Tuesday, August 16, 2005
Knife Steel
by Bob Engnanth
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. (It may still be selectively drawn with a softer back, if desired.) An excellent steel for swords, or any other blade that will have to take some battering. The choice of Jim Hrisoulas who makes some of the finest working swords in the business. 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. Ed Fowler has developed a superior heat treating technique for this steel.
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. Phil Hartsfield get incredible cutting ability out of this steel. 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 lath 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 not worth a damn 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, but holds an edge for much longer and is much more difficult to grind.
154 CM 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, 154 CM 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 154 CM. Import restrictions have been eased somewhat, although they were forced to raise the price by 50%. Cleaner than the 154 CM. (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-34 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. We now stock a belt the is specifically designed to remove this scale. ATS-34 is a trade name. 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. If it doesn't work, or makes the shop smell like a salad, blame Doug Brack, who gave me this hint.
AEBL seems to be about 440B. Extremely easy to grind, in fact, I think I may have set a world record with it a few years back, over a hundred blades from bar stock to 220 grit within eight hours. 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. "Hoss" uses this in his beautiful stainless Damascus and reports that it holds up very well.
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 Stellite's 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.
Copyright ©1997 By Blades 'N' Stuff - ALL RIGHTS RESERVED We expect folks to copy and distribute this information without restriction as long as we're listed as the source.
BENCHMADE
Jump to:Edge Configurations Blade Finishes & Coatings Blade Steels Blade Styles Heat-Treatment
EDGE CONFIGURATIONS - This refers to the cutting edge itself, and we currently offer two primary edge configurations. PLAIN EDGE, which is the traditional straight ground cutting edge. This edge is the most common used in knives due in part to its relative ease of resharpening and overall blade utility. COMBOEDGE™ is the Benchmade term for a blade which is mostly plain edge, but also has a partially serrated edge. This blade enhancement is beneficial to the knife user who has a need for cutting fibrous materials such as rope or webbing on a regular basis. The serration provides a scalpel sharp cutting surface while increasing the cutting edge length in a shorter distance. Benchmade has also created a hook blade in the Rescue Hook models, which is designed to readily cut fibrous materials like a serrated edge, but without the exposed blade edge.
BLADE FINISHES & COATINGS - Blade finishes refers to the surface treatment of the blade, which can be anything from the way in which the steel is processed, to a multitude of blade coatings which are applied to the blade itself. We use a variety of finish methods to "dress" our blades. The two most common terms used to describe Benchmade blade finishes are SATIN, POLISHED, BEAD BLAST, BK1, or BP1.
SATIN FINISH - creates a low-luster sheen to the blade steel surface. Several common forms of satin finish include:
STONEWASH - the blade surface is refined using abrasive tumbling media or "stones" that leave a pronounced random "scratch pattern" on the blade. This finish tends to mask any scratches that may occur with use. Examples- Model 805, 813
SCOTCHBRITE - this finish softly blends the grinding lines on the blade leaving a pleasant "grained" or "brushed" look. Typically the graining pattern goes from spine to edge. Examples- Model 190, 4530
TUMBLED or VIBED- similar to a stonewash finish; this finish leaves the blades bright and smooth with a faint random scratch pattern. Examples- Griptilians, Bali-Songs
BURNISHED - usually applied using non-abrasive media, whether by hand or in vibratory equipment. This finish refines the blade surface without much of a discernable graining or scratch pattern. Examples- Model 770, 941
HAND RUBBED - a finish typically done only by custom knife makers, it is similar to a scotchbrite finish with the main exception being that the graining goes from tang to tip.
POLISHED FINISH - can be defined as any highly-reflective or glossy finish that refines and smoothes the metal surface. This finish aids in corrosion resistance as microscopic peaks and valleys of the blade surface are smoothed out leaving less surface area exposed.
BEAD BLAST FINISH - can be defined as any non-reflective finish applied to the metal surface by bead blasting or sand blasting the blade with any of a variety of media. The intent is to roughen the surface for anti-glare. The trade off is it tends to be more susceptible to corrosion due to the increased surface area exposed. This finish is also commonly referred to as a "military finish".
BK1 BenchKote™ BLADE COATING - Our own proprietary blade coating offering excellent corrosion resistance, which exceeds the ASTM-117 specification for saltwater corrosion resistance. BK1 is a poly-ceramic coating (a blend of polymers and ceramic). It's thinner than the previous blade coating BT2, has equal to or better corrosion resistance (exceeding the ASTM salt spray standard) and unlike BT2 has much better wear resistance due to the ceramic.
BP1 BLADE COATING - BP1 is a physical vapor deposition or 'PVD' process. It offers an extremely hard, thin ceramic surface layer to the blade, and it is applied in a vacuum chamber. Its extreme hardness and excellent adhesion provide wear resistance and lubricity while creating an attractive visual distinction in the process.
BLADE STEELS (Table of Common Steels) When it comes to blade steels, Benchmade not only selects premium grades for their natural qualities, but we also have perfected our own proprietary custom heat treat process which maximizes each steel's edge toughness and cutting performance.
154CM - An American made premium grade stainless steel originally developed for turbine blades in jet engines. The predecessor to ATS-34, which has now seen a strong resurgence in the knife market. Good corrosion resistance with excellent toughness and edge quality.
S30V - An American made and developed premium grade stainless steel created especially for knives. It is a powder made steel with uniform structure and clean steel properties. As a blade it offers excellent corrosion resistance and excellent edge qualities.
D2 - An air-hardened tool steel, which offers good corrosion resistance and excellent mileage in wear resistance. A good choice for hard use environments.
440C - A high-chromium stainless steel with an excellent balance of good hardness and excellent corrosion resistance. 440C takes a nice edge and comes back fairly easy as well. An excellent value priced steel for its performance.
M2 - A very tough, tool grade high-speed steel used primarily as a cutting steel in the industrial area. It offers excellent strength and wear resistance. Due to its make up, it is highly susceptible to corrosion, so we always apply our BT2® coating for corrosion resistance. An excellent choice for hard use environments.
N690 - An Austrian made stainless steel, which is comparable to 440C in performance and value. Keen edge qualities with excellent corrosion resistance.
AUS8 - A high-carbon, low chromium stainless steel, which offers a good balance of toughness, edge sharpness and corrosion resistance. H1- A high-chromium stainless steel, which offers maximum corrosion resistance in both salt water and fresh water-100-percent corrosion resistant. The tradeoff in performance is good edge quality with good edge toughness, so we use it in wet environment rescue or emergency tool applications.
DAMASCUS - A specially forged, layered steel makeup of a variety of steels. It offers excellent toughness and edge quality. For finishing, the surface layers or lines are exposed through an acid etch, which creates a very unique visual effect. Used in special applications due to its inherent high cost and artistic nature.
BLADE STYLES - Tanto- Most tantos seen on the American cutlery market are Americanized formats. Like the Japanese tanto, the Americanized tanto has a high point in-line with the pivot. A flat grind is applied to the point, leaving it very thick and extraordinarily strong. this thick area helps absorb the impact from piercing, as the tanto was originally designed for armor piercing. The front edge meets the bottom edge at an obtuse angle rather than curving to meet it as seen in the Japanese tanto.The only negative aspect of the tanto blade shape is the cutting surface area is sacrificed to gain tip strength.
Drop-Point - A slow convex-curved drop in the point characterizes a drop-point blade. The drop-point format lowers the point for control but adds strength to the tip. Usually coupled with plenty of belly for slicing, this format is often used for hunting knives. It is also a fantastic all-around blade format. This blade shape can be found on a wide array of knives.
Sheepsfoot - This blade shape has no point on the tip, very little to no belly and the spine of the blade curves down to meet the edge. It is used in applications where slicing is the main requirement, and a point is either not needed or would actively get in the way. Emergency rescue blades are usually of this design. The lack of a point prevents the rescuer from inadvertently injuring a victim who is being cut free from something restrictive.
HEAT-TREATMENT - Over the years we have developed a "special recipe" for heat-treating our blade steels. This process maximizes the steels' molecular structure for a custom toughness and Benchmade superior performance. All steels may be created equally, but that is where it stops when it comes to making a Benchmade.
