This information is supplied by Blades `N' Stuff, a knifemakers' supply outfit in Glendale, CA. We normally offer all of this in our sales catalog. A friend offered to put the useful parts on the net, for all to use without having to send the five dollars that we charge for the catalog.
We aren't here to provide a really neat and exciting web site with a whole bunch of trick stuff. This is pure text information and just about every bit of it is useful to the knifemaker.
Our specialty is working with new knifemakers. We sell pre-ground blades, and this information is specifically aimed at how to finish those blades. Much of it will be useful in other areas, and with your own projects. This is not a complete FAQ on knifemaking. Through the years, we have added bits and pieces of information to the catalog as we found recurring questions from customers. This is also not the last word on any subject mentioned. there are many other methods of doing just about everything mentioned.
If you find the pages interesting, and wish to get our catalog, we are at 1019 E. Palmer Ave, Glendale, CA 91205. Phone 818 956-5110, fax 818 956-5110. No exceptions to the $5.00 price.
We mention the names of a lot of knifemakers in this text. This does not imply endorsement by them. We are merely trying to give credit for a source of information.
STEELS USED BY KNIFE MAKERS
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 wariation, 440-V doesn't seem to get quite as hard, but holds an edge for much longer and is much more difficult to grind.
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. 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 ia 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 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.
Powdered, cast and fused stainless and tool steel alloys, (Alphabet Alloys ) have popped up all over during the past few years, and they are some of the darndest steels ever encountered. The advantage is that elements can just be stirred in to create desirable properties. ( A vastly simplified description.) Virtually all of them are terribly tough to grind, but hold a cutting edge beyond all reasonable expectation. The names of these alloys change weekly, and they're too numerous to list, but they work in a lot of applications that send normal knife steels running for cover. The one possible drawback is unusual brittleness.
Many steel mills hang their own labels on regular alloys. This confuses things no end. Then, cutlery manufactures jump in with trick names for the alloys they use and fuzz it up even worse. A blade marked 440 is hardly ever 440-C, the best of the three 440 alloys. If it was, they would have marked it with the C. Trick names, like Tungsten 6 or Vanadium 3 are usually an effort to capitalize on a trace of desirable alloying element in a generally poor quality steel. If the steel is any good, a knife manufacturer will not hesitate to tell you what the alloy is, using the proper standard name.
Hack sawing any bar stock into knife sized chunks can be a real chore, and will use up a lot of saw blades. Abrasive wheel cutoff saws are now very competitively priced and a labor saving gadget when it comes to chopping steel. Bargain wheels run around $4 for a 14 inch disc. Get the externally re-enforced type. They last about three times as long as the internally re-enforced versions. Keep an old jacket or long sleeved shirt in the shop to shield your arms from the fiberglass that the wheel sheds while it's working. The darn stuff itches like crazy.
If anyone knows of a small rolling mill that would take 500 lb lots of, say, 52100 round rod, and roll it into rectangular bar stock, please let us know. In fact let everybody in knife making know. There are dozens of great alloys out there that distributors refuse to stock in useful sizes, and a custom rolling mill would help all of us.
HARDENING SIMPLE STEELS
All of the really low alloy steels have one feature which make them virtually foolproof when it comes to cooking them for hardening. When one of the low alloy steels reaches the critical temperature where it can be hardened by quenching, it turns non - magnetic. As the steel heats, check it with a magnet. At a certain point, the magnet won't stick. That's usually at a temperature ( color ) far lower than you would think. Once the magnet won't stick to the blade, give it a moment more in the fire and then into the quench it goes. ( An extra 50 degrees over the critical temperature insures better hardening and won't hurt the steel.)
The simple aloys can also be selectively hardened, not with a fancy temper line, but with a softer back that will make the spine and tang less susceptible to breakage. All you have to do is take the blade up to heat very quickly, getting the thin parts along the edge hot before the thicker spine. You could also just dip the cutting edge into the oil, allowing the spine to cool more slowly, not hardening it.
Should you err and get the spine too hot and inadvertently harden it, you can use a torch to partially anneal the critical areas. I recommend that all stick tang blades have a softer section where the tang joins the blade.
When the hot blade hits the oil, you will almost always get some fire. Don't leave the tang half out of the oil. It is near red hot, sticking out of the oil and acting like the wick of a candle to start a fire in the tank. NEVER use a small tank of oil to quench a lot of blades. Sooner or later, you'll find the flash point of the oil. That's where it starts burning all by itself, and you won't like that one little bit.
Forged blades will always have stress than needs to be worked out before hardening. They should be annealed, preferably several times before hardening. Some knife makers have had wonderful results by annealing their blade steel three times before hardening. It reduces grain size significantly, making a much tougher blade.
SERIOUS HEAT TREATING
1040 to 1050 steel Water quench from 1525 to 1550 F. Hardens to approx. RC 58. Very easy to get cracks with water quenching. Draw at 350 F. for spring temper, best for daggers, etc. Shallow hardening and can be done with beautiful, Japanese style temper lines.
1050 to 1095 steel Brine quench from 1475 to 1500 F. hardens to RC 60 to 65. Draw immediately. Oil quench at the same temperatures for slightly lower hardness. Shallow hardening and can be done in the Japanese style with a decorative temper line.
4150, 5150, 6150 steel Oil quench from 1525 to 1600 F.
5160 steel Oil quench from 1525 to 1600 F.
52100 steel Oil quench from 1525 to 1600 F. Harden, cool and let the blade settle for a day (24 hours). Re-harden twice more at the same interval. Cutting edge toughness is fantastic. Draw at about 350 F, three times, and the spine may be torch drawn to spring temper. Ed Fowler gets incredible cutting and flexibility with this method.
O-1, O-2, O-6, O-7 steel Preheat slowly to 1200 F. Oil quench from 1450 to 1500 F. Draw at about 350 F. O-6 reaches RC 65.
W-1, W-2, W-3 steel Preheat slowly to 1050 F. Water (brine) quench from 1400 to 1500 F. Draw immediately. May also be oil hardened if cross sections are radical, or simply for less chance of cracking. Shallow hardening and will work with Japanese temper lines.
L-6, L-7 steel Quench from 1450 to 1550 F in water or brine. Doesn't really need to be drawn. L-7 will give slightly more hardness.
D-2, D-7 steel Preheat at 1500 F. Harden from 1850 to 1875 F. Draw immediately.
A-2 steel Preheat at 1450. Air harden from 1700 to 1800 F. Draw at 350 F.
S-1, S-2, S-5, S-7 steel Preheat at 1200 to 1300 F. Harden from 1650 to 1750 F for S-1, 1550 to 1650 F for S-2, 1600 to 1700 F for S-5 and 1700 to 1750 F for S-7. Draw at 350 to 400 F.
M-2 steel Preheat at 1400. Oil or air quench from 2175 to 2250 F. Draw at 1000 F.
440-C steel Air harden from 1850 to 1950 F. Draw at 325 F. Freezing to dry ice temperature for several hours before the draw will enhance toughness and hardness remarkably. Don't bother with 440-A or 440-B.
154 CM, ATS 34 steel Air harden from 1975 F. Straighten before they cool below 250. Freeze at -220 F for 6 to 8 hours. Double draw at 950 F, two hours each cycle. (Paul Bos method) Gives RC 59 - 60 and marvelous durability.
Damascus Harden to specifications of the highest carbon content component. Damascus may be treated a bit rougher than homogenous alloys. San-mai Damascus sometimes has severe shrinking problems which will pull apart the center layer.
Water hardening is a mis-used term. In virtually all cases where a steel is referred to as water hardening, they're actually talking about quenching in brine, heated to a temperature of 170 degrees, (F) or above. Brine is made by dissolving non-iodized salt in water until a egg will float in it. Jim Hrisoulas uses bluing salts to make his brine. The whole idea is to raise the boiling temperature of the liquid and make it transfer heat better. Brine will eat right through an ordinary steel barrel in a very short time. Jim Ferguson just mixes in borax and detergent to reduce the surface tension.
Drawing is normally done for 30 minutes when one has the equipment to properly maintain the temperature. Flash drawing, that is, heating to show a certain oxide color on the metal surface and then letting it cool, is fine for softening a spine, but not best for the cutting edge.
Any steel which has a low draw temperature may be drawn to a softer temper along the spine to give it better shock resistance. If this is done, the blade will almost always curve a bit towards the softer part of the blade. This works better on shallow hardening steel than on others but can be done on 5160, 52100, A-2, 440-C and others.
Many of the low alloy steels, like 0-1 and 5160, will show a temper line if the blade is selectively hardened, but the line is rather plain, merely a division between hard and soft. A proper, decorative line, needs either the 10 series, or W series of steel. Oil quenching will produce a temper line in those steels, but water quenching is necessary if one desires the more intricate details of the Japanese style line.
SPARKS GIVE A CLUE TO COMPOSITION
The spark from a steel with .15 to.40 of one percent carbon will simply fork.
Steel with at least .45 of one per cent carbon will show a small but distinct secondary burst. This is considered the minimum for hardening into a useful knife.
Carbon over one per cent will give an intense and multiple bursts.
Moderate silicon makes a spark that is short and ends with a sharp white flash.
Nickel sparks have a small, very intense and bright white color.
Molybdenum gives a spark with a distinct, separate head.
Sparks are best judged by looking at the last third of the trail. Alloys with several additives will confuse the heck out of anyone.
OVEN DRAWING COLORS
If you want to do your own heat treating on some of the easier steel types, you will have to first harden the steel all the way, then draw its' hardness back a bit to keep it from being too brittle to use as a knife. You can do this in an ordinary kitchen oven, but most ovens have a crude thermostat that is not much better that taking an educated guess at the temperature. The scientific term is SWAG, scientific wild assed guess.
A note here, to keep peace in the household. Any blade that goes into the kitchen oven for drawing must be wiped clean of quenching oil and then soaked in the sink with plenty of dish washing detergent for awhile, getting the last traces of oil off. Why? Putting an oily blade in the oven and heating it to four hundred degrees creates an absolutely terrible smell that lingers for days. Your wife won't let you forget it for a lot longer than that.
Oxide colors will form on clean steel as it is heated. You've seen them many times, as the steel got hot where you're grinding.
Contrary to some belief, these do not indicate that the steel has had its' carbon burned out. All it means is that the steel got hot, and if hardened, lost some of the hardness. ( Burning carbon out of a blade takes bright yellow heat applied for more than just a minute.)
The colors are a very precise indicator of temperature with simple carbon steel.
400 degrees, pale straw
425 degrees, straw
490 degrees, golden yellow
500 degrees, brown
525 degrees, brown purple
570 degrees, purple
600 degrees, bright blue
650 degrees, pale blue
There is one little catch when using the color with any steel more complex than 0-1. They don't all react to a given temperature with the same color. D-2, for instance, looks a lot different from 0-1 at 450 degrees. It's best to put a scrap piece of 0-1 or 1095 in with the complex stuff when running the draw cycle, and use it as a precise indicator.
RED HEAT TEMPERATURES
Faintest dull red 900F
Dull red 1200F
Cherry red 1400F
Orange red 1500F
Bright salmon orange 1600F
Brilliant orange 1640F
Temperatures should be judged in a dimly lit area. If you are working outside, colors will appear at least one or possible two steps too low, and you will severely overheat the steel. I have become intimately familiar with this problem. One fellow has a open barrel set horizontal beside the forge, providing a shaded spot to stick the blade into for judging steel temperature.
If you want the spine of a carbon steel blade drawn softer than the cutting edge, the process isn't nearly as difficult as you might think. All you need is an inexpensive wallpaper tray, filled with water, and a torch. A propane torch will work, but the oxyacetylene type works a lot better.
You hold the blade above the tray, edge down, and begin heating the spine until you start to see some color. You always start at the heaviest part of the blade. The first color will be a pale yellow.
At this point, try to keep at least half an inch of the cutting edge in the water. This will keep the heat from running down to the parts that have to stay hard. Work the heat only on the very spine, and work slowly towards the tip. Stop well back from the tip. It will heat easily and you want it to stay hard.
If you are using a acetylene torch. the flame must be aimed directly down at the spine of the blade. If you heat from the side, the blade will warp. This is not a problem with the slower heating L P torch. After you melt a tray or two, you'll also want to use a metal tank.
When the length of the spine has a rich blue color, it will be drawn to a high 40 or low 50 Rockwell, which is right where you want it. On stick tang blades, you should cook the junction of tang and blade to at least a good rich brown to prevent any brittle fracture at that point. The end half of a tang doesn't need to be hardened at all.
Some of the more complex alloys with low drawing temperatures, like 440-C and A-2 may also be treated to soften the back with this technique.
Copyright Bob Engnath 1997