS OF STEEL
At its most simple, steel is iron with carbon in it. Other alloys are
added to make the steel perform differently. Here are the important
steel alloys 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 but,
added in isolation, decreases toughness. We
usually want knife-grade steel to have >.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 typically deemed "stainless" steel, though
another definition says the steel must have at least 11.5%
*free* chromium (as opposed to being tied up in carbides) to
be considered "stainless". Despite the name, all steel can
rust if not maintained properly. Adding chromium in high
amounts decreases toughness. Chromium is a carbide-former,
which is why it increases wear resistance.
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: A carbide former, prevents brittleness & maintains
the steel's strength at high temperatures. 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: Adds toughness. Present in
L-6 and AUS-6 and AUS-8. Nickel is widely believed to
play a role in corrosion resistance as well, but this
is probably incorrect.
Phosphorus: Present in small amounts in most steels, phosphorus is
a essentially a contaminent which reduces toughness.
Silicon: Contributes to strength. Like manganese, it makes the steel
more sound while it's being manufactured.
Sulfur: Typically not desireable in cutlery steel, sulfur increases
machinability but decreases toughness.
Tungsten: A carbide former, it increases wear resistance. When
combined properly with chromium or molybdenum, tungsten will
make the steel to be a high-speed steel. The high-speed steel
M-2 has a high amount of tungsten. The strongest carbide
former behind vanadium.
Vanadium: Contributes to wear resistance and hardenability, and as
a carbide former (in fact, vanadium carbides are the hardest
carbides) it contribute to wear resistance. It also refines the
grain of the steel, which contributes to toughness and
allows the blade to take a very sharp edge. 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.
IV. STEELS
A. Non-stainless Steels (carbon, alloy, and tool steels):
These steels are the steels most often forged. Stainless steels can
be forged (guys like Sean McWilliams do forge stainless), but it is
very difficult. In addition, carbon steels can be differentially
tempered, to give a hard edge-holding 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 a little bit less of a crap shoot than
stainless steels -- I believe all the steels named below are fine
performers when heat treated properly.
In the AISI steel designation system, 10xx is carbon steel, any other
steels are alloy steels. For example, the 50xx series are chromium
steels.
In the SAE designation system, steels with letter designations (e.g.,
W-2, A-2) are tool steels.
There is an ASM classification system as well, but it isn't seen often
in the discussion of cutlery steels, so I'll ignore it for now.
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.
D-2
D-2 is sometimes called a "semi-stainless". It has a fairly high
chrome 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 wear resistance. D-2 is much tougher than
the premium stainless steels like ATS-34, but not as tough as many of
the other non-stainless steels mentioned here. The combination of
great wear resistance, almost-stainlessness, and good toughness make
it a great choice for a number of knife styles. Bob Dozier is one
maker who uses D-2. Benchmade has begun using D-2 in its Axis AFCK.
M-2
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 slightly tougher, and is slightly more wear resistant,
than D-2. However, M-2 rusts easily. Benchmade has started using M-2
in one of their AFCK 710 variations.
A-2
An excellent air-hardening tool steel, it is tougher than D-2 and M-2,
with less wear resistance . As an air-hardening steel, don't expect
it to be differentially tempered. Its good toughness makes it a
frequent choice for combat knives. Chris Reeve and Phil Hartsfield
both use A-2.
O-1
This is a 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 tough (although not as tough as, say, 5160).
It rusts easily, however. Randall Knives uses O-1, so does Mad Dog
Knives.
W-2
Reasonably tough and holds an edge well, due to its .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).
The 10-series -- 1095 (and 1084, 1070, 1060, 1050, etc.) Many of the
10-series steels for cutlery, though 1095 is the most popular for
knives. When you go in order from 1095-1050, you generally go from
more carbon to less, from more wear resistance to less wear
resistance, and tough to tougher to toughest. As such, you'll see
1060 and 1050, used often for swords. For knives, 1095 is sort of the
"standard" carbon steel, not too expensive and performs well. It is
reasonably tough and holds an edge well, and is easy to sharpen. It
rusts easily. This is a simple steel, which contains only two
alloying elements: .95% carbon and .4% manganese. The various kabars
are usually 1095 with a black coating.
Carbon V
Carbon V is a trademarked term by Cold Steel, and as such is not
necessarily one particular kind of steel; rather, it describes
whatever steel Cold Steel happens to be using, and there is an
indication they do change steels from time to time. Carbon V performs
roughly between 1095-ish and O-1-ish, in my opinion, and rusts like
O-1 as well. I've heard rumors that Carbon V is O-1 (which I think is
unlikely) or 1095. Numerous industry insiders insist it is 0170-6.
Some spark tests done by a rec.knives reader seem to point the finger
at 50100-B. Since 50100-B and 0170-6 are the same steel (see below),
this is likely the current Carbon V.
0170-6 - 50100-B
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.
L-6
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. In a poll on the knifemakers email list back in the 1990s,
when asked what the makers would use for their personal knife, L-6
emerged as the top choice.
5160
A steel popular with forgers, it is popular now for a variety of knife
styles, but usually bigger blades that need more toughness. It is
essentially a simple spring steel with chromium added for
hardenability. It has good wear resistance, but is known especially
for its outstanding toughness. This steel performs well over a wide
range of hardnesses, showing great toughess when hardened in the low
50s Rc for swords, and hardened up near the 60s for knives needing
more edge holding.
52100
Formerly a ball-bearing steel, and as such previously only used by
forgers, it's available in bar stock now. It is similar to 5160
(though it has around 1% carbon vs. 5160 ~.60%), but holds an edge
better. It is less tough than 5160. 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 wear resistance. However, with
the continued improvement of 52100 heat treat, this steel is starting
to show up in larger knives and showing excellent toughness. A
modified 52100 is being used by Jerry Busse in his lower-cost
production line, and such high-performance knife luminaries as Ed
Fowler strongly favor 52100.
CPM 10V
Crucible's somewhat-stain-resistant 10V provides incredible wear
resistance with D-2-class toughness. It is an oustanding choice when
maximum wear resistance is desired, but not super toughness.
CPM 3V
CPM's incredibly tough 3V gives excellent wear resistance and good
stain resistance as well, although when it does stain, it is said to
pit rather than surface rust. When maximum toughness is desired, with
very good wear resistance, 3V is a great choice.
INFI
INFI is currently only used by Jerry Busse. In place of some of the
carbon (INFI contains .5% carbon), INFI has nitrogen. The result is a
non-stainless steel that is nevertheless extremely stain resistant
(informally reported at close to D-2, or even better), incredibly
tough for a high-alloy ingot steel, and with extremely good wear
resistance.
Vascowear
A very hard-to-find steel, with a high vanadium content. It is
extremely difficult to work and very wear-resistant. It is out of
production.
B. Stainless Steels
Remember that all steels can rust. But the following steels, by
virtue of their > 13% chromium, have much more rust resistance than
the above steels. I should point 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. It probably makes more sense to
measure stainlessness byt he amount of free chromium (chromium not
tied up in carbides), because free chromium is what forms the chromium
oxide on the blade surface that offers stain resistance. 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.
Because any particular stainless steel is often heat treated to around
the same hardness (i.e., 440C is usually around 57 Rc, ATS-34 is 59-61
Rc, S60V is getting consensus at around 56 Rc, etc.) even by different
manufacturers, it's a bit easier to give a general feeling of the
performance you'll get from different classes of stainless steels,
without introducing too many inaccuracies. Please note, though, that
the act of grouping differing steels in classes definitely does
oversimplify, and some of these steels might more properly fit between
the class it's in, and the following (or previous) one. In addition,
better heat treat can move a steel up in performance significantly.
Last disclaimer: not everyone will agree with the groupings I have
here. Whew, all that said, here is a general categorization of
stainless steels:
420 and 420J represent the low end of stainless steels. They are very
stain resistant, and are tough due to being very soft. However, they
are also very weak, and not very wear resistant. Generally speaking,
expect these steels to lose their edge quickly through abrasion and
impaction. They are used in less-expensive knives due to their ease
of machining.
440A and its relative peers, 425M, 420HC, 12C27, and 6A are the next
group. They can be hardened more than the previous group, for better
strength, and they are more wear resistant, though wear resistance is
just getting to the point of acceptability. 440A and 12C27 are the
leaders of this group, with solid heat treat both perform okay. 12C27
is said to be particularly pure and can perform very well when heat
treated properly. 6A trails those two steels, though with its
vanadium content, can take a razor edge. 425M and 420HC trail the
rest.
Gin-1, ATS-55, 8A, and 440C comprise the next group. These steels
will usually be stronger than the previous group, and more
wear-resistant. Generally speaking, they retain excellent stain
resistance properties, though ATS-55 sticks out here as not
particularly stain resistant. 8A is also worth a mention, with some
vanadium content, it can take an extremely sharp edge very easily, but
is also the weakest and least wear-resistant of this group.
ATS-34/154CM, VG-10, and S60V are the next group up. It's difficult
to make generalizations about ATS-34 and 154-CM -- they are in such
widespread use that heat treat varies widely. These steels provide a
high-end performance benchmark for stainless steels, and hold an edge
well, and are tough enough for many uses (though not on par with good
non-stainlesses). They aren't very stain resistant, however. VG-10
can be thought of as being like ATS-34 and 154-CM, but doing just
about everything a hair better. It's a little more stain resistant,
tougher, holds an edge a little better. And VG-10 has vanadium in it,
it's fine-grained and takes the best edge of this group. S60V has by
far the best wear resistance of the group, though consensus is
becoming that it should be left around the same hardness as 440C
(56ish Rc), which means it will be relatively weak compared to ATS-34,
154-CM, and VG-10, and so it will indent and lose its edge quickly
when strength is required. S60V is the winner here when pure
abrasion resistance is much more important than edge strength.
BG-42, S90V, and S30V constitute the next group. BG-42 has better
wear resistance than all the previous steels except for S60V. It is
tougher than ATS-34, and more stain resistant. It is wear resistant
to the point where it can be difficult to sharpen. S90V represents
the ultimate in wear resistance in the steels discussed so far. Also
tougher than ATS-34, and more stain resistant. It can be very
difficult to put an edge on. It is difficult enough to machine than
it is used almost exclusively in custom knives, not production
knives. In your buying decisions, you might want to take into account
the difficulty of sharpening these steels. S30V backs off on the wear
resistance of S90V, but is significantly tougher and easier to
sharpen. It is more wear resistant than BG-42. The jury is still
out, but it may end up this week's ultimate high-end all-around
stainless steel, due to high performance coupled with easier
machineability and sharpenability than the other steels in this class.
Okay, on to the steels in more detail:
420
Lower carbon content (<.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.
420HC
420 modified with more carbon, to be roughly comparable to 440A.
440 A - 440 B - 440C
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, very
tough and with good edge-holding at that hardness. 440C was the king
of stainless cutlery steels in the 1980s, before ATS-34 took the title
in the 1990s. 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 a very good general-use
stainless, tougher and more stain resistant than ATS-34 but with less
edge-holding and weaker. If your knife is marked with just "440", it
is probably the less expensive 440A; if a manufacturer had used the
more expensive 440C, he'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 treat (we've heard good
reports on the heat treat of SOG's 440A blades, don't know who does
the work for them). 440-B is a very solid performer and 440-C is
excellent.
425M - 12C27
Both are very similar to 440A. 425M (.5% carbon) is used by Buck
knives. 12C27 (.6% carbon) is a Scandanavian steel used often in
Finish puukkos and Norwegian knives. 12C27 is said to perform very
well when carefully heat treated, due to its high purity. When done
right, it may be a slighter better choice than 440A and its ilk.
AUS-6 - AUS-8 - AUS-10 (aka 6A 8A 10A)
Japanese stainless steels, roughly comparable in carbon content to
440A (AUS-6, .65% carbon) and 440B (AUS-8, .75% carbon) and 440C
(AUS-10, 1.1% carbon). AUS-6 is used by Al Mar, and is a competitor
to low-end steels like 420J. Cold Steel's use of AUS-8 has made it
pretty popular, as heat treated by CS it won't hold an edge like
ATS-34, but is a bit softer (and therefore weaker) and tougher. 8A is
a competitor of middle-tier steels like ATS-55 and Gin-1. 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. It competes with higher-end steels, like ATS-34
and above. All 3 steels have some vanadium added (which the 440
series lacks), which will improve wear resistance and refines the
grain for both good toughness, and the ability to sharpen to a very
keen edge. Many people have reported that they are able to get knives
using steels that include vanadium, like 8A, sharper than they can get
non-vanadium steels like ATS-34.
GIN-1 aka G-2
A steel with slightly less carbon, slightly more chromium, and much
less moly than ATS-34, it used to be used often by Spyderco in their
less-expensive knives. Spyderco has since switched to ATS-55 and 8A,
but Benchmade is now using Gin-1 in their less-expensive knives. A
very good stainless steel, with a bit less wear resistance and strength
than ATS-34.
ATS-34 - 154-CM
ATS-34 was the hottest high-end stainless in the 1990s. 154-CM
is the original American version, but for a long time was not
manufactured to the high quality standards knifemakers expect, so
knifemakers switched over to ATS-34. CPM is again making high-quality
154-CM, and some companies seeking to stick with American-made
products (like Microtech) are using it. ATS-34 is a Hitachi product
that is very, very similar to 154-CM. Normally hardened to around 60
Rc, it holds an edge very well and is tough enough even at that high
hardness. Not 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.
Contrary to popular belief, both steels are manufactured through
the Argon/Oxygen/Decarburization process (AOD), not vacuum
remelted.
ATS-55
Similar to ATS-34, but with the moly removed and some other
elements added. This steel is a good cutlery steel but a tier behind
ATS-34 and its closest competitors (other steels in ATS-55's class
might be Gin-1 and AUS-8). With the molybdenum removed, ATS-55 does
not seem to hold an edge quite like ATS-34, and reports are that it's
less rust-resistant. My guess is that with the moly gone, more
chromium is tied up in carbides -- which means less free chromium for
rust resistance, and softer chromium carbides replacing moly carbides
for less wear resistance.
VG-10
Another vanadium-containing high-end stainless steel. Due to the
vanadium content, VG-10 takes a killer edge, just like other vanadium
steels like BG-42 and AUS-8. VG-10 is also tougher and more
rust-resistant than ATS-34, and seems to hold an edge better.
BG-42
Bob Loveless announced a while back that he's switching from ATS-34 to
this steel. Keep an eye out for it, it's bound to catch on, although
the higher cost, limited stock-size availability, and added difficulty
of manufacturing are holding BG-42's popularity back. BG-42 is
somewhat similar to ATS-34, with two major differences: It has twice
as much manganese as ATS-34, and has 1.2% vanadium (ATS-34 has no
vanadium), so look for significantly better edge-holding than ATS-34.
The addition of vanadium and the clean manufacturing process (VIM/VAR)
also gives BG-42 better toughness than ATS-34. Chris Reeve has
switched from ATS-34 to BG-42 in his Sebenzas.
S30V - S60V (CPM T440V) - S90V (CPM T420V)
Two steels that hold an edge superbly, world class type edgeholding,
but it can be difficult to get the edge there in the first place.
These steels are made with Crucible's particle metallurgy process, and
that process allows these steels to be packed with more alloying
elements than traditional steel manufacturing methods would allow.
Both steels are very high in vanadium, which accounts for their
incredible wear resistanceg. Spyderco offers at least one model in CPM
S60V. Spyderco, one major user of S60V, has cut back hardness
down to 55-56Rc, in order to keep toughness acceptable, but that
sacrifices strength so there is a tradeoff. S90V is CPM's
follow-on to 440V, and with less chromium and almost double the
vanadium, is more wear-resistant and tougher than S60V -- and, in
fact, is probably more wear-resistant than any other stainless
steel used in the cutlery industry. As such, S90V
is in the running with steels like BG-42 as among the best
general-purpose stainless steels; however, S90V is even more expensive
and difficult to work than BG-42, so it's strictly in the realm of
custom makers currently..
CPM S30V:
The newest stainless steel from Crucible, purpose-designed as a
cutlery steel. This steel gives A-2-class toughness and almost-S90V
class wear resistance, at reasonable hardness (~59-60 Rc). This mix
of attributes is making S30V one of the hottest stainless steels
going, with makes such as Chris Reeve switching from BG-42 to S30V.
Will this be the new king of general-purpose stainless cutlery steels?
We'll know over the next couple of years.
400 Series Stainless
Before Cold Steel switched to AUS-8, many of their stainless products
were marketed as being of "400 Series Stainless". Other knife
companies are beginning to use the same term. What exactly *is* 400
Series Stainless? I always imagined it was 440-A, but there's nothing
to keep a company from using any 4xx steel, like 420 or 425M, and
calling it 400 Series Stainless.
C. Damascus Steel -- see www.dfoggknives.com for much more detail
Damascus steels are made by forge-welding two or more different metals
(usually steels). The billets are heated and welded; to get an idea
of the process, see Don Fogg's URL listed in the bibliography. The
damascus is then acid-etched. The different metals etch at different
rates, and depth and color contrast are revealed.
Damascus can be made with performance and/or aesthetic objectives in
mind. Aesthetically, the choice of materials is important. One
shiney steel and one darker steel etch out to show the most striking
pattern. If the maker is going more for beauty than performance, he
might even go with nickel, which is bright but does not perform as
well as steel for cutlery applications. The other factor affecting
beauty is of course the welding pattern. Many patterns of damascus
are available today, from random to star to ladder, and a whole lot
more.
The following steels will provide bright lines:
L-6 and 15N20 (the Swedish version of L-6) -- nickel content
O-1 -- chromium content
ASTM 203 E -- nickel content
Nickel
The following steels will provide dark lines:
1095
1084
5160
52100
W-2
D. Non-steels used for cutlery
Talonite - Stellite 6K - Boye Dendritic Cobalt (BDC)
These cobalt alloys have incredible wear resistance, and are
practically corrosion resistant. Stellite 6K has been around for
years, but was expensive and very difficult to work, and so is only
rarely seen. Talonite is easier to work, and as a result has been
gaining in popularity, especially among web-based knife buyers. David
Boye uses his casting process to manufacture Boye Dendritic Cobalt.
This material is tough and has great wear resistance, but is relatively
weak.
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
these days, because the SEALs use it as their knife when working
around magnetic-detonated mines. Mission knives uses titanium.
Tygrys makes a knife with a steel edge sandwiched by titanium.
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
this type of ceramic. Kevin McClungcame 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 incredibly well.
IV: SELECTED URLs FOR STEEL INFORMATION
In no particular order:
# An extensive list of steel links
http://www.metalwork.0catch.com/list.htm
# Principal Metals vast database of steel properties & terms
http://www.principalmetals.com
# Matweb's steel database
http://www.matweb.com/
# Crucible's Steel Pages, loaded with info on composition/selection/etc.
http://www.crucibleservice.com/cscd/crumain2.htm
# Suppliers Online huge database of steel info
http://www.suppliersonline.com
#A.G. Russell's FAQ Pages
http://agrussell.com/faq/index.html
#Spyderco's Steel Page
http://www.spyderco.com/education/steelchart.asp
# Knives.com entire site is interesting, but hit "Tech", then "Steel"
http://www.knives.com
# Metal Mart's dictionary of metallurgical terms
http://www.metal-mart.com/dictlist.htm
# A list of metallurgical sites, schools, organizations, and journals
http://www.mlc.lib.mi.us/~stewarca/metallurgy.html
# Titanium Info
http://www.halperntitanium.com/
# Don Fogg's excellent info pages
www.dfoggknives.com
# A good steel chart
http://www.pizzini.at/steellist.htm
V. BIBLIOGRAPHY
I got theinformation for this FAQ
from my own experience as a collector and amateur knifemaker, and from
conversations with custom makers. There are too many people on
the internet who have taught me about steels for me to name them all,
but I've particulary sought out the posts of people like Jerry Hossom and
Cliff Stamp. I've also read plenty of
articles on steels, but here are the ones that I actually had in front
of me:
Bob Engnath's Blades and Stuff Catalog. Bob's catalog is a
must-see for everyone, even for just collectors, as it contains
a wealth of information on all kinds of great knife subjects.
There is a section on knife steels. Bob passed away in 1998,
but if you can find an old copy of his catalog, grab it.
"The Secrets of Steel," by Butch Winter, _Tactical
Knives_, Spring 1995.
"What Alloys Do For Blade Steel," by Wayne Goddard, _Blade_,
June 1994.
Email conversation with Wayne Goddard, February 1998.
Don Fogg's article on damascus steels from his website
www.dfoggknives.com (information used by permission)
"Inside Steel: What the Alloying Elements Do For Your
Blade", by Ed Severson with Steve Shackleford, _Blade, August 1999.
sst...@physics.mun.ca
> I. What makes a steel perform?
> A. Introduction
> B. Sharpen for performance
> C. Design for performance
> D. Properties of performance steels
> E. What's the "best steel"?
The above sections provide a wealth of information, reading this would solve
a lot of problems, and cut through a lot of promotional hype. In the
properties selection you might want to add a reference to ductility which is
important to durability in both a gross sense (the knife snapping in half)
as well as preventing edge tears and the like.
> Edge holding:
[snip excellent overview]
Corrosion resistance can also be a large factor in edge retention.
> CPM 10V
> Crucible's somewhat-stain-resistant 10V provides incredible wear
> resistance with D-2-class toughness. It is an oustanding choice when
> maximum wear resistance is desired, but not super toughness.
Just a comment here, CPM-10V has slightly better toughness than D2, though I
would agree that it isn't a good choice for high toughness applications.
> CPM 3V
[SNIP]
> ... when it does stain, it is said to pit rather than surface rust
I have soaked it, Ed Schott heat treatment, no significant pitting, far less
than ATS-34 and the like (VG-10, D2, etc.) which pit very badly.
> 440A and its relative peers, 425M, 420HC, 12C27, and 6A ...
"420HC" is actually a name like Carbon V in the sense that it applies to a
family of steels. It just means AISI 420 with more carbon, the range of
carbon can be quite high, on the extreme end the steel can be 58 HRC after
tempering (Camillus / Buck) which puts it pretty much right on top of 440C.
Most use lower carbon versions however and the hardness is ~ 55 HRC.
> BG-42, S90V, and S30V constitute the next group.
Some comment on max hardness might be useful here (and in general), BG-42
and S90V can get 1-2 HRC points higher than S30V.
> BG-42
> Bob Loveless announced a while back that he's switching from ATS-34 to
> this steel. Keep an eye out for it, it's bound to catch on ...
This is a bit dated, its time it passed, no one will use BG-42 with S30V now
available, the promotional advantage of S30V, the "hotness", is simply too
great.
[SNIP]
> Chris Reeve has switched from ATS-34 to BG-42 in his Sebenzas.
and now to S30V.
> Talonite - Stellite 6K - Boye Dendritic Cobalt (BDC)
[snip]
> This material is tough and has great wear resistance, but is relatively
> weak.
and soft, yes you have already clarified the relation ship between hardness
and strength in the above, however I would still note the much lower working
hardness of the Cobalt alloys, ~45 HRC for most, even lower for Boyes.
--
Cliff Stamp
sst...@physics.mun.ca http://www.physics.mun.ca/~sstamp/
The one unforgivable sin, the offence against one's own integrity,
is to accept anything at all simply on authority -- Maureen Johnson Long
Anyone can hold the helm when the sea is calm. -- Publilius Syrus
alv...@xx.com
> One new thing I tried: most people didn't just want descriptions
> of steels, they wanted direct comparisons.
Man that is tough to find information on "stainless and heat
resistant steels" (usually abbreviated to just "stainless steel"),
I couldn't find any worth anything. It's like it's not important
to industry, how strong it is or how good it holds an edge, since
it's usually not used that way.
Tool steels, on the the other hand, are all about comparisons of
their strengths and weaknesses and their edge holding ability.
Tool steel is easy as anything to find detailed comparisons on.
> Steel is the heart of the blade. The search for higher-performance
> steels has to a number of wonderful materials in recent years. Steel
> by itself isn't the sole determiner of knife performance, of course.
> Heat treatment, blade geometry, handle geometry and materials all
> effect how a knife performs for a particular job. However, those
> other qualities can be difficult to measure. You can't tell by
> looking at it how well a blade has been heat-treated, and you can only
> make educated guesses on how well the blade and handle geometry will
> work. With steel, however, you can get a full listing of its alloying
> elements, something measureable and somehow satisfying.
That is so true sounding to me, I can hardly believe I'm reading it
and not spewing it for a change! :)
> ...-- and smaller edge
> angles radically out-perform bigger edge angles. It's easy to get a
> 10-to-1 perform advantage for certain cutting jobs by cutting 5
> degrees off your sharpening angle.
YeeeHaaaw! :) And most of the makers of fancy high dollar knives
prefer L6 for their own personal knives. It holds an edge ever bit
as good as stainless steel and is so much stronger they can make the
knife edge thin and sharpened sorta like a straight razor. These
are the same guys that make and sell stainless steel knives too.
> This leads to the general rule:
> To really see the advantages of a better steel, exploit that
> steel in your sharpening program. If you're going to sharpen
> all your knives at the same angle regardless of steel, you
> might de-emphasize steel choice somewhat.
This is soooo cool Joe! :)
> On the internet, I'll often see someone posting about wanting to
> upgrade from their ATS-34 folder to one that has S30V, and then in a
> different post, declare that they sharpen all their knives at
> 20-degrees-per-side. Why spend all that extra money for S30V, just to
> get some marginal wear resistance advantages but no other performance
> advantages? If that same user would take advantage of S30V's superior
> toughness and drop the edge angle to 15-degrees-per-side, they would
> see a large leap in cutting performance, along with the extra wear
> resistance. Because of choosing the right sharpening angle, the more
> expensive S30V knife now gives an impressive return on investment.
> *Now* you can see what all the fuss is about!
Is that true? :/
If so, looks like I'm going to have to get some S30V and hand it
over to my "testers". :)
> If the same maker moves to much-tougher S30V, he might be able
> to thin out the edge, thin out the entire knife, and raise the
> hardness, bringing up performance as a whole.
Something I want are numbers showing a comparison of S30V and O1 (or
any "tool steel") in strength at various tempering temperatures and
the hardensses that go along with them. Now that would be cool. I
wonder if Carpenter would release those numbers to us? They already
have them, it's just a matter of them letting us see them.
> Wear resistance: Just like it sounds, wear resistance is the ability
> to withstand abrasion. Generally speaking, the amount, type, and
> distribution of carbides within the steel is what determines wear
> resistance.
Hmmm... Yeah but, hardness has a big part to play here too.
Sometimes minor, but sometimes the only thing that counts, no
kidding.
It's hard to find real numbers on "wear resistance" tho since it's
hard to measure. Most (98%?) of the information out there about wear
resistance is in the various steels' annealed condition. Like 4340
being way more wear resistant then 1095 is an example that messed me
up in my early days researching knife steels.
> Strength: The ability to take a load without permanently
> deforming. For many types of jobs, strength is extremely important.
> Any time something hard is being cut, or there's lateral stress put on
> the edge, strength becomes a critical factor. In steels, strength is
> directly correlated with hardness -- the harder the steel, the
> stronger it is. Note that with the Rockwell test used to measure
> hardness in a steel, it is the hardness of the steel matrix being
> measured, not the carbides. This, it's possible for a softer, weaker
> steel (measuring low on the Rockwell scale) to have more wear
> resistance than a harder steel. S60V, even at 56 Rc, still has more
> and harder carbides than ATS-34 at 60 Rc, and thus the S60V is more
> wear resistant, while the ATS-34 would be stronger.
Cool! And something like L6(4370) with Ni strengthening the iron
directly by "solid solution" is pretty hard to beat. But Ni has
it's problems, if there is much in the way of other alloying, so
just like Cr, too much, is still too much. Just right is still just
right and Cr is one of the best steel alloying elements we have.
L6(4370) or 0186(8670 modified) can be heat treated to a hardness
that's next to imposible to file (63hrc), so you can have both
properties in the same steel.
> 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.
Joe, please delete:
"Present in most cutlery steel except for A-2, L-6, and CPM 420V."
> Molybdenum: A carbide former, prevents brittleness & maintains
> the steel's strength at high temperatures. 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.
Joe, please delete:
"always have 1% or more molybdenum -- molybdenum is what gives
those steels the ability to harden in air."
Mn
Mo
Cr
Si
Ni
V
Mo helps but isn't the whole answer, Mn is more powerful that way,
and Cr is right behind Mo then Si and Ni. V too, but -only- if you
heat the steel high enough to dissolve all the vanadium carbides and
for knife blade steel like we're talking about here... that's way to
friggin high! :) (I figure that's one reason the carbon content
isn't all that high on high speed steels, the carbon is shared to
form a matrix)
> Nickel: Adds toughness. Present in
> L-6 and AUS-6 and AUS-8. Nickel is widely believed to
> play a role in corrosion resistance as well, but this
> is probably incorrect.
It's hard to find solid information about Ni's effect on corrosion
resistance since tool steels aren't usually formulated with
corrosion reisistance in mind. Ni does help with corrosion
resistance tho no doubt about that and so does Cu, Si and Mo.
Si is very important and so 1% Si is in nearly every stainless steel
formulation. Yep, there are some wierd exceptions like a leaded
stainless steel 414L.
Ni's role maybe in the advantage of being able to make a hard
"enough" steel using Ni so the C can be left extra low because
carbon is very detrimental to corrosion resistance. Maybe that's
where the idea comes from?
Cu helps by protecting the grain boundries but weakens the steel.
When speaking of "stainless and heat resistant steels" .35% to .65%
Cu is understood to be the copper content, unless otheriwise stated.
No kidding on that one. I believe I got that one form a book
dedicated to stainless steel and unable to find a reference to it in
my ASM books. It might be from the 18 volume ASM Metals Handbook
tho. <shrug> I need to refind it, my notes don't say where it's
from. :/
Tool steels are understood to have a -maximum- .25% Cu content
unless it's a W series then the max is .20% Cu. It weakens the
steel's grain boundries. In practice tool steels are much lower
than AISI/SAE's max Cu content, because the makers are all about
quality in performance and strength is usually high on the list.
Si and especially Ni+Si has a nasty property of causing the carbon
in the steel to graphatize (sort of like grey cast iron) and is
weakening to the steel but has a self lubricating property. O6 is a
tool steel they did that way on purpose and would make a dandy slip
joint spring but a really lousy straight razor!
> Silicon: Contributes to strength. Like manganese, it makes the steel
> more sound while it's being manufactured.
Like everything else... up to a certain amount, of course.
> M-2
> 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 slightly tougher, and is slightly more wear resistant,
> than D-2. However, M-2 rusts easily. Benchmade has started using M-2
> in one of their AFCK 710 variations.
Used in hand hacksaw blades too. Compare their edge holding to the
carbon steel hand hacksaw blades and you'll know it's an excellent
edge holder! :)
> L-6
> A band saw steel...
--> [and circular sawblades! both large and small]
But really turns out the majority of them haven't been L6 (4370) at
all but a cheaper version, 0186 (8670-modified) instead. A guy
prob'ly couldn't tell the difference anyway. :) The steel maker's
designation is 0186 but is also referred to as "8670-modified".
Good stuff no matter what you call it. :)
> A modified 52100 is being used by Jerry Busse in his lower-cost
> production line, and such high-performance knife luminaries as Ed
> Fowler strongly favor 52100.
0170-6 (50100-B/W7/6195) is a cheaper version of 52100 with a slight
increase in knife friendly properties, in my opinion. My 0170-6, I
got from Western Cutlery turned out to be a "vacuum electric remelt
product" (appearently?) since it has a -super- low Al content (which
is also good anyway;).
> CPM 3V
> CPM's incredibly tough 3V gives excellent wear resistance and good
> stain resistance as well, although when it does stain, it is said to
> pit rather than surface rust.
High speed steels are that way too, they don't seem to tarnish and
look cool, they stay shiny like stainless steel until it rusts then
it's only pits and looks like D2. In meat cutting service even 1095
doesn't rust, so an HSS skinning knife just looks like icky ol'
stainless. :/
> B. Stainless Steels
> ...but the ASM Metals Handbooks says "greater than 10%"...
Sure enough! :) But it wouldn't make a knife blade worth anything!
It'd be super low in carbon, for one thing, with other alloying for
corrosion resistance that are detrimental to knife edges for
another.
> [S30V] ...is more wear resistant than BG-42. The jury is still
> out, but it may end up this week's ultimate high-end all-around
> stainless steel, due to high performance coupled with easier
> machineability and sharpenability than the other steels in this
> class.
It's not like the others (ats-34 440c etc) it's the future and it's
here to stay. They might tweek it this way and that and call it
something different but it's not going to be improved on that much.
They did their homework this time.
Anyway, that's my guess. I want to know more about how S30V
compares to a tool steel (any tool steel) in strength, torsional
toughness test results would be best with total deflection and
force applied. A graph with both those curves against tempring
temperature and another tool steel super-imposed on it like a
(wrought/ingot) O1 or A2 tool steel. I've got access to one of
those where A2 and O1 are compared. A2 is stronger than O1.
> CPM S30V:
> The newest stainless steel from Crucible, purpose-designed as a
> cutlery steel. This steel gives A-2-class toughness and almost-S90V
> class wear resistance, at reasonable hardness (~59-60 Rc). This mix
> of attributes is making S30V one of the hottest stainless steels
> going, with makes such as Chris Reeve switching from BG-42 to S30V.
> Will this be the new king of general-purpose stainless cutlery steels?
> We'll know over the next couple of years.
Some of the steels in the "A2 class" are air-hardening, high-
manganese or high silicon steels and are relativly weak stuff,
weaker than O1 which has already a high enough manganese content to
make it oil hardening (cheaply!). That's why -A2- is stronger than
O1, A2(type 420), A3(type422) and Vascowear(type421) are all, low Si
and medium Cr+Mo based air hardening tool steel but the rest aren't.
The rest (7 of them) listed in ASM's "Tool Steels" are much weaker
(A4,A5,A6,A8,A9 + two "types" not listed by AISI).
A7 is in another ASM tool steel class and should be strong like A2
but next to impossible to work with like VascoWear. ;)
That's how I'm picturing S30V... like A7 or VascoWear only
"stainless"? But how are they different? Plus or minus, no
difference to me, just want to know for sure.
> L-6 and 15N20 (the Swedish version of L-6) -- nickel content
> O-1 -- chromium content
Could it be O1's high manganese content instead?
.50%Cr +.50%W + 1.25%Mn added together make a difference?
I haven't studied corrosion resistance enough to know the answer.
I have always had one eye on edge retention and strength (that the
edge needs) and not dove into the other details.
> The following steels will provide dark lines:
> 1095
> 1084
> 5160
> 52100
> W-2
52100 has about 1.5%Cr but is low on Mn and Si, the only real
difference between 52100(W5) and O1 is the high Mn content of
the O1, but still, that's not all there is to it, I figure.
I figure there's more to this than meets the eye in the steels'
compositions, we've moved into electro-chemistry and now absolutes
can only be stated when the contrasting materials are stated. Or
something like that. ;) In other words it matters what you have
sandwiched with what. :)
Alvin in AZ
Joe Talmadge
"please remove" parts. I'm pretty sure I had at least one, and maybe more
cutlery steel charts in front of me at the time I wrote that. Gotta go back
and double-check!
Joe
<alv...@XX.com> wrote in message news:bdlfng$l8s$1...@reader1.panix.com...
sst...@physics.mun.ca
[toughness of S30V]
Based on what I have seen, tests I have read, and the materials data
collected by Crucible which show it has the same impact toughness as 440C,
it isn't anything special in that department.
Consider this thread :
http://www.bladeforums.com/forums/showthread.php?s=&threadid=262446
The maker won't even use 15 degrees for a kitchen knife. I run axes at that
angle. It also breaks *really* easily, has almost no ductility.
If you want a stainless cutting steel use S90V which can get to 62/63 RC,
and has a very high wear resistance, more than twice than of 440C, and a
toughness inbetween 440C and D2.
The makers who are hyping S30V for toughness are the same guys who said the
same thing about ATS-34 and would use it in axes, machetes, swords etc. .
Carl.
news:be1tmp$gmu$1...@coranto.ucs.mun.ca...
> alv...@xx.com wrote:
> The makers who are hyping S30V for toughness are the same guys who said
the
> same thing about ATS-34 and would use it in axes, machetes, swords etc. .
I recall buying my first ATS34 knife (Al Mar of some sort). I commented
that the blade seemed a little thin, and the store owner told me that was OK
because the new steel was "stronger."
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alv...@xx.com
> Based on what I have seen, tests I have read, and the materials data
> collected by Crucible which show it has the same impact toughness as
> 440C, it isn't anything special in that department.
> Consider this thread :
> http://www.bladeforums.com/forums/showthread.php?s=&threadid=262446
[Thanks, I'll check it out with all the others I need to read when
I get a chance ;]
> If you want a stainless cutting steel use S90V which can get to
> 62/63 RC, and has a very high wear resistance, more than twice
> than of 440C, and a toughness inbetween 440C and D2.
> Cliff Stamp
Oh heck, I was hoping for more strength than that from PM products.
I don't want stainlessness just hoping for one that finally measures
up to the ingot/wrought carbon steels is all. :/ When a guy braggs
on his new knife being stainless steel and good both, I was hoping
I could, someday, finally agree with him! :)
Alvin in AZ
alv...@xx.com
> especially the "please remove" parts. I'm pretty sure I had at
> least one, and maybe more cutlery steel charts in front of me at
> the time I wrote that.
98% of my post was just me getting carried away and not written
for the faq really.
Don't believe "cutlery charts" for anything ok? ;)
Lots of mistakes have gotten copied and re-copied along with
ommisions "showing up" too. ;)
>> ...52100(W5)...
>> Alvin
Ooops. :/
52100 is like L1. (not W5)
50100 is like W5.
50100-B is like W7.
That information makes it easy to compare them since there's lots
of information about tool steels out there and since they are in
the information business instead of the knife business the writers
(metallurgists) are easier to trust?
Alvin in AZ
sst...@physics.mun.ca
> I don't want stainlessness just hoping for one that finally measures
> up to the ingot/wrought carbon steels is all.
According to Crucible, CPM-1V has the impact toughness of S7 at a slightly
higher hardness and the wear resistance of A2. CPM-3V has twice the impact
toughness of A2 and the wear resistance of D2.
alv...@xx.com
>> steel] that finally measures up to the ingot/wrought carbon
>> steels is all.
> According to Crucible, CPM-1V has the impact toughness of S7 at a
> slightly higher hardness and the wear resistance of A2. CPM-3V
> has twice the impact toughness of A2 and the wear resistance of
> D2.
> Cliff Stamp
Holy cow! :) S7 is -the- tool steel to beat for toughness/strength.
S7 is used to make jack hammer bits! But it's too soft for a good
edge holding knife blade. So CPM-1V is as strong as S7 and as hard
and wear resistant as A2? Holy cow. ;)
A2 for me, has always been thought of as the high end of alloying
content before certain bad traits start to show up, like grain
coarsening and other strength problems. Looks like that's been
passed up big time.
How "stainless" are CPM-1V and CPM-3V tho?
I need an updated tool steel book that includes the new P/M steels.
Almost all of them listed in my books are HSS versions and only two
that aren't a D2 version and CPM-10V (they use a space and leave
out the hyphen). CPM-10V looks like a P/M version of A7 only with
double the V content. But that's the P/M tool steel section.
MPIF, Metal Powder Industies Federation is what I need to check out.
MPIF's F-0008,
ASTM's B-310, class C,
SAE's 853 class 3,
...is a P/M high carbon low alloy steel .6% to 1.0%C.
There are two other class's a .3%C max that they call "P/M iron".
And a medium carbon steel .3% to .6%C class that MPIF calls F-0005.
All the rest are high copper steels with as high as 25%Cu obviously
for use as sinthered bearing and gear parts.
Do I sound out of date? ;)
Alvin in AZ
sst...@physics.mun.ca
>> According to Crucible, CPM-1V has the impact toughness of S7 at a
>> slightly higher hardness and the wear resistance of A2. CPM-3V
>> has twice the impact toughness of A2 and the wear resistance of
>> D2.
>> Cliff Stamp
>
> Holy cow! :) S7 is -the- tool steel to beat for toughness/strength.
> S7 is used to make jack hammer bits! But it's too soft for a good
> edge holding knife blade. So CPM-1V is as strong as S7 and as hard
> and wear resistant as A2? Holy cow. ;)
Just to correct myself, Jerry Hossom came out awhile ago promoting CPM-1V as
having twice the toughness of S7 at a higher hardness and the wear
resistance of D2. This claim was challenged, and the abilities of the steel
kept being reduced in a scramble to return to sanity. Last I checked it was
as I described in the above.
However I just rechecked the spec's from Crucible on their website and now
CPM-1V has the wear resistance of A2, but 90% the toughness of S7 at the
same hardness - 56 HRC. CPM-3V is still pretty good, at 62 HRC it has the
toughness of A2 at 60 HRC, and has a wear resistance exceeding D2 -
according to Crucible. Ref :
http://www.crucibleservice.com/datash.cfm
> How "stainless" are CPM-1V and CPM-3V tho?
No experience with 1V. 3V doesn't patina as fast as something like L6, 52100
etc., but can't withstand salt water soaks for long. Damage is minimal with
soaking though, it doesn't pit rapidly like the pseudo-stainless steels like
ATS-34.