Much of this information has been provided by Howard Clark of Morgan Valley Forge ; a consummate metallurgist and smith. All of this information is presented "as is".
Carbon Steel: A simple mixture of Iron and carbon. Carbon steels range from very low to very high carbon content. Carbon contents above .50% are classified as high carbon steels. The High-carbon steels are preferred for making knives and swords because they are easily hardenable while maintaining a reasonably high toughness.
Stainless Steels: Steels to which other elements such as chromium or vanadium have been added to reduce the effects of corrosion on the alloy. Many stainless steels are produced with high carbon contents in order to serve as blade steels (most notable among these is the venerable 440C) but the addition of large molecules of chromium, vanadium and other elements make these steels more brittle and susceptible to work hardening. Because of this, they are predominantly used for short blades.
Alloy Steels: In reality, all steels are alloys of iron, carbon and other materials. We generally refer to steels to which specific elements are added for varying purposes as alloy steels. It is possible to find an alloy steel that has almost any characteristics you desire these days.
Railroad Spikes: Railroad spikes used to be made
of simple carbon steels. Most had about .60 carbon. If you look at the butt and it has a "HC" it is a simple carbon steel, If it has a "W" (with/without a "HC" along with it) it is an older water-quenching steel. If it has an "O" (with/without a "HC" along with it) it was manufactured from O-1 oil-quenching steel. If it has a diamond or grid pattern it is a modern spike made of a low carbon, high manganese alloy and doesn't forge worth a darn.
You can also tell an older spike from a modern one by looking at the tip. If it's flat and looks like a cold chisel, it's an older one. If all four sides taper to the center so it resembles a square punch, it's a modern spike.
This information was sent to me a while back by the late Bob Engnath, a great smith who left a great legacy. Some of his vast store of knowledge is being preserved at Engnath.com and is well worth the look
0-1 is perhaps the most forgiving of any knife quality steel other than the very simple
alloy types, and produces a blade of excellent quality for most normal use. It can be heat
treated very easily. Further references? Well, the ole' master, Cooper, used it for many
years and folks do love his blades because they're tough. Awhile back, one of the best of
the blade smiths said that well treated 0-1 would out cut any Damascus, and no one argued
with him. Edge holding is exceptional. 0-1 is precision ground unless you're lucky enough
to stumble across some mill bar. Goof up the heat treat and 0-1 will let you try again as
often as you like, as long as you don't overheat the metal. Tough on grinding belts.
0-6 is the next step up from 0-1 easy heat treat but pure hell to grind. It's significantly
tougher, with finer crystalline structure and hard graphitic particles that resist wear.
Stock is both hot rolled and precision ground. Hot rolled prices are reasonable. Very tough
to grind. Edges are incredible, lasting even longer than the best Damascus and even 0-1.
Has an odd, rather orange spark.
W-1, W-2, and the series of 10-- steels from 1045 through 1095 are the
ultimate in simplicity and very shallow hardening so they may be used to make a selectively
hardened edge as one sees on old Japanese swords. Toughness is outstanding, with these
alloys being used for grader blade edges, truck springs and files. Uses up grinding belts
at quite a rapid rate. Edges are acceptable with 1045, good with 1060, nice with 1084, and
excellent with 1095, W-1 or W-2. Those last two are often referred to as O-F, old file. It
is very easy to get the higher carbon end of this series way too hard to make a good
knife.
5160 is a common spring steel, basically 1060 with one per-cent of chromium added to make
it deep hardening. An
excellent steel for swords, or any other blade that will have to take some battering.
Long blades are best around the mid 50's on the Rockwell scale, while small, working blades
can be put into service at a full 60 RC. Forged blades with a well packed edge seem to cut
forever! Rough on grinding belts. Jokingly called O-C-S, old chevy spring.
52100 is a ball bearing steel, generally not found in useful grinding sizes, but terrific
in edge holding and toughness. 52100 is 5160 with an attitude, more alloy and more carbon
that makes it harder and tougher. Like 5160, throws a brilliant yellow spark.
L-6 is the band or circular saw blade steel used in most lumber mills and downright hard to
find in any other form. Hardens in oil to about RC 57 and takes a fine edge for most
cutting, particularly where the edge might be steeled back into shape. Outstanding where
flexibility is needed but rusts easily, like virtually all of the simple carbon steels.
L-7 is the same stuff with a little more carbon.
A-2 is an exceptional steel, with fine wear-resisting qualities plus excellent resistance
to annealing and warping. Grinding is noticeably harder than 0-1 but not extremely
difficult. Sawing is tougher and relates to the five percent of chrome in this steels
chemical make up. Really nice to finish with the grinder and very little grain appearing
in buffing. Excellent flexibility. Several other of the A series will also make fine
blades.
D-2 offers another air hardening tool steel, but with 12% chrome and excellent, if not
superb, wear resistance. The resistance also holds true in both sawing and grinding, even
while the steel is fully annealed. While using belts up at a faster rate than average,
D-2 is not particularly hard to grind with fresh belts. Using old belts causes enough
heat to work harden the steel. D-2 anneals at somewhat higher temperature than A-2 and
will not take a true, mirror polish. Definitely a steel for the advanced craftsman. It's
major drawback is the orange peel appearance of the surface when finished to a high gloss.
One knife maker is often quoted as saying that D-2 takes a lousy edge and holds it forever.
Often found as surplus wood plainer blades. D-4 and D-7 are also good cutlery alloys, but
darn hard to find in the right sizes. Air hardening steels can work harden while you're
grinding them if you get the stock too hot. This doesn't mean much on the grinder, but when
you try to file a guard notch, the file will just slide.
M-2 is a high temperature steel made for lathe cutting tools, which has darn little to do
with knives, but allows you to really cook the blade in finishing after heat treat without
annealing it. M-2 is perhaps a bit better in edge holding than D-2. It is also rather
brittle and not recommended for large knives.
440C was the first generally accepted knife makers' stainless and remains quite popular,
particularly since the sub-zero process was developed to add toughness. On the grinder,
it's gummy and gets hot fast, but it cuts a lot faster and easier than any of the carbon
steels. Your belts will cut about 2 to 3 times as much 440-C than 0-1. Using hand hacksaws
on it will wear out a lot of blades in a hurry. But with the proper care, good heat treating
and finishing, 440C produces an excellent, serviceable and durable knife, even for the new
knife maker. Anneals at very low temperature. Please note that 440A and 440B are similar
alloys, often confused with 440C, but considered inferior to 440C for knife making use.
Commercial knife companies often mark blades 440 when they're one of the less desirable
versions, giving the real stuff a bad name. 440C is also available in more sizes and in
more places than just about any stainless alloy suitable for knives. It is also essential
to remember that collectors hate to see one of their prizes turn brown in the sheath, and
440C handles corrosion resistance very well. While the variation, 440-V doesn't seem to get
quite as hard, it holds an edge for much longer and is much more difficult to grind.
AUS-6 / AUS-8 / AUS-10 (aka 6A 8A 10A) Japanese stainless steels, roughly comparable
to 440A (AUS-6, .65% carbon) and 440B (AUS-8, .75% carbon) and 440C (AUS-10, 1.1% carbon).
AUS-10 has roughly the same carbon content as 440C but with slightly less chromium, so it
should be a bit less rust resistant but perhaps a bit tougher than 440C. All 3 steels have
some vanadium added (which the 440 series lacks), which will improve wear resistance.
154CM was considered by many to be super-steel, if you can find some of the old production
stock. The new batches are not manufactured to the standards that we've come to expect for
knife steel. While excellent in use, 154CM eats up the finest hacksaw blades in one
across-the-bar cut of 1-1/2". It's machining and grinding qualities are similar to 440C
and won't win it any awards for ease in working. In use though, this alloy has a definite
advantage in both hardness and toughness over 440C. 154 CM is not an accepted standard grade
designation, rather a manufacturers trade name.
ATS-34 Japanese made stainless considered the equal of 154CM. Import restrictions have been
eased somewhat, although they were forced to raise the price by 50%. Cleaner than the 154CM.
(154 CM is no longer used in government specified applications and is not the vacuum melt
product that we once appreciated.) ATS 34 is virtually the exact same alloy as 154 CM,
minus 0.04% of one of the less essential elements. ATS is double vacuum melted and very
clean. It also comes with a hard, black skin that will put a shine on your grinding belt
before you know it. We recommend knocking the skin off with old belts before tapering the
tang or Vee grinding. One fellow tried to take the skin off with an industrial motor driven
wire brush wheel. All he did was polish it.The three (154 CM, ATS 34 and 440-C) all have a
small, reddish spark that has a distinct, but hard to see carbon fork. ATS 34 is also a
trade name. That super hard black skin on some of these steels, as well as forging scale,
can be "pickled" to remove it. Buy a gallon of inexpensive white vinegar, and leave the
steel in it overnight. Works like magic.
AEBL seems to be about 440B. Extremely easy to grind, Heat treat like 440C. Edge holding is
best when heat treating includes a freeze cycle. Very easy to polish and buff. Very nice
choice for miniatures, kitchen knives, etc. AEBL has several quirky habits in grinding that
make it difficult to use on thicker or larger knives. Makes nice kitchen knives.
420 modified stainless, has been successfully used by some commercial knife producers, but
availability is not practical for the hobby knife maker since darn few of us order steel
in mill rolls.
VASCO WEAR is rather expensive but very, very good in edge holding. Resists grinding very
well too! You'll swear your belts have all gone dull when you try it. Do everything you
have to before heat treating, cause you sure aren't going to be able to do much afterward.
Priced like lobster tails, when you can find it. Try Vasco-Pacific in the Los Angeles area.
Vasco - Pacific uses their own series of names for their alloys.
DAMASCUS steel is such a widely made product that it is impossible to make too many general
statements about it, other than it seems to catch collectors better than any other type.
Each smith does his in a slightly different way, ranging from the fellow who toughs it out,
starting with three layers, to the guy who welds a 300 layer sandwich of shim stock into a
billet with one hit in a 40 ton press. They're all pretty. Reese Weiland suggests that the
last etch of a Damascus blade be done with phosphoric acid, which will sort of, parkerize
the metal and help protect it. He said that you have to play around with the concentration
of the acid and immersion times a bit, depending on the steel you're using. This will also
work on most carbon steel blades. If a Damascus blade has been hardened with a softer
section at the spine or guard, you will get a much better looking etch if you use muriatic
acid first, to get the depth you want, and then ferric chloride for adding color.
STELLITE 6-K fits into the same category as Vasco Wear in the wear resistance area, but
doesn't need heat treating since there is no iron in it at all. The trick is exceptionally
hard particles embedded in a rather soft alloy. Very flexible and easy to bend. Virtually
cannot be brought to a mirror finish. Stellite blades are very much in demand by some
collectors. The alloy best suited for knives now must be ordered from Canada and costs
about a hundred bucks a pound. Part of Stellites toughness comes from the rolling process
used to form the bars. Cast Stellite is not nearly as tough.
TITANIUM is only a marginally acceptable metal for a knife blade. It cannot be hardened
much past the mid 40's of the Rockwell C scale, and that's spring, or throwing knife
territory. Aside from that, I'm sure that there will soon be collectable titanium knives
on many custom makers tables, designed to catch collectors, and not for cutting.